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Influence of no-till and conventional tillage on insect pests and soil inhabiting predator populations in Florida soybean and corn cropping systems

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Title:
Influence of no-till and conventional tillage on insect pests and soil inhabiting predator populations in Florida soybean and corn cropping systems
Creator:
Lema, Ki-Munseki, 1945-
Publication Date:
Language:
English
Physical Description:
xix, 160 leaves : graphs ; 28 cm.

Subjects

Subjects / Keywords:
Conventional tillage ( jstor )
Corn ( jstor )
Infestation ( jstor )
Larvae ( jstor )
No tillage ( jstor )
Oats ( jstor )
Soybeans ( jstor )
Stubble ( jstor )
Subsoil ( jstor )
Tillage ( jstor )
Agricultural pests -- Florida ( lcsh )
Corn -- Diseases and pests -- Florida ( lcsh )
Cropping systems -- Florida ( lcsh )
Dissertations, Academic -- Entomology and Nematology -- UF
Entomology and Nematology thesis Ph. D
No-tillage -- Florida ( lcsh )
Soybean -- Diseases and pests -- Florida ( lcsh )
City of Gainesville ( local )
Genre:
bibliography ( marcgt )
non-fiction ( marcgt )

Notes

Thesis:
Thesis--University of Florida.
Bibliography:
Bibliography: leaves 148-158.
General Note:
Typescript.
General Note:
Vita.
Statement of Responsibility:
by Ki-Munseki Lema.

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INFLUENCE OF NO-TILL AND CONVENTIONAL TILLAGE
ON INSECT PESTS AND SOIL INHABITING PREDATOR POPULATIONS
IN FLORIDA SOYBEAN AND CORN CROPPING SYSTEMS














By

KI-MUNSEKI LEMA












A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY



UNIVERSITY OF FLORIDA

1980
































To my parents,

sisters, and

brothers














ACKNOWLEDGMENTS


I express my sincere appreciation to Dr. Reece I. Sailer, my major advisor, and to Dr. Donald C. Herzog, cochairman of my supervisory committee, for their guidance, advice and criticism throughout the course of this work. I wish to thank Dr. Raymond N. Gallaher not only for serving on the supervisory committee, but also for his invaluable assistance in the field and for his marked interest for this study.

I acknowledge the advice and assistance of Dr. S. L. Poe as former chairman of the supervisory committee.

I wish to express my gratitude to the Rockefeller

Foundation for its financial support through a fellowship, and to the Universit Nationale du Zaire for making possible the obtainment of this fellowship.

The author wishes to thank Dr. D. H. Habeck and P. M. Choate of the Division of Plant Industry for identification of many insect species. I also thank P. J. d'Almada for his assistance with statistics, and Lavelle Oswalt for her patience in typing this work.

Special gratitude is due to my wife, Lugwadio mi-Konde, for her support and devotion, and for helping the family financially when my fellowship ended before the end of my




iii










program. I also extend my gratitude to my daughter, Lukamba Nsunda, and to my son Kapela, for having gone through the numerous upheavals associated with my studies.













































iv














TABLE OF CONTENTS

Page
ACKNOWLEDGMENTS.................................... iii

LIST OF TABLES..................................... viii

LIST OF FIGURES.................................... xiv

ABSTRACT........................................... xviii

INTRODUCTION ....................................... 1

CHAPTER I, LITERATURE REVIEW ....................... 4
No-Tillage Systems .............................. 4
Advantages and Disadvantages of No Tillage... 4
Disadvantages.............................. 4
Advantages................................ 5
Economics of No-Tillage Systems.............. 7
Pest Problems in No-Tillage Agroecosystems... 9
Weeds in no tillage........................ 9
Crop diseases in no tillage............... 10
Effects of no tillage on insect pests..... 13
Soybean and Corn Insect Pests in Florida ........ 19
Soybean Insects .............................. 19
Three-cornered alfalfa hopper.............. 19
Lesser cornstalk borer .................... 20
Soybean looper ............................ 20
Velvetbean caterpillar .................... 21
Brown and southern green stink bugs ....... 22
Corn Insects ................................. 23
Lesser cornstalk borer .................... 23
Fall armyworm ............................. 24
Corn earworm .............................. 25
Soil-Inhabiting Predators ....................... 26
Carabid Beetles .............................. 26
The Striped Earwig ............................ 28

CHAPTER II, SOYBEAN CROP SYSTEMS ................... 30
Materials and Methods ........................... 30
Cultural Practices.. ......................... 30
Rye stubble experiment...................... 30
Corn stubble experiment .................... 32
Oat stubble experiment.................... 32








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Estimation of Tillage Effects on Insects..... 33
Soil arthropods ........................... 33
Above-ground insects ..................... 34
Results and Discussion .......................... 36
Soil-Pest Insects ............................ 36
Above-Ground Pest Insects.................... 38
Three-cornered alfalfa hopper............. 38
Soybean looper............................ 39
Southern green stink bug.................. 39
Velvetbean caterpillar .................... 42
Soil-Inhabiting Predators .................... 44
Ground spiders............................. 44
Striped earwig ............................ 45
Carabid beetles ........................... 48

CHAPTER III. CORN CROP SYSTEMS...................... 98
Materials and Methods........................... 98
Cultural Practices........................... 98
Vetch stubble experiment................... 98
Wheat stubble experiment.................. 99
Estimation of Insect Damage and Arthropod
Populations.................................. 100
Soil arthropods ........................... 100
Above-ground insects ...................... 101
Results and Discussion .......................... 102
Above-Ground Insects ......................... 102
Vetch stubble experiment................... 102
Wheat stubble experiment .................. 103
Soil Insect Pests ............................ 105
Wireworms.................................. 105
Lesser cornstalk borer in vetch stubble... 106 Lesser cornstalk borer in wheat stubble... 107 Cutworms in vetch and wheat stubble ....... 109
Soil-Inhabiting Predators .................... 111
Ground dwelling spiders ................... 111
Carabid beetles ........................... 113
Striped earwig ............................ 115

GENERAL CONCLUSIONS..... ........................... 137
Soybean Crop Systems............................ 137
Corn Crop Systems............................ ... 137
Arthropod Predators............................. 138
Corn and Soybean Yields......................... 138

APPENDICES

A CHEMICAL NAMES OF HERBICIDES MENTIONED OR
USED IN THE EXPERIMENTS ......................... 140

B PREDATORY ACTIVITY OF LABIDURA ON ANTICARSIA
IMMATURES........................................... 141



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Page
C YIELD OF "DEKALB XL 78 A" CORN FROM GREEN
ACRES........................................... 144

D AVERAGE YIELDS OF "COBB" SOYBEANS ............... 146

LITERATURE CITED................................... 148

BIOGRAPHICAL SKETCH................................ 159



















































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LIST OF TABLES


Table Page

1 Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus (Zeller), in notillage and conventional tillage "Cobb"
soybeans at Williston, Levy Co., Fla., 1978. Numbers are totals and averages of two rows per replication for three
weeks........................................... 51

2 Lesser cornstalk borer infestations in
no-tillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co.,
Fla., 1979. Estimations are based on two different rows observed weekly (for three
weeks) in each replication (four reps/treat.)... 52

3 Average number of the three-cornered alfalfa
hopper, Spissistilus festinus (Say),
collected by the plant shaking method
(1978) and sweep net (1979) from conventional
tillage and no-tillage soybeans at Green
Acres, Alachua Co., Fla. Numbers are
averages of eight weeks with eight shakes per treatment and three weeks with eight
sweeps per treatment ............................ 53

4 Soybean looper populations in no-tillage and conventional tillage "Cobb" soybeans
estimated by the shake cloth method at
Green Acres, Alachua Co., Fla., 1978 and 1979. Numbers are totals and averages of
eight (for 1978) and four (for 1979) weekly
shakes (sites) per treatment for 12 (1978)
and six (1979) weeks............................ 54

5 Effect of tillage on southern green stink bug populations estimated by the shake
cloth method in "Cobb" soybeans at
Williston, Levy Col, Fla., 1978. Numbers
represent totals and averages of eight
weekly shakes per treatment for seven
weeks ........................ ................... 55




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Table Page

6 Number of Nezara viridula (Linn.) collected
by the shake cloth method in no-tillage and conventional tillage "Cobb" soybeans at Green Acres, Alachua, Co., Fla., 1978.
The numbers represent totals and averages of eight weekly shakes per treatment for
nine weeks. The plots (all) were treated
with methomyl (once) and acephate (once)
for insect control .............................. 56

7 Number of Nezara viridula (Linn.) collected
by the plant shaking method in no-tillage
and conventional tillage "Cobb" soybeans at Green Acres, Alachua Co., Fla., 1979.
Numbers are averages of four weekly shakes
per treatment for four weeks. The plots
were sprayed twice with acephate for
insect control.................................. 57

8 Stink bug damage to seeds in no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1978.......... 58

9 Damage to seeds by the stink bug complex
in no-till and conventional till "Cobb"
soybeans at Green Acres, Alachua Co., Fla., 1979. Numbers are averages of
20 plants per treatment ......................... 59

10 Effect of tillage practice on populations of the velvetbean caterpillars, Anticarsia
gemmatilis Hubner, estimated by the plant
shaking method in "Cobb" soybeans at
Williston, Levy Co., Fla., April July,
1978. Numbers are averages of four weekly shakes per treatment for six weeks. Plots
were treated with methomyl (0.56 kg a.i./ha)
on September 27 for the control of velvetbean caterpillars............................... 60

11 Effect of tillage practice on population levels of the velvetbean caterpillar,
Anticarsia gemmatilis Hubner, monitored
by the plant shaking method in "Cobb"
soybeans at Green Acres, Alachua Co., Fla., 1978. Numbers are averages of eight weekly
shakes per treatment for eleven weeks for
small larvae and eight weeks for large
larvae. The plots were treated with methomyl
and acephate (once each) for insect control..... 61






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Table Page

12 Populations of the velvetbean caterpillar,
Anticarsia gemmatilis, estimated by the plant shaking method in no-tillage and conventional tillage "Cobb" soybeans at
Green Acres, Alachua Co., Fla., 1979.
Numbers represent four weekly shakes per
treatment for ten weeks. Soybeans were treated twice with acephate for insect
control......................................... 62

13 Activity of the striped earwig Labidura
riparia (Pallas), in no-tillage and
conventional tillage "Cobb" soybeans estimated by pitfall traps at Williston, Levy
Co., Fla., 1978. Four traps were used
for each treatment for 11 weeks ................. 63

14 Activity of the striped earwig, Labidura
riparia, in no-tillage and conventional
tillage late-planted "Cobb" soybeans
estimated by pitfall traps at the Robinson
farm, Williston, Levy Co., Fla., 1978.
Numbers are averages of three traps per
treatment for ten weeks. Plots were
treated once with methomyl for the control
of velvetbean caterpillars ...................... 64

15 Activity of the striped earwig, Labidura
riparia, in no-tillage and conventional
tillage "Cobb" soybeans estimated by
pitfall traps at Green Acres, Alachua Co.,
Fla., 1978. Numbers are averages of 14
weeks with four traps per treatment. Half
of each plot was treated with carbofuran (F)
at planting, the other half was untreated (C)... 65

16 Number of striped earwig, Labidura riparia,
collected in pitfall traps in no-tillage and conventional tillage "CObb" soybeans at Green Acres, Alachua Co., Fla., 1979.
Numbers are averages of 15 weeks and four traps per treatment. All the plots were
treated twice with acephate for insect
control......................................... 66

17 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Williston, Levy Co., Fla., April July,
1978. Totals of four traps per treatment
for 12 weeks.................................... 67


x







Table Page

18 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Williston, Levy Co., Fla., September November, 1978. Numbers are totals of
three traps per treatment for 10 weeks........... 68

19 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage and conventional tillage soybeans at Green Acres, Alachua Co., Fla., June September,
1978. Totals of four traps per treatment
for 14 weeks.................................... 69

20 Species and numbers of carabid beetles collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Green Acres, Alachua Co., Fla., June September, 1979. Totals of four traps
per treatment for 15 weeks ...................... 70

21 Foliage and ear damage caused by the fall armyworm, Spodoptera frugiperda (J. E.
Smith), and the corn earworm, Heliothis
zea (Boddie), in no-tillage and conventional
tillage corn at Green Acres, Alachua Co., Fla., 1978. Numbers are averages of 120
plants per treatment (each week) for four
weeks for foliage and three weeks for ears...... 118

22 Damage caused by the fall armyworm, Spodoptera frungiperda, and corn earworm,
Heliothis zea, to no-tillage and conventional
tillage field corn at Green Acres, Alachua
Co., Fla., 1979. Numbers are averages of 120 plants per treatment (each week) for five weeks for foliage and four weeks for
ears................ ...... ...................... 119

23 Infestations of the fall armyworm, Spodoptera frugiperda, and corn earworm, Heliothis zea, in no-tillage and conventional tillage field corn at Green Acres, Alachua Co., Fla., 1978.
Average based on 120 plants per treatment
per week............................................. 120
24 Infestations of the fall armyworm, Spodoptera frugiperda, and corn earworm, Heliothis zea, in no-tillage and conventional tillage field
corn at Green Acres, Alachua Co., Fla., 1979.... 121



xi









Table Page

25 Fall armyworm and corn earworm damage to the
conventional and no-tillage corn assessed
at the harvest time at Green Acres, Alachua Co., Fla., 1979. Thirty-two ears collected
per treatment................................. 122

26 Fall armyworm and corn earworm damage to the
conventional and no-tillage corn assessed
at the harvest time at Green Acres, Alachua Co., Fla., 1979. Forty ears were collected
per treatment................................. 123

27 Number of Conoderus amplicollis (Gyll.) and
C. falli Lane (Elateridae) collected in
pitaill traps from conventional tillage and
no-tillage field corn at Green Acres, Alachua
Co., Fla., 1979. Numbers are totals and averages of nine weeks for vetch and six
weeks for wheat with four traps per treatment ......................................... 124

28 Lesser cornstalk borer, [Elasmopalpus
lignosellus (Zeller)], infestations in notillage and conventional tillage field corn
at Green Acres, Alachua Co., Fla., 19781979. Estimation is based on eight rows
per treatment examined each week for three
weeks........................................ 125

29 Infestations of the lesser cornstalk borer
Elasmopalpus lignosellus, in no-tillage and
conventional tillage field corn at Green
Acres, Alachua Co., Fla., 1978................ 126

30 Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus, in no-tillage and
conventional tillage field corn at Green
Acres, Alachua Co., Fla., 1979................ 127

31 Activity of the granulated cutworm, Feltia subterranea (Fab.), monitored by nonbaited
pitfall traps in no-tillage and conventional
tillage corn at Green Acres, Alachua, Co.,
Fla., 1979. Numbers are totals and averages
of four traps per treatment for four weeks... 128

32 Number and species of carabid predators collected in pitfall traps from no-tillage
and conventional tillage field corn at Green
Acres, Alachua Co., Fla., May July, 1978.
Numbers are totals of four traps per treatment ... ..................................... 129


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Table Page

33 Numbers and species of carabid predators
collected in pitfall traps from no-tillage
and conventional tillage field corn at Green Acres, Alachua Co., Fla., April July, 1979. Numbers are totals of four
traps per treatment.......................... 130

34 Numbers and species of carabid predators collected in pitfall traps from no-tillage
and conventional tillage field corn at Green Acres, Alachua Co., Fla., July
August, 1979 ................................. 131







































xiii














LIST OF FIGURES

Figure Page

1 Average numbers of small (up to 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Williston, Levy Co., Fla., 1978.
Averages of eight shakes per treatment........... 71

2 Average numbers of large (over 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Williston, Levy Co., Fla., 1978.
Averages of eight shakes per treatment.......... 72

3 Average number of velvetbean caterpillars, Anticarsia gemmatilis,
collected by the plant shaking method
from no-tillage and conventional
tillage "Cobb" soybeans at Williston,
Levy Co., Fla., 1978. Averages of
eight shakes per treatment...................... 73

4 Average numbers of small (up to 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla.,
1978. Averages of eight shakes per
treatment....................................... 74

5 Average numbers of large (over 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1978.
Averages of eight shakes per treatment........... 75




xiv










Figure Page

6 Average numbers of velvetbean caterpillars, Anticarsia gemmatilis,
collected by the plant shaking method
from no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Average of
eight shakes per treatment ...................... 76

7 Average numbers of small (up to 1.5 cm)
velvetbean caterpillars, Anticarsia gemmatilis, collected by the plant shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Averages of four shakes per treatment ........... 77

8 Average numbers of medium (1.6 2.5 cm)
and large (over 2.5 cm) velvetbean caterpillars, Anticarsia gemmatilis, collected
by the plant shaking method from notillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co., Fla.,
1979. Averages of four shakes per
treatment ....................................... 78

9 Average numbers of velvetbean caterpillars,
Anticarsia gemmatilis, collected by the
plant shaking method from no-tillage
and conventional tillage "Cobb" soybeans at Green Acres, Alachua Co., Fla., 1979.
Average of four shakes per treatment............. 79

10 Average trap-week collections of Labidura riparia nymphs from no-tillage and
conventional tillage "Cobb" soybeans at Williston, Levy Co., Fla., April July, 1978. Four pitfall traps were placed in
each treatment .................................. 80

11 Average trap-week collections of Labidura riparia adults from no-tillage and
conventional tillage "Cobb" soybeans at Williston, Levy Co., Fla., April July, 1978. Four pitfall traps were placed in
each treatment ..................... ............. 81





xv









Figure Page

12 Average trap-week collections of Labidura
riparia (nymphs + adults) from no-tillage
and conventional tillage "Cobb" soybeans
at Williston, Levy, Co., Fla., April
July, 1978. Four pitfall traps were set
in each treatment ............................... 82

13 Average trap-week collections of Labidura
riparia nymphs from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., September
November, 1978. Averages of four traps
per treatment................................... 83

14 Average trap-week collections of Labidura
riparia adults from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., September November, 1978. Averages of four traps
per treatment................................... 84

15 Average trap-week collections of Labidura
riparia nymphs and adults from no-tillage
and conventional tillage "Cobb" soybeans at Williston, Levy Co., Fla., September
November, 1978. Averages of four traps
per treatment................................... 85

16 Weekly activity of Labidura riparia nymphs monitored by pitfall traps in
no-tillage and conventional tillage
"Cobb" soybeans at Green Acres, Alachua
Co., Fla., 1978. Four traps were
placed in each treatment ........................ 87

17 Weekly activity of Labidura riparia adults monitored by pitfall traps
in no-tillage and conventional tillage "Cobb" soybeans at Green Acres, Alachua
Co., Fla., 1978. Four traps were placed
in each treatment ............................... 89

18 Weekly activity of Labidura riDaria (nymphs + adults) monitored by pitfall
traps in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Four traps were
placed in each treatment ........................ 91



xvi










Figure Page

19 Weekly activity of Labidura riparia nymphs
monitored by pitfall traps (four in each treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979 ......................... 93

20 Weekly activity of Labidura riparia adults
monitored by pitfall traps (four in each treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979 ......................... 95

21 Weekly activity of Labidura riparia nymphs
and adults monitored by pitfall traps (four
in each treatment) in no-tillage and conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979 .................. 97

22 Weekly damage to field corn foliage and
ears caused by Spodoptera frugiperda and
Heliothis zea at Green Acres, Alachua Co.,
Fla., 1778.................................... 132

23 Weekly activity of Labidura riparia (nymphs + adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla., 1978....................................... 133

24 Weekly activity of Labidura riparia (nymphs + adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla., 1979....................................... 134

25 Weekly activity of Labidura riparia (nymphs + adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla., 1978...................................... 135

26 Weekly activity of Labidura riparia (nymphs + adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla., 1979...................................... 136








xvii














Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in Partial Fulfillment of the Requirements for the
Degree of Doctor of Philosophy


INFLUENCE OF NO-TILL AND CONVENTIONAL TILLAGE
ON INSECT PESTS AND SOIL INHABITING PREDATOR POPULATIONS
IN FLORIDA SOYBEAN AND CORN CROPPING SYSTEMS

By

Ki-Munseki Lema

March 1980


Chairman: R. I. Sailer
Co-Chairman: D. C. Herzog Major Department: Entomology and Nematology

The effect of no-tillage cropping on insect pests and ground-dwelling arthropod predators was assessed in soybean and corn crop systems in Levy and Alachua Counties, Florida, from April to November 1978 and 1979. No tillage and conventional tillage, with in-row subsoil as a subtreatment for both, were compared in rye (Secale cereale L.), corn (Zea mays L.), oat (Avena sativa L.), wheat (Triticum aestivum L.) and vetch (Vicia villosa Roth) stubble or mulch.

Damage to soybeans [Glycine max (L.) Merrill] and corn was determined weekly by visual observations. The sweep net and plant shaking methods were used to monitor pest populations in soybeans. The activity of ground-dwelling arthropods (pests and predators) was monitored in both corn and soybean systems using pitfall traps.



XVi11ii









In soybeans, above-ground insect pests and the lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), were generally unaffected by the no-tillage farming. No tillage did not significantly affect damage due to Spodoptera frugiperda (J. E. Smith) and Heliothis zea (Boddie) or populations of Conoderus spp. on corn. The results also indicated that no tillage greatly increased populations of the granulate cutworm, Feltia subterranea (Fab.), without affecting cutworm damage to corn seedlings. No tillage, however, significantly reduced lesser cornstalk borer damage in corn.

Populations of ground-dwelling spiders were not affected by the no-tillage practice, and the effect of this practice on the dermapteran Labidura riparia (Pallas) was not consistent. In soybeans no tillage significantly increased the activity of carabid beetles whereas in corn most carabids were collected from conventional tillage treatments.

Yields of soybeans were reduced in the no-tillage systems as compared to the conventional tillage. Corn yields, however, were not affected by the no-tillage practice.















xix













INTRODUCTION


No tillage or zero tillage is defined as the agronomic practice that consists of planting crop seeds in sod or crop residues in a previously unprepared soil (Young, 1970; Triplett and Van Doren, 1977). The soil is not disturbed except for a narrow (5-7 cm wide) slit made by the planter and in which the seeds are planted.

In the conventional tillage procedure a number (up to

ten) of trips across the field are made for soil preparation and weed control. According to Young (1970), any practice that reduces the number of these trips (e.g. plow and plant, chiseling and plant) is a minimum or reduced tillage, an operation distinctly different from the no tillage. Some workers, however, consider the no-tillage practice as a case of minimum tillage, and use the term "conservation tillage" to include both the minimum (reduced) and no tillage. The systems studied in this work are considered as no-tillage systems, and the terms no-till and no tillage are used interchangeably.

No-tillage cropping has numerous advantages over the

conventional tillage practice. Nontilled soils retain moisture longer than tilled fields (Moody et al., 1963; Triplett et al., 1968). Plant residues in no-tillage systems prevent or




1




2




reduce soil loss by water and wind erosion (Triplett et al., 1978). Crop yields obtained from no-tillage systems are reported to be higher than, or at least equal to, those from conventionally tilled fields when no tillage is practiced on well drained soils and weed control is adequate (Rask et al., 1967; Triplett and Van Doren, 1977; Lal, 1979). A great saving in energy and labor also results from no tillage. Rask et al., (1967) estimated that production costs can be reduced by as much as 75% in no-tillage systems due to the elimination of tillage operations.

Farmers are increasingly adopting the no-tillage practice as an alternative to the conventional tillage for crop production (Blevins et al., 1971). It is predicted that over 90% of the U. S. crop acreage will be grown under reduced tillage by the year 2010; at least half of this acreage will be under no-tillage farming (Triplett and Van Doren, 1977).

Fear of pest problems is one of the main objections to the adoption of the no-tillage practice by many growers. It is believed that, since the soil is not disturbed and crop residues are left on the soil surface in no-tillage systems, pest problems will be more severe in these systems than in conventionally tilled fields. Musick (1970a, b) reported that soil insects such as wireworms, seed corn maggots and cutworms cause considerable damage to no-tillage corn (Zea mays L.) in Ohio. Some crop diseases also cause more serious damage to no-tillage crops than to crops planted in conventionally tilled fields (Burns, 1973).




3



Doupnik et al. (1975) and All and Gallaher (1977)

observed that the conditions created in untilled fields were not favorable to all pest species, and that no tillage may have detrimental effects on some pest organisms. The lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), caused less damage in no-tillage than in conventional tillage corn (All and Gallaher, 1977), and stalk rot incidence of grain sorghum,[Sorghum bicolor (L.) Moenck], was higher in conventionally tilled than in nontilled blocks in Nebraska (Doupnik et al., 1975).

Because of the increasing adoption of no tillage as a crop production procedure, detailed studies are needed to better understand the biology and behavior of pest species, and to assess the importance of pest problems in no-tillage systems. Experiments were conducted in Alachua and Levy counties, Florida, in order to discern the influence of no tillage on the most important insect pests of corn and soybean [Glycine max (L.) Merrill] ecosystems. Data were also collected to determine the effects on soil-inhabiting arthropod predators.













CHAPTER I


LITERATURE REVIEW


No-Tillage Systems


Advantages and Disadvantages of No Tillage


Disadvantages. Several disadvantages are associated

with the no-tillage practice. Musick (1970b) reported slower corn seed germination due to lower soil temperatures in untilled fields. Early crop growth is also reported to be depressed temporarily in no-tillage systems (Moody et al., 1963). Late in the growing season, however, crop growth in no tillage is faster than in tilled fields because of high soil moisture associated with plant residues.

Plant density was observed to be generally lower in no-tillage fields than in conventionally tilled fields. This is due in part to the fact that some seeds do not get into the furrow and are eaten by birds and rodents. Growers in Illinois consider rodents to be important pests of crops in no-till culture (Herzog, personal communication, 1980).

Crop yields from no tillage may be lower than those

obtained from conventional tillage when no-tillage systems are established on some types of soils. Griffith et al.




4









(1973) observed that on poorly drained fine-structured soils, no-tillage corn gave lower yields than did the conventional tillage corn.

Musick (1970a, b) reported that conditions created in no-tillage systems (crop residues, high soil moisture and low temperatures) are conducive to pest activity. Pest problems are believed to be the principal disadvantage farmers associate to the no-tillage practice. Several pest organisms overwinter in plant residues, and readily attack the new crop when conditions become favorable. In conventional soil tillage such pests are usually controlled by physical destruction, exposure to unfavorable weather, and natural enemies.


Advantages. Among the numerous advantages of the notillage practice, the more important are those associated with protection of soil from erosion, reduction in energy input required for crop production, as well as increased crop growth and yields due to higher soil moisture. Moody et al. (1963) and Jones et al. (1968) found that soil moisture was higher in the no-tillage than in the conventional tillage corn, and that this higher soil moisture significantly increased corn growth and yields. Mulched corn was 64 cm taller at tasseling and produced 47 kg/ha more grain than conventional tillage corn (Moody et al., 1963). Triplett et al. (1968) also observed a significant





6




increase of plant height as the amount of surface cover increased in nontilled corn fields.

Runoff becomes a very important factor in the no tillage because of large quantities of herbicides used in these systems. Such runoff may increase the amount of soluble chemicals in streams (Holt et al., 1973). According to Unger and Phillips (1973), plant residues on untilled soil reduce evaporation, runoff, and prevent crusting of the soil surface.

The subject of soil erosion by water and wind has been treated by a number of authors including Wischmeier (1973), Woodruff and Siddoway (1973), and Triplett et al. (1978). Soil erosion results in a tremendous loss of topsoils in croplands. No-tillage practice greatly reduces soil erosion because of the mulch that remains on the soil surface. Triplett and Van Doren (1977) in Ohio observed that a 12.70 cm rainfall caused losses of up to 45 tons of soil/ha from conventional tillage corn fields with slopes of 6-8% whereas a 20% slope watershed with no-tillage corn had a loss of less than 112 kg/ha. Reduced and no-tillage systems can decrease erosion potential as much as 50-fold (Triplett et al., 1978).

No-tillage cropping procedure is particularly important for crop production on lands with slopes so steep that conventional tillage would cause unacceptable damage due to erosion. This is especially true in tropical regions where soils are highly erodible and rainfall intensities are high (Curfs, 1976). Curfs (1976) recommended no-tillage and





7




reduced tillage systems as an alternative for shifting cultivation widely practiced in the tropics. The traditional system of shifting cultivation protects the soil from erosion, but, according to Lal (1973), it supports only one person on 15 ha of land and continuous cropping under this system may ruin the soils.

The main advantage of the no tillage is undoubtedly

the tremendous reduction in crop production costs that result from reduced machinery use and associated reduction in fuel consumption. A great saving in time and labor also results from the no-tillage practice. The economics of the no tillage is reviewed in the next section.


Economics of No-Tillage Systems

The economic aspect is the most important factor considered by the farmers in accepting the "new" crop production practice. As discussed by Shipley and Osborn (1973), conservation tillage must produce a net return equal to, or greater than, that obtained with the conventional tillage if the farmer is to switch from the conventional to the conservation tillage.

Rask et al. (1967) obtained a reduction of as much as 75% in production costs and a saving in time of 70-80% in no-tillage corn. Doster (1976) calculated production costs in conventional and conservation tillage systems in Indiana and found that no tillage with coulter disc was the cheapest,




8




and spring plowing the most expensive system for corn production. In one study (Doster, 1976) total costs (machinery, herbicides, and part-time costs) were $62.49, $72.07, and $48.05 in conventional fall plow, conventional spring plow, and no tillage with coulter disc, respectively. The authors also reported that herbicides were the most expensive item in the no-tillage farming.

A tremendous saving in fuel results from reduced machinery use in no tillage. Triplett and Van Doren (1977) pointed out that fuel consumption in untilled corn was reduced by as much as two-thirds of the amount consumed in the conventional tillage.

Reports by various workers (Rask et al., 1967; Jones et al., 1968; Triplett and Van Doren, 1977) showed that yields from no tillage were 10-39% higher than those from the conventional tillage. Higher yields combined with reduced machinery costs and saving in labor results in significantly higher net profits.

Young (1970) reported that net money returns from notillage farming were usually greater than with conventional tillage systems. Doster (1976) evaluated net returns for 243 ha of corn continuously grown in various tillage systems in Indiana. He observed that spring plowing practiced on Tracy silt loam yielded net returns of $76,000 while no tillage with coulter gave a net return of $81,500. On Runnymede loam, however, spring plowing and no-tillage coulter yielded $94,000 and $68,000, respectively for the 243 ha.




9




Pest Problems in No-Tillage Agroecosystems

Weeds in no tillage. An effective chemical weed control is a prerequisite to acceptable crop yields from the no tillage. In a seven-year study, Triplett and Lytle (1972) confirmed weed control to be the dominant factor limiting high crop yields. Griffith et al. (1973) showed that crop yields in no-plow systems may be lower than those from conventionally plowed fields if weed control is not adequate.

Weed control is no longer a serious problem in no-plow

agroecosystems because of the development of effective herbicides. Several herbicides such as atrazine (see Appendix A for chemical names), paraquat, simazine, against grasses, and 2,4-D, etc., against broad-leaf weeds, have achieved satisfactory weed control in the no-tillage cropping procedure (Triplett, 1966; Triplett and Lytle, 1972).

Some problems related to weed control have developed

in no-tillage crop production due to the lack of soil tillage and cultivation. Triplett and Lytle (1972) observed that annual weed populations shifted with different herbicides, when corn was continuously grown on no tillage for seven years. Atrazine and simazine controlled most of the weeds, but the fall panicum (Panicum dichotomiflorum Michx.) became a major annual weed where those two herbicides were used. The authors also found that hemp dogbane (Apocynum cannabinum L.) became a serious problem after several years of continuous corn production under no-tillage farming (Triplett and Lytle, 1972).




10




Wiese and Staniforth (1973) also reported that hemp dogbane spreads rapidly where the soil is not tilled.

Peters (1972) and Triplett and Lytle (1972) found that several perennial weed species were tolerant to herbicides. The common milkweed (Asclepias syriaca L.), horsenettle (Solanum carolinense L.), groundcherry (Physalis sp.), and the tall ironweed (Vernonia altissima Nutt.), are some of those weed species that survive in untilled fields. Lewis (1970) concluded that bermudagrass [Cynodon dactylon (L.) Pers.], johnsongrass [Sorghum halepense (L.) Pers.], and dallisgrass (Paspalum dilatatum Poir) cannot be effectively controlled chemically in no-tillage systems.

Some of the herbicide applied in untilled, mulched

fields may be intercepted by crop residues; this reduces the amount of the chemical that reaches the target species (Triplett, 1976).

Crop diseases in no tillage. The problem of crop

diseases in conservation tillage has been investigated by several workers including Burns (1973), Roane et al. (1974), Yarham (1975), and White and Janney (1978). A large number of plant pathogens inhabit or overwinter in crop residues and the soil. They readily move to the new crop as soon as weather conditions become favorable and susceptible host plants are available (Graham, 1953; Kennedy, 1969; Daft and Leben, 1973).




11



The lack of soil disturbance as well as the presence of decaying plant material left on the ground may increase the incidence of the diseases in no-tillage fields. Boosalis and Doupnik (1976) reported that fungus and bacterial diseases are the principal diseases associated with reduced tillage.

Ledingham et al. (1960) compared root rot incidence in wheat (Triticum aestivum L.) grown in two tillage systems, a surface tillage that left a trash cover on the ground, and a moldboard-plowed stubble soil. The authors found that plowing was effective in reducing disease incidence during the seedling stages, but no significant difference was observed in infection levels as the crop matured.

Burns (1973) reported that the brown spot of corn

caused by Physoderma maydis, a fungus that overwinters in infested corn debris, was more severe in reduced tillage plots than in conventionally tilled plots. Burns (1973) also reported that both the virus that causes wheat streak mosaic and the mites that transmit it overwinter on living wheat and perennial grasses, and that the greatest damage to wheat was observed in fields planted close to wheat stubble.

Several reports have indicated that crop plants on notillage soil are not affected differently from those on conventionally plowed land. In some instances, conservation tillage practices were even reported to reduce disease incidence.

Keyworth (1942) in England demonstrated that soil

cultivation was the major factor for the spreading of the




12




Verticillium wilt within and from one garden to another. McCalla (1967) reported that tillage operations transport various kinds of soil microorganisms from one site to another.

In Oregon, Hall (1959) studied the effects of fertilization dates and plowing methods on the incidence of root rot of Burt wheat caused by Fusarium sp. The author concluded that stubble mulch did not increase the disease incidence as compared to plowed plots. In a similar study in Iowa, Parker and Burrows (1959) reached the same conclusion about the incidence of corn root and stalk rot: disease incidence was lowest in those tillage systems where corn stalk residue was left on the soil surface, and where no or low levels of N were applied.

Brooks and Dawson (1968) drilled winter wheat directly

into rye (Secale cereale L.) stubble to investigate the effects of this cultural practice on take-all (Ophiobolus graminis Sacc.) and eyespot (Cercosporella herpotrichoides Fron.). No differences in infection levels were found between plowed and unplowed plots before the first three months. Three months after planting, however, disease incidence increased greatly in plowed plots. The authors found that plants in untilled plots were infested earlier than those in conventional tillage plots, but that the rate of spread of the fungus was restricted by adverse soil conditions in no-tillage plots.

Doupnik et al. (1975) believed that factors such as increased water conservation, reduced soil temperature




13




fluctuations, and better chemical weed control contributed to the reduction of the stalk rot incidence observed in notillage grain sorghum seeded in wheat stubble in Nebraska.

After studying crop diseases in no-tillage cereals,

Yarham (1975) concluded that "increase in disease levels has not been sufficient to depress seriously the yields of the nonplowed plots. At the moment, it does not appear likely that cultivation-disease interaction will substantially influence the success or failure of nonplow techniques" (p. 247).

Effects of no tillage on insect pests. Soil plowing has been recommended for many years as an effective control measure against several insect pests (Barber and Dicke, 1937; Adkisson et al., 1960; Hardwick, 1965; and Frohlich and Rodewald, 1970). This practice reduces insect pest populations through physical destruction, exposure to natural enemies, and detrimental weather conditions.

Barber and Dicke (1937) compared the emergence of the

corn earworm [(Heliothis zea (Boddie)] moths from hibernation in various soil types and tillage systems in Virginia and Georgia. Fall and spring plowing and fall disking significantly reduced pest emergence as compared to the uncultivated soil. Spring plowing, however, was less effective than fall plowing or fall disking in reducing the corn earworm emergence. The authors also found that soil type affected the effectiveness of cultivation as control measure. Plowing was more effective in sandy loam soil than in red clay soil.




14




In the lower Rio Grande Valley of Texas, Fife and

Graham (1966) obtained a 100% control of both H. zea and the tobacco budworm [Heliothis virescens (Fab.)] after listing, disking and relisting the land in combination with a preplanting irrigation. Listing the land alone reduced the emergence of H. zea moths from pupae by about 55% in a pepper field.

When the larvae of these two species are fully grown, they leave their host plants and burrow into the soil to pupate in pupal cells. According to Fife and Graham (1966), these pupal cells are located at 1.27-15.24 cm below, and their tunnels extend near, the soil surface. Cultivation destroys most of the cells and tunnels in addition to the physical pupal destruction.

Destruction of stalk and other plant parts is also used to regulate insect pest populations (Metcalf, 1909). Several insect pest species remain in crop residues between cropping seasons and attack the new crop as soon as it is available. Adeyemi (1969) showed that stem borers such as Busseola fusca (Fuller), Sesamia calamistis Hamps., etc., can survive in corn stalks from season to season in large enough numbers to initiate borer infestations of the succeeding crop. An average borer population of 27 per 100 stems examined was found in stubble after the first-season corn harvest.

Fenton and Owen (1953), Noble (1955), and Fife et al. (1957) reported burial of cotton (Gossypium spp.) residues




15




through plowing to be an effective method in controlling the pink bollworm, Pectinophora gossypiella (Saund.), in Texas cotton fields. Adkisson et al. (1960) found that burying cotton material during the winter killed 76 to 83% of the pink bollworm larvae, and that an average of 51.6% of the larvae survived the winter in infested cotton left on the ground.

Conditions created in no-tillage systems are reported to be conducive to insect activity (Musick, 1970b). Insect problems in the no-tillage cropping are, therefore, believed to be more severe than in the conventionally tilled fields.

Musick (1970a, b) and Musick and Petty (1974) stated that soil insects constitute the most serious threat to no-tillage corn production. The seed corn maggot, Hylemya platura (Meigen), is active at low temperatures and female flies oviposit in soil where surface trash and decaying plant matter are abundant. This pest is believed likely to cause severe damage to no-tillage crops. Other soil insects such as seed corn beetles, wireworms, cutworms, white grubs, and corn rootworms are also a more serious threat in no tillage than in conventional tillage corn production.

In Ohio in 1969 (Musick, 1970b), soil insects, mostly wireworms and seed corn maggots, reduced the stand by 2025% more in the no-tillage portions of some fields than in the conventionally tilled portions. Other no-till fields





16




had up to more than 90% stand reduction. Musick and Collins (1971) documented that tillage system may influence the oviposition pattern of some insects. Females of the northern corn rootworm, Diabrotica longicornis Say, laid more eggs in no-till corn than in corn planted on conventionally plowed land.

Some above-ground insects are also expected to cause higher damage levels in untilled fields than in crops produced by the conventional tillage system (Gregory and Musick, 1976). The European corn borer (ECB), Ostrinia nubilalis (Hubner), overwinters as mature larvae in corn stalks, and populations of the ECB have been regulated by clean plowing. Damage due to this pest will be more severe in no-tillage corn than in plowed corn (Gregory and Musick, 1976). Musick (1973) and Musick and Suttle (1973) observed that the armyworm [Pseudaletia unipuncta (Haworth)] females preferentially oviposited in grassy areas, and that the incidence of armyworm damage was higher in no-tillage corn, especially when corn was seeded directly in grass or fall-planted wheat.

The blackfaced leafhopper, Graminella nigrifrons (Forbes), transmits two virus diseases to corn, the maize chlorotic dwarf (MCD) and maize dwarf mosaic (MDM). In a study involving no-tillage cropping, carbofuran and hybrid resistance to the diseases, All et al. (1977) found a greater leafhopper population in no till than in the conventional tillage, but no significant difference was observed in yield loss due to MCD infection. Incidence of MDM was generally very low.




17



As stated by Musick (1970a), not all insect pests will

cause serious problems in no-till culture. Some serious pests may become less important while the status of some secondary pests may be changed to that of destructive pests.

In Georgia, All and Gallaher (1977) and All et al. (1979) reported that infestations by the lesser cornstalk borer (LCB) were greatly reduced in no-tillage corn. All and Gallaher (1977) first speculated that higher soil moisture, lower soil temperatures and greater soil compaction near the surface in no-till systems were detrimental to the optimum development and survival of E. lignosellus larvae and, therefore, responsible for the lower infestations observed in these systems.

Cheshire et al. (1977) and Cheshire and All (1978), in a detailed study, however, found that crop residues left on the ground might be the most important factor in reducing the LCB damage in no-tillage corn. Crop residues "may inhibit LCB feeding by disrupting location of host plants by smell or by mechanically shielding the host plant" (Cheshire and All, 1978, p. 12). The facultative saprophagous larvae consequently feed on crop stubble instead of attacking crop plants.

All et al. (1979) also found that a combination of control measures applied against E. lignosellus were more effective in no-till blocks than in the conventional tillage. Early planting, preplanting weed control, and applications of carbofuran resulted in a better LCB control in untilled fields than in those conventionally tilled.




18




Rivers et al. (1977) planted corn into a sod field

infested with white grubs, Phyllophaga anxia (LeConte), to investigate the influence of tillage systems on grub populations. After two years of observations, the authors found that the populations of white grubs were significantly higher in the soil around plants in the conventional tillage than in the no-tillage plots. They believed that this phenomenon was due to the fact that grubs preferred to feed on the grass left between crop rows in the no tillage.

In Indiana, Sloderbeck and Edwards (1979) reported that changes in row width did not significantly affect population levels of the Mexican bean beetle, Epilachna varivestis Mulsant, and redlegged grasshopper, Melanoplus femurrubrum (De Geer), but that tilled soybeans harbored significantly more larval and adult Mexican bean beetles than no-till soybeans. No till in combination with double cropping, however, increased population levels of the redlegged grasshopper as it continuously provided a suitable habitat for the grasshopper.




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Soybean and Corn Insect Pests in Florida


Soybean Insects

Three-cornered alfalfa hopper. The biology and description of adults and nymphs of the three-cornered alfalfa hopper, Spissistilus festinus (Say), may be found in Turnipseed (1973). Damage to soybeans is caused by adults and nymphs that girdle the plants with their feeding punctures. According to Bailey et al. (1970), S. festinus feeds mostly on the lower portion of the stems, but on soybean plants taller than 25.4 cm, the insect prefers to feed on leaf petioles.

Girdled plants are weakened and may break over and lodge during high wind or heavy rains. Plant lodging may cause a stand reduction which may be associated with yield loss. In South Carolina and Oklahoma (Anonymous, 1975), S. festinus has caused economic damage to soybeans. Tugwell and Miner (1967) in Arkansas found that the hoppers girdled up to 55.2% of the plants, but caused no yield loss.

In addition to plant girdling, S. festinus may also indirectly affect soybean plants by transmitting or predisposing the plants to a fungal disease. The wounds made by the hoppers through feeding punctures provide entry for Sclerotium rolfsii Saccardo, the causal agent of sclerotial blight (Herzog et al., 1975).




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Lesser cornstalk borer. Several researchers including Luginbill and Ainslie (1917), King et al. (1961), Walton et al. (1964), Dupree (1965), and Leuck (1966) have made a complete study that included the biology and description of life stages of the lesser cornstalk borer.

The larvae of E. lignosellus feed on a variety of host plants, mostly grasses and legumes (Luginbill and Ainslie, 1917; Dempsey and Branthey, 1953; and Jordan, 1965). They damage soybeans by tunneling into young plants and girdling the stem of older ones. Small plants so injured wilt and usually die; damaged older plants may be broken off by high winds.

Wisely and Miner (1944) reported that in northwestern Arkansas, lesser cornstalk borer infestations were so high that more than 50% of the stand was lost in the fall beans. In one field, 80% of the bean plants were killed 10 days after the plants emerged.

Genung and Green (1965) reported that E. lignosellus infestations on Florida soybeans were light and confined to young plants, but that all the plants attacked died. Severe infestations occur most frequently in sandy soils and are usually associated with late planting or drought stress (Leuck, 1966; Turnipseed, 1973).

Soybean looper. The soybean looper [Pseudoplusia includens (Walker)] females preferentially oviposit on




21




vegetables and legumes (Deitz et al., 1976). Mitchell (1967) studied the life cycle of P. includens on soybeans.

Hensley et al. (1964) and Canerday and Arant (1966) reported that soybeans, peanuts, and sweet potatoes were the most preferred hosts for P. includens. On soybeans the loopers may inflict severe foliage damage and occasionally they cause damage to pods in the Gulf states (Deitz et al., 1976).

Velvetbean caterpillar. Watson (1916), Douglas (1930, and Greene et al., (1973) are some of many researchers who studied the life history and described the stages as well as feeding and mating behavior of Anticarsia gemmatilis Hubner. The eggs are laid on all portions of the soybean plants (Strayer, 1973), and require three days to hatch in August and September, and at least seven days in November, in Florida (Watson, 1916).

Watson (1916) and Douglas (1930) reported that the velvetbean caterpillars were preyed upon and parasitized by many species of birds and insects, but that the fungus Nomurea rileyi (Farlow) was the most important natural enemy that regulates populations of this pest.

The nature of damage caused by A. gemmatilis immatures to soybeans has been described by Watson (1916), Douglas (1930) and Hinds and Osterberger (1931). The first three instars cause less damage as they only remove the lower epidermis and mesophyll of the leaves. The last three instars,




22




however, will consume the whole leaf leaving only the midrib and large veins. When the infestations are high, the larvae eat up all the leaves and attack the tender portions of the stems, buds and small bean pods.

The velvetbean caterpillar is the most important defoliator of soybeans in north and central Florida where populations reach the peaks in late July, mid-August and early September (Strayer, 1973). Outbreak infestations during pod set and pod fill usually cause severe yield losses.

Brown and southern green stink bugs. Woodside (1946), DeCoursey and Esselbough (1962), and Mitchell and Mau (1969) described the stages and studied the biology of the brown stink bug, Euschistus servus (Say), and the southern green stink bug, Nezara viridula (L.).

Adult E. servus are grayish-yellow and measure 12.015.0 mm long. The eggs measure 1.2-1.3 mm in height, and hatch after 3-14 days in laboratory conditions (Rolston and Kendrick, 1961). The N.Tiridula eggs hatched after an average of 5.2 days in the laboratory. Both species pass through five nymphal instars, and have at least two generations per year. Hill (1975) reported three generations of N. viridula during nine months in Egypt; there are probably three or more in Florida (Sailer, personal communication, 1980).

The nature of stink bug damage to soybeans has been studied by many workers (Miner, 1961 and 1966; Daugherty et al., 1964; and Turner, 1967). Damage is caused when




23




nymphs and adults insert their mouthparts through the pods and into the beans to feed on the developing seed. Such seeds tend to shrivel and pods may abort when young pods are injured. Along with histolytic substances injected into the beans to liquefy cell contents, the bugs inject a yeastspot disease fungus, Nematospora coryli Peglion which further lowers the quality of the beans.

In Arkansas, Miner (1961) observed that damage by N. viridula lowered the oil content and slightly increased protein content of the seeds. Blickenstaff and Huggans (1962) reported a decrease in the yield of soybean seeds and an increase in the percentage of small seeds due to stink bug damage.


Corn Insects

Lesser cornstalk borer. Some information pertaining

to E. lignosellus has already been mentioned in the section of soybean insects. The feeding behavior of this insect on corn is the same as when it feeds on soybeans or other host plants.

According to Luginbill and Ainslie (1917), the lesser cornstalk borer attacks corn plants at, or just below the ground level. The larvae bore or tunnel into the stem of seedling plants and feed on roots or above the soil surface. Young plants so injured die quickly. Some infested plants may survive, but become distorted, curled and one sided.




24




On older corn, the larvae girdle the stems, although they may also tunnel into the stems. Metcalf et al. (1962) reported that when corn under 45 or 50 cm is damaged it fails to produce ears or good stalks.

Fall armyworm. The fall armyworm, Spodoptera frugiperda (J. E. Smith), is an important agricultural pest; the larvae feed on, and cause yield losses to, a variety of field, forage and vegetable crops (Luginbill, 1928).

Luginbill (1928) reported a very detailed study that included the biology and description of life stages of this pest. On corn, female S. frugiperda deposit the egg masses on the underside of the leaves. Oviposition occurs at night, and the incubation period lasts from two to ten days. The larvae mature, on the average, 10.9 to 13.4 days after they hatch. Pupation takes place in the soil in loose cocoons; adult moths emerge after 7-37 days. In Florida, moths emerged from buried pupae after 14-35 days (Wood, 1977).

The larvae of S. frugiperda are almost omnivorous,

but do show a marked preference for Gramineae (Luginbill, 1928). The first instars skeletonize the leaves and make holes while the fourth to sixth instars usually completely destroy small plants and strip larger ones.

Morrill and Green (1973) found that young larvae fed on the upper portions of corn plants whereas larger larvae




25




were found in whorls and furls. Fall armyworms also attack corn ears by burrowing into them either from the tip or from the side.

Corn earworm. The eggs of the corn earworm, Heliothis

zea (Boddie), hatch from two to eight days after oviposition, and the larval period lasts 13-28 days (Phillips and Barber, 1931). Mature larvae leave the host plants and drop to the ground to pupate under the soil surface in pupal cells. Pupation takes about 14 days.

Corn earworm has been characterized as the "worst pest of corn" in the U. S. (Metcalf et al., 1962). In a fiveyear study in Florida, Janes (1973) found that H. zea was the most important insect pest on the ears of sweet corn.

Although corn earworms may seriously damage the foliage of early planted corn, they cause more severe damage when they feed on ears where they may destroy most of the kernels (Phillips and Barber, 1931). Phillips and Barber (1931) observed that the larvae will leave all other parts of corn plants to attack silks and ears when these plant parts appear.

In the U. S., up to 70-98% of the ears of field

corn may be infested during outbreak infestations, and as much as 5 to 7% of the kernels of field corn and 10-15% of canning corn may be destroyed by the larvae (Metcalf et al., 1962).




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Soil-Inhabiting Predators


Carabid Beetles


Several species of carabid beetles constitute a

group of predators that play an important role in regulating pest populations in various agroecosystems. Members of the genera Calosoma, Pasimachus, Progaleritina, etc., have been reported as predators of arthropod pests, especially Lepidoptera larvae (Stone, 1941; Whitcomb and Bell, 1964; van den Bosch and Hagan, 1966; and Neal, 1974).

Calosoma sayi Dejean is one of the most commonly encountered carabid predators in Florida soybean fields. Watson (1916), Nickels (1926), Douglas (1930), and Hasse (1971) observed this carabid preying on larvae and pupae of A. gemmnatilis. Price and Shepard (1978) observed a build-up of adult C. sayi as a response to outbreaks of noctuid larvae in soybean fields in South Carolina. They also found a significant correlation between weekly populations of noctuid larvae and numbers of C. sayi from midAugust to soybean defoliation.

In Florida, Neal (1974) observed C. sayi on soybean

plants during daytime, but no predatory activity was observed. He reported that the carabid shows predatory activity only at night. Whitcomb and Bell (1964), however, mentioned that the predator fed on larvae of Alabama argillacea (Hubner) during daytime.




27



Neal (1974) recorded three species of Pasimachus in north Florida soybean fields. Only one species, P. sublaevis Beauvois, was common; the other two, P. subsulcatus Say and P. strenuus LeConte, were collected once and twice, respectively. Blatchley (1910) reported that Pasimachus spp. feed on a variety of larvae. In soybean fields Neal (1974) observed P. sublaevis preying upon various insects including larvae of C. sayi, velvetbean caterpillars, and crickets.

Three species of the genus Harpalus were collected in pitfall traps in Quincy, Florida (Neal, 1974). The H. caliginosus (Fabr.) was the least common, H. gravis LeConte was active from August to mid-September, and H. pennsylvanicus De Geer was active from mid-August to the middle of October. Harpalus pennsylvanicus was found feeding on larvae and pupae of A. gemmatilis and Gryllus spp. nymphs. Plant matter was also found in the gut content (Neal, 1974).

Progaleritina spp. are reported to feed only on arthropods; no plant material was found in their gut (Neal, 1974). Adults were observed feeding upon various noctuid larvae, Mexican bean beetle larvae, and cricket nymphs. Progaleritina lecontei Dejean is the most common of the three species (P. janus, P. bicolor) found in north and central Florida. Adults are active in soybean fields from mid-August through the middle of September (Neal, 1974).




28





Thiele (1977) made a detailed study of carabid beetles in relation to their habitats including the effects of cultural practices on carabid populations. Kabacic-Wasylik (1970, cited by Thiele, 1977) found that during rotation from one crop to another, the spectrum of dominance of carabids undergoes a corresponding shift.


The Striped Earwig

The striped earwig, Labidura riparia (Pallas), is an important soil-inhabiting predator and its biology and predatory behavior have been studied by several researchers (Schlinger et al., 1959; Afify and Farghaly, 1970; Caussanel, 1970, Tawfik et al., 1972; and Ammar and Farrag, 1974).

Adult L. riparia mate on the soil surface or in shallow tunnels, but the eggs are laid in deeper (average depth 5.8 cm) tunnels (Ammar and Farrag, 1974), which have no passage to the soil surface (Caussanel, 1970). The eggs hatch after an average of 9.9 days at 22-250 C. The females brood over the eggs, and bring food to newly hatched nymphs. The insect passes through six nymphal instars.

Tawfik et al. (1972) observed L. riparia climbing corn plants in search of prey. They also reported that this earwig fed on a variety of prey including such important pests as Spodoptera littoralis Boisd., Pieris rapae L., Vanessa cardui L., etc. A fifth- or sixth-instar nymph L. riparia may consume up to 4-7 young larvae or 2-4 large




29




larvae of S. littoralis per day. Dean and Schuster (1958) and Clements (1968) reported that the striped earwig preyed on armyworms, mites, scale insects, and aphids. In a laboratory study, Schlinger et al. (1959) found that L. riparia fed on various insects including Lepidoptera of all stages, elaterid larvae, aphids, and carabid larvae. Labidura riparia was also observed feeding on A. gemmatilis larvae, pupae and adults, L. riparia nymphs, small Calosoma larvae, Gryllus nymphs, wolf spiders, and adult Heliothis spp. (Neal, 1974).

Hassanein et al. (1968) and Afify and Farghaly (1970) compared the predatory effectiveness of L. riparia and that of Coccinella undecimpunctata Reiche on the cottonworm, Prodenia litura Fabr. and S. littoralis. They found that L. riparia was more efficient than Coccinella as an egg and larval predator.

Price and Shepard (1977) investigated the patterns

of colonization of soybean fields as well as the response to insecticides by L. riparia. The authors observed lower numbers in newly established fields than in older ones. Soybeans treated with methyl-parathion and methomyl early in the season had higher earwig populations than untreated fields. Reduction in numbers of ants and other insects that prey on earwigs, after insecticidal applications, was believed to be the reason for these lower populations.













CHAPTER II


SOYBEAN CROP SYSTEMS


Materials and Methods


Cultural Practices


Rye stubble experiment. Experiments were conducted simultaneously on the Robinson farm located in Williston, Levy county, about 33 km west of Gainesville, and at the Green Acres, a University of Florida agronomy farm located in Alachua county. These two locations will be referred to as Williston and Green Acres.

In Williston the observations were made in a large block measuring 73.17 m x 85.37 m previously planted to rye which was used either as hay (stubble) or mulch. The block was divided into four 12.20 m x 73.17 m main plots separated from each other by a 12.20 m wide alley. Each main plot was further divided into six 12.20 m x 12.20 m small plots making a total of 24 small plots for the whole block. Six tillage treatments were arranged in a randomized complete block design with each treatment being replicated four times. The six treatments whose effects were tested on insect populations were:





30




31




1. no tillage into rye stubble: "Cobb" soybeans

were seeded directly (without any previous

soil preparation) into the stubble of

"Wrens Abruzzi" rye.

2. no tillage plus in-row subsoil into rye

stubble: This treatment was the same as the first one except for the additional subsoiling made in the rows during the

planting operation.

3. no tillage into rye mulch;

4. no tillage plus in-row subsoil into rye

mulch.

5. conventional tillage into rye stubble:

The soil in the conventional tillage plots

was prepared according to the normal tillage

practice (moldboard plowing and disking)

before soybeans were planted.

6. conventional tillage plus in-row subsoil

into rye stubble.

"Cobb" soybeans were planted in all the plots on

March 21, 1978, in 76.2 cm rows with a 2-row Brown-Harden Super-seeder mounted on a 4600 Ford tractor. Seedling rate was about 112 kg/ha. The plots were fertilized with 672 kg/ha of 5-4.4-12.5 N-P-K applied at planting along with

0.42 kg a.i./ha of paraquat (see Appendix A for chemical names of all herbicides) plus Ortho X-77 (surfactant)at the label dose, 2.24 kg a.i./ha of alachlor and 0.28 kg a.i./ha




32



paraquat (with X-77) was made on April 10, 1978. No insecticide was used in this experiment.

Corn stubble experiment. A second crop of soybeans

was grown at Williston from August to November, 1978. The plots were close to, and of the same size as, those in the first season and were previously planted to corn (following rye) without any soil preparation except in the conventional tillage plots. The same six tillage treatments as above were evaluated in corn residues. The agronomic practices were the same as in the first experiment except that the plots were sprayed with methomyl at the rate of 0.56 kg a.i./ ha on September 27, 1978, for the control of the velevebean caterpillars.

Oat stubble experiment. The Green Acres experiment

was conducted from June to the middle of October, 1978, in a block that was previously planted to "FLorida 501" oats (Avena sativa L.). The following four tillage treatments were studied in this experiment:

1. no tillage into oat stubble

2.- no tillage plus in-row subsoil into oat

stubble

3. conventional tillage into oat stubble

4. conventional tillage plus in-row subsoil

into oat stubble.

Conventional tillage plots were prepared on June 2, 1978, with a moldboard plow and were disked twice. The




33



same cultivar of soybeans was planted in all the plots on June 3, 1978. The entire field was fertilized with 448 kg/ha of 5-4.4-12.5 N-P-K applied at planting. Metribuzin (0.28 kg a.i./ha), linuron (1.12 kg a.i./ha), and paraquat (0.42 kg a.i./ha) were also applied during the planting operation for weed control. No-tillage plots were also treated (directed sprays) with paraquat (0.28 kg a.i./ha) plus X-77 (surfactant) on June 29 and July 19, 1978. Each tillage treatment was divided into two portions; one half of the plot was treated with carbofuran at the rate of 1.12 kg a.i./ha to control soil insects. The other half was untreated and was used as a control. When populations of velvetbean caterpillars and stink bugs became high, all the plots were sprayed with methomyl (0.56 kg a.i./ha) on August 17 and September 7, and with acephate (0.84 kg a.i./ha) on September 13, 1978.

This experiment was repeated on the same block in 1979. "Cobb" soybeans were planted on June 12, 1979, according to the same cultural procedure as in the 1978 season except that carbofuran (or any other insecticide) was not used at planting. The plots were sprayed with acephate on August 30, 1979, to control the velvetbean caterpillars and on October 5, for stink bug control. Estimation of Tillage Effects on Insects

Soil arthropods. Damage caused by the lesser cornstalk borer was assessed by visual observations. Two different rows were randomly selected in each replication every week,




34



and all the plants in the row were carefully examined. Stunted, infested plants were pulled, counted and the number recorded. Infestation levels were calculated as the number of infested plants per row.

Populations of cutworms and soil-inhabiting predators (earwigs, spiders and carabid beetles) were monitored by means of pitfall traps. The traps consisted of cottage cheese cups about one-third filled with ethylene glycol that killed and preserved the catches. In order to prevent rains from filling the traps and to avoid disturbance of the traps by small animals, a piece of wood (20 cm x 20 cm x 0.5 cm) was positioned about 4 cm above each trap. One trap was placed in the middle of each replication and positioned within the row in order to prevent destruction by machines during farming operations. The traps were set in the plots from two days to two weeks after soybeans were planted. The insects were collected every week and brought into the laboratory where they were sorted by species and the numbers of each species recorded.

Above-ground insects. Soybean looper, velvetbean

caterpillar and stink bug populations were estimated by the plant shaking method. In 1978 two sample sites were randomly selected in each replication, but only one site was used in the 1979 crop season. After selecting the site the shake cloth was unrolled on the ground between two plant rows, and the plants over the cloth were shaken vigorously enough




35




to dislodge the insects which then fell onto the cloth. The insects were counted and numbers recorded by species. The shake cloth method was also used in the 1978 experiments to estimate population levels of the three-cornered alfalfa hoppers. Because adult hoppers fly quickly when disturbed, this method was abandoned in 1979. The sweep net method, as described by Boyer (1967) (method 1) was used instead.

Stink bug damage to seeds was determined (at Green Acres only) at the end of the season when the beans were dry and ready to be harvested. Three soybean plants were randomly chosen in each replication while walking diagonally across the plot. A total of 12 plants were observed for each treatment. All the pods were collected from each plant and placed into a paper bag. The bags containing the pods were brought into the laboratory and the seeds were examined for stink bug damage. The total number of seeds as well as number with at least one feeding puncture were recorded. The number of small, wrinkled seeds was also recorded. The number of plants selected per replication was increased to five in the 1979 experiment. This increase resulted in 20 plants observed per treatment.

All the data were transformed (log. transformation for numbers and arcsin transformation for percentages) before they were submitted to the statistical analysis.

An effort was made to relate fluctuations of pest

and predator populations to the phenology of the plants.





36




Developmental stages of the soybeans were recorded weekly according to the method described by Fehr and Caviness (1977).

Results and Discussion


Soil-Pest Insects

Lesser cornstalk borer infestations were not assessed

in the rye stubble experiment at Williston. Table 1 contains the results obtained from the corn stubble experiment. Although the weekly average number of infested plants per row was 2.04 in the conventional tillage and 1.92 in the no-tillage treatment, the analysis of variance was not significant. The results also indicated that in-row subsoiling did not affect E. lignosellus infestations, and that corn stubble was not statistically different from corn mulch with respect to lesser cornstalk borer infestations.

In 1978 some plants were killed by paraquat in the notillage plots at Green Acres (oat stubble experiment); this made observations difficult. Lesser cornstalk borer damage was, therefore, estimated only in the 1979 season. The results from the 1979 oat stubble experiment are shown in Table 2. Damage levels were significantly (P=0.01) higher in the no-tillage soybeans than in the conventional tillage soybeans. The weekly average number of damaged plants per




37




row was 4.29 and 1.42, respectively for the no tillage and conventional tillage. In-row subsoil had a significant impact on the borer infestations. The average number of infested plants was significantly lower in the no tillage plus subsoil than in the no tillage without subsoil. Infestations were also lower in the conventional tillage with subsoil than in the conventional tillage without subsoil (Table 2).

Damage to soybean seedlings was very low during the

two seasons at both Williston and Green Acres. The method used here to determine borer infestations, although commonly used, certainly underestimated infestation levels because only wilted and dead plants were detected and counted. Older seedlings do not wilt when infested. Collecting randomly a certain number of plants, wilted or not, throughout the field and examining roots and lower portions of the stems for borer infestation might have resulted in a better estimation of the damage.

In one experiment, the results showed that no-tillage

systems were not conducive to the buildup of lesser cornstalk borer infestations as compared to the conventional tillage. Results from another experiment, however, showed that E. lignosellus can be a more serious threat to no-till soybeans than to the conventionally tilled soybeans. The lesser cornstalk borers may remain in weeds or crop debris from which they migrate to attack crop seedlings (All and Gallaher, 1977). Crop residues and the lack of soil disturbance in





38



no-tillage systems would seem to explain why infestations were higher than those observed in the conventional tillage at Green Acres. However, crop debris left on the ground have been reported to reduce E. lignosellus infestations in no-tillage corn (All et al., 1979).


Above-Ground Pest Insects

Three-cornered alfalfa hopper. Hopper populations were monitored during 1978 and 1979 only at Green Acres. The plant shaking method was used in 1978, but was abandoned in 1979. The number of SDissistilus festinus (Say) collected was very low and most were nymphs thus confirming Boyer's (1967) earlier conclusion regarding inadequacy of the method. Therefore, during the 1979 season the sweep net was used, and numbers of S. festinus collected were relatively high. The average numbers of hoppers recorded from each tillage system are shown in Table 3 for both the 1978 and 1979 crop seasons.

The data indicated the hopper populations were statistically the same in all tillage treatments in 1978. Although the average number of hoppers was about three times higher in the no-tillage soybeans than in the conventional tillage plots in 1979, analysis of the data did not show any significant differences between treatment means. Spissistilus festinus did not manifest any preference for no-tillage soybeans as compared to the conventional tillage.




39




Soybean looper. Early-planted (April-July, 1978) soybeans in the Williston rye stubble experiment were not infested by the soybean looper, P. includens, and only trace numbers of loopers were recorded in the corn stalk experiment (late planted, August) at Williston. Numbers of loopers recorded in both 1978 and 1979 seasons at Green Acres are shown in Table 4. Looper populations were relatively low during the two seasons, but were higher in 1978 than in 1979. An average of 1.04 and 1.34 loopers per shake was recorded respectively from the no tillage and conventional tillage in 1978. In 1979, only 0.67 and 0.33 loopers per shake were collected from both treatments, respectively.

Such low looper populations were not believed to have caused significant damage to soybeans. No significant differences were detected between treatments for P. includens populations estimated by the plant shaking method. The notillage farming did not effect oviposition by Pseudoplusia moths (which may be attracted by plant residues) or the development of the larvae.

Southern green stink bug. The southern green stink bug, Nezara virdula (L.), was the most abundant of all species of stink bugs observed during the two years. The brown stink bug, Euschistus servus (Say), was the next abundant, but in trace numbers. Average numbers of N. viridula collected by the plant shaking method from Williston and Green Acres soybeans are shown in Tables 5, 6, and 7.





40



Results obtained from the first season at Williston (rye stubble experiment) showed that populations of the southern green stink bug were significantly (P=0.05) lower in the conventional tillage treatment than in any of the no-tillage treatments (Table 5). An average of 1.32 stink bugs per shake was collected weekly from the no-tillage soybeans, but only 0.96 stink bugs were collected from the conventional tillage. No significant differences were found between the two no-tillage treatments or between the conventional tillage and the conventional tillage plus in-row subsoil. Stink bug populations were very low in the corn stubble experiment at Williston.

Although N. viridula average population levels in the 1978 Green Acres experiment were 3.28 stink bugs per shake in the no tillage into oat stubble and 2.61 stink bugs per shake in the two conventional tillage treatments, analysis of variance was not significant (Table 6). In the 1979 experiment, population levels were generally high, but analysis of the data failed to show any significant differences among treatment means (Table 7). The weekly average for adult population was 4.94 and 4.88 stink bugs per shake, respectively, in conventional tillage and no-tillage soybeans. Stink bug damage to seed was assessed at the harvest time during the two years, and the results obtained are in Tables

8 and 9. In 1978, damage appeared to be lower in the no tillage with in-row subsoil than in all other treatments, but analysis





41



of data did not detect any significant differences among treatments. Analysis of data also revealed no significant differences between treatments in number of seed damaged. Although the percent of small, wrinkled and fungus-infected seeds was 38.92 in the no tillage into oat stubble and 19.28 in the conventional tillage, analysis of variance of the data was not significant (Table 9).

In 1978, stink bug populations at Green Acres reached the economic threshold recommended for Florida soybeans (Strayer and Greene, 1974). Peak levels (2.4 adults per shake average of all the treatments) occurred during the week of September 21 when soybeans were in R5-R6 stages (beginning and full seed stages; Fehr and Caviness, 1977). This peak followed three applications of methomyl, the last two being made on September 7 and 13, 1978. Methomyl did not apparently affect stink bug populations. In 1979, adult population was about four times higher than the recommended economic threshold.

Except the Williston first experiment in which populations of the southern green stink bug were significantly lower in the conventional tillage than in no-tillage treatments, the tillage systems studied in all other experiments did not show any significant effect on either stink bug populations or stink bug damage to soybeans. No-tillage systems in these experiments apparently did not provide a more favorable environment than that found in the conventional




42




tillage, in order to attract and harbor higher populations than those that would colonize conventionally tilled soybeans. Stink bugs are known to fly across the field from the area of the initial infestations in search of pods (Miner, 1966). Such movements are likely to reduce any effect that the notillage systems may have. On the basis of the data presented in Tables 5-9, it is believed that, when wild hosts are effectively eliminated from the no-tillage systems through good weed control, stink bug infestations are not likely to be more serious in these systems than in the conventionally tilled fields.

Velvetbean caterpillar. The early-planted (April-July,

1978) soybeans in the first Williston experiment (rye stubble) were not infested by velvetbean caterpillars. In the second season experiment, however, populations of A. gemmatilis reached such high levels that an application of methomyl was made on September 27. A weekly average of up to three large (over 2.5 cm) larvae per shake was recorded. Average numbers of caterpillars collected by the shake cloth method are contained in Table 10. The analysis of the data showed that no-tillage systems did not significantly affect population levels of either the small (up to 2.5 cm) or large larvae as compared to the conventional tillage.

Figures 1-3 show the weekly trend of small, large and total populations of the velvetbean caterpillars. Although




43




analysis of the data did not detect any significant differences between treatments, the figures show that before the plots were sprayed with methomyl, populations of small larvae were highest in the conventional tillage whereas populations of large larvae were highest in the no-tillage into corn mulch. After application of methomyl, populations of both age groups were highest in the no-tillage into corn stubble.

Data obtained from the Green Acres 1978 experiment also failed to show any significant effect of no-tillage treatment on velvetbean caterpillar populations as compared to the conventional tillage (Table 11, Figures 4, 5, and 6). After the second application of methomyl (September 7), all the larvae collected were very small (up to 1 cm) (Figures 4, 5 and 6). Soybeans were in the R5-R6 stage and these small larvae could not cause any significant damage to the soybeans.

In 1979 at Green Acres velvetbean caterpillars were

classified into small (up to 1.5 cm), medium (1.6-2.5 cm), and large (over 2.5 cm) larvae. The average numbers of larvae per shake for each age group are shown in Table 12, and the weekly population trend is illustrated by Figures 7,

8 and 9. Populations of small larvae were significantly (P=0.05) lower in no-tillage into oat stubble than in the conventional tillage treatments or in no-tillage plus in-row subsoil. Figure 7 shows that throughout the cropping season,




44




populations of small larvae were consistently lower in the no-tillage than in the conventional tillage except for the weeks of August 23 and September 13. No-tillage treatments did not significantly affect medium and large larval populations (Table 12 and Figure 8).

The exact reason for fewer small larvae observed in

the no tillage than in the conventional tillage is not known. This might have been an indication that A. gemmatilis moths preferred to oviposit in the conventional tillage soybeans which were cleaner than the no-tillage soybeans with some weeds and crop resideus. Sloderbeck and Edwards (1979) found that adults and larvae of the Mexican bean beetle preferred tilled to nontilled soybeans. The authors believed that this might have been due to "a preference of adult beetles for the tilled soybeans" which were almost free of weeds and residues.


Soil-Inhabiting Predators

Ground spiders. Populations of ground spiders were

monitored at Green Acres along with those of soil insects. Since no attempt was made to identify the different species of spiders collected in pitfall traps, all the species will be collectively referred to as ground spiders.

In 1978 spider populations were statistically identical in conventional tillage and no-tillage plots. The weekly average numbers were 1.0 and 1.7 spiders per trap, respectively,




45



in the no tillage and conventional tillage. In-row subsoil did not significatnly affect spider populations either in conventional tillage treatments or in no-tillage plots.

Spider populations reached the peak about four weeks before the peaks of pest populations. During the week of peak populations the average number for the entire field (all treatments combined) was 3.91 spiders per trap. Ground spiders were in low numbers (field average, 0.41) when most pest species increased in number.

In 1979 spider populations were high and peaked during the second week of the sampling period, i.e. before most pest species appeared. The analysis of data revealed no significant differences between treatments. The weekly average numbers were 3.78 and 2.40 spiders per trap in conventional tillage and no-tillage soybeans, respectively.

A reduction in number of spiders in a crop system may result in increased pest populations in that system since spiders constitute an important part of the predator complex in crop systems (Whitcomb and Bell, 1964). The activity of spiders, as indicated by the results, was not affected by the tillage systems investigated in this study.

Striped earwig. Average numbers of the striped earwig, Labidura riparia, observed at Williston from April to July 1978 are in Table 13. Both nymphal and adult populations were significantly (P=0.05) lower in the conventional tillage




46




plus in-row subsoil than in any of the no-tillage treatments. The conventional tillage plus in-row subsoil also harbored significantly more earwigs than the conventional tillage without subsoil. Adult populations were significantly higher in no tillage into rye stubble and no tillage into rye mulch than in the conventional tillage (Table 13). No till into rye stubble did not significantly differ from no till into rye mulch.

Figures 10, 11 and 12 show the weekly trend of nymphal, adult and total populations of Labidura respectively in no tillage into rye stubble, no tillage into rye mulch and conventional tillage treatments. Earwig populations remained higher in the no tillage into rye mulch than in any of the other two treatments during the first half of the sampling period.

Earwig populations were very high in the second season at Williston. An average of up to 245.77 nymphs and adults per trap were collected from one treatment (Table 14). Although populations appeared to be highest in the no till plus in-row subsoil into corn mulch, analysis of the data did not detect any significant differences between treatment means. This was also shown by Figures 13, 14, and 15 which illustrate weekly foraging activity of the earwigs in the conventional till, no till into rye-corn stubble and no till into rye-corn mulch.




47




The average numbers of Labidura collected in pitfall traps at Green Acres in 1978 are in Table 15. Except for the conventional tillage plus in-row subsoil, nymphal populations in all other treatments appeared to be higher in the carbofuran-treated portion than in the untreated other half of the plots. The differences among treatment means, however, were not significant for either nymphs or adults. Price and Shepard (1977) also found that soybeans treated with insecticides harbored more earwigs than untreated ones. When the untreated no tillage was compared to the untreated conventional tillage for adult populations, it was found that the conventional tillage harbored significantly more adult Labidura than did the no tillage (Table 15). The weekly activity of the earwigs in no tillage and conventional tillage is shown in Figures 16, 17, and 18.

Table 16 contains average numbers of nymphs and adult Labidura collected at Green Acres in 1979. Nymphal and adult populations appeared to be higher in the conventional tillage than in the no tillage, but the analysis of the data failed to show any significant differences among treatments.

Colonization patterns of no-tillage soybeans by L. riparia did not differ from those of the conventionally tilled soybeans, and were similar to those reported by Price and Shepard (1977) for conventional tillage soybeans. Young, newly established no-tillage and conventional till




48




soybeans had very low earwig populations. In the firstseason experiment in Williston the earwig populations reached peak at the end of the sampling season. In the second experiment, however, populations peaked at the beginning of the season (Figure 15), when soybeans were in the V4-V5 stages. At Green Acres in 1979 populations remained relatively high in the conventional tillage at the end of the sampling period, but were very low in the no tillage. The average nymphal population was almost zero in the no tillage at the end of the season (Figures 19, 20, and 21).

The results indicated that no-tillage farming did not generally affect populations of L. riparia. This earwig was active and in large numbers throughout the second half of the crop season, when pest species appeared or were in large numbers. Labidura did not apparently have any significant impact on pest populations; no noticeable reduction of pest populations was observed in spite of large Labidura populations. This of course does not rule out the possibility that the pest populations would have been higher in the absence of L. riparia. In confinement this earwig killed many more Anticarsia larvae than it consumed (see Appendix B).

Carabid beetles. Fifty carabid beetles belonging to eight different species were collected in pitfall traps from April to




49




July, 1978, in rye stubble at Williston. The different species recorded are in Table 17. Colliuris pennsylvanica

(L.) was the most abundant carabid species, representing 34% of all the species collected. Harpalus caliginosus Fab. was the next species with 18%. Anisodactylus merula Germar and Pasimachus sublaevis Beauv. each comprised 16% of the total population.

With respect to tillage systems, the results indicated that carabids were more active in no-tillage plots than in conventional tillage plots. No carabid beetles were collected from the conventional tillage during the entire sampling period (Table 17). The conventional till plus in-row subsoil, like no till plus in-row subsoil and no tillage into rye mulch, harbored 16% of the beetles each. The majority of carabids were collected from no till into rye stubble (30%) and no tillage plus in-row subsoil into rye mulch (22%).

The total number of carabid beetles collected from no-till and conventional till soybeans increased to 112 in the corn stubble experiment at Williston. Table 18 shows the different species and numbers of beetles recorded. The highest population (25.89%) of carabids was recorded from the no till plus in-row subsoil into corn stubble. No tillage into corn stubble harbored 18.75% of the carabids collected, and the conventional till contained the lowest (12.50%) population of carabid beetles. Over 43% of the




50



carabid beetles collected were P. sublaevis. Anisodactylus merula was the next abundant (11.61%) species collected.

Populations of carabid beetles were relatively high at Green Acres in the 1978 oat stubble experiment where a total of 320 carabids were collected (Table 19). Harpalus pennsylvanicus De Geer, A. merula and Calosoma sayi Dejean were the most abundant species counting for 45.31, 37.19, and 14.38% of the total, respectively. The no till into oat stubble had the highest (46.86%) carabid population, and the conventional tillage had the lowest with 14.69%. In 1979, the numbers were low at Green Acres; 81 individuals only were collected, with 34.57% from the no-tillage soybeans and 20.98% from the conventionally tilled plots. Harpalus pennsylvanicus and C. sayi were the most prevalent species representing 39.51 and 23.46%, respectively. The species and numbers of carabid-.beetles collected at Green Acres in 1979 are shown in Table 20.

Data collected over two years showed that no-tillage systems significantly increased the activity of carabid beetles. However, catches of most species were so erratic and their numbers so low that it is not believed that carabid beetles played any important role in regulating pest populations.





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Table 1. Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus (Zeller), in notillage and conventional tillage "Cobb" soybeans at Williston, Levy Co., Fla., 1978.
Numbers are totals and averages of two rows
per replication for three weeks.


Infested plants

Treatment Total Number Average/row

No tillage into corn
stubble (in rye residue) 46 1.92

No till plus in-row subsoil
into corn stubble (in rye residue) 32 1.33

No tillage into corn mulch (in rye residue) 46 1.92

No tillage plus subsoil
into corn mulch (in rye residue) 41 1.71

Conventional tillage (into corn stubble) 49 2.04

Conventional tillage plus in-row subsoil 51 2.13


In no-till plots corn was seeded into rye stubble (hay) or mulch and soybeans into corn stubble or mulch (following corn).
**In the analysis of variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.




52








Table 2. Lesser cornstalk borer infestations in no-tillage
and conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979. Estimations are based on two different rows observed weekly (for
three weeks) in each replication (four reps/treat.).


Infested plants
Treatment Total Number Average/row

No tillage into oat stubble 103 4.29a

No tillage plus in-row
subsoil into oat stubble 46 1.92b

Conventional tillage into oat stubble 34 1.42b

Conventional tillage plus in-row subsoil into oat
stubble 20 0.83c


Values not followed by the same letter are significantly different at the 0.05 level by Duncan's new multiple range test.




53





Table 3. Average number of the three-cornered alfalfa hopper,
Spissistilus festinus (Say), collected by the plant
shaking method (1978) and sweep net (1979) from conventional tillage and no-tillage soybeans at
Green Acres, Alachua Co., Fla. Numbers are averages
of eight weeks with eight shakes per treatment and
three weeks with eight sweeps per treatment.


No. hoppers collected*
Treatment Avg./shake Avg./sweep

No tillage into oat stubble 0.55 3.38 No tillage plus in-row subsoil into oat stubble 0.36 2.17 Conventional tillage 0.42 1.58
Conventional tillage plus
in-row subsoil 0.42 1.83

In the analysis of variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.




54








Table 4. Soybean looper populations in no-tillage and
conventional tillage "Cobb" soybeans estimated
by the shake cloth method at Green Acres, Alachua Co., Fla., 1978 and 1979. Numbers are totals and
averages of eight (for 1978) and four (for 1979)
weekly shakes (sites) per treatment for 12 (1978)
and six (1979) weeks.


Looper Population
Treatment Total Number Average/shake


1978 1979 1978 1979

No tillage into oat stubble 100 16 1.04 0.67

No tillage plus in-row
subsoil into oat stubble 137 5 1.43 0.21

Conventional tillage
into oat stubble 129 8 1.34 0.33

Conventional tillage plus in-row subsoil into oat
stubble 105 9 1.09 0.38

No statistical analysis was done on the data the means being about equal.




55









Table 5. Effect of tillage on southern green stink bug
populations estimated by the shake cloth method in "Cobb" soybeans at Williston, Levy Co., Fla., 1978. Numbers represent totals and averages of
eight weekly shakes per treatment for seven weeks.

Stink bug Population
Treatment Total Number Average/shake


No tillage into rye stubble 74 1.32ab

No tillage plus in-row subsoil into rye stubble 86 1.54b

No tillage into rye mulch 97 1.73b

No tillage plus in-row
subsoil into rye mulch 106 1.89b

Conventional tillage into
rye stubble 54 0.96a

Conventional tillage plus
in-row subsoil into rye stubble 61 1.09ab

Values followed by the same letter are not significantly different at 0.05 level by Duncan's new multiple range test.





56








Table 6. Number of Nezara viridula (Linn.) collected by the
shake cloth method in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua, Co.,
Fla., 1978. The numbers represent totals and
averages of eight weekly shakes per treatment for
nine weeks. The plots (all) were treated with methomyl (once) and acephate (once) for insect
control.


Average/shake*
Nymph Adult Nymph + Treatment Adult


No tillage into oat stubble 1.19 2.08 3.28

No tillage plus in-row
subsoil into oat stubble 0.56 1.58 2.14

Conventional tillage into oat stubble 0.83 1.78 2.61

Conventional tillage plus in-row subsoil into oat
stubble 0.47 2.14 2.61

In the analysis of variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.




57








Table 7. Number of Nezara viridula (Linn.) collected by the
plant shaking method in no-tillage and conventional tillage "Cobb" soybeans at Green Acres, Alachua Co.,
Fla., 1979. Numbers are averages of four weekly
shakes per treatment for four weeks. The plots
were sprayed twice with acephate for insect control.


Average/ shake*
Nymph Nymph Adult N 4-5 + Treatment 1-3** 4-5 Adults

No tillage into oat stubble 2.94 1.69 4.88 6.56

No tillage plus in-row
subsoil into oat stubble 1.38 1.19 4.69 5.88

Conventional tillage
into oat stubble 1.06 1.50 4.94 6.44

Conventional tillage plus
in-row subsoil into oat
stubble 2.25 1.63 3.94 5.56

In the analysis of variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.

1-5, first to fifth instars.




58







Table 8. Stink bug damage to seeds in no-tillage and
conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1978.


Number of Seeds
Total %
Treatment Examined Damaged Damaged*
No tillage into oat stubble 784 59 7.52 No tillage plus in-row
subsoil into oat stubble 673 26 3.86 Conventional tillage 629 53 8.43 Conventional tillage
plus in-row subsoil 532 40 7.52

In the analysis of variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.




59








Table 9. Damage to seeds by the stink bug complex in no-till
and conventional till "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979. Numbers are averages of
20 plants per treatment.


%*
Treatment Damage** Small Seeds

No tillage into oat stubble 16.34 38.92

No-till plus in-row subsoil
into oat stubble 14.25 28.87

Conventional till into oat stubble 15.02 19.28

Conventional till plus in-row subsoil into oat stubble 17.00 20.69

In the analysis of the variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.

Damage: seeds with at least one feeding puncture. Small
seeds: small, wrinkled and fungus infected seeds.




60








Table 10. Effect of tillage practice on populations of the
velvetbean caterpillars, Anticarsia gemmatilis
Hubner, estimated by the plant shaking method in
"Cobb" soybeans at Williston, Levy Co., Fla.,
April July, 1978. Numbers are averages of four weekly shakes per treatment for six weeks. Plots
were treated with methomyl (0.56 kg a.i./ha) on
September 27 for the control of velvetbean
caterpillars.


Average Number Larvae/shake*
Treatment Small Large Small + Large

No tillage into corn stubble 7.46 2.54 10.00

No tillage plus in-row
subsoil into corn stubble 9.58 3.50 13.08

No tillage into corn mulch 6.92 3.21 10.13

No tillage plus in-row
subsoil into corn mulch 7.54 2.71 10.25

Conventional tillage
into corn stubble 8.33 2.46 10.79

Conventional tillage plus in-row subsoil into corn
stubble 7.50 2.79 10.29

In the analysis of variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.




61








Table 11. Effect of tillage practice on population levels of
the velvetbean caterpillar, Anticarsia gemmatilis Hubner, monitored by the plant shaking method in
"Cobb" soybeans at Green Acres, Alachua Co., Fla.,
1978. Numbers are averages of eight weekly
shakes per treatment for eleven weeks for small
larvae and eight weeks for large larvae. The plots were treated with methomyl and acephate
(once each) for insect control.


Average Number Larvae/hake*
Treatment Small Large Small + Large


No tillage into oat stubble 7.91 2.95 10.16

No tillage plus in-row
subsoil into oat stubble 8.39 2.17 10.56

Conventional tillage into oat stubble 8.64 1.78 10.42

Conventional tillage plus in-row subsoil into oat
stubble 8.50 3.45 11.95

In the analysis of variance no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.




62








Table 12. Populations of the velvetbean caterpillar,
Anticarsia gemmatilis, estimated by the plant shaking method in no-tillage and conventional
tillage "Cobb" soybeans. at Green Acres, Alachua Co., Fla., 1979. Numbers represent four weekly
shakes per treatment for ten weeks. Soybeans
were treated twice with acephate for insect
control.


Average Number Larvae/shake*
Treatment Small Medium Large Total


No tillage into oat stubble 11.43a 1.93c 1.78d 15.14e

No tillage plus in-row
subsoil into oat stubble 16.13b 2.85c 2.15d 21.13f

Conventional tillage into oat stubble 17.15b 2.68c 1.10d 20.93f

Conventional tillage plus
in-row subsoil into oat stubble 16.38b 2.90c 1.65d 20.93f

Values in each column followed by the same letter are not significantly different at the 0.05 level by Duncan's new multiple range test.




63








Table 13. Activity of the striped earwig Labidura riparia
(Pallas), in no-tillage and conventional tillage
"Cobb" soybeans estimated by pitfall traps at
Williston, Levy Co., Fla., 1978. Four traps were
used for each treatment for 11 weeks.


Earwig population
Average/trap*
Treatment Nymphs Adults Nymphs + Adults

No tillage into rye
stubble 31.14ac 30.91c 62.05ac

No tillage plus in-row
subsoil into rye stubble 31.64c 27.18a 58.82ad

No tillage into rye
mulch 31.61c 30.25c 61.86c

No tillage plus in-row
subsoil into rye mulch 31.27ac 26.91a 58.18d

Conventional tillage
into rye stubble 30.34a 26.27a 56.61a

Conventional tillage
plus in-row subsoil into rye stubble 22.59b 12.18b 34.77b

Values followed by the same letter in each column are not significantly different at the 0.05 level by Duncan's new multiple range test.




64







Table 14. Activity of the striped earwig, Labidura riparia,
in no-tillage and conventional tillage lateplanted "Cobb" soybeans estimated by pitfall
traps at the Robinson farm, Williston, Levy Co., Fla., 1978. Numbers are averages of three traps per treatment for ten weeks. Plots were treated once with methomyl for the control of velvetbean
caterpillars.


Average! trap*
Treatment Nymphs Adults Nymphs + Adults


No tillage into corn stubble 122.03 107.60 229.63

No tillage plus in-row
subsoil into corn stubble 117.57 105.87 223.43

No tillage into corn mulch 125.03 101.50 226.53

No tillage plus in-row
subsoil into corn mulch 136.40 109.37 245.77

Conventional tillage
into corn stubble 118.20 111.13 234.13

Conventional tillage plus
in-row subsoil into corn
stubble

In the analysis of variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.




65







Table 15. Activity of the striped earwig, Labidura riparia,
in no-tillage and conventional tillage "Cobb"
soybeans estimated by pitfall traps at Green Acres, Alachua Co., Fla., 1978. Numbers are
averages of 14 weeks with four traps per treatment. Half of each plot was treated with
carbofuran (F) at planting, the other half was
untreated (C).

Average Number/trap*
Treatment Nymph Adult Nymph + Adult

No tillage into oat stubble C 38.64 22.09cd 60.73cd F 42.88 24.48bc 67.36bc

No tillage plus in-row
subsoil into oat stubble C 35.57 19.16d 54.73d F 43.13 20.38d 63.50cd

Conventional tillage into oat stubble C 44.39 35.57a 79.96ab F 52.68 34.00ab 86.68ab

Conventional tillage
plus in-row subsoil C 51.84 37.48ab 89.32ab F 49.50 33.13a 82.63a

Analysis of variance not significant for nymphs. Values followed by the same letter in each column are not significantly different at the 0.05 level by Duncan's new multiple range test.




66









Table 16. Number of striped earwig, Labidura riparia,
collected in pitfall traps in no-tillage and
conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979. Numbers are
averages of 15 weeks and four traps per treatment. All the plots were treated twice with
acephate for insect control.


Average/ trap*
Treatment Nymphs Adults Nymphs +Adults


No tillage into oat stubble 26.95 21.13 48.08

No tillage plus in-row
subsoil into oat stubble 41.30 24.42 65.72

Conventional tillage
into oat stubble 43.55 36.12 79.67

Conventional tillage plus in-row subsoil into oat stubble 34.20 41.63 75.83

In the analysis of variance, no significant differences were detected among the means. Therefore, Duncan's comparisons were not made.




67







Table 17. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Williston, Levy Co., Fla., April July, 1978. Totals of four traps per
treatment for 12 weeks.


Treatment*
Species CRS CRS+s NRS NRS+s NRM NRM+s


Anisodactylus merula Germar 0 1 4 0 3 0 Calosoma sayi Dejean 0 0 1 0 0 0 Chlaenius laticollis Say 0 0 1 1 0 1 Colliuris pennsylvanica (L.) 0 2 4 5 1 5 Harpalus caliginosus Fab. 0 4 2 1 0 2 H. pennsylvanicus DeGeer 0 0 1 0 1 0 Pasimachus sublaevis Beauv. 0 0 1 1 3 3 Scarites subterraneus (Fab.) 0 1 1 0 0 0

CRS-conventional tillage into rye stubble
CRS+s-conventional tillage plus in-row subsoil into
rye stubble
NRS-no tillage into rye stubble
NRS+s-no tillage plus in-row subsoil into rye stubble NRM-no tillage into rye mulch
NRM+s-no tillage plus in-row subsoil into rye mulch




68







Table 18. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Williston, Levy Co., Fla.,
September November, 1978. Numbers are totals
of three traps per treatment for 10 weeks.


Treatment*
Species CCS CCS+s NCS NCS+s NCM NCM+s


Anisodactylus merula Germar 4 2 4 1 1 1 Calosoma sayi Dejean 0 0 1 1 2 5
Chlaenius tomentosus Say 0 0 0 0 1 1 Colliuris pennsylvanica (L.) 0 0 1 0 0 0 Galerita lecontei Dejean 0 0 0 2 0 0 Harpalus caliginosus Fab. 1 2 0 1 1 2 H. pennsylvanicus DeGeer 1 1 3 1 1 1 Pasimachus subsulcatus Say 1 1 1 2 2 0 P. sublaevis Beauv. 7 5 8 8 5 16 Solenophorus sp. 0 4 2 2 2 0 Scarites subterraneus(Fab.) 0 0 1 0 0 3


CCS-conventional tillage into corn stubble
CCS+s-conventional tillage plus in-row subsoil into corn
stubble
NCS-no tillage into corn stubble
NCS+s-no tillage plus in-row subsoil into corn stubble
NCM-no tillage into corn mulch
NCM+s-no tillage plus in-row subsoil into corn mulch




69







Table 19. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Green Acres, Alachua Co., Fla.,
June September, 1978. Totals of four traps per
treatment for 14 weeks.


Treatment*
Species CT CT+s NOS NOS+s

Anisodactylus merula Germar 8 8 80 23 Calosoma sayi Dejean 18 14 6 8 Colliuris pennsylvanica (L.) 2 1 1 1 Galerita janus Fab. 0 0 0 1 Harpalus caliginosus Fab. 0 0 1 0 H. pennsylvanicus DeGeer 19 39 60 27 Pasimachus subsulcatus Say 0 0 2 0 Scarites subterraneus Fab.) 0 0 0 1

CT-conventional tillage
CT+s-conventional tillage plus in-row subsoil NOS-no tillage into oat stubble NOS+s-no tillage plus in-row subsoil into oat stubble




70








Table 20. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Green Acres, Alachua Co., Fla.,
June September, 1979. Totals of four traps per
treatment for 15 weeks.


Treatment*
Species CT CT+s NOS NOS+s

Anisodactylus merula Germar 2 5 4 4 Calosoma sayi Dejean 3 2 8 6 C. scrutator (Fab.) 1 0 0 0 Chlaenius tomentosus Say 2 1 0 0 Colliuris pennsylvanica (L.) 1 0 0 0 Galerita lecontei Dejean 2 0 1 5 Harpalus caliginosus Fab. 0 0 0 1 H. pennsylvanicus DeGeer 5 5 15 7 Scarites subterraneus (Fab.) 1 0 0 0

CT-conventional tillage
CT+s-conventional tillage plus in-row subsoil NOS-no tillage into oat stubble NOS+s-no tillage plus in-row subsoil into oat stubble





71








2.5




2.0

Ix10


ui 1.5

















19 26 3 10 17 24
Sept Oct
SAMPLING PERIOD Figure 1. Average numbers of small (up to 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and
conventional tillage "Cobb" soybeans at Williston,
Levy Co., Fla., 1978. Averages of eight shakes
per treatment.
---: conventional tillage
----: no tillage into corn stubble
--~-: no tillage into corn mulch
Arrow indicates insecticidal treatment




72









2.5




2.0

!xl


>1.5





L.0


/ \

0.5 / \


I I



19 26 3 I0 17 24
Sept Oct
SAMPLING PERIOD Figure 2. Average numbers of large (over 2.5 cm) velvetbean caterpillars, Anticarsia gemmatilis, collected by the plant shaking method from no-tillage and conventional tillage "Cobb" soybeans at Williston, Levy Co., Fla., 1978. Averages of eight shakes
per treatment.
conventional tillage
----: no tillage into corn stubble
----: no tillage into corn mulch
Arrow indicates insecticidal treatment




73








3.0




2.5









1











0.5






19 26 3 10 17 24
Sept Oct
SAMPLING PERIOD
Figure 3. Average number of velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method
from no-tillage and conventional tillage "Cobb"
soybeans at Williston, Levy Co., Fla., 1978. Averages
of eight shakes per treatment.
conventional tillage
no tillage into corn stubble
-0-: no tillage into corn mulch
Arrow indicates insecticidal treatment.
LL

\ L'
/ \
/ \

05 /"






















Arrow indicates insecticidal treatment.




74










4.5

4 .O


3.5

~'" 3.0

- 2.52.0

4'

1.0


0.5



19 26 1 8 15 22 29 5 12 19 26 3
July Aug Sept Oct SAMPLING PERIOD
Figure 4. Average numbers of small (up to 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by the plant shaking method from no-tillage and conventional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Averages of eight shakes
per treatment.
no tillage into oat stubble
----: conventional tillage
Arrow indicates insecticidal treatment.




75










4.5

4.0


3.53.0
(I,

2.5


S2.0




1.0

0.5



19 26 I 8 15 22 29 5 12 19
July Aug Sept SAMPLING PERIOD Figure 5. Average numbers of large (over 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by the plant shaking method from no-tillage and conventional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Averages of eight shakes
per treatment.
no tillage into oat stubble
----: conventional tillage
Arrow indicates insecticidal treatment.




76






60

5.5

5.0

4.5

- 4.0

3.5.
IJ

3 .0

2.5

< 2.0..J
1.5 -I

/ \
1.0-/ \

0.5 \



19 26 I 8 15 22 29 5 12 19 26 3 July Aug Sept Oct SAMPLING PERIOD Figure 6. Average numbers of velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method
from no-tillage and conventional tillage "Cobb" soybeans at Green Acres, Alachua Co., Fla., 1978. Average of eight shakes per treatment.
no tillage into oat stubble conventional tillage Arrow indicates insecticidal treatment.




77











2.5




x 2.0





0.5 /
/. A


















Aug Sept Oct SAMPLING PERIOD Figure 7. Average numbers of small (up to 1.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and conventional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979. Averages of four shakes
per treatment.
no tillage into oat stubble
conventional tillage
Arrow indicates insecticidal treatment.
Arrow indicates insecticidal treatment.




78














2.0




0.5






LJ










2 9 16 23 30 6 13 20 27 4 Aug Sept Oct SAMPLING PERIOD Figure 8. Average numbers of medium (1.6 2.5 cm) and large
(over 2.5 cm) velvetbean caterpillars, Anticarsia gemmatilis, collected by the plant shaking method
from no-tillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co., Fla., 1979.
Averages of four shakes per treatment.
no tillage into oat stubble
----: conventional tillage
Arrow indicates insecticidal treatment.




79










2.5




-2.0










0. 15SAMPLING PERIOD
















conventional tillage
0.5-/






2 9 16 23 30 6 13 20 27 4
Aug Sept Oct SAMPLING PERIOD Figure 9. Average numbers of velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method from
no-tillage and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979. Average of
four shakes per treatment.
no tillage into oat stubble conventional tillage Arrow indicates insecticidal treatment.




80











2.5





I) 2.0

I


a. /K










0.5





iI I I






nymphs from no-tillage and conventional tillage

July, 1978. Four pitfall traps were placed in each
treatment.
conventional tillage
----: no tillage into rye stubble
------: no tillage into rye mulch




81
















2.0




0.




0 1.0- /




0.51 /







25 2 9 16 23 30 6 13 20 27 4 11
Apr May June July SAMPLING PERIOD Figure 11. Average trap-week collections of Labidura riparia
adults from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla., April
July, 1978. Four pitfall traps were placed in each
treatment.
conventional tillage no tillage into rye stubble
--a1-: no tillage into rye mulch




Full Text
68
Table 18. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Williston, Levy Co., Fla.,
September November, 1978. Numbers are totals
of three traps per treatment for 10 weeks.
Species
CCS
CCS+s
Treatment*
NCS NCS+s
NCM
NCM+s
Anisodactylus merula Germar
4
2
4
1
1
1
Calosoma sayi Deiean
0
0
1
1
2
5
Chlaenius tomentosus Say
0
0
0
0
1
1
Colliuris pennsylvanica (L.)
0
0
1
0
0
0
Galerita lecontei Deiean
0
0
0
2
0
0
Harpalus caliginosus Fab.
1
2
0
1
1
2
H. pennsylvanicus DeGeer
1
1
3
1
1
1
Pasimachus subsulcatus Say
1
1
1
2
2
0
P. sublaevis Beauv.
7
5
8
8
5
16
Solenophorus sp.
0
4
2
2
2
0
Scarites subterraneus(Fab.)
0
0
1
0
0
3
CCS-conventional tillage into com stubble
CCS+s-conventional tillage plus in-row subsoil into com
stubble
NCS-no tillage into com stubble
NCS+s-no tillage plus in-row subsoil into com stubble
NCM-no tillage into com mulch
NCM+s-no tillage plus in-row subsoil into com mulch


ADULTS/TRAP (LOG x)
81
2.5
2.0-
1.0-
0.5 -
r

i i i i i i i i i i i
25 2 9 16 23 30 6 13 20 27 4 II
Apr May June July
SAMPLING PERIOD
Figure 11. Average trap-week collections of Labidura riparia
adults from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla., April -
July, 1978. Four pitfall traps were placed in each
treatment.
: conventional tillage
: no tillage into rye stubble
: no tillage into rye mulch


123
Table 26. Fall armyworm and corn earworm damage to the
conventional and no-tillage corn assessed at
the harvest time at Green Acres, Alachua Co.,
Fla., 1979. Forty ears were collected per
treatment.
Ears with
Damaged Damaged
Treatment Ears* Kernels*
No.
%**
No.
%**
No tillage into wheat stubble
38
95.0
31
77.50
No tillage plus in-row
subsoil into wheat stubble
33
82.50
27
67.50
Conventional tillage
39
97.50
34
85.0
Conventional tillage plus
in-row subsoil
39
97.50
37
92.50
Damaged ears: ears with any outside damage level. Damaged
kernels: ears with a damaged area extending to one or more
centimeters within the kernel rows.
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
not made.


18
Rivers et al. (1977) planted com into a sod field
infested with white grubs, Phyllophaga anxia (LeConte), to
investigate the influence of tillage systems on grub popula
tions. After two years of observations, the authors found
that the populations of white grubs were significantly
higher in the soil around plants in the conventional tillage
than in the no-tillage plots. They believed that this
phenomenon was due to the fact that grubs preferred to
feed on the grass left between crop rows in the no tillage.
In Indiana, Sloderbeck and Edwards (1979) reported
that changes in row width did not significantly affect
population levels of the Mexican bean beetle, Epilachna
varivestis Mulsant, and redlegged grasshopper, Melanoplus
femurrubrum (De Geer), but that tilled soybeans harbored
significantly more larval and adult Mexican bean beetles
than no-till soybeans. No till in combination with double
cropping, however, increased population levels of the
redlegged grasshopper as it continuously provided a suitable
habitat for the grasshopper.


APPENDIX B
PREDATORY ACTIVITY OF LABIDURA
ON ANTICARSIA IMMATURES
The effectiveness of L. riparia as a predator on
A. gemmatilis immatures was assessed in the laboratory
by introducing one Labidura male into a cottage cheese cup
containing 5 or 15 Anticarsia larvae. Some cups (with larvae
and Labidura) were placed on a table for direct observations.
Others were kept in a growth chamber (temperature 28 C) for
24 hours. Predation on pupae was studied by placing three
pupae into each cup; the pupae were covered with 1 cm of
sand. One male Labidura was introduced into each cup and
the cups were kept in the growth chamber.
Direct observations indicated that small and medium
larvae (1-2.0 cm) were more easily caught and killed than
larger (over 2 cm) larvae. Large larvae were punctured after
a few minutes of struggle, but were not generally consumed.
Labidura were observed to kill five small larvae within two
minutes without completely consuming any or consumed only
one. An average of 5.2 minutes were required to consume a
small larva. These observations agreed with an earlier con
clusion by Bishara (1934, cited by Price and Shepard, 1977)
that L. riparia may kill more prey than it consumes.
141


Table 3. Average number of the three-cornered alfalfa hopper,
Spissistilus festinus (Say), collected by the plant
shaking method (1978) and sweep net (1979) from
conventional tillage and no-tillage soybeans at
Green Acres, Alachua Co., Fla. Numbers are averages
of eight weeks with eight shakes per treatment and
three weeks with eight sweeps per treatment.
No. hoppers
collected*
Treatment
Avg./shake
Avg./sweep
No tillage into oat stubble
0.55
3.38
No tillage plus in-row subsoil
into oat stubble
0.36
2.17
Conventional tillage
0.42
1.58
Conventional tillage plus
in-row subsoil
*
0.42
1.83
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in
Partial Fulfillment of the Requirements for the
Degree of Doctor of Philosophy
INFLUENCE OF NO-TILL AND CONVENTIONAL TILLAGE
ON INSECT PESTS AND SOIL INHABITING PREDATOR POPULATIONS
IN FLORIDA SOYBEAN AND CORN CROPPING SYSTEMS
By
Ki-Munseki Lema
March 1980
Chairman: R. I. Sailer
Co-Chairman: D. C. Herzog
Major Department: Entomology and Nematology
The effect of no-tillage cropping on insect pests, and
ground-dwelling arthropod predators was assessed in soybean
and corn crop systems in Levy and Alachua Counties, Florida,
from April to November 1978 and 1979. No tillage and
conventional tillage, with in-row subsoil as a subtreatment
for both, were compared in rye (Secale cereale L.), com
(Zea mays L.), oat (Avena sativa L.), wheat (Triticum aestivum
L.) and vetch (Vicia villosa Roth) stubble or mulch.
Damage to soybeans [Glycine max (L.) Merrill] and corn
was determined weekly by visual observations. The sweep net
and plant shaking methods were used to monitor pest popula
tions in soybeans. The activity of ground-dwelling arthro
pods (pests and predators) was monitored in both corn and
soybean systems using pitfall traps.
xviii


105
tilled com (Musick and Suttle, 1973). These insects
are generally attracted by, and oviposit in, grassy areas
of the no-till com. The fall armyworm females usually
oviposit on green plants, and corn earworm females on
larval host plants (Metcalf et al., 1962). Crop residues
in no-tillage plots apparently did not attract female
moths to oviposit in these plots. If such an attraction
and concentration had occurred, more infested plants would
have been observed in no-till plots, especially during
the first weeks. Weekly, as well as overall analysis
of the data failed to show any significant preference
by female moths for the no-till com.
Conceivably, pest populations might have been higher
in the no till than in the conventional tillage and subse
quently reduced by higher predator populations in the
no-till plots. However, results obtained on ground predators
showed that predator numbers were lower in the no-till
plots than in conventional plots. It is believed that
female moths indiscriminately laid eggs on com plants
in all the plots because no-till plots did not provide
better above-ground conditions than those in the conventional
tillage plots.
Soil Insect Pests
Wireworms. Two species of wireworms (Elateridae),
Conoderus amplicollis (Gyll.) and C. falli Lane, were


program. I also extend my gratitude to my daughter, Lukamba
Nsunda, and to my son Kapela, for having gone through the
numerous upheavals associated with my studies.
iv


23
nymphs and adults insert their mouthparts through the pods
and into the beans to feed on the developing seed. Such
seeds tend to shrivel and pods may abort when young pods
are injured. Along with histolytic substances injected into
the beans to liquefy cell contents, the bugs inject a yeast-
spot disease fungus, Nematospora coryli Peglion which further
lowers the quality of the beans.
In Arkansas, Miner (1961) observed that damage by N.
viridula lowered the oil content and slightly increased
protein content of the seeds. Blickenstaff and Huggans
(1962) reported a decrease in the yield of soybean seeds and
an increase in the percentage of small seeds due to stink
bug damage.
Corn Insects
Lesser cornstalk borer. Some information pertaining
to E. lignosellus has already been mentioned in the section
of soybean insects. The feeding behavior of this insect on
corn is the same as when it feeds on soybeans or other
host plants.
According to Luginbill and Ainslie (1917), the lesser
cornstalk borer attacks corn plants at, or just below the
ground level. The larvae bore or tunnel into the stem of
seedling plants and feed on roots or above the soil surface.
Young plants so injured die quickly. Some infested plants
may survive, but become distorted, curled and one sided.


Table
Page
6 Number of Nezara viridula (Linn.) collected
by the shake cloth method in no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua, Co., Fla., 1978.
The numbers represent totals and averages
of eight weekly shakes per treatment for
nine weeks. The plots (all) were treated
with methomyl (once) and acephate (once)
for insect control 56
7 Number of Nezara viridula (Linn.) collected
by the plant shaking method in no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Numbers are averages of four weekly shakes
per treatment for four weeks. The plots
were sprayed twice with acephate for
insect control 57
8 Stink bug damage to seeds in no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1978 58
9 Damage to seeds by the stink bug complex
in no-till and conventional till "Cobb"
soybeans at Green Acres, Alachua Co.,
Fla., 1979. Numbers are averages of
20 plants per treatment 59
10 Effect of tillage practice on populations
of the velvetbean caterpillars, Anticarsia
gemmatilis Hubner, estimated by the plant
shaking method in "Cobb" soybeans at
Williston, Levy Co., Fla., April July,
1978. Numbers are averages of four weekly
shakes per treatment for six weeks. Plots
were treated with methomyl (0.56 kg a.i./ha)
on September 27 for the control of velvet-
bean caterpillars 60
11 Effect of tillage practice on population
levels of the velvetbean caterpillar,
Anticarsia gemmatilis Hubner, monitored
by the plant shaking method in "Cobb"
soybeans at Green Acres, Alachua Co., Fla.,
1978. Numbers are averages of eight weekly
shakes per treatment for eleven weeks for
small larvae and eight weeks for large
larvae. The plots were treated with methomyl
and acephate (once each) for insect control 61
IX


26
Soil-Inhabiting Predators
Carabid Beetles
Several species of carabid beetles constitute a
group of predators that play an important role in regulating
pest populations in various agroecosystems. Members
of the genera Calosoma, Pasimachus, Progaleritina, etc., have
been reported as predators of arthropod pests, especially
Lepidoptera larvae (Stone, 1941; Whitcomb and Bell, 1964;
van den Bosch and Hagan, 1966; and Neal, 1974).
Calosoma sayi Dejean is one of the most commonly en
countered carabid predators in Florida soybean fields.
Watson (1916), Nickels (1926), Douglas (1930), and Hasse
(1971) observed this carabid preying on larvae and pupae
of A. gemmatilis. Price and Shepard (1978) observed a
build-up of adult C. sayi as a response to outbreaks of
noctuid larvae in soybean fields in South Carolina. They
also found a significant correlation between weekly popu
lations of noctuid larvae and numbers of C. sayi from mid-
August to soybean defoliation.
In Florida, Neal (1974) observed C. sayi on soybean
plants during daytime, but no predatory activity was observed.
He reported that the carabid shows predatory activity only
at night. Whitcomb and Bell (1964), however, mentioned
that the predator fed on larvae of Alabama argillacea
(Hubner) during daytime.


NYMPHS + ADULTS/TRAP(LOG x)
82
2.5-
2.0-
1.5 -
1.0-
0.5-
25 2 9 ¡6 23 30 6 13 20 27 4 I!
April May June July
SAMPLING PERIOD
Figure 12. Average trap-week collections of Labidura riparia
(nymphs + adults) from no-tillage and conventional
tillage "Cobb" soybeans at Williston, Levy, Co.,
Fla., April July, 1978. Four pitfall traps were
set in each treatment.
: conventional tillage
: no tillage into rye stubble
O: no tillage into rye mulch


13
fluctuations, and better chemical weed control contributed
to the reduction of the stalk rot incidence observed in no
tillage grain sorghum seeded in wheat stubble in Nebraska.
After studying crop diseases in no-tillage cereals,
Yarham (1975) concluded that "increase in disease levels has
not been sufficient to depress seriously the yields of the
nonplowed plots. At the moment, it does not appear likely
that cultivation-disease interaction will substantially influ
ence the success or failure of nonplow techniques" (p. 247).
Effects of no tillage on insect pests. Soil plowing has
been recommended for many years as an effective control
measure against several insect pests (Barber and Dicke, 1937;
Adkisson et al., 1960; Hardwick, 1965; and Frohlich and Rodewald,
1970). This practice reduces insect pest populations through
physical destruction, exposure to natural enemies, and detri
mental weather conditions.
Barber and Dicke (1937) compared the emergence of the
com earworm [(Heliothis zea (Boddie)] moths from hibernation
in various soil types and tillage systems in Virginia and
Georgia. Fall and spring plowing and fall disking signif
icantly reduced pest emergence as compared to the unculti
vated soil. Spring plowing, however, was less effective
than fall plowing or fall disking in reducing the corn ear-
worm emergence. The authors also found that soil type
affected the effectiveness of cultivation as control measure.
Plowing was more effective in sandy loam soil than in red clay
soil.


151
Dupree, M. 1965. Observations on the life history of the
lesser cornstalk borer. J. Econ. Entomol. 58:1156-7.
Fehr, W. R., and C. E. Caviness. 1977. Stages of soybean
development. Iowa State Univ. Coop. Ext. Serv. Agrie.
Exp. Stn. Spec. Rep. 80. 11 pp.
Fenton, F. A., and W. L. Owen. 1953. The pink bollworm of
cotton in Texas. Texas Agrie. Exp. Stn. Mise. Publ.
100.
Fife, L. C., C. B. Cowan, Jr., and J. W. Davis. 1957.
Factors influencing pink bollowrm winter carry-over in
central Texas. J. Econ. Entomol. 50:642-4.
Fife, L. C., and H. M. Graham. 1966. Cultural control of
overwintering bollworm and tobacco budworm. J. Econ.
Entomol. 59:1123-5.
Frohlich, G., and W. Rodewald. 1970. Pests and diseases
of tropical crops and their control. Pergamon Press.
London, 371 pp.
Galvez, S. E. C. 1979. Seasonal abundance of pest and
beneficial arthropods in response to management strat
egies in corn. Dissertation, Univ. of Florida,
Gainesville. 128 pp.
Genung, W. G., and V. E. Green, Jr. 1965. Some stem boring
insects associated with soybeans in Florida. Fla.
Entomol. 48:29-33.
Graham, J. H. 1953. Overwintering of three bacterial
pathogens of soybean. Phytopathology 43:189-92.
Greene, G. L., J. C. Reid, V. N. Blount, and T. C. Riddle.
1973. Mating and oviposition behavior of the velvet-
bean caterpillar in soybeans. Environ. Entomol. 2:
1113-5.
Gregory, W. W., and G. J. Musick. 1976. Insect management
in reduced tillage systems. Bull. Entomol. Soc. Amer.
22:302-4.
Griffith, D. R., J. V. Mannering, H. M. Galloway, S. D.
Parsons, and C. B. Richey. 1973. Effect of eight
tillage-planting systems on soil temperature, percent
stand, plant growth and yield of com on five Indiana
soils. Agron. J. 65:321-6.


Figure 19. Weekly activity of Labidura riparia nymphs monitored by pitfall
traps (four in each treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua Co,, Fla,, 1979,
: no tillage into oat stubble
: conventional tillage


BIOGRAPHICAL SKETCH
Ki-Munseki Lema was bom on August 7, 1945, in Luvanga
(Kivulu), Bas-Zaire, a few miles away from Kinshasa,
capital of Zaire. He pursued his secondary education
at and was graduated with honors from the "Ecole Technique
Secondaire d'Agriculture" (Gombe-Matadi), in June 1967. In
December, 1967, he entered the "Universite Officielle du
Congo," now known as "Universite Nationale du Zaire, Campus
de Lubumbashi," and obtained the diploma of "Candidat en
Sciences Agronomiques." In November, 1969, he entered the
"Universite Lovanium" at Kinshasa (now Universite Nationale
du Zaire, Campus de Kinshasa) and received the degree of
"Ingenieur Agronome des Regions Tropicales," with distinc
tion, in June, 1972. Thereafter he joined the faculty of
agriculture at Kinshasa where he worked from 1972 to 1973
as Assistant Lecturer in Entomology.
In July, 1973, he was selected as a possible candidate
for a Rockefeller Foundation fellowship, and was sent to Ibadan,
Nigeria, for an intensive couse in English, after which he
entered the University of Florida and was awarded a Rockefeller
Foundation fellowship to pursue graduate studies in entomology.
He obtained the degree of Master of Science in December, 1976,
and the fellowship was extended for the Ph.D. program in
January, 1977.
159


47
The average numbers of Labidura collected in pitfall
traps at Green Acres in 1978 are in Table 15. Except
for the conventional tillage plus in-row subsoil, nymphal
populations in all other treatments appeared to be higher
in the carbofuran-treated portion than in the untreated
other half of the plots. The differences among treatment
means, however, were not significant for either nymphs
or adults. Price and Shepard (1977) also found that soybeans
treated with insecticides harbored more earwigs than untreat
ed ones. When the untreated no tillage was compared to
the untreated conventional tillage for adult populations,
it was found that the conventional tillage harbored signif
icantly more adult Labidura than did the no tillage
(Table 15). The weekly activity of the earwigs in no
tillage and conventional tillage is shown in Figures 16,
17, and 18.
Table 16 contains average numbers of nymphs and adult
Labidura collected at Green Acres in 1979. Nymphal and
adult populations appeared to be higher in the conventional
tillage than in the no tillage, but the analysis of the data
failed to show any significant differences among treatments.
Colonization patterns of no-tillage soybeans by L.
riparia did not differ from those of the conventionally
tilled soybeans, and were similar to those reported by
Price and Shepard (1977) for conventional tillage soybeans.
Young, newly established no-tillage and conventional till


soybeans had very low earwig populations. In the first-
season experiment in Williston the earwig populations
reached peak at the end of the sampling season. In the
second experiment, however, populations peaked at the
beginning of the season (Figure 15), when soybeans were in
the V4-V5 stages. At Green Acres in 1979 populations
remained relatively high in the conventional tillage at
the end of the sampling period, but were very low in the
no tillage. The average nymphal population was almost
zero in the no tillage at the end of the season (Figures
19, 20, and 21).
The results indicated that no-tillage farming did
not generally affect populations of L. riparia. This
earwig was active and in large numbers throughout the
second half of the crop season, when pest species appeared
or were in large numbers. Labidura did not apparently
have any significant impact on pest populations; no noticeable
reduction of pest populations was observed in spite of large
Labidura populations. This of course does not rule out
the possibility that the pest populations would have been
higher in the absence of L. riparia. In confinement this
earwig killed many more Anticarsia larvae than it consumed
(see Appendix B).
Carabid beetles. Fifty carabid beetles belonging to eight
different species were collected in pitfall traps from April to


9
Pest Problems in No-Tillage Agroecosystems
Weeds in no tillage. An effective chemical weed control
is a prerequisite to acceptable crop yields from the no
tillage. In a seven-year study, Triplett and Lytle (1972)
confirmed weed control to be the dominant factor limiting
high crop yields. Griffith et al. (1973) showed that crop
yields in no-plow systems may be lower than those from con
ventionally plowed fields if weed control is not adequate.
Weed control is no longer a serious problem in no-plow
agroecosystems because of the development of effective herbi
cides. Several herbicides such as atrazine (see Appendix A
for chemical names), paraquat, simazine, against grasses,
and 2,4-D, etc., against broad-leaf weeds, have achieved
satisfactory weed control in the no-tillage cropping pro
cedure (Triplett, 1966; Triplett and Lytle, 1972).
Some problems related to weed control have developed
in no-tillage crop production due to the lack of soil tillage
and cultivation. Triplett and Lytle (1972) observed that
annual weed populations shifted with different herbicides,
when com was continuously grown on no tillage for seven
years. Atrazine and simazine controlled most of the weeds,
but the fall panicum (Panicum dichotomiflorum Michx.) became a
major annual weed where those two herbicides were used. The
authors also found that hemp dogbane (Apocynum cannabinum L.)
became a serious problem after several years of continuous com
production under no-tillage farming (Triplett and Lytle, 1972).


25
were found in whorls and furls. Fall armyworms also attack
com ears by burrowing into them either from the tip or
from the side.
Com earworm. The eggs of the com earworm, Heliothis
zea (Boddie), hatch from two to eight days after oviposition,
and the larval period lasts 13-28 days (Phillips and Barber,
1931). Mature larvae leave the host plants and drop to the
ground to pupate under the soil surface in pupal cells.
Pupation takes about 14 days.
Com earworm has been characterized as the "worst pest
of com" in the U. S. (Metcalf et al., 1962). In a five-
year study in Florida, Janes (1973) found that H. zea
was the most important insect pest on the ears of sweet
com.
Although com earworms may seriously damage the foliage
of early planted com, they cause more severe damage when
they feed on ears where they may destroy most of the kernels
(Phillips and Barber, 1931). Phillips and Barber (1931)
observed that the larvae will leave all other parts of
corn plants to attack silks and ears when these plant
parts appear.
In the U. S., up to 70-98% of the ears of field
com may be infested during outbreak infestations, and as
much as 5 to 7% of the kernels of field corn and 10-15% of
canning corn may be destroyed by the larvae (Metcalf et
al., 1962).


LARVAE/SHAKE (LOG X)
77
SAMPLING PERIOD
Figure 7. Average numbers of small (up to 1.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method rrom no-tillage and conven
tional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979. Averages of four shakes
per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.


128
Table 31. Activity of the granulated cutworm, Feltia
subterrnea (Fab.), monitored by nonbaited
pitfall traps in no-tillage and conventional
tillage com at Green Acres, Alachua Co., Fla.,
1979. Numbers are totals and average of four
traps per treatment for four weeks.
Treatment
Cutworm population
Tot. No. Avg./trap
No tillage into vetch stubble
160
10.0a*
No tillage plus in-row subsoil
into vetch stubble
345
21.6a
Conventional tillage
34
2.1b
Conventional tillage plus
in-row subsoil
5
0.3b
Values not followed by the same letter are significantly
different by Duncan's new multiple range test at the 0.05
level.


17
As stated by Musick (1970a), not all insect pests will
cause serious problems in no-till culture. Some serious pests
may become less important while the status of some secondary
pests may be changed to that of destructive pests.
In Georgia, All and Gallaher (1977) and All et al. (1979)
reported that infestations by the lesser cornstalk borer (LCB)
were greatly reduced in no-tillage corn. All and Gallaher
(1977) first speculated that higher soil moisture, lower
soil temperatures and greater soil compaction near the surface
in no-till systems were detrimental to the optimum develop
ment and survival of E. lignosellus larvae and, therefore,
responsible for the lower infestations observed in these
systems.
Cheshire et al. (1977) and Cheshire and All (1978) in
a detailed study, however, found that crop residues left on
the ground might be the most important factor in reducing the
LCB damage in no-tillage corn. Crop residues "may inhibit
LCB feeding by disrupting location of host plants by smell or
by mechanically shielding the host plant" (Cheshire and All,
1978, p. 12). The facultative saprophagous larvae consequently
feed on crop stubble instead of attacking crop plants.
All et al. (1979) also found that a combination of con
trol measures applied against E. lignosellus were more effec
tive in no-till blocks than in the conventional tillage.
Early planting, preplanting weed control, and applications
of carbofuran resulted in a better LCB control in untilled
fields than in those conventionally tilled.


NYMPHS/TRAP(LOG x)
SAMPLING PERIOD


115
tillage plots. Since pest populations in the conventional
tillage plots were not significantly higher than those
in the no-till plots, it may be assumed that the beetles
werse attracted by the more favorable edaphic conditions
in these plots rather than by pest populations. The absence
of carabid larvae (only four, not identified, were caught)
in the traps might indicate that most of the carabids
were originating from the neighboring wooded area or fields.
Striped earwig. Data on the foraging activity of
L. riparia are presented in graphs and analyzed on a weekly
basis (in addition to the overall analysis) in order to
show the effect of the tillage practice throughout the
cropping season. Figure 23 shows the weekly activity
of the earwig (all stages combined) in the vetch stubble
experiment in 1978. The overall analysis of the data
indicated that no-tillage practice, as compared to the
conventional tillage, did not significantly affect the
populations of earwigs.
The weekly analysis showed that during the second
week of the sampling period (about four weeks after com
was planted), the Labidura population was significantly
higher in the conventional tillage than in the no-tillage
com. During the third week a significant difference
between treatments was found only for the nymphal population
(not shown separately on the graph) which was higher in
the conventional tillage than in the no-tillage com.


160
The author is a member of the Florida Entomological
Society and the Entomological Society of America.
He is married to the former Lugwadio mi-Konde. They
are the parents of a wonderful four-year-old daughter,
Lukamba Nsunda, and a "troublesome" two-year-old son, Kapela.


52
Table 2. Lesser cornstalk borer infestations in no-tillage
and conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979. Estimations are
based on two different rows observed weekly (for
three weeks) in each replication (four reps/treat.).
Treatment
Infested plants
Total Number Average/row
No tillage into oat stubble
103
4.29a
No tillage plus in-row
subsoil into oat stubble
46
1.92b
Conventional tillage into
oat stubble
34
1.42b
Conventional tillage plus
in-row subsoil into oat
stubble
20
0.83c
k
Values not followed by the same letter are significantly
different at the 0.05 level by Duncan's new multiple range
test.


21
vegetables and legumes (Deitz et al., 1976). Mitchell (1967)
studied the life cycle of P. includens on soybeans.
Hensley et al. (1964) and Canerday and Arant (1966)
reported that soybeans, peanuts, and sweet potatoes were
the most preferred hosts for P. includens. On soybeans the
loopers may inflict severe foliage damage and occasionally
they cause damage to pods in the Gulf states (Deitz et al.,
1976) .
Velvetbean caterpillar. Watson (1916), Douglas (1930,
and Greene et al., (1973) are some of many researchers who
studied the life history and described the stages as well
as feeding and mating behavior of Anticarsia gemmatilis
Hubner. The eggs are laid on all portions of the soybean
plants (Strayer, 1973), and require three days to hatch in
August and September, and at least seven days in November,
in Florida (Watson, 1916).
Watson (1916) and Douglas (1930) reported that the velvet
bean caterpillars were preyed upon and parasitized by many
species of birds and insects, but that the fungus Nomurea
rileyi (Farlow) was the most important natural enemy that
regulates populations of this pest.
The nature of damage caused by A. gemmatilis immatures
to soybeans has been described by Watson (1916), Douglas
(1930) and Hinds and Osterberger (1931). The first three
instars cause less damage as they only remove the lower
epidermis and mesophyll of the leaves. The last three instars


NYMPHS/TRAP (LOGx)
83
2.5 -
.5-
.0-1
I 1 1 1 ¡ I i 1 1
¡2 19 26 3 10 17 24 31 7 14
Sept Oct Nov
SAMPLING PERIOD
Figure 13. Average trap-week collections of Labidura riparia
nymphs from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla.,
September November, 1978. Averages of four
traps per treatment.
conventional tillage
no tillage into com stubble (after rye)
no tillage into corn mulch (after rye)


139
(see Appendix C). Herbicide costs and fuel consumption,
in this case, determine net money returns from the no
tillage farming. If (no cost/benefit analysis was done)
herbicide costs exceeded the saving from reduced fuel
consumption, no-tillage resulted in decreased benefits
in this study.
No-tillage farming resulted in lower yields in soybean
crop systems (see Appendix D). Inadequate weed control
was believed to be the reason for lower yields recorded
from the no tillage. These results confirmed that good
weed control is a prerequisite to acceptable crop yields
from no-tillage systems.


16
had up to more than 90% stand reduction. Musick and Collins
(1971) documented that tillage system may influence the ovi-
position pattern of some insects. Females of the northern
com rootworm, Diabrotica longicomis Say, laid more eggs
in no-till com than in corn planted on conventionally plowed
land.
Some above-ground insects are also expected to cause
higher damage levels in untilled fields than in crops pro
duced by the conventional tillage system (Gregory and Musick,
1976). The European com borer (ECB), Ostrinia nubilalis
(Hubner), overwinters as mature larvae in corn stalks, and
populations of the ECB have been regulated by clean plowing.
Damage due to this pest will be more severe in no-tillage
corn than in plowed corn (Gregory and Musick, 1976). Musick
(1973) and Musick and Suttle (1973) observed that the army-
worm [Pseudaletia unipuncta (Haworth)] females preferentially
oviposited in grassy areas, and that the incidence of army-
worm damage was higher in no-tillage com, especially when
com was seeded directly in grass or fall-planted wheat.
The blackfaced leafhopper, Graminella nigrifrons (Forbes)
transmits two vims diseases to com, the maize chlorotic
dwarf (MCD) and maize dwarf mosaic (MDM). In a study invol
ving no-tillage cropping, carbofuran and hybrid resistance
to the diseases, All et al. (1977) found a greater leafhopper
population in no till than in the conventional tillage, but
no significant difference was observed in yield loss due to
MCD infection. Incidence of MDM was generally very low.


2
reduce soil loss by water and wind erosion (Triplett et al.,
1978). Crop yields obtained from no-tillage systems are
reported to be higher than, or at least equal to, those from
conventionally tilled fields when no tillage is practiced on
well drained soils and weed control is adequate (Rask et al.,
1967; Triplett and Van Doren, 1977; Lai, 1979). A great
saving in energy and labor also results from no tillage.
Rask et al., (1967) estimated that production costs can be
reduced by as much as 75% in no-tillage systems due to the
elimination of tillage operations.
Farmers are increasingly adopting the no-tillage practice
as an alternative to the conventional tillage for crop produc
tion (Blevins et al., 1971). It is predicted that over 90% of
the U. S. crop acreage will be grown under reduced tillage by
the year 2010; at least half of this acreage will be under
no-tillage farming (Triplett and Van Doren, 1977).
Fear of pest problems is one of the main objections to
the adoption of the no-tillage practice by many growers. It
is believed that, since the soil is not disturbed and crop
residues are left on the soil surface in no-tillage systems,
pest problems will be more severe in these systems than in
conventionally tilled fields. Musick (1970a, b) reported
that soil insects such as wireworms, seed corn maggots and
cutworms cause considerable damage to no-tillage com (Zea
ma7s L.) rn Ohio. Some crop diseases also cause more serious
damage to no-tillage crops than to crops planted in conven
tionally tilled fields (Bums, 1973).


154
Miner, F. D. 1966. Biology and control of stink bugs on
soybeans. Ark. Agrie. Exp. Stn. Bull. 708, 40 pp.
Mitchell, E. R. 1967. Life history of Pseudoplusia
includens (Walker) (Lepidoptera: Noctuidae). J.
Georgia Entomol. Soc. 2:53-7.
Mitchell, W. C., and F. L. Mau. 1969. Sexual activity and
longevity of the southern green stink bug, Nezara
viridula. Entomol. Soc. Amer. Ann. 62:1246-7.
Moody, J. E., J. N. Jones, Jr., and J. H. Lillard. 1963.
Influence of straw mulch on soil moisture, soil
temperature and the growth of com. Soil Sci. Soc.
Amer. Proc. 27:700-3.
Morrill, W. L., and G. L. Green. 1973. Distribution of
fall armyworm larvae 1. Regions of field corn plants
infested by larvae. Environ. Entomol. 2:195-8.
Musick, G. J. 1970a. Insect problems associated with no
tillage corn production. Proc. Nat. No-tillage Res.
Conf. Univ. of Kentucky, Lexington, pp. 44-59.
Musick, G. J. 1970b. Problems with no-tillage crops.
Insects. Crops and Soils Magazine. 23:18-9.
Musick, G. J. 1973. Control of armyworm in no-tillage com.
Ohio Rep. 58:42-5.
Musick, G. J., and D. L. Collins. 1971. Northern corn
rootworm affected by tillage. Ohio Rep. 56:88-91.
Musick, G. J., and G. B. Petty. 1974. Insect control in
conservation tillage systems. Conservation tillage.
A handbook for farmers. Soil Cons. Soc. Amer., Ankeny,
Iowa. 52 pp.
Musick, G. J., and P. J. Suttle. 1973. Suppression of
armyworm damage to no-tillage corn with granular
carbofuran. J. Econ. Entomol. 66:735-7.
Neal, T. M. 1974. Predaceous arthropods in the Florida
soybean ecosystem. M. S. Thesis. Univ. of Florida,
Gainesville, 196 pp.
Nickels, C. B. 1926. An important outbreak of insects
infesting soybeans in lower South Carolina. J. Econ.
Entomol. 19:614-8.


Page
Figure
6 Average numbers of velvetbean cater
pillars, Anticarsia gemmatilis,
collected by the plant shaking method
from no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Average of
eight shakes per treatment 76
7 Average numbers of small (up to 1.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Averages of four shakes per treatment 77
8 Average numbers of medium (1.6 2.5 cm)
and large (over 2.5 cm) velvetbean cater
pillars, Anticarsia gemmatilis, collected
by the plant shaking method from no-
tillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co., Fla.,
1979. Averages of four shakes per
treatment 78
9 Average numbers of velvetbean caterpillars,
Anticarsia gemmatilis, collected by the
plant shaking method from no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Average of four shakes per treatment 79
10 Average trap-week collections of Labidura
riparia nymphs from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., April July,
1978. Four pitfall traps were placed in
each treatment 80
11 Average trap-week collections of Labidura
riparia adults from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., April July,
1978. Four pitfall traps were placed in
each treatment 81
xv


152
Hall, W. E. 1959. The effect of plowing methods and dates
of fertilizer application on the incidence of fusarium
root rot in Burt wheat. Plant Dis. Rep. 43:175-6.
Hanway, J. J. 1966. How a com plant develops. Iowa State
Univ. Coop. Ext. Serv. Agrie. Exp. Stn. Spec. Rep. 48.
17 pp.
Hardwick, D. F. 1965. The com earworm complex. Entomol.
Soc. Can. Memoirs 40, 247 pp.
Hassanein, M. H., A. M. Afify, and H. C. Farghaly. 1968.
Comparative laboratory studies of the efficiency of
Labidura riparia Pall, and Coccinella undecimpunetata
Reiche as cottonworm predators. Entomol. Rev. 47:271-3.
Hasse, W. L. 1971. Predaceous arthropods of Florida soybean
fields. M. S. Thesis. Univ. of Florida, Gainesville,
66 pp.
Hensley, S. D., L. D. Newsom, and J. Chapin. 1964. Obser
vations on the looper complex of the noctuid subfamily
Plusinnae. J. Econ. Entomol. 57:1006-7.
Herzog, D. C., J. W. Thomas, R. L. Jensen, and L. D. Newsom.
1975. Association of sclerotial blight with Spissistilus
festinus girdling in-jury on soybean. Environ. Entomol.
4:986-8.
Hill, D. S. 1975. Agricultural insect pests of the tropics
and their control. Cambridge Univ. Press, London,
516 pp.
Hinds, W. E., and B. A. Osterberger. 1931. The soybean
caterpillar in Louisiana. J. Econ. Entomol. 24:1168-73.
Holt, R. F., H. P. Johnson, and L. L. McDowell. 1973.
Surface water quality. Conservation tillage. Proc.
Nat. Conf. Soil Cons. Soc. Amer. Des Moines, Iowa,
pp. 141-56.
Isely, D., and F. D. Miner. 1944. The lesser cornstalk borer,
a pest of fall beans. J. Kans. Entomol. Soc. 17:51-7.
Janes, M. J. 1973. Com earworm and fall armyworm occurrence
and control on sweet com ears in south Florida. J.
Econ. Entomol. 66:973-4.
Jones, J. N., Jr., J. E. Moody, G. M. Shear, and W. W.
Moschler. 1968. The no-tillage system for com (Zea
mays L.). Agron. J. 60:17-20.


10
Wiese and Staniforth (1973) also reported that hemp dogbane
spreads rapidly where the soil is not tilled.
Peters (1972) and Triplett and Lytle (1972) found that
several perennial weed species were tolerant to herbicides.
The common milkweed (Asclepias syriaca L.), horsenettle
(Solanum carolinense L.), groundcherry (Physalis sp.), and
the tall ironweed (Vernonia altissima Nutt.), are some of
those weed species that survive in untilled fields. Lewis
(1970) concluded that bermudagrass [Cynodon dactylon (L.)
Pers.], johnsongrass [Sorghum halepense (L.) Pers.], and
dallisgrass (Paspalum dilataturn Poir) cannot be effectively
controlled chemically in no-tillage systems.
Some of the herbicide applied in untilled, mulched
fields may be intercepted by crop residues; this reduces the
amount of the chemical that reaches the target species (Trip
lett 1976) .
Crop diseases in no tillage. The problem of crop
diseases in conservation tillage has been investigated by
several workers including Bums (1973), Roane et al. (1974),
Yarham (1975), and White and Janney (1978). A large number
of plant pathogens inhabit or overwinter in crop residues
and the soil. They readily move to the new crop as soon
as weather conditions become favorable and susceptible
host plants are available (Graham, 1953; Kennedy, 1969;
Daft and Leben, 1973).


121
Table 24. Infestations of the fall armyworm, Spodoptera
frugiperda, and corn earworm, Heliothis zea, in
no-tillage and conventional tillage field com
at Green Acres, Alachua Co., Fla., 1979.
Inf
ested plants*
%
Treatment
Average
No./row
(on row
basis)
(on 120
plant basis)
No tillage into wheat stubble
31.42
68.94
91.67
No tillage plus in-row subsoil
into wheat stubble
35.25
71.80
92.09
Conventional tillage
26.96
60.30
87.50
Conventional tillage plus
in-row subsoil
30.71
64.54
88.75
a
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


5
(1973) observed that on poorly drained fine-structured soils,
no-tillage com gave lower yields than did the conventional
tillage com.
Musick (1970a, b) reported that conditions created in
no-tillage systems (crop residues, high soil moisture and
low temperatures) are conducive to pest activity. Pest
problems are believed to be the principal disadvantage farm
ers associate to the no-tillage practice. Several pest
organisms overwinter in plant residues, and readily attack
the new crop when conditions become favorable. In conven
tional soil tillage such pests are usually controlled by
physical destruction, exposure to unfavorable weather, and
natural enemies.
Advantages. Among the numerous advantages of the no
tillage practice, the more important are those associated
with protection of soil from erosion, reduction in energy
input required for crop production, as well as increased
crop growth and yields due to higher soil moisture. Moody
et al. (1963) and Jones et al. (1968) found that soil
moisture was higher in the no-tillage than in the conven
tional tillage com, and that this higher soil moisture
significantly increased com growth and yields. Mulched
com was 64 cm taller at tasseling and produced 47 kg/ha
more grain than conventional tillage com (Moody et al.,
1963). Triplett et al. (1968) also observed a significant


69
Table 19. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Green Acres, Alachua Co., Fla.,
June September, 1978. Totals of four traps per
treatment for 14 weeks.
Species
Treatment*
CT
CT+s
NOS
NOS+s
Anisodactylus merula Germar
8
8
80
23
Calosoma sayi Deiean
18
14
6
8
Colliuris pennsylvanica (L.)
2
1
1
1
Galerita janus Fab.
0
0
0
1
Harpalus caliginosus Fab.
0
0
1
0
H. pennsylvanicus DeGeer
19
39
60
27
Pasimachus subsulcatus Say
0
0
2
0
Scarites subterraneus (Fab.)
*
0
0
0
1
CT-conventional tillage
CT+s-conventional tillage plus in-row subsoil
NOS-no tillage into oat stubble
NOS+s-no tillage plus in-row subsoil into oat stubble


37
row was 4.29 and 1.42, respectively for the no tillage and
conventional tillage. In-row subsoil had a significant impact
on the borer infestations. The average number of infested
plants was significantly lower in the no tillage plus subsoil
than in the no tillage without subsoil. Infestations were
also lower in the conventional tillage with subsoil than in
the conventional tillage without subsoil (Table 2).
Damage to soybean seedlings was very low during the
two seasons at both Willis ton and Green Acres. The method
used here to determine borer infestations, although commonly
used, certainly underestimated infestation levels because
only wilted and dead plants were detected and counted. Older
seedlings do not wilt when infested. Collecting randomly
a certain number of plants, wilted or not, throughout the field
and examining roots and lower portions of the stems for borer
infestation might have resulted in a better estimation of
the damage.
In one experiment, the results showed that no-tillage
systems were not conducive to the buildup of lesser cornstalk
borer infestations as compared to the conventional tillage.
Results from another experiment, however, showed that E.
lignosellus can be a more serious threat to no-till soybeans
than to the conventionally tilled soybeans. The lesser
cornstalk borers may remain in weeds or crop debris from
which they migrate to attack crop seedlings (All and Gallaher,
1977). Crop residues and the lack of soil disturbance in


65
Table 15. Activity of the striped earwig, Labidura riparia,
in no-tillage and conventional tillage "Cobb"
soybeans estimated by pitfall traps at Green
Acres, Alachua Co., Fla., 1978. Numbers are
averages of 14 weeks with four traps per treat
ment. Half of each plot was treated with
carbofuran (F) at planting, the other half was
untreated (C).
Average Number/trap*
Treatment Nymph Adult Nymph + Adult
No tillage into oat stubble
C
38.64
22.09cd
60.73cd
F
42.88
24.48bc
67.36bc
No tillage plus in-row
subsoil into oat stubble
C
35.57
19.16d
54.73d
F
43.13
20.38d
63.50cd
Conventional tillage into
oat stubble
C
44.39
35.57a
79.96ab
F
52.68
34.OOab
86.68ab
Conventional tillage
plus in-row subsoil
C
51.84
37.48ab
89.32ab
F
49.50
33.13a
82.63a
Analysis of variance not significant for nymphs. Values
followed by the same letter in each column are not signif
icantly different at the 0.05 level by Duncan's new multiple
range test.


70
Table 20. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Green Acres, Alachua Co., Fla.,
June September,
treatment for 15
1979.
weeks.
Totals
of four
traps per
Species
CT
Treatment*
CT+s NOS
NOS+s
Anisodactylus merula Germar
2
5
4
4
Calosoma sayi Deiean
3
2
8
6
C. scrutator (Fab .)
1
0
0
0
Chlaenius tomentosus Say
2
1
0
0
Colliuris pennsylvanica (L.)
1
0
0
0
Galerita lecontei Deiean
2
0
1
5
Harpalus caliginosus Fab.
0
0
0
1
H. pennsylvanicus DeGeer
5
5
15
7
Scarites subterraneus (Fab.)
-P
1
0
0
0
CT-conventional tillage
CT+s-conventional tillage plus in-row subsoil
NOS-no tillage into oat stubble
NOS+s-no tillage plus in-row subsoil into oat stubble


46
plus in-row subsoil than in any of the no-tillage treatments.
The conventional tillage plus in-row subsoil also harbored
significantly more earwigs than the conventional tillage
without subsoil. Adult populations were significantly
higher in no tillage into rye stubble and no tillage into
rye mulch than in the conventional tillage (Table 13).
No till into rye stubble did not significantly differ from
no till into rye mulch.
Figures 10, 11 and 12 show the weekly trend of nymphal,
adult and total populations of Labidura respectively in
no tillage into rye stubble, no tillage into rye mulch
and conventional tillage treatments. Earwig populations
remained higher in the no tillage into rye mulch than in
any of the other two treatments during the first half of
the sampling period.
Earwig populations were very high in the second season
at Williston. An average of up to 245.77 nymphs and adults
per trap were collected from one treatment (Table 14).
Although populations appeared to be highest in the no till
plus in-row subsoil into com mulch, analysis of the data
did not detect any significant differences between treatment
means. This was also shown by Figures 13, 14, and 15
which illustrate weekly foraging activity of the earwigs
in the conventional till, no till into rye-corn stubble
and no till into rye-corn mulch.


Figure 20. Weekly activity of Labidura riparia adults monitored by pitfall
traps (four in each treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua Co., Fla., 1979.
: no tillage into oat stubble
: conventional tillage


NYMPHS/TRAP (LOGx)
2.5-
0.5 -
CO
i i i i i t i i i i i i r
30 7 14 21 28 4 II 18 25 I 8 15 22 29
June July Aug Sept
SAMPLING PERIOD


156
Shipley, J. L., and J. E. Osborn. 1973. Costs, input, and
returns in arid and semiarid areas. Nat. Cons. Tillage
Conf., Des Moines, Iowa. Soil Cons. Soc. Amer., Ankeny,
Iowa. pp. 168-79.
Sloderbeck, P. E., and C. R. Edwards. 1979. Effects of
soybean cropping practices on Mexican bean beetle and
redlegged grasshopper populations. J. Econ. Entomol.
72:850-3.
Stone, M. W. 1941. Life history of the sugar-beet wireworm
in south California. U. S. D. A. Tech. Bull. 744, 88 pp.
Strayer, J. R. 1973. Economic threshold studies and
sequential sampling for management of the velvetbean
caterpillar, Anticarsia gemmatilis Hubner, on soybeans.
Ph. D. Dissertation, Clemson Univ., N. C. 87 pp.
Strayer, J. R., and G. L. Green. 1974. Soybean insect
management. Florida Coop. Ext. Serv. Circ. 395. 15 pp.
Tawfik, M. F. S., S. Abul-Nasr, and M. M. El-Husseini. 1972.
The biology of Labidura riparia (Pallas). Bull. Soc.
Entomol. Egyptel 56:75-92.
Thiele, H. U. 1977. Carabid beetles in their environments:
A study on habitat selection by adaptations in physi
ology and behaviour. Springer-Verlag, New York. 369 pp.
Triplett, G. B., Jr. 1966. Herbicide systems for no-tillage
com (Zea mays L.) following sod. Agron. J. 58:157-9.
Triplett, G. B., Jr. 1976. Management of weeds in reduced
tillage systems. Bull. Entomol. Soc. Amer. 22:298-9.
Triplett, G. B., Jr., B. J. Conner, and W. M. Edwards. 1978.
Herbicide runoff from conventional and no-tillage
cornfields. Ohio Rep. 63:70-3.
Triplett, G. B., Jr., and G. D. Lyttle. 1972. Control and
ecology of weeds in continuous com grown without
tillage. Weed Sci. 20:453-7.
Triplett, G. B., Jr., and D. M. Van Doren, Jr. 1977.
Agriculture without tillage. Sci. Amer. 236:28-33.
Triplett, G. B., Jr., D. M. Van Doren, Jr., and B. L. Schmidt.
1968. Effect of corn (Zea mays L.) stover mulch on no
tillage corn yields and water infiltration. Agron. J.
60:236-9.


119
Table 22. Damage caused by the fall armyworm, Spodoptera
frungiperda, and corn earworm, Heliothis zea, to
no-tillage and conventional tillage field com at
Green Acres, Alachua Co., Fla., 1979. Numbers are
averages of 120 plants per treatment (each week)
for five weeks for foliage and four weeks for ears.
Com infestation*
Treatment
Avg.
plants
No./row
ears
% infestation
plants ears
No tillage into vetch stubble
0.38
2.75
1.50
10.61
No tillage plus in-row subsoil
into vetch stubble
0.50
3.60
2.00
14.60
Conventional tillage
0.65
1.97
1.50
5.36
Conventional tillage plus
in-row subsoil
0.44
3.38
0.83
9.95
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


LARVAE /SHAKE
71
SAMPLING PERIOD
Figure 1. Average numbers of small (up to 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and
conventional tillage "Cobb" soybeans at Williston,
Levy Co., Fla., 1978. Averages of eight shakes
per treatment.
: conventional tillage
: no tillage into com stubbie
0: no tillage into com mulch
Arrow indicates insecticidal treatment


113
Carabid beetles. Species and numbers of carabid
beetles collected in pitfall traps from the vetch stubble
experiment are in Tables 32 and 33, respectively for the
1978 and 1979 crop seasons. Five species were recorded
in the 1978 experiment, and all, except Galerita lecontei
(Dejean), were classified as very rare species, according
to Rivard's (1964) scale: "Very rare, 10 specimens or
less; Rare, 11 to 50; Common, 51 to 200; Abundant, over
200". Galerita lecontei was a rare species; 48.15% of
all the carabid predators collected were G. lecontei with
69.23% of the specimens being collected from the conventional
tillage plus in-row subsoil. None of the G. lecontei speci
mens was recorded from the no tillage, and only one specimen
was caught from the no tillage plus in-row subsoil (Table
32) .
In 1979, the number and species of carabids increased,
and 12 different species were recorded (Table 33). Only
G. lecontei, Harpalus pennsylvanicus DeGeer, and Selenophorus
pallia tus Fab. were rare species; the others were very
rare. About 47% of the carabids were collected from the
conventional tillage plus in-row subsoil; 30% were recorded
from the conventional tillage without subsoil. No till
and no till with subsoil harbored respectively 11.96 and
9.78% of the carabids collected.
The number of carabid beetles in the wheat experiment
was relatively low during the two cropping seasons. Twelve


38
no-tillage systems would seem to explain why infestations
were higher than those observed in the conventional tillage
at Green Acres. However, crop debris left on the ground
have been reported to reduce E. lignosellus infestations in
no-tillage corn (All et al., 1979).
Above-Ground Pest Insects
Three-cornered alfalfa hopper. Hopper populations
were monitored during 1978 and 1979 only at Green Acres.
The plant shaking method was used in 1978, but was abandbned
in 1979. The number of Snissistilus festinus (Say) collected
was very low and most were nymphs thus confirming Boyer's
(1967) earlier conclusion regarding inadequacy of the method.
Therefore, during the 1979 season the sweep net was used,
and numbers of S^. fes tinus collected were relatively high.
The average numbers of hoppers recorded from each tillage
system are shown in Table 3 for both the 1978 and 1979 crop
seasons.
The data indicated the hopper populations were statis
tically the same in all tillage treatments in 1978. Although
the average number of hoppers was about three times higher
in the no-tillage soybeans than in the conventional tillage
plots in 1979, analysis of the data did not show any signif
icant differences between treatment means. Spissistilus
festinus did not manifest any preference for no-tillage
soybeans as compared to the conventional tillage.


33
same cultivar of soybeans was planted in all the plots on
June 3, 1978. The entire field was fertilized with 448
kg/ha of 5-4.4-12.5 N-P-K applied at planting. Metribuzin
(0.28 kg a.i./ha), linuron (1.12 kg a.i./ha), and paraquat
(0.42 kg a.i./ha) were also applied during the planting
operation for weed control. No-tillage plots were also
treated (directed sprays) with paraquat (0.28 kg a.i./ha) plus
X-77 (surfactant) on June 29 and July 19, 1978. Each tillage
treatment was divided into two portions; one half of the
plot was treated with carbofuran at the rate of 1.12 kg a.i./ha
to control soil insects. The other half was untreated and was
used as a control. When populations of velvetbean caterpillars
and stink bugs became high, all the plots were sprayed with
methomyl (0.56 kg a.i./ha) on August 17 and September 7,
and with acephate (0.84 kg a.i./ha) on September 13, 1978.
This experiment was repeated on the same block in 1979.
"Cobb" soybeans were planted on June 12, 1979, according
to the same cultural procedure as in the 1978 season except
that carbofuran (or any other insecticide) was not used
at planting. The plots were sprayed with acephate on August
30, 1979, to control the velvetbean caterpillars and on
October 5, for stink bug control.
Estimation of Tillage Effects on Insects
Soil arthropods. Damage caused by the lesser cornstalk
borer was assessed by visual observations. Two different
rows were randomly selected in each replication every week,


108
When this experiment was repeated in the 1979 season,
no-tillage cropping did not significantly affect infestation
levels (Table 30), although the percentage of damaged
plants and the average number of infested plants per row
appeared to be slightly higher in conventionally tilled
plots than in untilled plots. In general, infestations
were higher during this season than in the previous season.
The average damage level for the whole field was only
2.89% of the plants infested in 1978, but 8.20% in 1979.
The results collected during the two years indicated
that E. lignosellus infestations were higher in the late
planted com (wheat stubble experiment) than in the early
planted com. The entire field in the vetch stubble experi
ment was treated with carbofuran at planting in 1978.
It was not possible, therefore, to determine whether the
low infestations observed in this field were due to the
insecticide or to the early planting (as reported by Leuck,
1966). Infestations might also have been naturally low
during that season. Half of the rows in the wheat stubble
experiment were treated, at planting, with carbofuran
in 1978. No significant differences in numbers of damaged
plants were found between treated and untreated rows within
a same tillage system. Carbofuran apparently did not
influence lesser cornstalk borer infestations. This may
be because infestation levels were naturally low during
the season.


44
populations of small larvae were consistently lower in the
no-tillage than in the conventional tillage except for the
weeks of August 23 and September 13. No-tillage treatments
did not significantly affect medium and large larval popula
tions (Table 12 and Figure 8).
The exact reason for fewer small larvae observed in
the no tillage than in the conventional tillage is not known.
This might have been an indication that A. gemmatilis moths
preferred to oviposit in the conventional tillage soybeans
which were cleaner than the no-tillage soybeans with some
weeds and crop resideus. Sloderbeck and Edwards (1979)
found that adults and larvae of the Mexican bean beetle
preferred tilled to nontilled soybeans. The authors believed
that this might have been due to "a preference of adult
beetles for the tilled soybeans" which were almost free of
weeds and residues.
Soil-Inhabiting Predators
Ground spiders. Populations of ground spiders were
monitored at Green Acres along with those of soil insects.
Since no attempt was made to identify the different species
of spiders collected in pitfall traps, all the species will
be collectively referred to as ground spiders.
In 1978 spider populations were statistically identical
in conventional tillage and no-tillage plots. The weekly
average numbers were 1.0 and 1.7 spiders per trap, respectively,


14
In the lower Rio Grande Valley of Texas, Fife and
Graham (1966) obtained a 100% control of both H. zea and
the tobacco budworm [Heliothis virescens (Fab.)] after
listing, disking and relisting the land in combination with
a preplanting irrigation. Listing the land alone reduced
the emergence of H. zea moths from pupae by about 55% in a
pepper field.
When the larvae of these two species are fully grown,
they leave their host plants and burrow into the soil to
pupate in pupal cells. According to Fife and Graham (1966),
these pupal cells are located at 1.27-15.24 cm below, and
their tunnels extend near, the soil surface. Cultivation
destroys most of the cells and tunnels in addition to the
physical pupal destruction.
Destruction of stalk and other plant parts is also used
to regulate insect pest populations (Metcalf, 1909). Several
insect pest species remain in crop residues between cropping
seasons and attack the new crop as soon as it is available.
Adeyemi (1969) showed that stem borers such as Busseola
fusca (Fuller), Sesamia calamistis Hamps., etc., can survive
in corn stalks from season to season in large enough numbers to
initiate borer infestations of the succeeding crop. An average
borer population of 27 per 100 stems examined was found in
stubble after the first-season corn harvest.
Fenton and Owen (1953), Noble (1955), and Fife et al.
(1957) reported burial of cotton (Gossypium spp.) residues


Table 34. Numbers and species of carabid predators collected in pitfall traps from
no-tillage and conventional tillage field corn at Green Acres, Alachua Co.,
Fla., July August, 1979.
Species
NWS
Treatment
NWS+s CT
CT+s
Tot.
%
Index**
Calosoma sayi De/jean
1
1
0
0
2
16.7
VR
Colliuris pennsylvanica (L.)
0
0
1
0
1
8.3
VR
Harpalus caliginosus Fab.
1
0
0
0
1
8.3
VR
Pasimachus sublaevis Beauv.
1
0
1
0
2
16.7
VR
Selenophorus palliatus Fab.
2
2
1
1
5
50.0
VR
Total
5
3
3
1
12
1
41.7
25.0
25.0
8.3
*NWS: no tillage into wheat stubble; NWS+s: no tillage plus in-row subsoil into wheat
stubble; CT: conventional tillage; CT+s : conventional tillage plus in-row subsoil.
**VR: very rare, 10 specimens or less; R: rare, 11 to 50 specimens (Rivard, 1964).
131


66
Table 16. Number of striped earwig, Lab idura riparia,
collected in pitfall traps in no-tillage and
conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979. Numbers are
averages of 15 weeks and four traps per treat
ment. All the plots were treated twice with
acephate for insect control.
Average/trap*
Treatment
Nymphs
Adults
Nymphs + Adults
No tillage into oat stubble
26.95
21.13
48.08
No tillage plus in-row
subsoil into oat stubble
41.30
24.42
65.72
Conventional tillage
into oat stubble
43.55
36.12
79.67
Conventional tillage plus
in-row subsoil into oat stubble
x
34.20
41.63
75.83
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


INFESTED PLANTS AND EARS
132
Damage On Foliage Damage On Ears
SAMPLING PERIOD
Figure 22. Weekly damage to field com foliage and ears
caused by Spodoptera frugiperda and Heliothis
zea at Green Acres, Alachua Co., Fla., 1978.
no tillage into vetch stubble
conventional tillage


50.
carabid beetles collected were P. sublaevis. Anisodactylus
merula was the next abundant (11.61%) species collected.
Populations of carabid beetles were relatively high
at Green Acres in the 1978 oat stubble experiment where
a total of 320 carabids were collected (Table 19). Harpalus
pennsylvanicus De Geer, A. merula and Calosoma sayi Dejean
were the most abundant species counting for 45.31, 37.19,
and 14.38% of the total, respectively. The no till into
oat stubble had the highest (46.86%) carabid population,
and the conventional tillage had the lowest with 14.69%.
In 1979, the numbers were low at Green Acres; 81 individuals
only were collected, with 34.57% from the no-tillage soybeans
and 20.98% from the conventionally tilled plots. Harpalus
pennsylvanicus and C. sayi were the most prevalent species
representing 39.51 and 23.46%, respectively. The species
and numbers of carabid beetles collected at Green Acres
in 1979 are shown in Table 20.
Data collected over two years showed that no-tillage
systems significantly increased the activity of carabid
beetles. However, catches of most species were so erratic
and their numbers so low that it is not believed that
carabid beetles played any important role in regulating
pest populations.


NYMPHS + ADULTS/TRAP (LOG x )
2.5-
1 1 1 1 1 i 1 r i i i i r
30 7 14 21 28 4 II 18 25 I 8 15 22 29
June July Aug Sept
SAMPLING PERIOD


Figure
1
2
3
4
LIST OF FIGURES
Page
Average numbers of small (up to 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Williston, Levy Co., Fla., 1978.
Averages of eight shakes per treatment 71
Average numbers of large (over 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Williston, Levy Co., Fla., 1978.
Averages of eight shakes per treatment 7 2
Average number of velvetbean cater
pillars, Anticarsia gemmatilis,
collected by the plant shaking method
from no-tillage and conventional
tillage "Cobb" soybeans at Williston,
Levy Co., Fla., 1978. Averages of
eight shakes per treatment 73
Average numbers of small (up to 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla.,
1978. Averages of eight shakes per
treatment 74
Average numbers of large (over 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1978.
Averages of eight shakes per treatment 75
xiv


CHAPTER III
CORN CROP SYSTEMS
Materials and Methods
Cultural Practices
Vetch stubble experiment. Experiments on the effect
of no tillage practice on insects in com crop systems
were conducted in two different fields at Green Acres.
One field will be referred to as the vetch stubble
experiment and the other as the oat stubble experiment.
The vetch stubble experiment was run in a 92-m-long field
divided into eight plots and previously planted to "Hairy
vetch" (Vicia villosa Roth). Four tillage treatments
were compared in this experiment, namely no tillage into
vetch stubble, no tillage plus in-row subsoil into vetch
stubble, conventional tillage (vetch plowed under), and
conventional tillage plus in-row subsoil. Each treatment
was replicated four times in a randomized complete block
design.
The soil in the conventional tillage plots was prepared
with a moldboard plow (April 9, 1978) and a rototiller
(April 16, 1978), with vetch plowed under as green manure.
In no-tillage treatments com was seeded into the residues
of the vetch. On April 19, 1978, all the plots were planted
98


124
Table 27. Number of Conoderus amplicollis (Gyll.) and C.
falli Lane (Elateridae) collected in pitfall
traps from conventional tillage and no-tillage
field com at Green Acres, Alachua Co., Fla.,
1979. Numbers are totals and averages of nine
weeks for vetch and six weeks for wheat with
four traps per treatment.
Total
Number
Average/trap*
Treatment
Vetch
stubble
Wheat
stubble
Vetch
stubble
Wheat
stubble
No tillage
466
150
12.94
6.25
No tillage plus
in-row subsoil
368
207
10.22
8.62
Conventional tillage
389
265
10.80
11.04
Conventional tillage
plus in-row subsoil
280
173
7.78
7.21
In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's com
parisons were not made.


Table 17.
Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Williston, Levy Co., Fla.,
April July, 1978. Totals of four traps per
treatment for 12 weeks.
Species
CRS
CRS+s
Treatment*
NRS NRS+s NRM
NRM+s
Anisodactylus merula Germar
0
1
4
0
3
0
Calosoma sayi Deiean
0
0
1
0
0
0
Chlaenius laticollis Say
0
0
1
1
0
1
Colliuris pennsylvanica (L.)
0
2
4
5
1
5
Harpalus caliginosus Fab.
0
4
2
1
0
2
H. pennsylvanicus DeGeer
0
0
1
0
1
-L
0
Pasimachus sublaevis Beauv.
0
0
1
1
3
3
Scarites subcerraneus (Fab .)
*
0
1
1
0
0
0
CRS-conventional tillage into rye stubble
CRS+s-conventional tillage plus in-row subsoil into
rye stubble
NRS-no tillage into rye stubble
NRS+s-no tillage plus in-row subsoil into rye stubble
NRM-no tillage into rye mulch
NRM+s-no tillage plus in-row subsoil into rye mulch


AVERAGE NUMBER/TRAP(LOGx)
134
27 4 II 18 25 I 8 15 22 29 6
April May June July
SAMPLING PERIOD
Figure 24. Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field com at Green Acres, Alachua Co.,
Fla. 1979.
no tillage into vetch stubble
conventional tillage


49
July, 1978, in rye stubble at Williston. The different
species recorded are in Table 17. Colliuris pennsylvanica
(L.) was the most abundant carabid species, representing
34% of all the species collected. Harpalus caliginosus Fab.
was the next species with 18%. Anisodactylus merula Germar
and Pasimachus sublaevis Beauv. each comprised 16% of
the total population.
With respect to tillage systems, the results indicated
that carabids were more active in no-tillage plots than
in conventional tillage plots. No carabid beetles were
collected from the conventional tillage during the entire
sampling period (Table 17). The conventional till plus
in-row subsoil, like no till plus in-row subsoil and no
tillage into rye mulch, harbored 16% of the beetles each.
The majority of carabids were collected from no till into
rye stubble (30%) and no tillage plus in-row subsoil into
rye mulch (22%).
The total number of carabid beetles collected from
no-till and conventional till soybeans increased to 112
in the corn stubble experiment at Williston. Table 18
shows the different species and numbers of beetles recorded.
The highest population (25.89%) of carabids was recorded
from the no till plus in-row subsoil into com stubble.
No tillage into com stubble harbored 18.75% of the carabids
collected, and the conventional till contained the lowest
(12.50%) population of carabid beetles. Over 43% of the


Figure 18. Weekly activity of Labidura riparia (nymphs + adults) monitored by
pitfall traps in no-tillage and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1978. Four traps were placed in
each treatment.
: no tillage into oat stubble
: conventional tillate


Page
C YIELD OF "DEKALB XL 78 A" CORN FROM GREEN
ACRES 144
D AVERAGE YIELDS OF "COBB" SOYBEANS 146
LITERATURE CITED 148
BIOGRAPHICAL SKETCH 159
vii


LARVAE/SHAKE (
78
SAMPLING PERIOD
Figure 8. Average numbers of medium (1.6 2.5 cm) and large
(over 2.5 cm) velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method
from no-tillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co., Fla., 1S79.
Averages of four shakes per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.


27
Neal (1974) recorded three species of Pasimachus
in north Florida soybean fields. Only one species, P.
sublaevis Beauvois, was common; the other two, P. subsul-
catus Say and P. strenuus LeConte, were collected once
and twice, respectively. Blatchley (1910) reported that
Pasimachus spp. feed on a variety of larvae. In soybean
fields Neal (1974) observed P. sublaevis preying upon
various insects including larvae of C. sayi, velvetbean
caterpillars, and crickets.
Three species of the genus Harpalus were collected
in pitfall traps in Quincy, Florida (Neal, 1974). The H.
caliginosus (Fabr.) was the least common, H. gravis LeConte
was active from August to mid-September, and H. pennsyl-
vanicus De Geer was active from mid-August to the middle
of October. Harpalus pennsylvanicus was found feeding
on larvae and pupae of A. gemmatilis and Gryllus spp. nymphs.
Plant matter was also found in the gut content (Neal, 1974).
Progaleritina spp. are reported to feed only on arthro
pods; no plant material was found in their gut (Neal, 1974).
Adults were observed feeding upon various noctuid larvae,
Mexican bean beetle larvae, and cricket nymphs. Progaleritina
lecontei Dejean is the most common of the three species
(P. ianus, P. bicolor) found in north and central Florida.
Adults are active in soybean fields from mid-August through
the middle of September (Neal, 1974).


Table
Page
12 Populations of the velvetbean caterpillar,
Anticarsia gemmatilis, estimated by the
plant shaking method in no-tillage and
conventional tillage "Cobb" soybeans at
Green Acres, Alachua Co., Fla., 1979.
Numbers represent four weekly shakes per
treatment for ten weeks. Soybeans were
treated twice with acephate for insect
control 62
13 Activity of the striped earwig Labidura
riparia (Pallas), in no-tillage and
conventional tillage "Cobb" soybeans esti
mated by pitfall traps at Williston, Levy
Co., Fla., 1978. Four traps were used
for each treatment for 11 weeks 63
14 Activity of the striped earwig, Labidura
riparia, in no-tillage and conventional
tillage late-planted "Cobb" soybeans
estimated by pitfall traps at the Robinson
farm, Williston, Levy Co., Fla., 1978.
Numbers are averages of three traps per
treatment for ten weeks. Plots were
treated once with methomyl for the control
of velvetbean caterpillars 64
15 Activity of the striped earwig, Labidura
riparia, in no-tillage and conventional
tillage "Cobb" soybeans estimated by
pitfall traps at Green Acres, Alachua Co.,
Fla., 1978. Numbers are averages of 14
weeks with four traps per treatment. Half
of each plot was treated with carbofuran (F)
at planting, the other half was untreated (C)... 65
16 Number of striped earwig, Labidura riparia,
collected in pitfall traps in no-tillage
and conventional tillage "CObb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Numbers are averages of 15 weeks and four
traps per treatment. All the plots were
treated twice with acephate for insect
control 66
17 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Williston, Levy Co., Fla., April July,
1978. Totals of four traps per treatment
for 12 weeks 67
x


35
to dislodge the insects which then fell onto the cloth. The
insects were counted and numbers recorded by species. The
shake cloth method was also used in the 1978 experiments
to estimate population levels of the three-cornered alfalfa
hoppers. Because adult hoppers fly quickly when disturbed,
this method was abandoned in 1979. The sweep net method,
as described by Boyer (1967) (method 1) was used instead.
Stink bug damage to seeds was determined (at Green
Acres only) at the end of the season when the beans were
dry and ready to be harvested. Three soybean plants were
randomly chosen in each replication while walking diagonally
across the plot. A total of 12 plants were observed for
each treatment. All the pods were collected from each
plant and placed into a paper bag. The bags containing the
pods were brought into the laboratory and the seeds were
examined for stink bug damage. The total number of seeds
as well as number with at least one feeding puncture were
recorded. The number of small, wrinkled seeds was also
recorded. The number of plants selected per replication
was increased to five in the 1979 experiment. This increase
resulted in 20 plants observed per treatment.
All the data were transformed (log. transformation for
numbers and arcsin transformation for percentages) before
they were submitted to the statistical analysis.
An effort was made to relate fluctuations of pest
and predator populations to the phenology of the plants.


Table 12. Populations of the velvetbean caterpillar,
Anticarsia gemmatilis, estimated by the plant
shaking method in no-tillage and conventional
tillage "Cobb" soybeans, at Green Acres, Alachua
Co., Fla., 1979. Numbers represent four weekly
shakes per treatment for ten weeks. Soybeans
were treated twice with acephate for insect
control.
Average Number
Larvae/shake*
Treatment
Small
Medium
Large
Total
No tillage into oat stubble
11.43a
1.93c
1.78d
15.14e
No tillage plus in-row
subsoil into oat stubble
16.13b
2.85c
2.15d
21.13f
Conventional tillage into
oat stubble
17.15b
2.68c
l.lOd
20.93f
Conventional tillage plus
in-row subsoil into oat
stubble
7?
16.38b
2.90c
1.65d
20.93f
Values in each column followed by the same letter are not
significantly different at the 0.05 level by Duncan's new
multiple range test.


117
numbers of adults remained statistically the same in all
the plots. Lower nymphal populations in untilled plots
may be an indication that adult earwigs preferentially
moved to the tilled plots to breed (to oviposit) while
they indiscriminately spread into all the treatment plots
for foraging activity.


ADULTS/TRAP (LOGx)
2.5-
( r | | i i | | i | r
30 7 14 21 28 4 II 18 25 I 8 15 22 29
June July Aug Sept
SAMPLING PERIOD


39
Soybean looper. Early-planted (April-July, 1978) soy
beans in the Williston rye stubble experiment were not
infested by the soybean looper, P. includens, and only trace
numbers of loopers were recorded in the com stalk experiment
(late planted, August) at Williston. Numbers of loopers
recorded in both 1978 and 1979 seasons at Green Acres are
shown in Table 4. Looper populations were relatively low
during the two seasons, but were higher in 1978 than in 1979.
An average of 1.04 and 1.34 loopers per shake was recorded
respectively from the no tillage and conventional tillage
in 1978. In 1979, only 0.67 and 0.33 loopers per shake
were collected from both treatments, respectively.
Such low looper populations were not believed to have
caused significant damage to soybeans. No significant
differences were detected between treatments for P. includens
populations estimated by the plant shaking method. The no
tillage farming did not effect oviposition by Pseudoplusia
moths (which may be attracted by plant residues) or the
development of the larvae.
Southern green stink bug. The southern green stink
bug, Nezara virdula (L.), was the most abundant of all
species of stink bugs observed during the two years. The
brown stink bug, Euschistus servus (Say), was the next
abundant, but in trace numbers. Average numbers of N.
viridula collected by the plant shaking method from Williston
and Green Acres soybeans are shown in Tables 5, 6, and 7.


11
The lack of soil disturbance as well as the presence
of decaying plant material left on the ground may increase
the incidence of the diseases in no-tillage fields. Boosalis
and Doupnik (1976) reported that fungus and bacterial diseases
are the principal diseases associated with reduced tillage.
Ledingham et al. (1960) compared root rot incidence in
wheat (Triticum aestivum L.) grown in two tillage systems, a
surface tillage that left a trash cover on the ground, and
a moldboard-piowed stubble soil. The authors found that
plowing was effective in reducing disease incidence during
the seedling stages, but no significant difference was ob
served in infection levels as the crop matured.
Bums (1973) reported that the brown spot of corn
caused by Physoderma mavdis, a fungus that overwinters in
infested com debris, was more severe in reduced tillage
plots than in conventionally tilled plots. Burns (1973)
also reported that both the virus that causes wheat streak
mosaic and the mites that transmit it overwinter on living
wheat and perennial grasses, and that the greatest damage to
wheat was observed in fields planted close to wheat stubble.
Several reports have indicated that crop plants on no
tillage soil are not affected differently from these on con
ventionally plowed land. In some instances, conservation till
age practices were even reported to reduce disease incidence.
Keyworth (1942) in England demonstrated that soil
cultivation was the major factor for the spreading of the


This dissertation was submitted to the Graduate Faculty of the
College of Agriculture and to the Graduate Council, and was
accepted as partial fulfillment of the requirements for the
degree of Doctor of Philosophy.
March 1980
Dean, Graduate School


7
reduced tillage systems as an alternative for shifting
cultivation widely practiced in the tropics. The tradi
tional system of shifting cultivation protects the soil from
erosion, but, according to Lai (1973), it supports only one
person on 15 ha of land and continuous cropping under this
system may ruin the soils.
The main advantage of the no tillage is undoubtedly
the tremendous reduction in crop production costs that result
from reduced machinery use and associated reduction in fuel
consumption. A great saving in time and labor also results
from the no-tillage practice. The economics of the no tillage
is reviewed in the next section.
Economics of No-Tillage Systems
The economic aspect is the most important factor con
sidered by the farmers in accepting the "new" crop production
practice. As discussed by Shipley and Osborn (1973), conser
vation tillage must produce a net return equal to, or greater
than, that obtained with the conventional tillage if the
farmer is to switch from the conventional to the conserva
tion tillage.
Rask et al. (1967) obtained a reduction of as much as
75% in production costs and a saving in time of 70-80% in
no-tiliage corn. Doster (1976) calculated production costs
in conventional and conservation tillage systems in Indiana
and found that no tillage with coulter disc was the cheapest,


51
Table 1. Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus (Zeller), in no
tillage and conventional tillage "Cobb" soy
beans at Williston, Levy Co., Fla., 1978.
Numbers are totals and averages of two rows
per replication for three weeks.
k
Treatment
Infested plants
kk
Total Number Average/row
No tillage into corn
stubble (in rye residue)
46
1.92
No till plus in-row subsoil
into com stubble (in rye
residue)
32
1.33
No tillage into com mulch
(in rye residue)
46
1.92
No tillage plus subsoil
into com mulch (in rye
residue)
41
1.71
Conventional tillage (into
com stubble)
49
2.04
Conventional tillage plus
in-row subsoil
51
2.13
k
In no-till plots corn was seeded into rye stubble (hay) or
mulch and soybeans into corn stubble or mulch (following
com).
**In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's
comparisons were not made.


145
Treatment
Avg^_
1978
Yield
1979
(kg/ha)*
Total
No tillage into wheat stubble
5034
7253
6143
No tillage plus in-row subsoil
4892
7854
6373
Conventional tillage
5395
6053
5724
Conventional tillage plus
in-row subsoil
7C
5080
6844
5962
In the analysis of variance, no significant differences were
detected between the means. Therefore, Duncan's comparisons
were not made.
No tillage and conventional tillage produced 6143 and 5724 kg/ha
(average of two years), respectively, but these means were
not statistically different.
The no-tillage practice did not significantly affect
yields of corn seeded in either the vetch or wheat stubble.
Since yields of com were statistically the same in the
two tillage systems, the cost of herbicides and saving
in fuel consumption will determine net money returns.
Because if, for equal yields, costs of herbicides (used
in no tillage) exceed the saving due to reduced machinery
use, no-tillage farming will result in reduced net benefits.
Other factors such as soil protection against erosion,
possibility of two crops per year or per season when
no tillage is used, may also be considered when making
the decision to adopt the no-tillage farming.


32
paraquat (with X-77) was made on April 10, 1978. No insec
ticide was used in this experiment.
Com stubble experiment. A second crop of soybeans
was grown at Willis ton from August to November, 1978. The
plots were close to, and of the same size as, those in the
first season and were previously planted to com (following
rye) without any soil preparation except in the conventional
tillage plots. The same six tillage treatments as above
were evaluated in com residues. The agronomic practices
were the same as in the first experiment except that the
plots were sprayed with methomyl at the rate of 0.56 kg a.i./
ha on September 27, 1978, for the control of the velevebean
caterpillars.
Oat stubble experiment. The Green Acres experiment
was conducted from June to the middle of October, 1978, in
a block that was previously planted to "Florida 501" oats
(Avena sativa L.). The following four tillage treatments
were studied in this experiment:
1. no tillage into oat stubble
2. no tillage plus in-row subsoil into oat
stubble
3. conventional tillage into oat stubble
4. conventional tillage plus in-row subsoil
into oat stubble.
Conventional tillage plots were prepared on June 2,
1978, with a moldboard plow and were disked twice. The


LIST OF TABLES
Table
1
2
3
4
Page
Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus (Zeller), in no-
tillage and conventional tillage "Cobb
soybeans at Willis ton, Levy Co., Fla.,
1978. Numbers are totals and averages
of two rows per replication for three
weeks 51
Lesser cornstalk borer infestations in
no-tillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co.,
Fla., 1979. Estimations are based on two
different rows observed weekly (for three
weeks) in each replication (four reps/treat.)... 52
Average number of the three-cornered alfalfa
hopper, Spissistilus festinus (Say),
collected by the plant shaking method
(1978) and sweep net (1979) from conventional
tillage and no-tillage soybeans at Green
Acres, Alachua Co., Fla. Numbers are
averages of eight weeks with eight shakes
per treatment and three weeks with eight
sweeps per treatment 53
Soybean looper populations in no-tillage
and conventional tillage "Cobb" soybeans
estimated by the shake cloth method at
Green Acres, Alachua Co., Fla., 1978 and
1979. Numbers are totals and averages of
eight (for 1978) and four (for 1979) weekly
shakes (sites) per treatment for 12 (1978)
and six (1979) weeks 54
Effect of tillage on southern green stink
bug populations estimated by the shake
cloth method in "Cobb" soybeans at
Williston, Levy Col, Fla., 1978. Numbers
represent totals and averages of eight
weekly shakes per treatment for seven
weeks
viii
55


APPENDIX C
YIELD OF "DEKALB XL 78 A" CORN
FROM GREEN ACRES
To estimate the yield, corn ears were collected from
all the plants in two center rows (6.10 m long) of each rep
lication in the vetch stubble experiment. In the wheat stubble
experiment, all the plants in the two rows were collected,
and the yield was estimated as dry matter (but not as
grain). The yield of corn recorded from the vetch stubble
experiment is shown below (yield reported at 15.5% moisture):
Avg.
Yield
(kg/ha)*
Treatment
1978
1979
Total
No tillage into vetch stubble
3031
5932
4472
No tillage plus in-row subsoil
2887
5932
4409
Conventional tillage
2464
3107
2785
Conventional tillage plus
in-row subsoil
*
2668
3562
3115
In the analysis of variance, no significant differences were
detected between the means. Therefore Duncan's comparisons
were not made.
The analysis of data revealed no significant differences
between treatments for yield either in 1978 or 1979.
Com yields (dry matter) from the wheat stubble experi
ment are shown in the table below (yield reported at 15.5%
moisture):
144


100
Ortho X-77 surfactant) on June 3, 1978. All the treatment
received 672.60 kg/ha of 5-4.4-12.5 (N,P,K) on June 3.
An additional application of 56 kg/ha of N was made in
all the plots on June 12, 1978. Half of the rows in each
plot were treated with carbofuran (2.24 kg a.i./ha) during
the planting operation. The other rows were not treated.
In 1979 the experiment was repeated without the carbo
furan application, but all other practices were the same
as in the 1978 season. Conventional tillage plots were
prepared on June 4, and com was planted on June 12, 1979.
Estimation of Insect Damage and Arthropod Populations
Soil arthropods. Damage to corn by soil insects
was assessed by randomly selecting two rows per replication
every week and counting the number of damaged plants.
Numbers of stunted, wilted or dead plants, characteristic
of the lesser cornstalk borer damage, as well as numbers
of cut, chewed plants (cutworms), were recorded. In the
wheat experiment, the total number of plants in the two
selected rows was recorded along with damaged plants in
order to estimate the percentages of damaged plants.
Populations of soil-inhabiting pest insects and arthropod
predators were monitored by means of pitfall traps as
described in the soybean section above. One trap was
placed in the middle row of each replication when com
was in stage 0.5 or stage 1 (Hanway, 1966). The traps
were kept in the field until corn was mature or until ears
were dry.


101
Above-ground insects. Fall armyworm and com earworm
damage was estimated by weekly visual observations. Two
rows were randomly chosen in each replication, and 15
consecutive plants were carefully observed in each row.
A total of 120 plants were thus examined weekly for each
treatment. The number of damaged plants (showing any
damage level, but whorl not destroyed) and the number
of plants with completely damaged whorl was recorded.
When com started tasseling (Stages 4 and 5, Hanway, 1966),
damage to the tassel was determined in the wheat stubble
experiment by recording the number of plants having at
least half of the tassel destroyed.
After ear shoots appeared, observations were no longer
made on the foliage, but only on ears. The combined damage
of Spcdoptera frugiperda (J. E. Smith) and Heliothis zea
(Bcddie) to com ears was estimated by counting and recording
the number of damaged ears on 30 plants randomly selected
from two rows in each replication (120 plants per treatment).
Two other rows were randomly chosen in each plot and the
number of damaged ears was recorded. Damage to ears was
also assessed at the harvest time. Each replication (plot)
was crossed diagonally and eight ears were collected.
A total of 32 ears were thus collected from each treatment.
The ears were placed in paper bags and brought into the
laboratory where the number of damaged ears (showing any
outside damage level) and the number of ears with a damaged area
extending to one or more centimeters within the kernel rows
were recorded.


54
Table 4. Soybean looper populations in no-tillage and
conventional tillage "Cobb" soybeans estimated
by the shake cloth method at Green Acres, Alachua
Co., Fla., 1978 and 1979. Numbers are totals and
averages of eight (for 1978) and four (for 1979)
weekly shakes (sites) per treatment for 12 (1978)
and six (1979) weeks.

Looper
Population
Treatment
Total
Number
Average/ shake''
1978
1979
1978
1979
No tillage into oat stubble
100
16
1.04
0.67
No tillage plus in-row
subsoil into oat stubble
137
5
1.43
0.21
Conventional tillage
into oat stubble
129
8
1.34
0.33
Conventional tillage plus
in-row subsoil into oat
stubble
105
9
1.09
0.38
No statistical analysis was done on the data the means
being about equal.


ADULTS/TRAP (LOGx )
84
0.5-r
¡2 19 26 3 10 17 24 31 7 14
Sept Oct Nov
SAMPLING PERIOD
Figure 14. Average trap-week collections of Labidura riparia
adults from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla.,
September November, 1978. Averages of four
traps per treatment.
conventional tillage
no tillage into com stubble (after rye)
no tillage into corn mulch (after rye)


Figure 21. Weekly activity of Labidura riparia nymphs and adults monitored by pitfall
traps (four in each treatment) in no-tillage and conventional tillage
"Cobb" soybeans at Green Acres, Alachua Co., Fla., 1979.
: no tillage into oat stubble
: conventional tillage


114
specimens belonging to five species were recorded in 1978
(Table 34). All the species were very rare, and S. palliatus
accounted for about 50% of all the species collected.
Most of the carabids (42%) were collected from the no
tillage com. Selenophorus was also the most predominant
species in the 1979 season, but the activity of the beetles
was monitored for four weeks only in this experiment in
1979.
One species, G. lecontei, was active throughout the
season until the com was mature. The highest numbers
were recorded two to three weeks after ears appeared.
At this stage, a relatively high percent of the ears were
already infested by the Heliothis-Spodoptera complex.
Selenophorus palliatus was collected most often toward
the end of the season. Pasimachus spp. were more active
during the first five weeks of the sampling period, i.e.
six to seven weeks after com was planted. The catches
for other species were very erratic. These results agreed
with the report by Galvez (1979) who found that the activity
of the carabid beetles in com at Green Acres was inconsistent
during the entire study period, and that carabid fauna
generally was either rare or very rare. Carabid populations
were in such low numbers, and appeared so infrequently
that it is not believed that these predators played any
important role in regulating pest populations.
With respect to the tillage systems, the results
indicated a preference by the carabids to colonize conventional


Table
Page
25
26
27
28
29
30
31
32
Fall armyworm and com earworm damage to the
conventional and no-tillage corn assessed
at the harvest time at Green Acres, Alachua
Co., Fla., 1979. Thirty-two ears collected
per treatment 122
Fall armyworm and corn earworm damage to the
conventional and no-tillage corn assessed
at the harvest time at Green Acres, Alachua
Co., Fla., 1979. Forty ears were collected
per treatment 123
Number of Conoderus amplicollis (Gyll.) and
C. falii Lane (Elateridae) collected in
pitfall traps from conventional tillage and
no-tillage field com at Green Acres, Alachua
Co., Fla., 1979. Numbers are totals and
averages of nine weeks for vetch and six
weeks for wheat with four traps per treat
ment 124
Lesser cornstalk borer, [Elasmopalpus
lignosellus (Zeller)], infestations in no
tillage and conventional tillage field corn
at Green Acres, Alachua Co., Fla., 1978-
1979. Estimation is based on eight rows
per treatment examined each week for three
weeks 125
Infestations of the lesser cornstalk borer
Elasmopalpus lignosellus. in no-tillage and
conventional tillage field com at Green
Acres, Alachua Co., Fla., 1978 126
Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus, in no-tillage and
conventional tillage field com at Green
Acres, Alachua Co., Fla., 1979 127
Activity of the granulated cutworm, Feltia
subterrnea (Fab.), monitored by nonbaited
pitfall traps in no-tillage and conventional
tillage com at Green Acres, Alachua, Co.,
Fla., 1979. Numbers are totals and averages
of four traps per treatment for four weeks... 128
Number and species of carabid predators
collected in pitfall traps from no-tillage
and conventional tillage field corn at Green
Acres, Alachua Co., Fla., May July, 1978.
Numbers are totals of four traps per treat
ment 129
Xll


110
cutworms than any of the conventional tillage treatments.
The weekly average numbers of cutworms per trap were 10.0
and 2.1, respectively, in the no-tillage and conventional
tillage plots. Subsoiling did not significantly increase
cutworm numbers within a same tillage system, although
the average number in no tillage plus subsoil was twice
higher than in the no tillage without subsoil (Table 31).
Although cutworm populations were high in the no
till plots, damage to corn seedlings was very low. Total
numbers of damaged plants recorded were one, zero, three
and one, respectively, from the conventional tillage,
conventional tillage plus subsoil, no tillage, and no
tillage plus subsoil. The corresponding plant population
was estimated in each treatment plot by randomly selecting
three rows per replication and counting the total number
of plants. The average numbers of plants per row were
26.5, 35.3, 38.0, and 38.0, for no till, no till plus
subsoil, conventional tillage, and conventional tillage
plus subsoil. Damage levels might have been underestimated
because some plants might have been infested but did not
fall down or were not completely cut. No noticeable cutworm
damage, however, was observed throughout the field.
It is not clear whether low cutworm numbers in 1978
were due to the carbofuran treatment of the soil. Cutworms
are known to vary greatly in numbers from one year to
another (Metcalf et al., 1962); populations are believed


127
Table 30. Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus, in no-tillage and
conventional tillage field corn at Green Acres,
Alachua Co., Fla., 1979.
No. plants
Infestation*
Total
Number
Treatment
observed
infested
1
Avg/row
No tillage into wheat stubble
No tillage plus in-row
1138
90
7.91
3.75
subsoil into wheat stubble
1171
89
7.60
3.71
Conventional tillage
Conventional tillage plus
1160
109
9.40
4.54
in-row subsoil
1140
90
7.89
3.75
In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's
comparisons were not made.


150
Clements, R. H. 1968. Important earwigs. Dermaptera, of
central and south Florida and the biology and control
of the primary species, Labidura riparia (Pallas)
under laboratory conditions. M. S. Thesis. Univ. of
Florida, Gainesville, 66 pp.
Curfs, H. P. F. 1976. Systems development in agricultural
mechanization with special reference to soil tillage
and weed control. Meded. Landbouwhogeschool Wageningen.
76, 179 pp.
Daft, G. G., and C. Leben. 1973. Bacterial blight of
soybeans: Field overwintered Pseudomonas glycinea or
possible primary inoculum. Plant Dis. Rep. 57:156-7.
Daugherty, D. M., M. H. Neustadt, C. W. Gehrke, L. E. Cavanah,
L. F. Williams, and D. E. Green. 1964. An evaluation
of damage to soybeans by brown and green stink bugs.
J. Econ. Entomol. 57:719-22.
Dean, H. A., and M. F. Schuster. 1958. Biological control
of Rhodesgrass scale in Texas. J. Econ. Entomol. 51:
363-6.
DeCoursey, R. M. ,- and C. 0. Esselbaugh. 1962. Description of
the nymphal stages of some North American Pentatomidae
(Hemiptera-Heteroptera). Entomol. Soc. Amer. Ann.
55:323-42.
Deitz, L. L., J. W. Van Duyn, J. R. Bradley, Jr., R. L. Rabb,
W. M. Brooks, and R. E. Stinner. 1976. A guide to the
identification and biology of soybean arthropods in
North Carolina. North Carolina Agrie. Exp. Stn. Tech.
Bull. 238, 264 pp.
Dempsey, A. H., and B. B. Brantley. 1953. Pimiento produc
tion in Georgia. Ga. Agrie. Exp. Stn. Bull. 277, 27 pp.
Doster, D. H. 1976. Economics of alternative tillage systems.
Bull. Entomol. Soc. Amer. 22:295-7.
Douglas, W. A. 1930. The velvetbean caterpillar as a pest
of soybeans in southern Louisiana and Texas. J. Econ.
Entomol. 23:684-90.
Doupnik, B., Jr., M. G. Boosalis, G. Wicks, and D. Smika.
1975. Ecofallow reduces stalk rot in grain sorghum.
Phytopathology. 65:1021-2.


LARVAE / SHAKE (
74
July Aug Sept Oct
SAMPLING PERIOD
Figure 4. Average numbers of small (up to 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and con
ventional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Averages of eight shakes
per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.


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120
Table 23. Infestations of the fall armyworm, Spodoptera
frugiperda, and com earworm, Heliotnis zea ~in
no-tillage and conventional tillage field com
at Green Acres, Alachua Co., Fla., 1978. Average
based on 120 plants per treatment per week.
% infestation*
Plants with
destroyed
Treatment
Plants
Whorl
Tassel
Ears
No tillage into wheat stubble
77.50
94.58
74.16
86.86
No tillage plus in row sub
soil into wheat stubble
77.83
90.83
70.88
78.47
Conventional tillage
74.83
93.33
84.34
82.31
Conventional tillage plus
in-row subsoil
*
76.17
94.58
83.17
72.10
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


Ill
to have been naturally low in the area in 1978, although
the insecticide might have had some effect. Cutworms
generally overwinter in the soil, under trash or clumps
of grasses, and female moths emerge from the soil in the
spring and oviposit on grasses and other plants. No
tillage systems provide an adequate environment for F.
subterrnea development because of the trash left on the
ground and the lack of soil tillage to destroy the larvae
and pupae.
That cutworms cause more severe damage to no-tillage
com than to the conventional tillage com has already
been documented (Musick, 1970b). It is not known, however,
why these relatively high cutworm populations caused prac
tically no damage to com seedlings in this experiment.
The same mechanism as that reported by Cheshire and All
(1978) for the lesser cornstalk borer may be involved
here. Crop residues in the no-till plots might have served
as food for the larvae, and prevented them from easily
locating com plants.
Soil-Inhabiting Predators
Ground dwelling spiders. The activity of ground
dwelling spiders was monitored in com in 1978 and 1979
in the vetch stubble experiment and in 1979 in wheat stubble.
Statistical analyses of data did not detect any significant
differences between the treatments. The weekly average
numbers were 1.30, 1.19, 1.28 and 1.47 spiders per trap


12
Verticillium wilt within and from one garden to another.
McCalla (1967) reported that tillage operations transport
various kinds of soil microorganisms from one site to another.
In Oregon, Hall (1959) studied the effects of fertiliza
tion dates and plowing methods on the incidence of root rot
of Burt wheat caused by Fusarium sp. The author concluded
that stubble mulch did not increase the disease incidence as
compared to plowed plots. In a similar study in Iowa, Parker
and Burrows (1959) reached the same conclusion about the
incidence of com root and stalk rot: disease incidence was
lowest in those tillage systems where com stalk residue was
left on the soil surface, and where no or low levels of N
were applied.
Brooks and Dawson (1968) drilled winter wheat directly
into rye (Secale cereale L.) stubble to investigate the effects
of this cultural practice on take-all (Ophiobolus graminis
Sacc.) and eyespot (Cercosporella herpotrichoides Fron.). No
differences in infection levels were found between plowed and
unplowed plots before the first three months. Three months
after planting, however, disease incidence increased greatly
in plowed plots. The authors found that plants in untilled
plots were infested earlier than those in conventional tillage
plots, but that the rate of spread of the fungus was restricted
by adverse soil conditions in no-tillage plots.
Doupnik et al. (1975) believed that factors such as
increased water conservation, reduced soil temperature


103
that no-tillage practice did not significantly affect
frugiperda and H. zea damage to field com foliage
and ears, as compared to the conventional tillage corn
(Table 22). The weekly analysis of the data failed to
show any single week during which the difference between
treatment means was significant. Infestation levels in
the no till were 0.38 infested plants and 2.75 infested
ears per row-week; percent infestation was 1.5% infested
plants and 10.6% infested ears. In the conventional tillage
an average of 0.65 plants and 1.97 ears were infested
in each row every week. In terms of percent, 1.5% of
the plants and 5.4% of the ears were infested.
Wheat stubble experiment. Com in this experiment
was late planted in both 1978 and 1979, and Spodoptera-
Heliothis infestations were very high. Damage levels
were assessed on leaves, tassels, and ears in 1978. Table
23 contains the results. The average percent of plants
with infested foliage (but whorl not destroyed) and that
of plants with destroyed whorl were statistically the
same in all the treatments. Damage levels on tassel were
very high and appeared to be higher in the conventional
tillage plots than in the no-tillage plots, but the analysis
of the data did not detect any significant differences
among treatments. Differences between treatments also
were not significant for damage to ears. About 95% of
the plants observed in no till and 93% in conventional


155
Noble, L. W. 1955. Investigations of the pink bollworm and
hemipterous cotton insects in the El Paso area of Texas
1944-52. U. S. D. A. Circ. 957. 16 pp.
Parker, D. T., and W. C. Burrows. 1959. Root and stalk
rot in corn as affected by fertilizer and tillage
treatment. Agron. J. 51:414-7.
Peters, R. A. 1972. Control of weeds in no-tillage crops.
Proc. No-tillage Systems Sym. Ohio State Univ. Columbus,
pp. 132-9.
Phillips, W. J., and G. W. Barber. 1931. The corn earworm
as an enemy of field corn in the eastern states.
Farmers' Bull. 1651, 91 pp.
Price, J. F., and M. Shepard. 1977. Striped earwig, Labidura
riparia, colonization of soybean fields and response
to insecticides. Environ. Entomol. 6:679-83.
Price, J. F., and M. Shepard. 1978. Calosoma sayi:
Seasonal history and response to insecticides in
soybeans. Environ. Entomol. 7:359-63.
Rask, N., G. B. Triplett, Jr., and D. M. Van Doren, Jr.
1967. A cost analysis of no-tillage corn. Ohio Rep.
52:14-5.
Rivard, I. 1964. Carabid beetles (Coleptera: Carabidae)
from agricultural lands near Belleville, Ontario. Can.
Entomol. 96:517-20.
Rivers, R. L., K. S. Pike, and Z. B. Mayo. 1977. Influence
of insecticides and corn tillage systems on larval
control of Phyllophaga anxia. J. Econ. Entomol. 70:794-6.
Roane, C. W., R. L. Harrison, and C. F. Center. 1974.
Observations on gray leaf spot of maize in Virginia.
Plant Dis. Rep. 58:456-9.
Rolston, L. H., and R. L. Kendrick. 1961. Biology of the
brown stink bug, Euschistus servus Say. Kans. Entomol.
Soc. J. 34:151-7.
Schlinger, E. I., R. van den Bosch, and E. J. Dietrick.
1959. Biological notes on the predaceous earwigs,
Labidura riparia (Pallas), a recent immigrant to
California (Dermaptera: Labiduridae). J. Econ. Entomol.
52:247-9.


143
fields. This impact, however, is believed to be less than
what was observed in confinement. Velvetbean caterpillars
wriggle vigorously and drop from the plant when disturbed.
Such a behavior prevents a predator from easily catching
the larvae. Moreover, L. riparia feeds on a variety of
prey and would "prefer" to prey on those small arthropods
it can easily kill.


INTRODUCTION
No tillage or zero tillage is defined as the agronomic
practice that consists of planting crop seeds in sod or
crop residues in a previously unprepared soil (Young, 1970;
Triplett and Van Doren, 1977). The soil is not disturbed
except for a narrow (5-7 cm wide) slit made by the planter
and in which the seeds are planted.
In the conventional tillage procedure a number (up to
ten) of trips across the field are made for soil preparation
and weed control. According to Young (1970), any practice
that reduces the number of these trips (e.g. plow and plant,
chiseling and plant) is a minimum or reduced tillage, an
operation distinctly different from the no tillage. Some
workers, however, consider the no-tillage practice as a case
of minimum tillage, and use the term "conservation tillage"
to include both the minimum (reduced) and no tillage. The
systems studied in this work are considered as no-tillage sys
tems, and the terms no-till and no tillage are used interchangeably.
No-tillage cropping has numerous advantages over the
conventional tillage practice. Nontilled soils retain moisture
longer than tilled fields (Moody et al., 1963; Triplett et al.,
1968). Plant residues in no-tillage systems prevent or
1


ACKNOWLEDGMENTS
I express my sincere appreciation to Dr. Reece I.
Sailer, my major advisor, and to Dr. Donald C. Herzog,
cochairman of my supervisory committee, for their guidance,
advice and criticism throughout the course of this work.
I wish to thank Dr. Raymond N. Gallaher not only for serving
on the supervisory committee, but also for his invaluable
assistance in the field and for his marked interest for
this study.
I acknowledge the advice and assistance of Dr. S.
L. Poe as former chairman of the supervisory committee.
I wish to express my gratitude to the Rockefeller
Foundation for its financial support through a fellowship,
and to the Universite Nationale du Zaire for making possible
the obtainment of this fellowship.
The author wishes to thank Dr. D, H. Habeck and P. M.
Choate of the Division of Plant Industry for identification
of many insect species. I also thank P. J. d'Almada for
his assistance with statistics, and Lavelle Oswalt for
her patience in typing this work.
Special gratitude is due to my wife, Lugwadio mi-Konde,
for her support and devotion, and for helping the family
financially when my fellowship ended before the end of my
in


Table
Page
18 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Williston, Levy Co., Fla., September -
November, 1978. Numbers are totals of
three traps per treatment for 10 weeks 68
19 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at Green
Acres, Alachua Co., Fla., June September,
1978. Totals of four traps per treatment
for 14 weeks 69
20 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Green Acres, Alachua Co., Fla., June -
September, 1979. Totals of four traps
per treatment for 15 weeks 70
21 Foliage and ear damage caused by the fall
armyworm, Spodoptera frugiperda (J. E.
Smith), and the corn earworm, Heliothis
zea (Boddie), in no-tillage and conventional
tillage corn at Green Acres, Alachua Co.,
Fla., 1978. Numbers are averages of 120
plants per treatment (each week) for four
weeks for foliage and three weeks for ears 118
22 Damage caused by the fall armyworm,
Spodoptera frungiperda, and corn earworm,
Heliothis zea, to no-tillage and conventional
tillage field com at Green Acres, Alachua
Co., Fla., 1979. Numbers are averages of
120 plants per treatment (each week) for
five weeks for foliage and four weeks for
ears 119
23 Infestations of the fall armyworm, Spodoptera
frugiperda, and corn earworm, Heliothis zea,
in no-tillage and conventional tillage field
corn at Green Acres, Alachua Co., Fla., 1978.
Average based on 120 plants per treatment
per week 120
24 Infestations of the fall armyworm, Spodoptera
frugiperda, and com earworm, Heliothis zea,
in no-tillage and conventional tillage field
corn at Green Acres, Alachua Co., Fla., 1979.... 121
xr


55
Table 5. Effect of tillage on southern green stink bug
populations estimated by the shake cloth method
in "Cobb" soybeans at Williston, Levy Co., Fla.,
1978. Numbers represent totals and averages of
eight weekly shakes per treatment for seven weeks.
Treatment
Stink bug Population
Total Number Average/shake"
No tillage into rye stubble
74
1.32ab
No tillage plus in-row subsoil
into rye stubble
86
1.54b
No tillage into rye mulch
97
1.73b
No tillage plus in-row
subsoil into rye mulch
106
1.89b
Conventional tillage into
rye stubble
54
0.96a
Conventional tillage plus
in-row subsoil into rye stubble
61
1.09ab
Values followed by the same letter are not significantly
different at 0.05 level by Duncan's new multiple range test.


63
Table 13. Activity of the striped earwig Labidura riparia
(Pallas), in no-tillage and conventional tillage
"Cobb" soybeans estimated by pitfall traps at
Williston, Levy Co., Fla., 1978. Four traps were
used for each treatment for 11 weeks.
Earwig i
population
Average/trap*
Treatment
Nymphs
Adults
Nymphs + Adults
No tillage into rye
stubble
31.14ac
30.91c
62.05ac
No tillage plus in-row
subsoil into rye stubble
31.64c
27.18a
58.82ad
No tillage into rye
mulch
31.61c
30.25c
61.86c
No tillage plus in-row
subsoil into rye mulch
31.27ac
26.91a
58.18d
Conventional tillage
into rye stubble
30.34a
26.27a
56.61a
Conventional tillage
plus in-row subsoil into
rye stubble
-r
22.59b
12.18b
34.77b
Values followed by the same letter in each column are not
significantly different at the 0.05 level by Duncan's
new multiple range test.


45
in the no tillage and conventional tillage. In-row subsoil
did not significatnly affect spider populations either
in conventional tillage treatments or in no-tillage plots.
Spider populations reached the peak about four weeks
before the peaks of pest populations. During the week
of peak populations the average number for the entire
field (all treatments combined) was 3.91 spiders per trap.
Ground spiders were in low numbers (field average, 0.41)
when most pest species increased in number.
In 1979 spider populations were high and peaked during
the second week of the sampling period, i.e. before most
pest species appeared. The analysis of data revealed
no significant differences between treatments. The weekly
average numbers were 3.78 and 2.40 spiders per trap in
conventional tillage and no-tillage soybeans, respectively.
A reduction in number of spiders in a crop system
may result in increased pest populations in that system
since spiders constitute an important part of the predator
complex in crop systems (Whitcomb and Bell, 1964). The
activity of spiders, as indicated by the results, was
not affected by the tillage systems investigated in this
s tudy.
Striped earwig. Average numbers of the striped earwig,
Labidura riparia, observed at Williston from April to July
1978 are in Table 13. Both nymphal and adult populations
were significantly (P=0.05) lower in the conventional tillage


LARVAE/SHAKE (LOG x )
79
Aug Sept Oct
SAMPLING PERIOD
Figure 9. Average numbers of velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method from
no-tillage and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979. Average of
four shakes per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.


61
Table 11. Effect of tillage practice on population levels of
the velvetbean caterpillar, Anticarsia gemmatilis
Hubner, monitored by the plant shaking method in
"Cobb" soybeans at Green Acres, Alachua Co., Fla.,
1978. Numbers are averages of eight weekly
shakes per treatment for eleven weeks for small
larvae and eight weeks for large larvae. The
plots were treated with methomyl and acephate
(once each) for insect control.
Averag
e Number
Larvae/shake
Treatment
Small
Large
Small + Large
No tillage into oat stubble
7.91
2.95
10.16
No tillage plus in-row
subsoil into oat stubble
8.39
2.17
10.56
Conventional tillage into
oat stubble
8.64
1.78
10.42
Conventional tillage plus
in-row subsoil into oat
stubble
W
8.50
3.45
11.95
In the analysis of variance no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


Figure 17. Weekly activity of Labidura riparia adults monitored by pitfall
traps in no-tillage and conventional tillage "Cobb" soybeans at
Green Acres, Alachua Co., Fla., 1978. Four traps were placed
in each treatment.
: no tillage into oat stubble
: conventional tillage


28
Thiele (1977) made a detailed study of carabid beetles
in relation to their habitats including the effects of
cultural practices on carabid populations. Kabacic-Wasylik
(1970, cited by Thiele, 1977) found that during rotation
from one crop to another, the spectrum of dominance of
carabids undergoes a corresponding shift.
The Striped Earwig
The striped earwig, Labi dura riparia (Pallas), is an
important soil-inhabiting predator and its biology and
predatory behavior have been studied by several researchers
(Schlinger et al., 1959; Afify and Farghaly, 1970; Caussanel,
1970, Tawfik et al., 1972; and Ammar and Farrag, 1974).
Adult L. riparia mate on the soil surface or in shallow
tunnels, but the eggs are laid in deeper (average depth
5.8 cm) tunnels (Ammar and Farrag, 1974), which have no
passage to the soil surface (Caussanel, 1970). The eggs
hatch after an average of 9.9 days at 22-25 C. The females
brood over the eggs, and bring food to newly hatched nymphs.
The insect passes through six nymphal instars.
Tawfik et al. (1972) observed L. riparia climbing
com plants in search of prey. They also reported that
this earwig fed on a variety of prey including such impor
tant pests as Spodoptera littoralis Boisd., Pieris rapae L.,
Vanessa cardui L., etc. A fifth- or sixth-instar nymph L.
riparia may consume up to 4-7 young larvae or 2-4 large


106
collected in large numbers from the vetch and wheat stubble
expreiments. Of the two species, C. amplicollis was more
abundant than C. falli in both experiments. Conoderus spp.
are not important pests on com in Florida, but their
numbers were recorded in order to detect any tillage effect.
Data collected in 1979 from both experiments are
shown in Table 27. Statistical analysis of data showed
that no-tillage cropping, as well as in-row subsoil did
not affect significantly populations of Conoderus spp.
as compared to the conventional tillage. Wireworm popula
tions were highest toward the end of the crop season;
at the beginning of the season, when com could be in
the most susceptible (relative to these pests) stage,
wireworms were in low numbers.
Lesser cornstalk borer in vetch stubble. The average
numbers of damaged plants recorded from the vetch experiment
in 1978 and 1979 are shown in Table 28. Lesser cornstalk
borer infestations were relatively low in both seasons.
In the 1978 cropping season, infestations were significantly
(P=0.05) lower in the no-tillage corn than in the conven
tionally tilled com. The weekly average number of damaged
plants per row was 0.13 and 1.33, respectively in the
no-till and conventional till com (Table 28). The results
also showed that subsoiling into the furrows did not signif
icantly affect infestation levels in either no-tillage
or the conventional tillage treatments.


153
Jordan, C. R. 1965. Lesser cornstalk borer control on
beans, peas, soybeans, corn, sorghum and millet. Univ.
of Georgia Coll. Agrie, and U. S. D. A. Coop. Entomol.
Leaflet 22. Rev.
Kennedy, B. W. 1969. Detection and distribution of Pseudo
monas glycinea in soybean. Phytopathology 59 :1618-9 .
Keyworth, W. G. 1942. Verticillium wilt of the hop (Humulus
lupulus). Ann. Appl. Biol. 29:346-57.
King, D. R., J. A. Harding, and B. C. Langley. 1961. Peanut
insects in Texas. Texas Agrie. Exp. Stn. Mise. Publ.
550, 14 pp.
Lai, R. 1973. Soil erosion and shifting cultivation. FAO
Regional Sem. on Shifting Cultivation and Soil Cons, in
Africa. Ibadan, Nigeria, July 2-21.
Lai, R. 1979. Influence of six years of no-tillage and
conventional plowing on fertilizer response of maize
(Zea mays L.) on an alfisol in the tropics. Soil Sci.
Soc. Amer. J. 43:399-403.
Ledingham, R. J., R. J. Sallans, and A. Wennhardt. 1960.
Influence of culture practice on incidence of common
root rot of wheat. Can. J. Plant Sci. 40:310-6.
Lewis, W. M. 1970. No-tillage crop production in sod or
pasture. Nat. Conf. No-tillage Crop Prod., Univ. of
Kentucky, Lexington, pp. 52-4.
Leuck, D. B. 1966. Bioloby of the lesser cornstalk borer
in south Georgia. J. Econ. Entomol. 59:797-801.
Luginbill, P. 1928. The fall armyworm. U. S. D. A. Tech.
Bull. 34, 91 pp.
Luginbill, P., and G. G. Ainslie. 1917. The lesser cornstalk
borer. U. S. D. A. Bur. Entomol. Bull. 539, 27 pp.
McCalla, T. M. 1967. Effect of tillage on plant growth as
influenced by soil organisms. Conf. Proct. Tillage for
Greater Crop Prod., Detroit, Michigan. Amer. Soc.
Agrie. Eng., St. Joseph, Michigan, pp. 19-25.
Metcalf, C. L., W. P. Flint, and R. L. Metcalf. 1962.
Destructive and useful insects: Their habits and
control. 4th ed. McGraw-Hill, New York. 1087 pp.
Metcalf, Z. P. 1909. Insect enemies to tobacco. North
Carolina Dep. Agrie. Spec. Bull., 72 pp.
Miner, F. D. 1961. Stink bug damage to soybeans. Ark.
Farm Res. 10:12.


42
tillage, in order to attract and harbor higher populations
than those that would colonize conventionally tilled soybeans.
Stink bugs are known to fly across the field from the area
of the initial infestations in search of pods (Miner, 1966).
Such movements are likely to reduce any effect that the no
tillage systems may have. On the basis of the data presented
in Tables 5-9, it is believed that, when wild hosts are
effectively eliminated from the no-tillage systems through
good weed control, stink bug infestations are not likely to
be more serious in these systems than in the conventionally
tilled fields.
Velvetbean caterpillar. The early-planted (April-July,
1978) soybeans in the first Williston experiment (rye stubble)
were not infested by velvetbean caterpillars. In the second
season experiment, however, populations of A. gemmatilis
reached such high levels that an application of methomyl was
made on September 27. A weekly average of up to three large
(over 2.5 cm) larvae per shake was recorded. Average numbers
of caterpillars collected by the shake cloth method are
contained in Table 10. The analysis of the data showed that
no-tillage systems did not significantly affect population
levels of either the small (up to 2.5 cm) or large larvae as
compared to the conventional tillage.
Figures 1-3 show the weekly trend of small, large and
total populations of the velvetbean caterpillars. Although


109
No-tillage practice failed to significantly affect
lesser cornstalk borer infestations in the 1979 cropping
season when com was seeded into vetch or wheat stubble.
In the 1978 season, this practice significantly reduced
E. lignosellus infestations in both experiments. These
results agreed with those reported by All and Gallaher
(1977) and All et al. (1979). They found that lesser
cornstalk borer infestations were greatly reduced in no
tillage com as compared to com planted in conventionally
tilled blocks. Crop residues left on the ground in no
till systems were found to be the most important factor
contributing to these low infestations (Cheshire et al.,
1977; Cheshire and All, 1978). Crop residues reduce infes
tations by either providing food to the saprophagous larvae
or by disrupting the feeding behavior of the larvae through
odor or mechanical shielding of the host plants.
Cutworms in vetch and wheat stubble. During the
1978 season very few granulate cutworms [Feltia subterrnea
(Fab.)] were found in the traps in the vetch stubble and
wheat stubble experiments. One cutworm was collected
in 1979 in the wheat experiment. Cutworm populations
in the vetch experiment, however, were high in the 1979
season. The results recorded during that season are in
Table 31. Numbers of cutworms were significantly (P=0.05)
higher in the no-till corn than in the conventional till
corn. The no tillage plus subsoil also harbored more


126
Table 29. Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus, in no-tillage and
conventional tillage field com at Green Acres,
Alachua Co., Fla., 1978.
Infestation*
No. plants
No.
Plants/
Treatment
observed
infested
l
row
No tillage into wheat
stubble
1987
31
1.56a
0.97c
No tillage plus in-row
subsoil into wheat stubble
2751
104
3.78b
3.25d
Conventional tillage
Conventional tillage plus
2507
88
3.51b
2.75d
in-row subsoil
m- -
2966
80
2.70b
2.50d
Values in each column not followed by the same letter are
significantly different at the 0.05 level by Duncan's new
multiple range test.


Estimation of Tillage Effects on Insects 33
Soil arthropods 33
Above-ground insects 34
Results and Discussion 36
Soil-Pest Insects 36
Above-Ground Pest Insects 38
Three-cornered alfalfa hopper 38
Soybean looper 39
Southern green stink bug 39
Velvetbean caterpillar 42
Soil-Inhabiting Predators 44
Ground spiders 44
Striped earwig 45
Carabid beetles 48
CHAPTER III. CORN CROP SYSTEMS 98
Materials and Methods 98
Cultural Practices 98
Vetch stubble experiment 98
Wheat stubble experiment 99
Estimation of Insect Damage and Arthropod
Populations 100
Soil arthropods 100
Above-ground insects 101
Results and Discussion 102
Above-Ground Insects 102
Vetch stubble experiment 102
Wheat stubble experiment 103
Soil Insect Pests 105
Wireworms 105
Lesser cornstalk borer in vetch stubble... 106
Lesser cornstalk borer in wheat stubble... 107
Cutworms in vetch and wheat stubble 109
Soil-Inhabiting Predators Ill
Ground dwelling spiders Ill
Carabid beetles 113
Striped earwig 115
GENERAL CONCLUSIONS 137
Soybean Crop Systems 137
Corn Crop Systems 137
Arthropod Predators 138
Corn and Soybean Yields 138
APPENDICES
A CHEMICAL NAMES OF HERBICIDES MENTIONED OR
USED IN THE EXPERIMENTS 140
B PREDATORY ACTIVITY OF LABIDURA ON ANTICARSIA
IMMATURES 141


112
in no tillage, no tillage plus in-row subsoil, conventional
tillage and conventional tillage plus in-row subsoil,
respectively.
When the data were analyzed on a weekly basis, however,
they revealed significant differences among treatments
during the third, seventh and eighth weeks of the sampling
period. During the third week, the activity of the spiders
was significantly (P=0.01) higher in the no tillage than
in the conventional tillage. The average numbers were
2.5 and 0.25 spiders per trap, respectively in the no
tillage com and conventional tillage com. The activity
of the spiders was significantly (P=0.05) reduced in no
tillage plots during the seventh week but increased during
the eighth week.
In 1979 populations of ground spiders were very high
as compared to the 1978 crop season. The weekly averages
were 5.68, 7.66, 7.02 and 7.04 spiders per trap, respectively,
in no till, no till plus in-row subsoil, conventional
tillage and conventional tillage plus in-row subsoil. No
significant differences were found between these means.
The average numbers of spiders collected from the wheat
stubble experiment were 2.96, 3.50, 3.00 and 3.50 spiders
per trap, respectively in no tillage, no tillage plus
in-row subsoil, conventional tillage and conventional
tillage plus in-row subsoil. Spider populations were
not affected by the tillage method in corn crop systems.


AVERAGE NUMBER/TRAP (LOGx)
135
0.5J
i
0 -| j ¡ 1 j 1 1 1 1
23 30 7 14 21 28 4 II 18 25
June July August
SAMPLING PERIOD
Figure 25. Weekly activity of Lab idura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field com at Green Acres, Alachua Co.,
Fla., 1978.
no tillage into wheat stubble
conventional tillage


Page
Figure
12
13
14
15
16
17
18
Average trap-week collections of Labidura
riparia (nymphs + adults) from no-tillage
and conventional tillage "Cobb" soybeans
at Williston, Levy, Co., Fla., April -
July, 1978. Four pitfall traps were set
in each treatment 82
Average trap-week collections of Labidura
riparia nymphs from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., September -
November, 1978. Averages of four traps
per treatment 83
Average trap-week collections of Labidura
riparia adults from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., September -
November, 1978. Averages of four traps
per treatment 84
Average trap-week collections of Labidura
riparia nymphs and adults from no-tillage
and conventional tillage "Cobb" soybeans
at Williston, Levy Co., Fla., September -
November, 1978. Averages of four traps
per treatment 85
Weekly activity of Labidura riparia
nymphs monitored by pitfall traps in
no-tillage and conventional tillage
"Cobb soybeans at Green Acres, Alachua
Co., Fla., 1978. Four traps were
placed in each treatment 87
Weekly activity of Labidura riparia
adults monitored by pitfall traps
in no-tillage and conventional tillage
"Cobb" soybeans at Green Acres, Alachua
Co., Fla., 1978. Four traps were placed
in each treatment 89
Weekly activity of Labidura riparia
(nymphs + adults) monitored by pitfall
traps in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Four traps were
placed in each treatment 91
xvi


INFLUENCE OF NO-TILL AND CONVENTIONAL TILLAGE
ON INSECT PESTS AND SOIL INHABITING PREDATOR POPULATIONS
IN FLORIDA SOYBEAN AND CORN CROPPING SYSTEMS
By
KI-MUNSEKI LEMA
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1980


24
On older corn, the larvae girdle the stems, although they
may also tunnel into the stems. Metcalf et al. (1962)
reported that when com under 45 or 50 cm is damaged it
fails to produce ears or good stalks.
Fall armyworm. The fall armyworm, Spodoptera frugiperda
(J. E. Smith), is an important agricultural pest; the
larvae feed on, and cause yield losses to, a variety of
field, forage and vegetable crops (Luginbill, 1928).
Luginbill (1928) reported a very detailed study that
included the biology and description of life stages of
this pest. On com, female S. frugiperda deposit the egg
masses on the underside of the leaves. Oviposition occurs
at night, and the incubation period lasts from two to ten
days. The larvae mature, on the average, 10.9 to 13.4
days after they hatch. Pupation takes place in the soil
in loose cocoons; adult moths emerge after 7-37 days. In
Florida, moths emerged from buried pupae after 14-35 days
(Wood, 1977).
The larvae of S^. frugiperda are almost omnivorous,
but do show a marked preference for Gramineae (Luginbill,
1928). The first instars skeletonize the leaves and make
holes while the fourth to sixth instars usually completely
destroy small plants and strip larger ones.
Morrill and Green (1973) found that young larvae fed
on the upper portions of com plants whereas larger larvae


102
Results and Discussion
Above-Ground Insects
Vetch stubble experiment. Damage to com foliage
and ears caused by Spodoptera frugiperda and Heliothis zea
in the 1978 vetch experiment is shown in Table 21. The
percent of plants with damaged foliage was 24.59 in the
no tillage and 30.83 in the conventional tillage; that
of ear damage was 50.78 in the conventional tillage plus
in-row subsoil and 44.32 in the no tillage. The difference
between treatments, however, were not significant. Damage
on ears was higher than on the foliage; 44% of the ears
in the no till and 43% in the conventional tillage were
damaged. Weekly damage levels on the foliage and ears
are shown in Figure 22.
The data were analyzed on a weekly basis, in addition
to the overall analysis, to detect any tillage effect
throughout the cropping season. Such an effect may disappear
as field conditions change during the season. No significant
differences were found between treatments on a weekly
basis for foliage damage (Fig. 22), but the percent of
infested ears was significantly higher in the no-tillage
corn than in the conventional tillage com during the
week when com plants were in the dent-physiologic maturity
stage (Hanway, 1966).
Infestations were comparatively low during the second
season. The 1979 data from the vetch experiment showed


I certify that I have read this study and that in
my opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.
Leece 1. Sailer, Chairman
Professor of Entomology
and Nematology
I certify that I have read this study and that in
my opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.
Donald C iferzg-,
Assistant Profess^
irman
Entomology and Nematology
I certify that I have read this study and that in
my opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.
Associate Professor of
Agronomy


Figure 16. Weekly activity of Labidura riparia nymphs monitored by pitfall
traps in no-tillage and conventional tillage "Cobb" soybeans at
Green Acres, Alachua Co., Fla., 1978. Four traps were placed in
each treatment.
: no tillage into oat stubble
: conventional tillage


NYMPHS + ADULTS/ TRAP (LOG x)
85
Sspt Oct Nov
SAMPLING PERIOD
Figure 15. Average trap-week collections of Labidura riparia
nymphs and adults from no-tillage and conventional
tillage "Cobb" soybeans at Williston, Levy Co.,
Fla., September November, 1978. Averages of four
traps per treatment.
: conventional tillage
: no tillage into com stubble (after rye)
: no tillage into corn mulch (after rye)


116
The results obtained from the wheat stubble experiment
in both the 1978 and 1979 seasons are shown in Figures
25 and 26, respectively. In 1978, nymphal and adult Labidura
populations remained statistically the same in the no
tillage and conventional tillage com throughout the sampling
period, except during the eighth week when the nymphal
population was significantly (P=0.05) higher in the conven
tional tillage than in the no tillage.
In the 1979 season (Figure 26), the conventional
tillage com harbored significantly more earwig nymphs
during the first two weeks of the sampling period than
did the no-tillage com. During the fifth week, the adult
population was higher in the conventional tillage than
in the no-tillage com; at the end of the sampling period,
the total (nymphs and adults) population was significantly
(P=0.01) higher in the conventional tillage plots than
in the no-tillage plots. The difference between treatment
means (no till vs. conventional till) were highly significant
(P=0.01) for both the nymphal and the adult populations.
Data collected during the two years from silage corn
planted into either vetch or wheat stubble indicated that
the no-tillage com generally harbored lower L. riparia popu
lations than the conventional tillage corn. This trend
was more apparent for the nymphal population than for
the adult population. In fact, in most of the experiments
where no-tillage farming significantly affected the earwig
populations, numbers of nymphs were lower in no-tillage
plots than in the conventional tillage ones while the


34
and all the plants in the row were carefully examined.
Stunted, infested plants were pulled, counted and the number
recorded. Infestation levels were calculated as the number
of infested plants per row.
Populations of cutworms and soil-inhabiting predators
(earwigs, spiders and carabid beetles) were monitored by
means of pitfall traps. The traps consisted of cottage cheese
cups about one-third filled with ethylene glycol that killed
and preserved the catches. In order to prevent rains from
filling the traps and to avoid disturbance of the traps by
small animals, a piece of wood (20 cm x 20 cm x 0.5 cm) was
positioned about 4 cm above each trap. One trap was placed
in the middle of each replication and positioned within the
row in order to prevent destruction by machines during
farming operations. The traps were set in the plots from
two days to two weeks after soybeans were planted. The
insects were collected every week and brought into the
laboratory where they were sorted by species and the numbers
of each species recorded.
Above-ground insects. Soybean looper, velvetbean
caterpillar and stink bug populations were estimated by the
plant shaking method. In 1978 two sample sites were randomly
selected in each replication, but only one site was used in
the 1979 crop season. After selecting the site the shake
cloth was unrolled on the ground between two plant rows,
and the plants over the cloth were shaken vigorously enough


41
of data did not detect any significant differences among
treatments. Analysis of data also revealed no significant
differences between treatments in number of seed damaged.
Although the percent of small, wrinkled and fungus-infected
seeds was 38.92 in the no tillage into oat stubble and 19.28
in the conventional tillage, analysis of variance of the
data was not significant (Table 9).
In 1978, stink bug populations at Green Acres reached
the economic threshold recommended for Florida soybeans
(Strayer and Greene, 1974). Peak levels (2.4 adults per shake
average of all the treatments) occurred during the week of
September 21 when soybeans were in R5-R6 stages (beginning
and full seed stages; Fehr and Caviness, 1977). This peak
followed three applications of methomyl, the last two being
made on September 7 and 13, 1978. Methomyl did not apparently
affect stink bug populations. In 1979, adult population was
about four times higher than the recommended economic
threshold.
Except the Williston first experiment in which popula
tions of the southern green stink bug were significantly
lower in the conventional tillage than in no-tillage treat
ments, the tillage systems studied in all other experiments
did not show any significant effect on either stink bug
populations or stink bug damage to soybeans. No-tillage
systems in these experiments apparently did not provide a more
favorable environment than that found in the conventional


59
Table 9. Damage to seeds by the stink bug complex in no-till
and conventional till "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979.
20 plants per treatment.
Numbers are
averages of
i*
Treatment
Damage**
Small Seeds
No tillage into oat stubble
16.34
38.92
No-till plus in-row subsoil
into oat stubble
14.25
28.87
Conventional till into oat stubble
15.02
19.28
Conventional till plus in-row
subsoil into oat stubble
17.00
20.69
In the analysis of the variance, no significant differences
were detected among the means. Therefore, Duncan's comparisons
were not made.
kk
Damage: seeds with at least one feeding puncture. Small
seeds: small, wrinkled and fungus infected seeds.


43
analysis of the data did not detect any significant differ
ences between treatments, the figures show that before
the plots were sprayed with methomyl, populations of small
larvae were highest in the conventional tillage whereas
populations of large larvae were highest in the no-tillage
into corn mulch. After application of methomyl, populations
of both age groups were highest in the no-tillage into com
stubble.
Data obtained from the Green Acres 1978 experiment also
failed to show any significant effect of no-tillage treatment
on velvetbean caterpillar populations as compared to the
conventional tillage (Table 11, Figures 4, 5, and 6).
After the second application of methomyl (September 7), all
the larvae collected were very small (up to 1 cm) (Figures
4, 5 and 6). Soybeans were in the R5-R6 stage and these
small larvae could not cause any significant damage to the
soybeans.
In 1979 at Green Acres velvetbean caterpillars were
classified into small (up to 1.5 cm), medium (1.6-2.5 cm),
and large (over 2.5 cm) larvae. The average numbers of
larvae per shake for each age group are shown in Table 12,
and the weekly population trend is illustrated by Figures 7,
8 and 9. Populations of small larvae were significantly
(P=0.05) lower in no-tillage into oat stubble than in the
conventional tillage treatments or in no-tillage plus in-row
subsoil. Figure 7 shows that throughout the cropping season,


Table 33. Numbers and species of carabid predators collected in pitfall traps from
no-tillage and conventional tillage field corn at Green Acres, Alachua Co.,
Fla., April-July, 1979. Numbers are totals of four traps per treatment.
Species
NVS
Treatment
NVS+s CT
CT+s
Tot.
1
Index**
Calosoma sayi De/jean
0
0
1
1
2
7.4
VR
Colliuris pennsylvanica
(L.)
0
1
3
0
4
14.8
VR
Galerita lecontei
0
1
3
9
13
48.1
R
Harpalus pennsylvanicus
DeGeer
1
1
0
1
3
11.1
VR
Pasimachus sublaevis Beauv.
1
1
2
1
5
18.5
VR
Total
2
4
9
12
27
1
7.4
14.8
33.3
44.4
*NVS: no tillage into vetch stubble; NVS+s; no tillage plus in-row subsoil into
vetch stubble; CT: conventional tillage; CT+s: conventional tillage plus in-row
subsoil.
**VR: very rare, 10 specimens or less; R: rare 11 to 50 specimens (Rivard, 1964).
130


147
for lower yields in the no tillage. It is believed that
reduced yields recorded from the no tillage were due
to inadequate weed control, especially the bahiagrass
(Paspalum notaturn Flugge) which has colonized those plots
that were not tilled for three successive years. Several
workers (Triplett and Lytle, 1972; Griffith et al.,
1973) recorded lower crop yields from no-tillage systems
when weed control was not adequate. Although no cost/benefit
analysis was done, it is believed that this yield reduction
resulted in reduced net money returns.


149
Barber, G. W., and F. F. Dicke. 1937. The effectiveness of
cultivation as a control for the com earworm. U. S.
D. A. Tech. Bull. 561, 16 pp.
Blatchley, W. S. 1910. An illustrated descriptive catalogue
of the Coleptera known to occur in Indiana. The Nature
Publ. Co., Indianapolis. 1386 pp.
Blickenstaff, C. C., and J. L. Huggans. 1962. Soybean
insects and related arthropods in Missouri. Mo. Agrie.
Exp. Stn. Res. Bull. 803, 51 pp.
Blevins, R. L., D. Cooks, S. H. Phillips, and R. E. Phillips.
1971. Influence of no-tillage on soil moisture. Agron.
J. 63:593-6.
Boosalis, M. G., and B. Doupnik, Jr. 1976. Management of
crop diseases in reduced tillage systems. Bull. Entomol.
Soc. Amer. 22:300-2.
Boyer, W. P. 1967. Survey method for three-cornered alfalfa
hopper (Spissistilus festinus) in soybeans in Arkansas.
Coop. Plant Pest Rep. 17 :324-5.
Brooks, D. H., and M. G. Dawson. 1968. Influence of direct-
drilling of winter wheat on incidence of take-all and
eyespot. Ann. Appl. Biol. 61:57-64.
Bums, E. E. 1973. Will conservation tillage increase the
incidence of plant disease? Ill. Res. 15:8-9.
Canerday, T. D., and F. S. Arant. 1966. Biology of Pseudo
plus ia includens and notes on biology of Trichoplusia
ni, Rachiplusia ou, and Autographa biloba. J. Econ.
Entomol. 60:870-1.
Caussanel, Cl. 1970. Principales exigences ecophysiologiques
du forficule des sables, Labidura riparia (Derm.
Labiduridae). Ann. Soc. Entomol. Fr. (N. S.). 6:589-
612.
Cheshire, J. M., Jr., and J. N. All. 1978. Monitoring lesser
cornstalk borer larval movement in no-tillage and con
ventional tillage com systems. Georgia Agrie. Res.
20:10-3.
Cheshire, J. M., Jr., J. Henningson, and J. N. All. 1977.
Radiolabeling lesser cornstalk borer larvae for
monitoring movement in soil habitats. J. Econ. Entomol.
70:578-80.


GENERAL CONCLUSIONS
Soybean Crop Systems
According to their population levels, four insects, S.
festinus, P. includens, N. viridula and A. gemmatilis, were
the most important above-ground pests observed during the
two years. Populations of these insects, as well as injury
levels caused did not differ significantly in soybeans
grown in no-tillage and conventional tillage systems. How
ever, if serious infestations of E. lignosellus are to be
avoided, cultural practices must include applications of
a good soil insecticide, early planting and irrigation.
Com Crop Systems
Infestations due to S. frugiperda and H. zea, the most
important above-ground pests observed on corn, were more
severe in late planted than in early planted field corn,
but were not affected by the tillage methods. These pests
are not, according to the results, expected to cause more
damage in no-tillage corn than in conventionally tilled
com.
Wireworm populations were not affected by the no-tillage
practice. Although no tillage greatly increased cutworm
populations, no apparent damage was done to corn by these
insects. However, cutworms may be expected to cause more
137


AVERAGE NUMBER/TRAP(LOGx)
SAMPLING PERIOD
Figure 23. Weekly activity of Labidura riparia (nymphs + adults) monitored by pitfall
traps (4/treat.) in field corn at Green Acres, Alachua Co., Fla., 1978.
: no tillage into vetch stubble
: conventional tillage
133


157
Tugwell, P., and F. D. Miner. 1967. Soybean injury by the
three-cornered alfalfa hopper. Ark. Farm Res. 16:12.
Turner, J. W. 1967. The nature of damage by Nezara
viridula (L.) to soybean seed. Queensland J. Agrie.
Anim. Sci. 24:105-7.
Turnipseed, S. G. 1973. Insects. Pp. 545-72. In Soybeans:
Improvement, production, and uses. B. E. Caldwell (ed.).
Amer. Soc. Agron., Inc. Madison, Wisconsin.
Unger, P. W., and R. E. Phillips. 1973. Soil water evapora
tion and storage. Conservation tillage. Proc. Nat.
Conf. Des Moines, Iowa. Soil Cons. Soc. Amer. Pp. 42-
54.
van den Bosch, R., and K. Hagan. 1966. Predaceous arthropods
in California cotton fields. Cali. Agrie. Exp. Stn. Bull.
820, 32 pp.
Walton, R. R., R. S. Matlock, and J. P. Boyd. 1964. Effect
of the lesser cornstalk borer on peanuts in Oklahoma.
Okla. State Univ. Exp. Stn. Processed Ser., 10 pp.
Watson, J. R. 1916. Life history of the velvetbean cater
pillar (Anticarsia gemmatilis Hubner). J. Econ. Entomol.
9:521-8.
Whitcomb, W. H., and K. Bell. 1964. Predaceous insects,
spiders and mites of Arkansas cotton fields. Ark.
Agrie. Exp. Stn. Bull. 690, 84 pp.
White, D. G., and J. L. Janney. 1978. Corn anthracnose
leaf blight and stalk rot spread into Illinois. Ill.
Res. 20:6-7.
Wiese, A. F., and D. W. Staniforth. 1973. Weed control in
conservation tillage. Cons. Tillage. Proc. Nat.
Tillage Conf. Des Moines, Iowa. Soil Cons. Soc. Amer.
Ankeny, Iowa. Pp. 108-14.
Wischmeier, W. H. 1973. Conservation tillage to control
water erosion. Cons. Tillage. Proc. Nat. Tillage Conf.
Des Moines, Iowa. Soil Cons. Soc. Amer. Ankeny, Iowa.
Pp. 133-41.
Wood, J. R. 1977. Survival of fall armyworm pupae buried
during the winter in Florida. M. S. Thesis, Univ. of
Florida, Gainesville, 68 pp.


29
larvae of S. littoralis per day. Dean and Schuster (1958)
and Clements (1968) reported that the striped earwig preyed
on armyworms, mites, scale insects, and aphids. In a labora
tory study, Schlinger et al. (1959) found that L. riparia
fed on various insects including Lepidoptera of all stages,
elaterid larvae, aphids, and carabid larvae. Labidura riparia
was also observed feeding on A. gemmatilis larvae, pupae and
adults, L. riparia nymphs, small Calosoma larvae, Gryllus
nymphs, wolf spiders, and adult Heliothis spp. (Neal, 1974).
Hassanein et al. (1968) and Afify and Farghaly (1970)
compared the predatory effectiveness of L. riparia and
that of Coccinella undecimpune tata Reiche on the cottonworm,
Prodenia litura Fabr. and S. littoralis. They found that
L. riparia was more efficient than Coccinella as an egg
and larval predator.
Price and Shepard (1977) investigated the patterns
of colonization of soybean fields as well as the response
to insecticides by L. riparia. The authors observed lower
numbers in newly established fields than in older ones.
Soybeans treated with methyl-parathion and methomyl early
in the season had higher earwig populations than untreated
fields. Reduction in numbers of ants and other insects
that prey on earwigs, after insecticidal applications,
was believed to be the reason for these lower populations.


TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS iii
LIST OF TABLES viii
LIST OF FIGURES xiv
ABSTRACT xviii
INTRODUCTION 1
CHAPTER I, LITERATURE REVIEW 4
No-Tillage Systems? 4
Advantages and Disadvantages of No Tillage... 4
Disadvantages 4
Advantages 5
Economics of No-Tillage Systems 7
Pest Problems in No-Tillage Agroecosystems... 9
Weeds in no tillage 9
Crop diseases in no tillage 10
Effects of no tillage on insect pests 13
Soybean and Corn Insect Pests in Florida 19
Soybean Insects 19
Three-cornered alfalfa hopper 19
Lesser cornstalk borer 20
Soybean looper 20
Velvetbean caterpillar 21
Brown and southern green stink bugs 22
Corn Insects 23
Lesser cornstalk borer 23
Fall armyworm 24
Corn earworm 25
Soil-Inhabiting Predators 26
Carabid Beetles 26
The Striped Earwig 28
CHAPTER II, SOYBEAN CROP SYSTEMS 30
Materials and Methods 30
Cultural Practices 30
Rye stubble experiment 30
Com stubble experiment 32
Oat stubble experiment 32
v


104
till plots had a damaged whorl. Plant regrowth occurred,
but the stand reduction remained very high. Ears were
also very severely damaged in the late planted corn. More
than 86% of the ears in the no till, and 82% in the conven
tional till plots had Spodoptera-Heliothis damage.
Data collected in the second (1979) season from the
wheat experiment are in Table 24. Damage to the foliage
was estimated as average numbers of damaged plants per
row, percent of damaged plants calculated on a row basis,
and percent of infested plants calculated on the basis
of 120 plants observed per treatment and per week. The
analysis of the data showed that, whatever the method
used to estimate the damage, no-tillage cropping did not
have a significant impact on fall armyworm and corn earworm
infestations as compared to the conventional tillage (Table
24) .
The fall armyworm and corn earworm damage to ears
assessed at the harvest time is shown in Tables 25 and
26, respectively for the vetch stubble and wheat stubble
experiments. No significant differences were detected
between treatments in the two experiments.
No-till practice into vetch and wheat stubble did
not, in this study, significantly affect S^. frugiperda and
H. zea infestations on field com during the two years
of observation. Some above-ground insects such as the
armyworm (Pseudaletia unipuncta) are reported to cause
more severe damage to no-till corn than to the conventionally


LARVAE /SHAKE ( f5
75
4.5-
4.0-
3.5-
3.0-
2.5-
2.0-
July Aug Sept
SAMPLING PERIOD
Figure 5. Average numbers of large (over 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and con
ventional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Averages of eight shakes
per treatment.
: mo tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.


Table 6. Number of Nezara viridula (Linn.) collected by the
shake cloth method in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua, Co.
Fla., 1978. The numbers represent totals and
averages of eight weekly shakes per treatment for
nine weeks. The plots (all) were treated with
methomyl (once) and acephate (once) for insect
control.
Average/shake
Nymph
Adult
Nymph +
Treatment
Adult
No tillage into oat stubble
1.19
2.08
3.28
No tillage plus in-row
subsoil into oat stubble
0.56
1.58
2.14
Conventional tillage into
oat stubble
0.83
1.78
2.61
Conventional tillage plus
in-row subsoil into oat
stubble
a
0.47
2.14
2.61
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


99
(using the Super-Seeder already mentioned) with "DeKalb
XL 78A" com in rows 76 cm apart. Paraquat (0.42 kg a.i./ha)
was used at planting, and 2,4-D (0.28 kg a.i./ha) and
atrazine (2.24 kg a.i./ha) after emergence, for weed control.
The entire field was fertilized at planting with 0-7.92-
29.88 (N,P,K) at the rate of 448 kg/ha. Additional appli
cations of N (28 kg/ha) were, made on April 22 and June 10,
1978. During the planting operation, the plots were treated
with carbofuran at the rate of 2.24 kg a.i./ha.
This experiment was repeated in the 1979 cropping
season with the same cultural practices, except that no
insecticide was used as soil treatment. The soil was
prepared in conventional tillage plots on March 30, 1979,
and corn (same hybrid) was planted on April 6, 1979.
Wheat stubble experiment. The effect of the no tillage
was also determined in corn seeded into wheat ("Holly")
stubble. The field (same size as in the vetch experiment)
was divided into eight plots in which the same tillage
treatments as above were displayed in a randomized complete
block design. The soil in the conventional tillage treat
ments was plowed and disked twice on June 2, 1978. On
June 3, all the plots were planted with "DeKalb XL 78A"
corn in 76 cm rows. The plots were treated with alachlor
(1,12 kg a.i./ha) and atrazine (1.68 kg a.i./ha) for weed
control. In addition to these two herbicides, no-tillage
plots were treated with paraquat (0.42 kg a.i./ha, plus


20
Lesser cornstalk borer. Several researchers including
Luginbill and Ainslie (1917), King et al. (1961), Walton
et al. (1964), Dupree (1965), and Leuck (1966) have made
a complete study that included the biology and description
of life stages of the lesser cornstalk borer.
The larvae of E. lignosellus feed on a variety of
host plants, mostly grasses and legumes (Luginbill and
Ainslie, 1917; Dempsey and Branthey, 1953; and Jordan,
1965). They damage soybeans by tunneling into young plants
and girdling the stem of older ones. Small plants so
injured wilt and usually die; damaged older plants may be
broken off by high winds.
Isely and Miner (1944) reported that in northwestern
Arkansas, lesser cornstalk borer infestations were so high
that more than 50% of the stand was lost in the fall beans.
In one field, 80% of the bean plants were killed 10 days
after the plants emerged.
Genung and Green (1965) reported that E. lignosellus
infestations on Florida soybeans were light and confined
to young plants, but that all the plants attacked died.
Severe infestations occur most frequently in sandy soils
and are usually associated with late planting or drought
stress (Leuck, 1966; Turnipseed, 1973).
Soybean looper. The soybean looper [Pseudoplusia
includens (Walker)] females preferentially oviposit on


118
Table 21. Foliage and ear damage caused by the fall army-
worm, Spodoptera frugiperda (J. E. Smith), and
the com earworm, Heliothis zea (Boddie), in
no-tillage and conventional tillage com at
Green Acres, Alachua Co., Fla., 1978. Numbers
are averages of 120 plants per treatment (each
week) for four weeks for foliage and three weeks
for ears.
% infestation*
Treatment
Foliage
Ears
No tillage into vetch stubble
No tillage plus in-row subsoil
24.59
44.32
into vetch stubble
37.46
38.40
Conventional tillage
30.83
43.25
Conventional tillage plus
in-row subsoil
22.71
50.78
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


ADULTS/TRAP (LOG x )
SAMPLING PERIOD


31
1. no tillage into rye stubble: "Cobb" soybeans
were seeded directly (without any previous
soil preparation) into the stubble of
"Wrens Abruzzi" rye.
2. no tillage plus in-row subsoil into rye
stubble: This treatment was the same as
the first one except for the additional
subsoiling made in the rows during the
planting operation.
3. no tillage into rye mulch;
4. no tillage plus in-row subsoil into rye
mulch.
5. conventional tillage into rye stubble:
The soil in the conventional tillage plots
was prepared according to the normal tillage
practice (moldboard plowing and disking)
before soybeans were planted.
6. conventional tillage plus in-row subsoil
into rye stubble.
"Cobb" soybeans were planted in all the plots on
March 21, 1978, in 76.2 cm rows with a 2-row Brown-Harden
(r)
Super-seeder^mounted on a 4600 Ford tractor. Seedling
rate was about 112 kg/ha. The plots were fertilized with
672 kg/ha of 5-4.4-12.5 N-P-K applied at planting along with
0.42 kg a.i./ha of paraquat (see Appendix A for chemical
names of all herbicides) plus Ortho X-77 (surfactant)at the
label dose, 2.24 kg a.i./ha of alachlor and 0.28 kg a.i./ha


CHAPTER II
SOYBEAN CROP SYSTEMS
Materials and Methods
Cultural Practices
Rye stuhble experiment. Experiments were conducted
simultaneously on the Robinson farm located in Williston,
Levy county, about 33 km west of Gainesville, and at the
Green Acres, a University of Florida agronomy farm located
in Alachua county. These two locations will be referred
to as Williston and Green Acres.
In Williston the observations were made in a large
block measuring 73.17 m x 85.37 m previously planted to
rye which was used either as hay (stubble) or mulch. The
block was divided into four 12.20 m x 73.17 m main plots
separated from each other by a 12.20 m wide alley. Each
main plot was further divided into six 12.20 m x 12.20 m
small plots making a total of 24 small plots for the whole
block. Six tillage treatments were arranged in a randomized
complete block design with each treatment being replicated
four times. The six treatments whose effects were tested on
insect populations were:
30


Table 8.
Stink bug damage to seeds in no-tillage and
conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1978.
Number of Seeds
Treatment
Total
Examined
Damaged
~T~
Damaged*
No tillage into oat stubble
784
59
7.52
No tillage plus in-row
subsoil into oat stubble
673
26
3.86
Conventional tillage
629
53
8.43
Conventional tillage
plus in-row subsoil
532
40
7.52
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


To my parents,
sisters, and
brothers


15
through plowing to be an effective method in controlling
the pink bollworm, Pectinophora gossypiella (Saund.), in
Texas cotton fields. Adkisson et al. (1960) found that
burying cotton material during the winter killed 76 to 83%
of the pink bollworm larvae, and that an average of 51.6%
of the larvae survived the winter in infested cotton left
on the ground.
Conditions created in no-tillage systems are reported
to be conducive to insect activity (Musick, 1970b). Insect
problems in the no-tillage cropping are, therefore, believed
to be more severe than in the conventionally tilled fields.
Musick (1970a, b) and Musick and Petty (1974) stated
that soil insects constitute the most serious threat to
no-tillage com production. The seed com maggot, Hylemya
platura (Meigen), is active at low temperatures and female
flies oviposit in soil where surface trash and decaying
plant matter are abundant. This pest is believed likely
to cause severe damage to no-tillage crops. Other soil
insects such as seed com beetles, wireworms, cutworms,
white grubs, and corn rootworms are also a more serious
threat in no tillage than in conventional tillage com
production.
In Ohio in 1969 (Musick, 1970b), soil insects, mostly
wireworms and seed com maggots, reduced the stand by 20-
25% more in the no-tillage portions of some fields than in
the conventionally tilled portions. Other no-till fields


INFLUENCE OF NO-TILL AND CONVENTIONAL TILLAGE
ON INSECT PESTS AND SOIL INHABITING PREDATOR POPULATIONS
IN FLORIDA SOYBEAN AND CORN CROPPING SYSTEMS
By
KI-MUNSEKI LEMA
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1980

To my parents,
sisters, and
brothers

ACKNOWLEDGMENTS
I express my sincere appreciation to Dr. Reece I.
Sailer, my major advisor, and to Dr. Donald C. Herzog,
cochairman of my supervisory committee, for their guidance,
advice and criticism throughout the course of this work.
I wish to thank Dr. Raymond N. Gallaher not only for serving
on the supervisory committee, but also for his invaluable
assistance in the field and for his marked interest for
this study.
I acknowledge the advice and assistance of Dr. S.
L. Poe as former chairman of the supervisory committee.
I wish to express my gratitude to the Rockefeller
Foundation for its financial support through a fellowship,
and to the Universite Nationale du Zaire for making possible
the obtainment of this fellowship.
The author wishes to thank Dr. D, H. Habeck and P. M.
Choate of the Division of Plant Industry for identification
of many insect species. I also thank P. J. d'Almada for
his assistance with statistics, and Lavelle Oswalt for
her patience in typing this work.
Special gratitude is due to my wife, Lugwadio mi-Konde,
for her support and devotion, and for helping the family
financially when my fellowship ended before the end of my
in

program. I also extend my gratitude to my daughter, Lukamba
Nsunda, and to my son Kapela, for having gone through the
numerous upheavals associated with my studies.
iv

TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS iii
LIST OF TABLES viii
LIST OF FIGURES xiv
ABSTRACT xviii
INTRODUCTION 1
CHAPTER I, LITERATURE REVIEW 4
No-Tillage Systems? 4
Advantages and Disadvantages of No Tillage... 4
Disadvantages 4
Advantages 5
Economics of No-Tillage Systems 7
Pest Problems in No-Tillage Agroecosystems... 9
Weeds in no tillage 9
Crop diseases in no tillage 10
Effects of no tillage on insect pests 13
Soybean and Corn Insect Pests in Florida 19
Soybean Insects 19
Three-cornered alfalfa hopper 19
Lesser cornstalk borer 20
Soybean looper 20
Velvetbean caterpillar 21
Brown and southern green stink bugs 22
Corn Insects 23
Lesser cornstalk borer 23
Fall armyworm 24
Corn earworm 25
Soil-Inhabiting Predators 26
Carabid Beetles 26
The Striped Earwig 28
CHAPTER II, SOYBEAN CROP SYSTEMS 30
Materials and Methods 30
Cultural Practices 30
Rye stubble experiment 30
Com stubble experiment 32
Oat stubble experiment 32
v

Estimation of Tillage Effects on Insects 33
Soil arthropods 33
Above-ground insects 34
Results and Discussion 36
Soil-Pest Insects 36
Above-Ground Pest Insects 38
Three-cornered alfalfa hopper 38
Soybean looper 39
Southern green stink bug 39
Velvetbean caterpillar 42
Soil-Inhabiting Predators 44
Ground spiders 44
Striped earwig 45
Carabid beetles 48
CHAPTER III. CORN CROP SYSTEMS 98
Materials and Methods 98
Cultural Practices 98
Vetch stubble experiment 98
Wheat stubble experiment 99
Estimation of Insect Damage and Arthropod
Populations 100
Soil arthropods 100
Above-ground insects 101
Results and Discussion 102
Above-Ground Insects 102
Vetch stubble experiment 102
Wheat stubble experiment 103
Soil Insect Pests 105
Wireworms 105
Lesser cornstalk borer in vetch stubble... 106
Lesser cornstalk borer in wheat stubble... 107
Cutworms in vetch and wheat stubble 109
Soil-Inhabiting Predators Ill
Ground dwelling spiders Ill
Carabid beetles 113
Striped earwig 115
GENERAL CONCLUSIONS 137
Soybean Crop Systems 137
Corn Crop Systems 137
Arthropod Predators 138
Corn and Soybean Yields 138
APPENDICES
A CHEMICAL NAMES OF HERBICIDES MENTIONED OR
USED IN THE EXPERIMENTS 140
B PREDATORY ACTIVITY OF LABIDURA ON ANTICARSIA
IMMATURES 141

Page
C YIELD OF "DEKALB XL 78 A" CORN FROM GREEN
ACRES 144
D AVERAGE YIELDS OF "COBB" SOYBEANS 146
LITERATURE CITED 148
BIOGRAPHICAL SKETCH 159
vii

LIST OF TABLES
Table
1
2
3
4
Page
Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus (Zeller), in no-
tillage and conventional tillage "Cobb
soybeans at Willis ton, Levy Co., Fla.,
1978. Numbers are totals and averages
of two rows per replication for three
weeks 51
Lesser cornstalk borer infestations in
no-tillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co.,
Fla., 1979. Estimations are based on two
different rows observed weekly (for three
weeks) in each replication (four reps/treat.)... 52
Average number of the three-cornered alfalfa
hopper, Spissistilus festinus (Say),
collected by the plant shaking method
(1978) and sweep net (1979) from conventional
tillage and no-tillage soybeans at Green
Acres, Alachua Co., Fla. Numbers are
averages of eight weeks with eight shakes
per treatment and three weeks with eight
sweeps per treatment 53
Soybean looper populations in no-tillage
and conventional tillage "Cobb" soybeans
estimated by the shake cloth method at
Green Acres, Alachua Co., Fla., 1978 and
1979. Numbers are totals and averages of
eight (for 1978) and four (for 1979) weekly
shakes (sites) per treatment for 12 (1978)
and six (1979) weeks 54
Effect of tillage on southern green stink
bug populations estimated by the shake
cloth method in "Cobb" soybeans at
Williston, Levy Col, Fla., 1978. Numbers
represent totals and averages of eight
weekly shakes per treatment for seven
weeks
viii
55

Table
Page
6 Number of Nezara viridula (Linn.) collected
by the shake cloth method in no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua, Co., Fla., 1978.
The numbers represent totals and averages
of eight weekly shakes per treatment for
nine weeks. The plots (all) were treated
with methomyl (once) and acephate (once)
for insect control 56
7 Number of Nezara viridula (Linn.) collected
by the plant shaking method in no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Numbers are averages of four weekly shakes
per treatment for four weeks. The plots
were sprayed twice with acephate for
insect control 57
8 Stink bug damage to seeds in no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1978 58
9 Damage to seeds by the stink bug complex
in no-till and conventional till "Cobb"
soybeans at Green Acres, Alachua Co.,
Fla., 1979. Numbers are averages of
20 plants per treatment 59
10 Effect of tillage practice on populations
of the velvetbean caterpillars, Anticarsia
gemmatilis Hubner, estimated by the plant
shaking method in "Cobb" soybeans at
Williston, Levy Co., Fla., April July,
1978. Numbers are averages of four weekly
shakes per treatment for six weeks. Plots
were treated with methomyl (0.56 kg a.i./ha)
on September 27 for the control of velvet-
bean caterpillars 60
11 Effect of tillage practice on population
levels of the velvetbean caterpillar,
Anticarsia gemmatilis Hubner, monitored
by the plant shaking method in "Cobb"
soybeans at Green Acres, Alachua Co., Fla.,
1978. Numbers are averages of eight weekly
shakes per treatment for eleven weeks for
small larvae and eight weeks for large
larvae. The plots were treated with methomyl
and acephate (once each) for insect control 61
IX

Table
Page
12 Populations of the velvetbean caterpillar,
Anticarsia gemmatilis, estimated by the
plant shaking method in no-tillage and
conventional tillage "Cobb" soybeans at
Green Acres, Alachua Co., Fla., 1979.
Numbers represent four weekly shakes per
treatment for ten weeks. Soybeans were
treated twice with acephate for insect
control 62
13 Activity of the striped earwig Labidura
riparia (Pallas), in no-tillage and
conventional tillage "Cobb" soybeans esti
mated by pitfall traps at Williston, Levy
Co., Fla., 1978. Four traps were used
for each treatment for 11 weeks 63
14 Activity of the striped earwig, Labidura
riparia, in no-tillage and conventional
tillage late-planted "Cobb" soybeans
estimated by pitfall traps at the Robinson
farm, Williston, Levy Co., Fla., 1978.
Numbers are averages of three traps per
treatment for ten weeks. Plots were
treated once with methomyl for the control
of velvetbean caterpillars 64
15 Activity of the striped earwig, Labidura
riparia, in no-tillage and conventional
tillage "Cobb" soybeans estimated by
pitfall traps at Green Acres, Alachua Co.,
Fla., 1978. Numbers are averages of 14
weeks with four traps per treatment. Half
of each plot was treated with carbofuran (F)
at planting, the other half was untreated (C)... 65
16 Number of striped earwig, Labidura riparia,
collected in pitfall traps in no-tillage
and conventional tillage "CObb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Numbers are averages of 15 weeks and four
traps per treatment. All the plots were
treated twice with acephate for insect
control 66
17 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Williston, Levy Co., Fla., April July,
1978. Totals of four traps per treatment
for 12 weeks 67
x

Table
Page
18 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Williston, Levy Co., Fla., September -
November, 1978. Numbers are totals of
three traps per treatment for 10 weeks 68
19 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at Green
Acres, Alachua Co., Fla., June September,
1978. Totals of four traps per treatment
for 14 weeks 69
20 Species and numbers of carabid beetles
collected in pitfall traps from no-tillage
and conventional tillage soybeans at
Green Acres, Alachua Co., Fla., June -
September, 1979. Totals of four traps
per treatment for 15 weeks 70
21 Foliage and ear damage caused by the fall
armyworm, Spodoptera frugiperda (J. E.
Smith), and the corn earworm, Heliothis
zea (Boddie), in no-tillage and conventional
tillage corn at Green Acres, Alachua Co.,
Fla., 1978. Numbers are averages of 120
plants per treatment (each week) for four
weeks for foliage and three weeks for ears 118
22 Damage caused by the fall armyworm,
Spodoptera frungiperda, and corn earworm,
Heliothis zea, to no-tillage and conventional
tillage field com at Green Acres, Alachua
Co., Fla., 1979. Numbers are averages of
120 plants per treatment (each week) for
five weeks for foliage and four weeks for
ears 119
23 Infestations of the fall armyworm, Spodoptera
frugiperda, and corn earworm, Heliothis zea,
in no-tillage and conventional tillage field
corn at Green Acres, Alachua Co., Fla., 1978.
Average based on 120 plants per treatment
per week 120
24 Infestations of the fall armyworm, Spodoptera
frugiperda, and com earworm, Heliothis zea,
in no-tillage and conventional tillage field
corn at Green Acres, Alachua Co., Fla., 1979.... 121
xr

Table
Page
25
26
27
28
29
30
31
32
Fall armyworm and com earworm damage to the
conventional and no-tillage corn assessed
at the harvest time at Green Acres, Alachua
Co., Fla., 1979. Thirty-two ears collected
per treatment 122
Fall armyworm and corn earworm damage to the
conventional and no-tillage corn assessed
at the harvest time at Green Acres, Alachua
Co., Fla., 1979. Forty ears were collected
per treatment 123
Number of Conoderus amplicollis (Gyll.) and
C. falii Lane (Elateridae) collected in
pitfall traps from conventional tillage and
no-tillage field com at Green Acres, Alachua
Co., Fla., 1979. Numbers are totals and
averages of nine weeks for vetch and six
weeks for wheat with four traps per treat
ment 124
Lesser cornstalk borer, [Elasmopalpus
lignosellus (Zeller)], infestations in no
tillage and conventional tillage field corn
at Green Acres, Alachua Co., Fla., 1978-
1979. Estimation is based on eight rows
per treatment examined each week for three
weeks 125
Infestations of the lesser cornstalk borer
Elasmopalpus lignosellus. in no-tillage and
conventional tillage field com at Green
Acres, Alachua Co., Fla., 1978 126
Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus, in no-tillage and
conventional tillage field com at Green
Acres, Alachua Co., Fla., 1979 127
Activity of the granulated cutworm, Feltia
subterrnea (Fab.), monitored by nonbaited
pitfall traps in no-tillage and conventional
tillage com at Green Acres, Alachua, Co.,
Fla., 1979. Numbers are totals and averages
of four traps per treatment for four weeks... 128
Number and species of carabid predators
collected in pitfall traps from no-tillage
and conventional tillage field corn at Green
Acres, Alachua Co., Fla., May July, 1978.
Numbers are totals of four traps per treat
ment 129
Xll

Table
Page
33 Numbers and species of carabid predators
collected in pitfall traps from no-tillage
and conventional tillage field corn at
Green Acres, Alachua Co., Fla., April -
July, 1979. Numbers are totals of four
traps per treatment 130
34 Numbers and species of carabid predators
collected in pitfall traps from no-tillage
and conventional tillage field corn at
Green Acres, Alachua Co., Fla., July -
August, 1979 131
xi n

Figure
1
2
3
4
LIST OF FIGURES
Page
Average numbers of small (up to 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Williston, Levy Co., Fla., 1978.
Averages of eight shakes per treatment 71
Average numbers of large (over 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Williston, Levy Co., Fla., 1978.
Averages of eight shakes per treatment 7 2
Average number of velvetbean cater
pillars, Anticarsia gemmatilis,
collected by the plant shaking method
from no-tillage and conventional
tillage "Cobb" soybeans at Williston,
Levy Co., Fla., 1978. Averages of
eight shakes per treatment 73
Average numbers of small (up to 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla.,
1978. Averages of eight shakes per
treatment 74
Average numbers of large (over 2.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1978.
Averages of eight shakes per treatment 75
xiv

Page
Figure
6 Average numbers of velvetbean cater
pillars, Anticarsia gemmatilis,
collected by the plant shaking method
from no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Average of
eight shakes per treatment 76
7 Average numbers of small (up to 1.5 cm)
velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant
shaking method from no-tillage and
conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Averages of four shakes per treatment 77
8 Average numbers of medium (1.6 2.5 cm)
and large (over 2.5 cm) velvetbean cater
pillars, Anticarsia gemmatilis, collected
by the plant shaking method from no-
tillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co., Fla.,
1979. Averages of four shakes per
treatment 78
9 Average numbers of velvetbean caterpillars,
Anticarsia gemmatilis, collected by the
plant shaking method from no-tillage
and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979.
Average of four shakes per treatment 79
10 Average trap-week collections of Labidura
riparia nymphs from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., April July,
1978. Four pitfall traps were placed in
each treatment 80
11 Average trap-week collections of Labidura
riparia adults from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., April July,
1978. Four pitfall traps were placed in
each treatment 81
xv

Page
Figure
12
13
14
15
16
17
18
Average trap-week collections of Labidura
riparia (nymphs + adults) from no-tillage
and conventional tillage "Cobb" soybeans
at Williston, Levy, Co., Fla., April -
July, 1978. Four pitfall traps were set
in each treatment 82
Average trap-week collections of Labidura
riparia nymphs from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., September -
November, 1978. Averages of four traps
per treatment 83
Average trap-week collections of Labidura
riparia adults from no-tillage and
conventional tillage "Cobb" soybeans at
Williston, Levy Co., Fla., September -
November, 1978. Averages of four traps
per treatment 84
Average trap-week collections of Labidura
riparia nymphs and adults from no-tillage
and conventional tillage "Cobb" soybeans
at Williston, Levy Co., Fla., September -
November, 1978. Averages of four traps
per treatment 85
Weekly activity of Labidura riparia
nymphs monitored by pitfall traps in
no-tillage and conventional tillage
"Cobb soybeans at Green Acres, Alachua
Co., Fla., 1978. Four traps were
placed in each treatment 87
Weekly activity of Labidura riparia
adults monitored by pitfall traps
in no-tillage and conventional tillage
"Cobb" soybeans at Green Acres, Alachua
Co., Fla., 1978. Four traps were placed
in each treatment 89
Weekly activity of Labidura riparia
(nymphs + adults) monitored by pitfall
traps in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Four traps were
placed in each treatment 91
xvi

Page
Figure
19 Weekly activity of Labidura riparia nymphs
monitored by pitfall traps (four in each
treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979 93
20 Weekly activity of Labidura riparia adults
monitored by pitfall traps (four in each
treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979 95
21 Weekly activity of Labidura riparia nymphs
and adults monitored by pitfall traps (four
in each treatment) in no-tillage and con
ventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979 97
22 Weekly damage to field corn foliage and
ears caused by Spodoptera frugiperda and
Heliothis zea at Green Acres, Alachua Co.,
Fla. 1^78 132
23 Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field com at Green Acres, Alachua Co.,
Fla. 1978 133
24 Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla. 1979 134
25 Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field com at Green Acres, Alachua Co.,
Fla., 1978 135
26 Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla., 1979 136
xvii

Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in
Partial Fulfillment of the Requirements for the
Degree of Doctor of Philosophy
INFLUENCE OF NO-TILL AND CONVENTIONAL TILLAGE
ON INSECT PESTS AND SOIL INHABITING PREDATOR POPULATIONS
IN FLORIDA SOYBEAN AND CORN CROPPING SYSTEMS
By
Ki-Munseki Lema
March 1980
Chairman: R. I. Sailer
Co-Chairman: D. C. Herzog
Major Department: Entomology and Nematology
The effect of no-tillage cropping on insect pests, and
ground-dwelling arthropod predators was assessed in soybean
and corn crop systems in Levy and Alachua Counties, Florida,
from April to November 1978 and 1979. No tillage and
conventional tillage, with in-row subsoil as a subtreatment
for both, were compared in rye (Secale cereale L.), com
(Zea mays L.), oat (Avena sativa L.), wheat (Triticum aestivum
L.) and vetch (Vicia villosa Roth) stubble or mulch.
Damage to soybeans [Glycine max (L.) Merrill] and corn
was determined weekly by visual observations. The sweep net
and plant shaking methods were used to monitor pest popula
tions in soybeans. The activity of ground-dwelling arthro
pods (pests and predators) was monitored in both corn and
soybean systems using pitfall traps.
xviii

In soybeans, above-ground insect pests and the lesser
cornstalk borer, Elasmopalpus lignosellus (Zeller), were
generally unaffected by the no-tillage fanning. No tillage
did not significantly affect damage due to Spodoptera
frugiperda (J. E. Smith) and Heliothis zea (Boddie) or
populations of Conoderus spp. on com. The results also
indicated that no tillage greatly increased populations of
the granulate cutworm, Feltia subterrnea (Fab.), without
affecting cutworm damage to com seedlings. No tillage,
however, significantly reduced lesser cornstalk borer
damage in com.
Populations of ground-dwelling spiders were not affected
by the no-tillage practice, and the effect of this practice
on the dermapteran Labidura riparia (Pallas) was not consis
tent. In soybeans no tillage significantly increased the
activity of carabid beetles whereas in com most carabids
were collected from conventional tillage treatments.
Yields of soybeans were reduced in the no-tillage sys
tems as compared to the conventional tillage. Com yields,
however, were not affected by the no-tillage practice.
xxx

INTRODUCTION
No tillage or zero tillage is defined as the agronomic
practice that consists of planting crop seeds in sod or
crop residues in a previously unprepared soil (Young, 1970;
Triplett and Van Doren, 1977). The soil is not disturbed
except for a narrow (5-7 cm wide) slit made by the planter
and in which the seeds are planted.
In the conventional tillage procedure a number (up to
ten) of trips across the field are made for soil preparation
and weed control. According to Young (1970), any practice
that reduces the number of these trips (e.g. plow and plant,
chiseling and plant) is a minimum or reduced tillage, an
operation distinctly different from the no tillage. Some
workers, however, consider the no-tillage practice as a case
of minimum tillage, and use the term "conservation tillage"
to include both the minimum (reduced) and no tillage. The
systems studied in this work are considered as no-tillage sys
tems, and the terms no-till and no tillage are used interchangeably.
No-tillage cropping has numerous advantages over the
conventional tillage practice. Nontilled soils retain moisture
longer than tilled fields (Moody et al., 1963; Triplett et al.,
1968). Plant residues in no-tillage systems prevent or
1

2
reduce soil loss by water and wind erosion (Triplett et al.,
1978). Crop yields obtained from no-tillage systems are
reported to be higher than, or at least equal to, those from
conventionally tilled fields when no tillage is practiced on
well drained soils and weed control is adequate (Rask et al.,
1967; Triplett and Van Doren, 1977; Lai, 1979). A great
saving in energy and labor also results from no tillage.
Rask et al., (1967) estimated that production costs can be
reduced by as much as 75% in no-tillage systems due to the
elimination of tillage operations.
Farmers are increasingly adopting the no-tillage practice
as an alternative to the conventional tillage for crop produc
tion (Blevins et al., 1971). It is predicted that over 90% of
the U. S. crop acreage will be grown under reduced tillage by
the year 2010; at least half of this acreage will be under
no-tillage farming (Triplett and Van Doren, 1977).
Fear of pest problems is one of the main objections to
the adoption of the no-tillage practice by many growers. It
is believed that, since the soil is not disturbed and crop
residues are left on the soil surface in no-tillage systems,
pest problems will be more severe in these systems than in
conventionally tilled fields. Musick (1970a, b) reported
that soil insects such as wireworms, seed corn maggots and
cutworms cause considerable damage to no-tillage com (Zea
ma7s L.) rn Ohio. Some crop diseases also cause more serious
damage to no-tillage crops than to crops planted in conven
tionally tilled fields (Bums, 1973).

3
Doupnik et al. (1975) and All and Gallaher (1977)
observed that the conditions created in untilled fields were
not favorable to all pest species, and that no tillage may
have detrimental effects on some pest organisms. The lesser
cornstalk borer, Elasmopalpus lignosellus (Zeller), caused
less damage in no-tillage than in conventional tillage corn
(All and Gallaher, 1977), and stalk rot incidence of grain
sorghum,[Sorghum bicolor (L.) Moenck], was higher in conven
tionally tilled than in nontilled blocks in Nebraska (Doupnik
et al., 1975).
Because of the increasing adoption of no tillage as a
crop production procedure, detailed studies are needed to
better understand the biology and behavior of pest species,
and to assess the importance of pest problems in no-tillage
systems. Experiments were conducted in Alachua and Levy
counties, Florida, in order to discern the influence of no
tillage on the most important insect pests of com and soy
bean [Glycine max (L.) Merrill] ecosystems. Data were also
collected to determine the effects on soil-inhabiting arthro
pod predators.

CHAPTER I
LITERATURE REVIEW
No-Tillage Systems
Advantages and Disadvantages of No Tillage
Disadvantages Several disadvantages are associated
with the no-tillage practice. Musick (1970b) reported slower
com seed germination due to lower soil temperatures in
untilled fields. Early crop growth is also reported to be
depressed temporarily in no-tillage systems (Moody et al.,
1963). Late in the growing season, however, crop growth in
no tillage is faster than in tilled fields because of high
soil moisture associated with plant residues.
Plant density was observed to be generally lower in
no-tillage fields than in conventionally tilled fields.
This is due in part to the fact that some seeds do not get
into the furrow and are eaten by birds and rodents. Growers
in Illinois consider rodents to be important pests of crops
in no-till culture (Herzog, personal communication, 1980) .
Crop yields from no tillage may be lower than those
obtained from conventional tillage when no-tillage systems
are established on some types of soils. Griffith et al.
/
<4

5
(1973) observed that on poorly drained fine-structured soils,
no-tillage com gave lower yields than did the conventional
tillage com.
Musick (1970a, b) reported that conditions created in
no-tillage systems (crop residues, high soil moisture and
low temperatures) are conducive to pest activity. Pest
problems are believed to be the principal disadvantage farm
ers associate to the no-tillage practice. Several pest
organisms overwinter in plant residues, and readily attack
the new crop when conditions become favorable. In conven
tional soil tillage such pests are usually controlled by
physical destruction, exposure to unfavorable weather, and
natural enemies.
Advantages. Among the numerous advantages of the no
tillage practice, the more important are those associated
with protection of soil from erosion, reduction in energy
input required for crop production, as well as increased
crop growth and yields due to higher soil moisture. Moody
et al. (1963) and Jones et al. (1968) found that soil
moisture was higher in the no-tillage than in the conven
tional tillage com, and that this higher soil moisture
significantly increased com growth and yields. Mulched
com was 64 cm taller at tasseling and produced 47 kg/ha
more grain than conventional tillage com (Moody et al.,
1963). Triplett et al. (1968) also observed a significant

6
increase of plant height as the amount of surface cover
increased in nontilled corn fields.
Runoff becomes a very important factor in the no tillage
because of large quantities of herbicides used in these
systems. Such runoff may increase the amount of soluble
chemicals in streams (Holt et al., 1973). According to Unger
and Phillips (1973), plant residues on untilled soil reduce
evaporation, runoff, and prevent crusting of the soil surface
The subject of soil erosion by water and wind has been
treated by a number of authors including Wischmeier (1973),
Woodruff and Siddoway (1973), and Triplett et al. (1978).
Soil erosion results in a tremendous loss of topsoils in
croplands. No-tillage practice greatly reduces soil erosion
because of the mulch that remains on the soil surface.
Triplett and Van Doren (1977) in Ohio observed that a 12.70
cm rainfall caused losses of up to 45 tons of soil/ha from
conventional tillage corn fields with slopes of 6-8% where
as a 20% slope watershed with no-tillage corn had a loss of
less than 112 kg/ha. Reduced and no-tillage systems can
decrease erosion potential as much as 50-fold (Triplett et al
1978) .
No-tillage cropping procedure is particularly important
for crop production on lands with slopes so steep that con
ventional tillage would cause unacceptable damage due to
erosion. This is especially true in tropical regions where
soils are highly erodible and rainfall intensities are
high (Curfs, 1976). Curfs (1976) recommended no-tillage and

7
reduced tillage systems as an alternative for shifting
cultivation widely practiced in the tropics. The tradi
tional system of shifting cultivation protects the soil from
erosion, but, according to Lai (1973), it supports only one
person on 15 ha of land and continuous cropping under this
system may ruin the soils.
The main advantage of the no tillage is undoubtedly
the tremendous reduction in crop production costs that result
from reduced machinery use and associated reduction in fuel
consumption. A great saving in time and labor also results
from the no-tillage practice. The economics of the no tillage
is reviewed in the next section.
Economics of No-Tillage Systems
The economic aspect is the most important factor con
sidered by the farmers in accepting the "new" crop production
practice. As discussed by Shipley and Osborn (1973), conser
vation tillage must produce a net return equal to, or greater
than, that obtained with the conventional tillage if the
farmer is to switch from the conventional to the conserva
tion tillage.
Rask et al. (1967) obtained a reduction of as much as
75% in production costs and a saving in time of 70-80% in
no-tiliage corn. Doster (1976) calculated production costs
in conventional and conservation tillage systems in Indiana
and found that no tillage with coulter disc was the cheapest,

8
and spring plowing the most expensive system for com produc
tion. In one study (Doster, 1976) total costs (machinery,
herbicides, and part-time costs) were $62,49, $72.07, and
$48.05 in conventional fall plow, conventional spring plow,
and no tillage with coulter disc, respectively. The authors
also reported that herbicides were the most expensive item in
the no-tillage farming.
A tremendous saving in fuel results from reduced machin
ery use in no tillage. Triplett and Van Doren (1977) pointed
out that fuel consumption in untilled com was reduced by as
much as two-thirds of the amount consumed in the conventional
tillage.
Reports by various workers (Rask et al., 1967; Jones
et al., 1968; Triplett and Van Doren, 1977) showed that
yields from no tillage were 10-39% higher than those from
the conventional tillage. Higher yields combined with
reduced machinery costs and saving in labor results in
significantly higher net profits.
Young (1970) reported that net money returns from no
tillage farming were usually greater than with conventional
tillage systems. Doster (1976) evaluated net returns
for 243 ha of corn continuously grown in various tillage
systems in Indiana. He observed that spring plowing practiced
on Tracy silt loam yielded net returns of $76,000 while no
tillage with coulter gave a net return of $81,500. On
Runnymede loam, however, spring plowing and no-tillage coulter
yielded $94,000 and $68,000, respectively for the 243 ha.

9
Pest Problems in No-Tillage Agroecosystems
Weeds in no tillage. An effective chemical weed control
is a prerequisite to acceptable crop yields from the no
tillage. In a seven-year study, Triplett and Lytle (1972)
confirmed weed control to be the dominant factor limiting
high crop yields. Griffith et al. (1973) showed that crop
yields in no-plow systems may be lower than those from con
ventionally plowed fields if weed control is not adequate.
Weed control is no longer a serious problem in no-plow
agroecosystems because of the development of effective herbi
cides. Several herbicides such as atrazine (see Appendix A
for chemical names), paraquat, simazine, against grasses,
and 2,4-D, etc., against broad-leaf weeds, have achieved
satisfactory weed control in the no-tillage cropping pro
cedure (Triplett, 1966; Triplett and Lytle, 1972).
Some problems related to weed control have developed
in no-tillage crop production due to the lack of soil tillage
and cultivation. Triplett and Lytle (1972) observed that
annual weed populations shifted with different herbicides,
when com was continuously grown on no tillage for seven
years. Atrazine and simazine controlled most of the weeds,
but the fall panicum (Panicum dichotomiflorum Michx.) became a
major annual weed where those two herbicides were used. The
authors also found that hemp dogbane (Apocynum cannabinum L.)
became a serious problem after several years of continuous com
production under no-tillage farming (Triplett and Lytle, 1972).

10
Wiese and Staniforth (1973) also reported that hemp dogbane
spreads rapidly where the soil is not tilled.
Peters (1972) and Triplett and Lytle (1972) found that
several perennial weed species were tolerant to herbicides.
The common milkweed (Asclepias syriaca L.), horsenettle
(Solanum carolinense L.), groundcherry (Physalis sp.), and
the tall ironweed (Vernonia altissima Nutt.), are some of
those weed species that survive in untilled fields. Lewis
(1970) concluded that bermudagrass [Cynodon dactylon (L.)
Pers.], johnsongrass [Sorghum halepense (L.) Pers.], and
dallisgrass (Paspalum dilataturn Poir) cannot be effectively
controlled chemically in no-tillage systems.
Some of the herbicide applied in untilled, mulched
fields may be intercepted by crop residues; this reduces the
amount of the chemical that reaches the target species (Trip
lett 1976) .
Crop diseases in no tillage. The problem of crop
diseases in conservation tillage has been investigated by
several workers including Bums (1973), Roane et al. (1974),
Yarham (1975), and White and Janney (1978). A large number
of plant pathogens inhabit or overwinter in crop residues
and the soil. They readily move to the new crop as soon
as weather conditions become favorable and susceptible
host plants are available (Graham, 1953; Kennedy, 1969;
Daft and Leben, 1973).

11
The lack of soil disturbance as well as the presence
of decaying plant material left on the ground may increase
the incidence of the diseases in no-tillage fields. Boosalis
and Doupnik (1976) reported that fungus and bacterial diseases
are the principal diseases associated with reduced tillage.
Ledingham et al. (1960) compared root rot incidence in
wheat (Triticum aestivum L.) grown in two tillage systems, a
surface tillage that left a trash cover on the ground, and
a moldboard-piowed stubble soil. The authors found that
plowing was effective in reducing disease incidence during
the seedling stages, but no significant difference was ob
served in infection levels as the crop matured.
Bums (1973) reported that the brown spot of corn
caused by Physoderma mavdis, a fungus that overwinters in
infested com debris, was more severe in reduced tillage
plots than in conventionally tilled plots. Burns (1973)
also reported that both the virus that causes wheat streak
mosaic and the mites that transmit it overwinter on living
wheat and perennial grasses, and that the greatest damage to
wheat was observed in fields planted close to wheat stubble.
Several reports have indicated that crop plants on no
tillage soil are not affected differently from these on con
ventionally plowed land. In some instances, conservation till
age practices were even reported to reduce disease incidence.
Keyworth (1942) in England demonstrated that soil
cultivation was the major factor for the spreading of the

12
Verticillium wilt within and from one garden to another.
McCalla (1967) reported that tillage operations transport
various kinds of soil microorganisms from one site to another.
In Oregon, Hall (1959) studied the effects of fertiliza
tion dates and plowing methods on the incidence of root rot
of Burt wheat caused by Fusarium sp. The author concluded
that stubble mulch did not increase the disease incidence as
compared to plowed plots. In a similar study in Iowa, Parker
and Burrows (1959) reached the same conclusion about the
incidence of com root and stalk rot: disease incidence was
lowest in those tillage systems where com stalk residue was
left on the soil surface, and where no or low levels of N
were applied.
Brooks and Dawson (1968) drilled winter wheat directly
into rye (Secale cereale L.) stubble to investigate the effects
of this cultural practice on take-all (Ophiobolus graminis
Sacc.) and eyespot (Cercosporella herpotrichoides Fron.). No
differences in infection levels were found between plowed and
unplowed plots before the first three months. Three months
after planting, however, disease incidence increased greatly
in plowed plots. The authors found that plants in untilled
plots were infested earlier than those in conventional tillage
plots, but that the rate of spread of the fungus was restricted
by adverse soil conditions in no-tillage plots.
Doupnik et al. (1975) believed that factors such as
increased water conservation, reduced soil temperature

13
fluctuations, and better chemical weed control contributed
to the reduction of the stalk rot incidence observed in no
tillage grain sorghum seeded in wheat stubble in Nebraska.
After studying crop diseases in no-tillage cereals,
Yarham (1975) concluded that "increase in disease levels has
not been sufficient to depress seriously the yields of the
nonplowed plots. At the moment, it does not appear likely
that cultivation-disease interaction will substantially influ
ence the success or failure of nonplow techniques" (p. 247).
Effects of no tillage on insect pests. Soil plowing has
been recommended for many years as an effective control
measure against several insect pests (Barber and Dicke, 1937;
Adkisson et al., 1960; Hardwick, 1965; and Frohlich and Rodewald,
1970). This practice reduces insect pest populations through
physical destruction, exposure to natural enemies, and detri
mental weather conditions.
Barber and Dicke (1937) compared the emergence of the
com earworm [(Heliothis zea (Boddie)] moths from hibernation
in various soil types and tillage systems in Virginia and
Georgia. Fall and spring plowing and fall disking signif
icantly reduced pest emergence as compared to the unculti
vated soil. Spring plowing, however, was less effective
than fall plowing or fall disking in reducing the corn ear-
worm emergence. The authors also found that soil type
affected the effectiveness of cultivation as control measure.
Plowing was more effective in sandy loam soil than in red clay
soil.

14
In the lower Rio Grande Valley of Texas, Fife and
Graham (1966) obtained a 100% control of both H. zea and
the tobacco budworm [Heliothis virescens (Fab.)] after
listing, disking and relisting the land in combination with
a preplanting irrigation. Listing the land alone reduced
the emergence of H. zea moths from pupae by about 55% in a
pepper field.
When the larvae of these two species are fully grown,
they leave their host plants and burrow into the soil to
pupate in pupal cells. According to Fife and Graham (1966),
these pupal cells are located at 1.27-15.24 cm below, and
their tunnels extend near, the soil surface. Cultivation
destroys most of the cells and tunnels in addition to the
physical pupal destruction.
Destruction of stalk and other plant parts is also used
to regulate insect pest populations (Metcalf, 1909). Several
insect pest species remain in crop residues between cropping
seasons and attack the new crop as soon as it is available.
Adeyemi (1969) showed that stem borers such as Busseola
fusca (Fuller), Sesamia calamistis Hamps., etc., can survive
in corn stalks from season to season in large enough numbers to
initiate borer infestations of the succeeding crop. An average
borer population of 27 per 100 stems examined was found in
stubble after the first-season corn harvest.
Fenton and Owen (1953), Noble (1955), and Fife et al.
(1957) reported burial of cotton (Gossypium spp.) residues

15
through plowing to be an effective method in controlling
the pink bollworm, Pectinophora gossypiella (Saund.), in
Texas cotton fields. Adkisson et al. (1960) found that
burying cotton material during the winter killed 76 to 83%
of the pink bollworm larvae, and that an average of 51.6%
of the larvae survived the winter in infested cotton left
on the ground.
Conditions created in no-tillage systems are reported
to be conducive to insect activity (Musick, 1970b). Insect
problems in the no-tillage cropping are, therefore, believed
to be more severe than in the conventionally tilled fields.
Musick (1970a, b) and Musick and Petty (1974) stated
that soil insects constitute the most serious threat to
no-tillage com production. The seed com maggot, Hylemya
platura (Meigen), is active at low temperatures and female
flies oviposit in soil where surface trash and decaying
plant matter are abundant. This pest is believed likely
to cause severe damage to no-tillage crops. Other soil
insects such as seed com beetles, wireworms, cutworms,
white grubs, and corn rootworms are also a more serious
threat in no tillage than in conventional tillage com
production.
In Ohio in 1969 (Musick, 1970b), soil insects, mostly
wireworms and seed com maggots, reduced the stand by 20-
25% more in the no-tillage portions of some fields than in
the conventionally tilled portions. Other no-till fields

16
had up to more than 90% stand reduction. Musick and Collins
(1971) documented that tillage system may influence the ovi-
position pattern of some insects. Females of the northern
com rootworm, Diabrotica longicomis Say, laid more eggs
in no-till com than in corn planted on conventionally plowed
land.
Some above-ground insects are also expected to cause
higher damage levels in untilled fields than in crops pro
duced by the conventional tillage system (Gregory and Musick,
1976). The European com borer (ECB), Ostrinia nubilalis
(Hubner), overwinters as mature larvae in corn stalks, and
populations of the ECB have been regulated by clean plowing.
Damage due to this pest will be more severe in no-tillage
corn than in plowed corn (Gregory and Musick, 1976). Musick
(1973) and Musick and Suttle (1973) observed that the army-
worm [Pseudaletia unipuncta (Haworth)] females preferentially
oviposited in grassy areas, and that the incidence of army-
worm damage was higher in no-tillage com, especially when
com was seeded directly in grass or fall-planted wheat.
The blackfaced leafhopper, Graminella nigrifrons (Forbes)
transmits two vims diseases to com, the maize chlorotic
dwarf (MCD) and maize dwarf mosaic (MDM). In a study invol
ving no-tillage cropping, carbofuran and hybrid resistance
to the diseases, All et al. (1977) found a greater leafhopper
population in no till than in the conventional tillage, but
no significant difference was observed in yield loss due to
MCD infection. Incidence of MDM was generally very low.

17
As stated by Musick (1970a), not all insect pests will
cause serious problems in no-till culture. Some serious pests
may become less important while the status of some secondary
pests may be changed to that of destructive pests.
In Georgia, All and Gallaher (1977) and All et al. (1979)
reported that infestations by the lesser cornstalk borer (LCB)
were greatly reduced in no-tillage corn. All and Gallaher
(1977) first speculated that higher soil moisture, lower
soil temperatures and greater soil compaction near the surface
in no-till systems were detrimental to the optimum develop
ment and survival of E. lignosellus larvae and, therefore,
responsible for the lower infestations observed in these
systems.
Cheshire et al. (1977) and Cheshire and All (1978) in
a detailed study, however, found that crop residues left on
the ground might be the most important factor in reducing the
LCB damage in no-tillage corn. Crop residues "may inhibit
LCB feeding by disrupting location of host plants by smell or
by mechanically shielding the host plant" (Cheshire and All,
1978, p. 12). The facultative saprophagous larvae consequently
feed on crop stubble instead of attacking crop plants.
All et al. (1979) also found that a combination of con
trol measures applied against E. lignosellus were more effec
tive in no-till blocks than in the conventional tillage.
Early planting, preplanting weed control, and applications
of carbofuran resulted in a better LCB control in untilled
fields than in those conventionally tilled.

18
Rivers et al. (1977) planted com into a sod field
infested with white grubs, Phyllophaga anxia (LeConte), to
investigate the influence of tillage systems on grub popula
tions. After two years of observations, the authors found
that the populations of white grubs were significantly
higher in the soil around plants in the conventional tillage
than in the no-tillage plots. They believed that this
phenomenon was due to the fact that grubs preferred to
feed on the grass left between crop rows in the no tillage.
In Indiana, Sloderbeck and Edwards (1979) reported
that changes in row width did not significantly affect
population levels of the Mexican bean beetle, Epilachna
varivestis Mulsant, and redlegged grasshopper, Melanoplus
femurrubrum (De Geer), but that tilled soybeans harbored
significantly more larval and adult Mexican bean beetles
than no-till soybeans. No till in combination with double
cropping, however, increased population levels of the
redlegged grasshopper as it continuously provided a suitable
habitat for the grasshopper.

19
Soybean and Com Insect Pests in Florida
Soybean Insects
Three-cornered alfalfa hopper. The biology and descrip
tion of adults and nymphs of the three-cornered alfalfa
hopper, Spissistilus festinus (Say), may be found in Turnip-
seed (1973). Damage to soybeans is caused by adults and
nymphs that girdle the plants with their feeding punctures.
According to Bailey et al. (1970), S. festinus feeds mostly
on the lower portion of the stems, but on soybean plants
taller than 25.4 cm, the insect prefers to feed on leaf
petioles.
Girdled plants are weakened and may break over and
lodge during high wind or heavy rains. Plant lodging
may cause a stand reduction which may be associated with
yield loss. In South Carolina and Oklahoma (Anonymous,
1975), S^. festinus has caused economic damage to soybeans.
Tugwell and Miner (1967) in Arkansas found that the hoppers
girdled up to 55.2% of the plants, but caused no yield
loss.
In addition to plant girdling, S. festinus may also
indirectly affect soybean plants by transmitting or pre
disposing the plants to a fungal disease. The wounds
made by the hoppers through feeding punctures provide
entry for Sclerotium rolfsii Saccardo, the causal agent
of sclerotial blight (Herzog et al., 1975).

20
Lesser cornstalk borer. Several researchers including
Luginbill and Ainslie (1917), King et al. (1961), Walton
et al. (1964), Dupree (1965), and Leuck (1966) have made
a complete study that included the biology and description
of life stages of the lesser cornstalk borer.
The larvae of E. lignosellus feed on a variety of
host plants, mostly grasses and legumes (Luginbill and
Ainslie, 1917; Dempsey and Branthey, 1953; and Jordan,
1965). They damage soybeans by tunneling into young plants
and girdling the stem of older ones. Small plants so
injured wilt and usually die; damaged older plants may be
broken off by high winds.
Isely and Miner (1944) reported that in northwestern
Arkansas, lesser cornstalk borer infestations were so high
that more than 50% of the stand was lost in the fall beans.
In one field, 80% of the bean plants were killed 10 days
after the plants emerged.
Genung and Green (1965) reported that E. lignosellus
infestations on Florida soybeans were light and confined
to young plants, but that all the plants attacked died.
Severe infestations occur most frequently in sandy soils
and are usually associated with late planting or drought
stress (Leuck, 1966; Turnipseed, 1973).
Soybean looper. The soybean looper [Pseudoplusia
includens (Walker)] females preferentially oviposit on

21
vegetables and legumes (Deitz et al., 1976). Mitchell (1967)
studied the life cycle of P. includens on soybeans.
Hensley et al. (1964) and Canerday and Arant (1966)
reported that soybeans, peanuts, and sweet potatoes were
the most preferred hosts for P. includens. On soybeans the
loopers may inflict severe foliage damage and occasionally
they cause damage to pods in the Gulf states (Deitz et al.,
1976) .
Velvetbean caterpillar. Watson (1916), Douglas (1930,
and Greene et al., (1973) are some of many researchers who
studied the life history and described the stages as well
as feeding and mating behavior of Anticarsia gemmatilis
Hubner. The eggs are laid on all portions of the soybean
plants (Strayer, 1973), and require three days to hatch in
August and September, and at least seven days in November,
in Florida (Watson, 1916).
Watson (1916) and Douglas (1930) reported that the velvet
bean caterpillars were preyed upon and parasitized by many
species of birds and insects, but that the fungus Nomurea
rileyi (Farlow) was the most important natural enemy that
regulates populations of this pest.
The nature of damage caused by A. gemmatilis immatures
to soybeans has been described by Watson (1916), Douglas
(1930) and Hinds and Osterberger (1931). The first three
instars cause less damage as they only remove the lower
epidermis and mesophyll of the leaves. The last three instars

22
however, will consume the whole leaf leaving only the midrib
and large veins. When the infestations are high, the larvae
eat up all the leaves and attack the tender portions of the
stems, buds and small bean pods.
The velvetbean caterpillar is the most important defol
iator of soybeans in north and central Florida where popula
tions reach the peaks in late July, mid-August and early
September (Strayer, 1973). Outbreak infestations during
pod set and pod fill usually cause severe yield losses.
Brown and southern green stink bugs. Woodside (1946),
DeCoursey and Esselbough (1962), and Mitchell and Mau (1969)
described the stages and studied the biology of the brown
stink bug, Euschistus servus (Say), and the southern green
stink bug, Nezara viridula (L.).
Adult E. servus are grayish-yellow and measure 12.0-
15.0 mm long. The eggs measure 1.2-1.3 mm in height, and
hatch after 3-14 days in laboratory conditions (Rolston and
Kendrick, 1961). The N.viridula eggs hatched after an average
of 5.2 days in the laboratory. Both species pass through
five nymphal instars, and have at least two generations per
year. Hill (1975) reported three generations of N. viridula
during nine months in Egypt; there are probably three or
more in Florida (Sailer, personal communication, 1980).
The nature of stink bug damage to soybeans has been
studied by many workers (Miner, 1961 and 1966; Daugherty
et al., 1964; and Turner, 1967). Damage is caused when

23
nymphs and adults insert their mouthparts through the pods
and into the beans to feed on the developing seed. Such
seeds tend to shrivel and pods may abort when young pods
are injured. Along with histolytic substances injected into
the beans to liquefy cell contents, the bugs inject a yeast-
spot disease fungus, Nematospora coryli Peglion which further
lowers the quality of the beans.
In Arkansas, Miner (1961) observed that damage by N.
viridula lowered the oil content and slightly increased
protein content of the seeds. Blickenstaff and Huggans
(1962) reported a decrease in the yield of soybean seeds and
an increase in the percentage of small seeds due to stink
bug damage.
Corn Insects
Lesser cornstalk borer. Some information pertaining
to E. lignosellus has already been mentioned in the section
of soybean insects. The feeding behavior of this insect on
corn is the same as when it feeds on soybeans or other
host plants.
According to Luginbill and Ainslie (1917), the lesser
cornstalk borer attacks corn plants at, or just below the
ground level. The larvae bore or tunnel into the stem of
seedling plants and feed on roots or above the soil surface.
Young plants so injured die quickly. Some infested plants
may survive, but become distorted, curled and one sided.

24
On older corn, the larvae girdle the stems, although they
may also tunnel into the stems. Metcalf et al. (1962)
reported that when com under 45 or 50 cm is damaged it
fails to produce ears or good stalks.
Fall armyworm. The fall armyworm, Spodoptera frugiperda
(J. E. Smith), is an important agricultural pest; the
larvae feed on, and cause yield losses to, a variety of
field, forage and vegetable crops (Luginbill, 1928).
Luginbill (1928) reported a very detailed study that
included the biology and description of life stages of
this pest. On com, female S. frugiperda deposit the egg
masses on the underside of the leaves. Oviposition occurs
at night, and the incubation period lasts from two to ten
days. The larvae mature, on the average, 10.9 to 13.4
days after they hatch. Pupation takes place in the soil
in loose cocoons; adult moths emerge after 7-37 days. In
Florida, moths emerged from buried pupae after 14-35 days
(Wood, 1977).
The larvae of S^. frugiperda are almost omnivorous,
but do show a marked preference for Gramineae (Luginbill,
1928). The first instars skeletonize the leaves and make
holes while the fourth to sixth instars usually completely
destroy small plants and strip larger ones.
Morrill and Green (1973) found that young larvae fed
on the upper portions of com plants whereas larger larvae

25
were found in whorls and furls. Fall armyworms also attack
com ears by burrowing into them either from the tip or
from the side.
Com earworm. The eggs of the com earworm, Heliothis
zea (Boddie), hatch from two to eight days after oviposition,
and the larval period lasts 13-28 days (Phillips and Barber,
1931). Mature larvae leave the host plants and drop to the
ground to pupate under the soil surface in pupal cells.
Pupation takes about 14 days.
Com earworm has been characterized as the "worst pest
of com" in the U. S. (Metcalf et al., 1962). In a five-
year study in Florida, Janes (1973) found that H. zea
was the most important insect pest on the ears of sweet
com.
Although com earworms may seriously damage the foliage
of early planted com, they cause more severe damage when
they feed on ears where they may destroy most of the kernels
(Phillips and Barber, 1931). Phillips and Barber (1931)
observed that the larvae will leave all other parts of
corn plants to attack silks and ears when these plant
parts appear.
In the U. S., up to 70-98% of the ears of field
com may be infested during outbreak infestations, and as
much as 5 to 7% of the kernels of field corn and 10-15% of
canning corn may be destroyed by the larvae (Metcalf et
al., 1962).

26
Soil-Inhabiting Predators
Carabid Beetles
Several species of carabid beetles constitute a
group of predators that play an important role in regulating
pest populations in various agroecosystems. Members
of the genera Calosoma, Pasimachus, Progaleritina, etc., have
been reported as predators of arthropod pests, especially
Lepidoptera larvae (Stone, 1941; Whitcomb and Bell, 1964;
van den Bosch and Hagan, 1966; and Neal, 1974).
Calosoma sayi Dejean is one of the most commonly en
countered carabid predators in Florida soybean fields.
Watson (1916), Nickels (1926), Douglas (1930), and Hasse
(1971) observed this carabid preying on larvae and pupae
of A. gemmatilis. Price and Shepard (1978) observed a
build-up of adult C. sayi as a response to outbreaks of
noctuid larvae in soybean fields in South Carolina. They
also found a significant correlation between weekly popu
lations of noctuid larvae and numbers of C. sayi from mid-
August to soybean defoliation.
In Florida, Neal (1974) observed C. sayi on soybean
plants during daytime, but no predatory activity was observed.
He reported that the carabid shows predatory activity only
at night. Whitcomb and Bell (1964), however, mentioned
that the predator fed on larvae of Alabama argillacea
(Hubner) during daytime.

27
Neal (1974) recorded three species of Pasimachus
in north Florida soybean fields. Only one species, P.
sublaevis Beauvois, was common; the other two, P. subsul-
catus Say and P. strenuus LeConte, were collected once
and twice, respectively. Blatchley (1910) reported that
Pasimachus spp. feed on a variety of larvae. In soybean
fields Neal (1974) observed P. sublaevis preying upon
various insects including larvae of C. sayi, velvetbean
caterpillars, and crickets.
Three species of the genus Harpalus were collected
in pitfall traps in Quincy, Florida (Neal, 1974). The H.
caliginosus (Fabr.) was the least common, H. gravis LeConte
was active from August to mid-September, and H. pennsyl-
vanicus De Geer was active from mid-August to the middle
of October. Harpalus pennsylvanicus was found feeding
on larvae and pupae of A. gemmatilis and Gryllus spp. nymphs.
Plant matter was also found in the gut content (Neal, 1974).
Progaleritina spp. are reported to feed only on arthro
pods; no plant material was found in their gut (Neal, 1974).
Adults were observed feeding upon various noctuid larvae,
Mexican bean beetle larvae, and cricket nymphs. Progaleritina
lecontei Dejean is the most common of the three species
(P. ianus, P. bicolor) found in north and central Florida.
Adults are active in soybean fields from mid-August through
the middle of September (Neal, 1974).

28
Thiele (1977) made a detailed study of carabid beetles
in relation to their habitats including the effects of
cultural practices on carabid populations. Kabacic-Wasylik
(1970, cited by Thiele, 1977) found that during rotation
from one crop to another, the spectrum of dominance of
carabids undergoes a corresponding shift.
The Striped Earwig
The striped earwig, Labi dura riparia (Pallas), is an
important soil-inhabiting predator and its biology and
predatory behavior have been studied by several researchers
(Schlinger et al., 1959; Afify and Farghaly, 1970; Caussanel,
1970, Tawfik et al., 1972; and Ammar and Farrag, 1974).
Adult L. riparia mate on the soil surface or in shallow
tunnels, but the eggs are laid in deeper (average depth
5.8 cm) tunnels (Ammar and Farrag, 1974), which have no
passage to the soil surface (Caussanel, 1970). The eggs
hatch after an average of 9.9 days at 22-25 C. The females
brood over the eggs, and bring food to newly hatched nymphs.
The insect passes through six nymphal instars.
Tawfik et al. (1972) observed L. riparia climbing
com plants in search of prey. They also reported that
this earwig fed on a variety of prey including such impor
tant pests as Spodoptera littoralis Boisd., Pieris rapae L.,
Vanessa cardui L., etc. A fifth- or sixth-instar nymph L.
riparia may consume up to 4-7 young larvae or 2-4 large

29
larvae of S. littoralis per day. Dean and Schuster (1958)
and Clements (1968) reported that the striped earwig preyed
on armyworms, mites, scale insects, and aphids. In a labora
tory study, Schlinger et al. (1959) found that L. riparia
fed on various insects including Lepidoptera of all stages,
elaterid larvae, aphids, and carabid larvae. Labidura riparia
was also observed feeding on A. gemmatilis larvae, pupae and
adults, L. riparia nymphs, small Calosoma larvae, Gryllus
nymphs, wolf spiders, and adult Heliothis spp. (Neal, 1974).
Hassanein et al. (1968) and Afify and Farghaly (1970)
compared the predatory effectiveness of L. riparia and
that of Coccinella undecimpune tata Reiche on the cottonworm,
Prodenia litura Fabr. and S. littoralis. They found that
L. riparia was more efficient than Coccinella as an egg
and larval predator.
Price and Shepard (1977) investigated the patterns
of colonization of soybean fields as well as the response
to insecticides by L. riparia. The authors observed lower
numbers in newly established fields than in older ones.
Soybeans treated with methyl-parathion and methomyl early
in the season had higher earwig populations than untreated
fields. Reduction in numbers of ants and other insects
that prey on earwigs, after insecticidal applications,
was believed to be the reason for these lower populations.

CHAPTER II
SOYBEAN CROP SYSTEMS
Materials and Methods
Cultural Practices
Rye stuhble experiment. Experiments were conducted
simultaneously on the Robinson farm located in Williston,
Levy county, about 33 km west of Gainesville, and at the
Green Acres, a University of Florida agronomy farm located
in Alachua county. These two locations will be referred
to as Williston and Green Acres.
In Williston the observations were made in a large
block measuring 73.17 m x 85.37 m previously planted to
rye which was used either as hay (stubble) or mulch. The
block was divided into four 12.20 m x 73.17 m main plots
separated from each other by a 12.20 m wide alley. Each
main plot was further divided into six 12.20 m x 12.20 m
small plots making a total of 24 small plots for the whole
block. Six tillage treatments were arranged in a randomized
complete block design with each treatment being replicated
four times. The six treatments whose effects were tested on
insect populations were:
30

31
1. no tillage into rye stubble: "Cobb" soybeans
were seeded directly (without any previous
soil preparation) into the stubble of
"Wrens Abruzzi" rye.
2. no tillage plus in-row subsoil into rye
stubble: This treatment was the same as
the first one except for the additional
subsoiling made in the rows during the
planting operation.
3. no tillage into rye mulch;
4. no tillage plus in-row subsoil into rye
mulch.
5. conventional tillage into rye stubble:
The soil in the conventional tillage plots
was prepared according to the normal tillage
practice (moldboard plowing and disking)
before soybeans were planted.
6. conventional tillage plus in-row subsoil
into rye stubble.
"Cobb" soybeans were planted in all the plots on
March 21, 1978, in 76.2 cm rows with a 2-row Brown-Harden
(r)
Super-seeder^mounted on a 4600 Ford tractor. Seedling
rate was about 112 kg/ha. The plots were fertilized with
672 kg/ha of 5-4.4-12.5 N-P-K applied at planting along with
0.42 kg a.i./ha of paraquat (see Appendix A for chemical
names of all herbicides) plus Ortho X-77 (surfactant)at the
label dose, 2.24 kg a.i./ha of alachlor and 0.28 kg a.i./ha

32
paraquat (with X-77) was made on April 10, 1978. No insec
ticide was used in this experiment.
Com stubble experiment. A second crop of soybeans
was grown at Willis ton from August to November, 1978. The
plots were close to, and of the same size as, those in the
first season and were previously planted to com (following
rye) without any soil preparation except in the conventional
tillage plots. The same six tillage treatments as above
were evaluated in com residues. The agronomic practices
were the same as in the first experiment except that the
plots were sprayed with methomyl at the rate of 0.56 kg a.i./
ha on September 27, 1978, for the control of the velevebean
caterpillars.
Oat stubble experiment. The Green Acres experiment
was conducted from June to the middle of October, 1978, in
a block that was previously planted to "Florida 501" oats
(Avena sativa L.). The following four tillage treatments
were studied in this experiment:
1. no tillage into oat stubble
2. no tillage plus in-row subsoil into oat
stubble
3. conventional tillage into oat stubble
4. conventional tillage plus in-row subsoil
into oat stubble.
Conventional tillage plots were prepared on June 2,
1978, with a moldboard plow and were disked twice. The

33
same cultivar of soybeans was planted in all the plots on
June 3, 1978. The entire field was fertilized with 448
kg/ha of 5-4.4-12.5 N-P-K applied at planting. Metribuzin
(0.28 kg a.i./ha), linuron (1.12 kg a.i./ha), and paraquat
(0.42 kg a.i./ha) were also applied during the planting
operation for weed control. No-tillage plots were also
treated (directed sprays) with paraquat (0.28 kg a.i./ha) plus
X-77 (surfactant) on June 29 and July 19, 1978. Each tillage
treatment was divided into two portions; one half of the
plot was treated with carbofuran at the rate of 1.12 kg a.i./ha
to control soil insects. The other half was untreated and was
used as a control. When populations of velvetbean caterpillars
and stink bugs became high, all the plots were sprayed with
methomyl (0.56 kg a.i./ha) on August 17 and September 7,
and with acephate (0.84 kg a.i./ha) on September 13, 1978.
This experiment was repeated on the same block in 1979.
"Cobb" soybeans were planted on June 12, 1979, according
to the same cultural procedure as in the 1978 season except
that carbofuran (or any other insecticide) was not used
at planting. The plots were sprayed with acephate on August
30, 1979, to control the velvetbean caterpillars and on
October 5, for stink bug control.
Estimation of Tillage Effects on Insects
Soil arthropods. Damage caused by the lesser cornstalk
borer was assessed by visual observations. Two different
rows were randomly selected in each replication every week,

34
and all the plants in the row were carefully examined.
Stunted, infested plants were pulled, counted and the number
recorded. Infestation levels were calculated as the number
of infested plants per row.
Populations of cutworms and soil-inhabiting predators
(earwigs, spiders and carabid beetles) were monitored by
means of pitfall traps. The traps consisted of cottage cheese
cups about one-third filled with ethylene glycol that killed
and preserved the catches. In order to prevent rains from
filling the traps and to avoid disturbance of the traps by
small animals, a piece of wood (20 cm x 20 cm x 0.5 cm) was
positioned about 4 cm above each trap. One trap was placed
in the middle of each replication and positioned within the
row in order to prevent destruction by machines during
farming operations. The traps were set in the plots from
two days to two weeks after soybeans were planted. The
insects were collected every week and brought into the
laboratory where they were sorted by species and the numbers
of each species recorded.
Above-ground insects. Soybean looper, velvetbean
caterpillar and stink bug populations were estimated by the
plant shaking method. In 1978 two sample sites were randomly
selected in each replication, but only one site was used in
the 1979 crop season. After selecting the site the shake
cloth was unrolled on the ground between two plant rows,
and the plants over the cloth were shaken vigorously enough

35
to dislodge the insects which then fell onto the cloth. The
insects were counted and numbers recorded by species. The
shake cloth method was also used in the 1978 experiments
to estimate population levels of the three-cornered alfalfa
hoppers. Because adult hoppers fly quickly when disturbed,
this method was abandoned in 1979. The sweep net method,
as described by Boyer (1967) (method 1) was used instead.
Stink bug damage to seeds was determined (at Green
Acres only) at the end of the season when the beans were
dry and ready to be harvested. Three soybean plants were
randomly chosen in each replication while walking diagonally
across the plot. A total of 12 plants were observed for
each treatment. All the pods were collected from each
plant and placed into a paper bag. The bags containing the
pods were brought into the laboratory and the seeds were
examined for stink bug damage. The total number of seeds
as well as number with at least one feeding puncture were
recorded. The number of small, wrinkled seeds was also
recorded. The number of plants selected per replication
was increased to five in the 1979 experiment. This increase
resulted in 20 plants observed per treatment.
All the data were transformed (log. transformation for
numbers and arcsin transformation for percentages) before
they were submitted to the statistical analysis.
An effort was made to relate fluctuations of pest
and predator populations to the phenology of the plants.

36
Developmental stages of the soybeans were recorded weekly
according to the method described by Fehr and Caviness
(1977).
Results and Discussion
Soil-Pest Insects
Lesser cornstalk borer infestations were not assessed
in the rye stubble experiment at Williston. Table 1 contains
the results obtained from the corn stubble experiment.
Although the weekly average number of infested plants per
row was 2.04 in the conventional tillage and 1.92 in the
no-tillage treatment, the analysis of variance was not
significant. The results also indicated that in-row sub
soiling did not affect E. lignosellus infestations, and
that com stubble was not statistically different from
com mulch with respect to lesser cornstalk borer infesta
tions .
In 1978 some plants were killed by paraquat in the no
tillage plots at Green Acres (oat stubble experiment); this
made observations difficult. Lesser cornstalk borer damage
was, therefore, estimated only in the 1979 season. The
results from the 1979 oat stubble experiment are shown in
Table 2. Damage levels were significantly (P=0.01) higher
in the no-tillage soybeans than in the conventional tillage
soybeans. The weekly average number of damaged plants per

37
row was 4.29 and 1.42, respectively for the no tillage and
conventional tillage. In-row subsoil had a significant impact
on the borer infestations. The average number of infested
plants was significantly lower in the no tillage plus subsoil
than in the no tillage without subsoil. Infestations were
also lower in the conventional tillage with subsoil than in
the conventional tillage without subsoil (Table 2).
Damage to soybean seedlings was very low during the
two seasons at both Willis ton and Green Acres. The method
used here to determine borer infestations, although commonly
used, certainly underestimated infestation levels because
only wilted and dead plants were detected and counted. Older
seedlings do not wilt when infested. Collecting randomly
a certain number of plants, wilted or not, throughout the field
and examining roots and lower portions of the stems for borer
infestation might have resulted in a better estimation of
the damage.
In one experiment, the results showed that no-tillage
systems were not conducive to the buildup of lesser cornstalk
borer infestations as compared to the conventional tillage.
Results from another experiment, however, showed that E.
lignosellus can be a more serious threat to no-till soybeans
than to the conventionally tilled soybeans. The lesser
cornstalk borers may remain in weeds or crop debris from
which they migrate to attack crop seedlings (All and Gallaher,
1977). Crop residues and the lack of soil disturbance in

38
no-tillage systems would seem to explain why infestations
were higher than those observed in the conventional tillage
at Green Acres. However, crop debris left on the ground
have been reported to reduce E. lignosellus infestations in
no-tillage corn (All et al., 1979).
Above-Ground Pest Insects
Three-cornered alfalfa hopper. Hopper populations
were monitored during 1978 and 1979 only at Green Acres.
The plant shaking method was used in 1978, but was abandbned
in 1979. The number of Snissistilus festinus (Say) collected
was very low and most were nymphs thus confirming Boyer's
(1967) earlier conclusion regarding inadequacy of the method.
Therefore, during the 1979 season the sweep net was used,
and numbers of S^. fes tinus collected were relatively high.
The average numbers of hoppers recorded from each tillage
system are shown in Table 3 for both the 1978 and 1979 crop
seasons.
The data indicated the hopper populations were statis
tically the same in all tillage treatments in 1978. Although
the average number of hoppers was about three times higher
in the no-tillage soybeans than in the conventional tillage
plots in 1979, analysis of the data did not show any signif
icant differences between treatment means. Spissistilus
festinus did not manifest any preference for no-tillage
soybeans as compared to the conventional tillage.

39
Soybean looper. Early-planted (April-July, 1978) soy
beans in the Williston rye stubble experiment were not
infested by the soybean looper, P. includens, and only trace
numbers of loopers were recorded in the com stalk experiment
(late planted, August) at Williston. Numbers of loopers
recorded in both 1978 and 1979 seasons at Green Acres are
shown in Table 4. Looper populations were relatively low
during the two seasons, but were higher in 1978 than in 1979.
An average of 1.04 and 1.34 loopers per shake was recorded
respectively from the no tillage and conventional tillage
in 1978. In 1979, only 0.67 and 0.33 loopers per shake
were collected from both treatments, respectively.
Such low looper populations were not believed to have
caused significant damage to soybeans. No significant
differences were detected between treatments for P. includens
populations estimated by the plant shaking method. The no
tillage farming did not effect oviposition by Pseudoplusia
moths (which may be attracted by plant residues) or the
development of the larvae.
Southern green stink bug. The southern green stink
bug, Nezara virdula (L.), was the most abundant of all
species of stink bugs observed during the two years. The
brown stink bug, Euschistus servus (Say), was the next
abundant, but in trace numbers. Average numbers of N.
viridula collected by the plant shaking method from Williston
and Green Acres soybeans are shown in Tables 5, 6, and 7.

40
Results obtained from the first season at Williston (rye
stubble experiment) showed that populations of the southern
green stink bug were significantly (P=0.05) lower in the
conventional tillage treatment than in any of the no-tillage
treatments (Table 5). An average of 1.32 stink bugs per
shake was collected weekly from the no-tillage soybeans, but
only 0.96 stink bugs were collected from the conventional
tillage. No significant differences were found between
the two no-tillage treatments or between the conventional
tillage and the conventional tillage plus in-row subsoil.
Stink bug populations were very low in the com stubbie
experiment at Williston.
Although N. viridula average population levels in the
1978 Green Acres experiment were 3.28 stink bugs per shake
in the no tillage into oat stubble and 2.61 stink bugs per
shake in the two conventional tillage treatments, analysis
of variance was not significant (Table 6). In the 1979
experiment, population levels were generally high, but
analysis of the data failed to show any significant differences
among treatment means (Table 7). The weekly average for
adult population was 4.94 and 4.88 stink bugs per shake,
respectively, in conventional tillage and no-tillage soybeans.
Stink bug damage to seed was assessed at the harvest time
during the two years, and the results obtained are in Tables
8 and 9. In 1978, damage appeared to be lower in the no tillage
with in-row subsoil than in all other treatments, but analysis

41
of data did not detect any significant differences among
treatments. Analysis of data also revealed no significant
differences between treatments in number of seed damaged.
Although the percent of small, wrinkled and fungus-infected
seeds was 38.92 in the no tillage into oat stubble and 19.28
in the conventional tillage, analysis of variance of the
data was not significant (Table 9).
In 1978, stink bug populations at Green Acres reached
the economic threshold recommended for Florida soybeans
(Strayer and Greene, 1974). Peak levels (2.4 adults per shake
average of all the treatments) occurred during the week of
September 21 when soybeans were in R5-R6 stages (beginning
and full seed stages; Fehr and Caviness, 1977). This peak
followed three applications of methomyl, the last two being
made on September 7 and 13, 1978. Methomyl did not apparently
affect stink bug populations. In 1979, adult population was
about four times higher than the recommended economic
threshold.
Except the Williston first experiment in which popula
tions of the southern green stink bug were significantly
lower in the conventional tillage than in no-tillage treat
ments, the tillage systems studied in all other experiments
did not show any significant effect on either stink bug
populations or stink bug damage to soybeans. No-tillage
systems in these experiments apparently did not provide a more
favorable environment than that found in the conventional

42
tillage, in order to attract and harbor higher populations
than those that would colonize conventionally tilled soybeans.
Stink bugs are known to fly across the field from the area
of the initial infestations in search of pods (Miner, 1966).
Such movements are likely to reduce any effect that the no
tillage systems may have. On the basis of the data presented
in Tables 5-9, it is believed that, when wild hosts are
effectively eliminated from the no-tillage systems through
good weed control, stink bug infestations are not likely to
be more serious in these systems than in the conventionally
tilled fields.
Velvetbean caterpillar. The early-planted (April-July,
1978) soybeans in the first Williston experiment (rye stubble)
were not infested by velvetbean caterpillars. In the second
season experiment, however, populations of A. gemmatilis
reached such high levels that an application of methomyl was
made on September 27. A weekly average of up to three large
(over 2.5 cm) larvae per shake was recorded. Average numbers
of caterpillars collected by the shake cloth method are
contained in Table 10. The analysis of the data showed that
no-tillage systems did not significantly affect population
levels of either the small (up to 2.5 cm) or large larvae as
compared to the conventional tillage.
Figures 1-3 show the weekly trend of small, large and
total populations of the velvetbean caterpillars. Although

43
analysis of the data did not detect any significant differ
ences between treatments, the figures show that before
the plots were sprayed with methomyl, populations of small
larvae were highest in the conventional tillage whereas
populations of large larvae were highest in the no-tillage
into corn mulch. After application of methomyl, populations
of both age groups were highest in the no-tillage into com
stubble.
Data obtained from the Green Acres 1978 experiment also
failed to show any significant effect of no-tillage treatment
on velvetbean caterpillar populations as compared to the
conventional tillage (Table 11, Figures 4, 5, and 6).
After the second application of methomyl (September 7), all
the larvae collected were very small (up to 1 cm) (Figures
4, 5 and 6). Soybeans were in the R5-R6 stage and these
small larvae could not cause any significant damage to the
soybeans.
In 1979 at Green Acres velvetbean caterpillars were
classified into small (up to 1.5 cm), medium (1.6-2.5 cm),
and large (over 2.5 cm) larvae. The average numbers of
larvae per shake for each age group are shown in Table 12,
and the weekly population trend is illustrated by Figures 7,
8 and 9. Populations of small larvae were significantly
(P=0.05) lower in no-tillage into oat stubble than in the
conventional tillage treatments or in no-tillage plus in-row
subsoil. Figure 7 shows that throughout the cropping season,

44
populations of small larvae were consistently lower in the
no-tillage than in the conventional tillage except for the
weeks of August 23 and September 13. No-tillage treatments
did not significantly affect medium and large larval popula
tions (Table 12 and Figure 8).
The exact reason for fewer small larvae observed in
the no tillage than in the conventional tillage is not known.
This might have been an indication that A. gemmatilis moths
preferred to oviposit in the conventional tillage soybeans
which were cleaner than the no-tillage soybeans with some
weeds and crop resideus. Sloderbeck and Edwards (1979)
found that adults and larvae of the Mexican bean beetle
preferred tilled to nontilled soybeans. The authors believed
that this might have been due to "a preference of adult
beetles for the tilled soybeans" which were almost free of
weeds and residues.
Soil-Inhabiting Predators
Ground spiders. Populations of ground spiders were
monitored at Green Acres along with those of soil insects.
Since no attempt was made to identify the different species
of spiders collected in pitfall traps, all the species will
be collectively referred to as ground spiders.
In 1978 spider populations were statistically identical
in conventional tillage and no-tillage plots. The weekly
average numbers were 1.0 and 1.7 spiders per trap, respectively,

45
in the no tillage and conventional tillage. In-row subsoil
did not significatnly affect spider populations either
in conventional tillage treatments or in no-tillage plots.
Spider populations reached the peak about four weeks
before the peaks of pest populations. During the week
of peak populations the average number for the entire
field (all treatments combined) was 3.91 spiders per trap.
Ground spiders were in low numbers (field average, 0.41)
when most pest species increased in number.
In 1979 spider populations were high and peaked during
the second week of the sampling period, i.e. before most
pest species appeared. The analysis of data revealed
no significant differences between treatments. The weekly
average numbers were 3.78 and 2.40 spiders per trap in
conventional tillage and no-tillage soybeans, respectively.
A reduction in number of spiders in a crop system
may result in increased pest populations in that system
since spiders constitute an important part of the predator
complex in crop systems (Whitcomb and Bell, 1964). The
activity of spiders, as indicated by the results, was
not affected by the tillage systems investigated in this
s tudy.
Striped earwig. Average numbers of the striped earwig,
Labidura riparia, observed at Williston from April to July
1978 are in Table 13. Both nymphal and adult populations
were significantly (P=0.05) lower in the conventional tillage

46
plus in-row subsoil than in any of the no-tillage treatments.
The conventional tillage plus in-row subsoil also harbored
significantly more earwigs than the conventional tillage
without subsoil. Adult populations were significantly
higher in no tillage into rye stubble and no tillage into
rye mulch than in the conventional tillage (Table 13).
No till into rye stubble did not significantly differ from
no till into rye mulch.
Figures 10, 11 and 12 show the weekly trend of nymphal,
adult and total populations of Labidura respectively in
no tillage into rye stubble, no tillage into rye mulch
and conventional tillage treatments. Earwig populations
remained higher in the no tillage into rye mulch than in
any of the other two treatments during the first half of
the sampling period.
Earwig populations were very high in the second season
at Williston. An average of up to 245.77 nymphs and adults
per trap were collected from one treatment (Table 14).
Although populations appeared to be highest in the no till
plus in-row subsoil into com mulch, analysis of the data
did not detect any significant differences between treatment
means. This was also shown by Figures 13, 14, and 15
which illustrate weekly foraging activity of the earwigs
in the conventional till, no till into rye-corn stubble
and no till into rye-corn mulch.

47
The average numbers of Labidura collected in pitfall
traps at Green Acres in 1978 are in Table 15. Except
for the conventional tillage plus in-row subsoil, nymphal
populations in all other treatments appeared to be higher
in the carbofuran-treated portion than in the untreated
other half of the plots. The differences among treatment
means, however, were not significant for either nymphs
or adults. Price and Shepard (1977) also found that soybeans
treated with insecticides harbored more earwigs than untreat
ed ones. When the untreated no tillage was compared to
the untreated conventional tillage for adult populations,
it was found that the conventional tillage harbored signif
icantly more adult Labidura than did the no tillage
(Table 15). The weekly activity of the earwigs in no
tillage and conventional tillage is shown in Figures 16,
17, and 18.
Table 16 contains average numbers of nymphs and adult
Labidura collected at Green Acres in 1979. Nymphal and
adult populations appeared to be higher in the conventional
tillage than in the no tillage, but the analysis of the data
failed to show any significant differences among treatments.
Colonization patterns of no-tillage soybeans by L.
riparia did not differ from those of the conventionally
tilled soybeans, and were similar to those reported by
Price and Shepard (1977) for conventional tillage soybeans.
Young, newly established no-tillage and conventional till

soybeans had very low earwig populations. In the first-
season experiment in Williston the earwig populations
reached peak at the end of the sampling season. In the
second experiment, however, populations peaked at the
beginning of the season (Figure 15), when soybeans were in
the V4-V5 stages. At Green Acres in 1979 populations
remained relatively high in the conventional tillage at
the end of the sampling period, but were very low in the
no tillage. The average nymphal population was almost
zero in the no tillage at the end of the season (Figures
19, 20, and 21).
The results indicated that no-tillage farming did
not generally affect populations of L. riparia. This
earwig was active and in large numbers throughout the
second half of the crop season, when pest species appeared
or were in large numbers. Labidura did not apparently
have any significant impact on pest populations; no noticeable
reduction of pest populations was observed in spite of large
Labidura populations. This of course does not rule out
the possibility that the pest populations would have been
higher in the absence of L. riparia. In confinement this
earwig killed many more Anticarsia larvae than it consumed
(see Appendix B).
Carabid beetles. Fifty carabid beetles belonging to eight
different species were collected in pitfall traps from April to

49
July, 1978, in rye stubble at Williston. The different
species recorded are in Table 17. Colliuris pennsylvanica
(L.) was the most abundant carabid species, representing
34% of all the species collected. Harpalus caliginosus Fab.
was the next species with 18%. Anisodactylus merula Germar
and Pasimachus sublaevis Beauv. each comprised 16% of
the total population.
With respect to tillage systems, the results indicated
that carabids were more active in no-tillage plots than
in conventional tillage plots. No carabid beetles were
collected from the conventional tillage during the entire
sampling period (Table 17). The conventional till plus
in-row subsoil, like no till plus in-row subsoil and no
tillage into rye mulch, harbored 16% of the beetles each.
The majority of carabids were collected from no till into
rye stubble (30%) and no tillage plus in-row subsoil into
rye mulch (22%).
The total number of carabid beetles collected from
no-till and conventional till soybeans increased to 112
in the corn stubble experiment at Williston. Table 18
shows the different species and numbers of beetles recorded.
The highest population (25.89%) of carabids was recorded
from the no till plus in-row subsoil into com stubble.
No tillage into com stubble harbored 18.75% of the carabids
collected, and the conventional till contained the lowest
(12.50%) population of carabid beetles. Over 43% of the

50.
carabid beetles collected were P. sublaevis. Anisodactylus
merula was the next abundant (11.61%) species collected.
Populations of carabid beetles were relatively high
at Green Acres in the 1978 oat stubble experiment where
a total of 320 carabids were collected (Table 19). Harpalus
pennsylvanicus De Geer, A. merula and Calosoma sayi Dejean
were the most abundant species counting for 45.31, 37.19,
and 14.38% of the total, respectively. The no till into
oat stubble had the highest (46.86%) carabid population,
and the conventional tillage had the lowest with 14.69%.
In 1979, the numbers were low at Green Acres; 81 individuals
only were collected, with 34.57% from the no-tillage soybeans
and 20.98% from the conventionally tilled plots. Harpalus
pennsylvanicus and C. sayi were the most prevalent species
representing 39.51 and 23.46%, respectively. The species
and numbers of carabid beetles collected at Green Acres
in 1979 are shown in Table 20.
Data collected over two years showed that no-tillage
systems significantly increased the activity of carabid
beetles. However, catches of most species were so erratic
and their numbers so low that it is not believed that
carabid beetles played any important role in regulating
pest populations.

51
Table 1. Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus (Zeller), in no
tillage and conventional tillage "Cobb" soy
beans at Williston, Levy Co., Fla., 1978.
Numbers are totals and averages of two rows
per replication for three weeks.
k
Treatment
Infested plants
kk
Total Number Average/row
No tillage into corn
stubble (in rye residue)
46
1.92
No till plus in-row subsoil
into com stubble (in rye
residue)
32
1.33
No tillage into com mulch
(in rye residue)
46
1.92
No tillage plus subsoil
into com mulch (in rye
residue)
41
1.71
Conventional tillage (into
com stubble)
49
2.04
Conventional tillage plus
in-row subsoil
51
2.13
k
In no-till plots corn was seeded into rye stubble (hay) or
mulch and soybeans into corn stubble or mulch (following
com).
**In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's
comparisons were not made.

52
Table 2. Lesser cornstalk borer infestations in no-tillage
and conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979. Estimations are
based on two different rows observed weekly (for
three weeks) in each replication (four reps/treat.).
Treatment
Infested plants
Total Number Average/row
No tillage into oat stubble
103
4.29a
No tillage plus in-row
subsoil into oat stubble
46
1.92b
Conventional tillage into
oat stubble
34
1.42b
Conventional tillage plus
in-row subsoil into oat
stubble
20
0.83c
k
Values not followed by the same letter are significantly
different at the 0.05 level by Duncan's new multiple range
test.

Table 3. Average number of the three-cornered alfalfa hopper,
Spissistilus festinus (Say), collected by the plant
shaking method (1978) and sweep net (1979) from
conventional tillage and no-tillage soybeans at
Green Acres, Alachua Co., Fla. Numbers are averages
of eight weeks with eight shakes per treatment and
three weeks with eight sweeps per treatment.
No. hoppers
collected*
Treatment
Avg./shake
Avg./sweep
No tillage into oat stubble
0.55
3.38
No tillage plus in-row subsoil
into oat stubble
0.36
2.17
Conventional tillage
0.42
1.58
Conventional tillage plus
in-row subsoil
*
0.42
1.83
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

54
Table 4. Soybean looper populations in no-tillage and
conventional tillage "Cobb" soybeans estimated
by the shake cloth method at Green Acres, Alachua
Co., Fla., 1978 and 1979. Numbers are totals and
averages of eight (for 1978) and four (for 1979)
weekly shakes (sites) per treatment for 12 (1978)
and six (1979) weeks.

Looper
Population
Treatment
Total
Number
Average/ shake''
1978
1979
1978
1979
No tillage into oat stubble
100
16
1.04
0.67
No tillage plus in-row
subsoil into oat stubble
137
5
1.43
0.21
Conventional tillage
into oat stubble
129
8
1.34
0.33
Conventional tillage plus
in-row subsoil into oat
stubble
105
9
1.09
0.38
No statistical analysis was done on the data the means
being about equal.

55
Table 5. Effect of tillage on southern green stink bug
populations estimated by the shake cloth method
in "Cobb" soybeans at Williston, Levy Co., Fla.,
1978. Numbers represent totals and averages of
eight weekly shakes per treatment for seven weeks.
Treatment
Stink bug Population
Total Number Average/shake"
No tillage into rye stubble
74
1.32ab
No tillage plus in-row subsoil
into rye stubble
86
1.54b
No tillage into rye mulch
97
1.73b
No tillage plus in-row
subsoil into rye mulch
106
1.89b
Conventional tillage into
rye stubble
54
0.96a
Conventional tillage plus
in-row subsoil into rye stubble
61
1.09ab
Values followed by the same letter are not significantly
different at 0.05 level by Duncan's new multiple range test.

Table 6. Number of Nezara viridula (Linn.) collected by the
shake cloth method in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua, Co.
Fla., 1978. The numbers represent totals and
averages of eight weekly shakes per treatment for
nine weeks. The plots (all) were treated with
methomyl (once) and acephate (once) for insect
control.
Average/shake
Nymph
Adult
Nymph +
Treatment
Adult
No tillage into oat stubble
1.19
2.08
3.28
No tillage plus in-row
subsoil into oat stubble
0.56
1.58
2.14
Conventional tillage into
oat stubble
0.83
1.78
2.61
Conventional tillage plus
in-row subsoil into oat
stubble
a
0.47
2.14
2.61
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

57
Table 7. Number of Nezara viridula (Linn.) collected by the
plant shaking method in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua Co.,
Fla., 1979. Numbers are averages of four weekly
shakes per treatment for four weeks. The plots
were sprayed twice with acephate for insect control.
Average/shake
Treatment
Nymph
1-3**
Nymph
4-5
Adult
N 4-5 +
Adults
No tillage into oat stubble
2.94
1.69
4.88
6.56
No tillage plus in-row
subsoil into oat stubble
1.38
1.19
4.69
5.88
Conventional tillage
into oat stubble
1.06
1.50
4.94
6.44
Conventional tillage plus
in-row subsoil into oat
stubble
*
2.25
1.63
3.94
5.56
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.
1-5, first to fifth instars.

Table 8.
Stink bug damage to seeds in no-tillage and
conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1978.
Number of Seeds
Treatment
Total
Examined
Damaged
~T~
Damaged*
No tillage into oat stubble
784
59
7.52
No tillage plus in-row
subsoil into oat stubble
673
26
3.86
Conventional tillage
629
53
8.43
Conventional tillage
plus in-row subsoil
532
40
7.52
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

59
Table 9. Damage to seeds by the stink bug complex in no-till
and conventional till "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979.
20 plants per treatment.
Numbers are
averages of
i*
Treatment
Damage**
Small Seeds
No tillage into oat stubble
16.34
38.92
No-till plus in-row subsoil
into oat stubble
14.25
28.87
Conventional till into oat stubble
15.02
19.28
Conventional till plus in-row
subsoil into oat stubble
17.00
20.69
In the analysis of the variance, no significant differences
were detected among the means. Therefore, Duncan's comparisons
were not made.
kk
Damage: seeds with at least one feeding puncture. Small
seeds: small, wrinkled and fungus infected seeds.

60
Table 10. Effect of tillage practice on populations of the
velvetbean caterpillars, Anticarsia gemmatilis
Hubner, estimated by the plant shaking method in
"Cobb" soybeans at Williston, Levy Co., Fla.,
April July, 1978. Numbers are averages of four
weekly shakes per treatment for six weeks. Plots
were treated with methomyl (0.56 kg a.i./ha) on
September 27 for the control of velvetbean
caterpillars.
Average
Number
Larvae/shake"
Treatment
Small
Large
Small + Large
No tillage into com stubble
7.46
2.54
10.00
No tillage plus in-row
subsoil into com stubble
9.58
3.50
13.08
No tillage into com mulch
6.92
3.21
10.13
No tillage plus in-row
subsoil into com mulch
7.54
2.71
10.25
Conventional tillage
into com stubble
8.33
2.46
10.79
Conventional tillage plus
in-row subsoil into com
stubble
7.50
2.79
10.29
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

61
Table 11. Effect of tillage practice on population levels of
the velvetbean caterpillar, Anticarsia gemmatilis
Hubner, monitored by the plant shaking method in
"Cobb" soybeans at Green Acres, Alachua Co., Fla.,
1978. Numbers are averages of eight weekly
shakes per treatment for eleven weeks for small
larvae and eight weeks for large larvae. The
plots were treated with methomyl and acephate
(once each) for insect control.
Averag
e Number
Larvae/shake
Treatment
Small
Large
Small + Large
No tillage into oat stubble
7.91
2.95
10.16
No tillage plus in-row
subsoil into oat stubble
8.39
2.17
10.56
Conventional tillage into
oat stubble
8.64
1.78
10.42
Conventional tillage plus
in-row subsoil into oat
stubble
W
8.50
3.45
11.95
In the analysis of variance no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

Table 12. Populations of the velvetbean caterpillar,
Anticarsia gemmatilis, estimated by the plant
shaking method in no-tillage and conventional
tillage "Cobb" soybeans, at Green Acres, Alachua
Co., Fla., 1979. Numbers represent four weekly
shakes per treatment for ten weeks. Soybeans
were treated twice with acephate for insect
control.
Average Number
Larvae/shake*
Treatment
Small
Medium
Large
Total
No tillage into oat stubble
11.43a
1.93c
1.78d
15.14e
No tillage plus in-row
subsoil into oat stubble
16.13b
2.85c
2.15d
21.13f
Conventional tillage into
oat stubble
17.15b
2.68c
l.lOd
20.93f
Conventional tillage plus
in-row subsoil into oat
stubble
7?
16.38b
2.90c
1.65d
20.93f
Values in each column followed by the same letter are not
significantly different at the 0.05 level by Duncan's new
multiple range test.

63
Table 13. Activity of the striped earwig Labidura riparia
(Pallas), in no-tillage and conventional tillage
"Cobb" soybeans estimated by pitfall traps at
Williston, Levy Co., Fla., 1978. Four traps were
used for each treatment for 11 weeks.
Earwig i
population
Average/trap*
Treatment
Nymphs
Adults
Nymphs + Adults
No tillage into rye
stubble
31.14ac
30.91c
62.05ac
No tillage plus in-row
subsoil into rye stubble
31.64c
27.18a
58.82ad
No tillage into rye
mulch
31.61c
30.25c
61.86c
No tillage plus in-row
subsoil into rye mulch
31.27ac
26.91a
58.18d
Conventional tillage
into rye stubble
30.34a
26.27a
56.61a
Conventional tillage
plus in-row subsoil into
rye stubble
-r
22.59b
12.18b
34.77b
Values followed by the same letter in each column are not
significantly different at the 0.05 level by Duncan's
new multiple range test.

64
Table 14. Activity of the striped earwig, Labidura riparia,
in no-tillage and conventional tillage late-
planted "Cobb" soybeans estimated by pitfall
traps at the Robinson farm, Williston, Levy Co.,
Fla., 1978. Numbers are averages of three traps
per treatment for ten weeks. Plots were treated
once with methomyl for the control of velvetbean
caterpillars.
Average/trap*
Treatment
Nymphs
Adults
Nymphs + Adults
No tillage into com stubble
122.03
107.60
229.63
No tillage plus in-row
subsoil into com stubble
117.57
105.87
223.43
No tillage into com mulch
125.03
101.50
226.53
No tillage plus in-row
subsoil into com mulch
136.40
109.37
245.77
Conventional tillage
into com stubble
118.20
111.13
234.13
Conventional tillage plus
in-row subsoil into com
s tubb1e
x
In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's comparisons
were not made.

65
Table 15. Activity of the striped earwig, Labidura riparia,
in no-tillage and conventional tillage "Cobb"
soybeans estimated by pitfall traps at Green
Acres, Alachua Co., Fla., 1978. Numbers are
averages of 14 weeks with four traps per treat
ment. Half of each plot was treated with
carbofuran (F) at planting, the other half was
untreated (C).
Average Number/trap*
Treatment Nymph Adult Nymph + Adult
No tillage into oat stubble
C
38.64
22.09cd
60.73cd
F
42.88
24.48bc
67.36bc
No tillage plus in-row
subsoil into oat stubble
C
35.57
19.16d
54.73d
F
43.13
20.38d
63.50cd
Conventional tillage into
oat stubble
C
44.39
35.57a
79.96ab
F
52.68
34.OOab
86.68ab
Conventional tillage
plus in-row subsoil
C
51.84
37.48ab
89.32ab
F
49.50
33.13a
82.63a
Analysis of variance not significant for nymphs. Values
followed by the same letter in each column are not signif
icantly different at the 0.05 level by Duncan's new multiple
range test.

66
Table 16. Number of striped earwig, Lab idura riparia,
collected in pitfall traps in no-tillage and
conventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979. Numbers are
averages of 15 weeks and four traps per treat
ment. All the plots were treated twice with
acephate for insect control.
Average/trap*
Treatment
Nymphs
Adults
Nymphs + Adults
No tillage into oat stubble
26.95
21.13
48.08
No tillage plus in-row
subsoil into oat stubble
41.30
24.42
65.72
Conventional tillage
into oat stubble
43.55
36.12
79.67
Conventional tillage plus
in-row subsoil into oat stubble
x
34.20
41.63
75.83
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

Table 17.
Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Williston, Levy Co., Fla.,
April July, 1978. Totals of four traps per
treatment for 12 weeks.
Species
CRS
CRS+s
Treatment*
NRS NRS+s NRM
NRM+s
Anisodactylus merula Germar
0
1
4
0
3
0
Calosoma sayi Deiean
0
0
1
0
0
0
Chlaenius laticollis Say
0
0
1
1
0
1
Colliuris pennsylvanica (L.)
0
2
4
5
1
5
Harpalus caliginosus Fab.
0
4
2
1
0
2
H. pennsylvanicus DeGeer
0
0
1
0
1
-L
0
Pasimachus sublaevis Beauv.
0
0
1
1
3
3
Scarites subcerraneus (Fab .)
*
0
1
1
0
0
0
CRS-conventional tillage into rye stubble
CRS+s-conventional tillage plus in-row subsoil into
rye stubble
NRS-no tillage into rye stubble
NRS+s-no tillage plus in-row subsoil into rye stubble
NRM-no tillage into rye mulch
NRM+s-no tillage plus in-row subsoil into rye mulch

68
Table 18. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Williston, Levy Co., Fla.,
September November, 1978. Numbers are totals
of three traps per treatment for 10 weeks.
Species
CCS
CCS+s
Treatment*
NCS NCS+s
NCM
NCM+s
Anisodactylus merula Germar
4
2
4
1
1
1
Calosoma sayi Deiean
0
0
1
1
2
5
Chlaenius tomentosus Say
0
0
0
0
1
1
Colliuris pennsylvanica (L.)
0
0
1
0
0
0
Galerita lecontei Deiean
0
0
0
2
0
0
Harpalus caliginosus Fab.
1
2
0
1
1
2
H. pennsylvanicus DeGeer
1
1
3
1
1
1
Pasimachus subsulcatus Say
1
1
1
2
2
0
P. sublaevis Beauv.
7
5
8
8
5
16
Solenophorus sp.
0
4
2
2
2
0
Scarites subterraneus(Fab.)
0
0
1
0
0
3
CCS-conventional tillage into com stubble
CCS+s-conventional tillage plus in-row subsoil into com
stubble
NCS-no tillage into com stubble
NCS+s-no tillage plus in-row subsoil into com stubble
NCM-no tillage into com mulch
NCM+s-no tillage plus in-row subsoil into com mulch

69
Table 19. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Green Acres, Alachua Co., Fla.,
June September, 1978. Totals of four traps per
treatment for 14 weeks.
Species
Treatment*
CT
CT+s
NOS
NOS+s
Anisodactylus merula Germar
8
8
80
23
Calosoma sayi Deiean
18
14
6
8
Colliuris pennsylvanica (L.)
2
1
1
1
Galerita janus Fab.
0
0
0
1
Harpalus caliginosus Fab.
0
0
1
0
H. pennsylvanicus DeGeer
19
39
60
27
Pasimachus subsulcatus Say
0
0
2
0
Scarites subterraneus (Fab.)
*
0
0
0
1
CT-conventional tillage
CT+s-conventional tillage plus in-row subsoil
NOS-no tillage into oat stubble
NOS+s-no tillage plus in-row subsoil into oat stubble

70
Table 20. Species and numbers of carabid beetles collected
in pitfall traps from no-tillage and conventional
tillage soybeans at Green Acres, Alachua Co., Fla.,
June September,
treatment for 15
1979.
weeks.
Totals
of four
traps per
Species
CT
Treatment*
CT+s NOS
NOS+s
Anisodactylus merula Germar
2
5
4
4
Calosoma sayi Deiean
3
2
8
6
C. scrutator (Fab .)
1
0
0
0
Chlaenius tomentosus Say
2
1
0
0
Colliuris pennsylvanica (L.)
1
0
0
0
Galerita lecontei Deiean
2
0
1
5
Harpalus caliginosus Fab.
0
0
0
1
H. pennsylvanicus DeGeer
5
5
15
7
Scarites subterraneus (Fab.)
-P
1
0
0
0
CT-conventional tillage
CT+s-conventional tillage plus in-row subsoil
NOS-no tillage into oat stubble
NOS+s-no tillage plus in-row subsoil into oat stubble

LARVAE /SHAKE
71
SAMPLING PERIOD
Figure 1. Average numbers of small (up to 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and
conventional tillage "Cobb" soybeans at Williston,
Levy Co., Fla., 1978. Averages of eight shakes
per treatment.
: conventional tillage
: no tillage into com stubbie
0: no tillage into com mulch
Arrow indicates insecticidal treatment

LARVAE /SHAKE (
72
SAMPLING PERIOD
Figure 2. Average numbers of large (over 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and con
ventional tillage "Cobb" soybeans at Williston,
Levy Co., Fla., 1978. Averages of eight shakes
per treatment.
: conventional tillage
: no tillage into corn stubble
O: no tillage into corn mulch
Arrow indicates insecticidal treatment

LARVAE / SHAKE (
73
SAMPLING PERIOD
Figure 3. Average number of velvetbean caterpillars, Anticarsia
femmatilis, collected by the plant shaking method
rom no-tillage and conventional tillage "Cobb"
soybeans at Williston, Levy Co., Fla., 1978. Averages
of eight shakes per treatment.
: conventional tillage
: no tillage into com stubble
a: no tillage into corn mulch
Arrow indicates insecticidal treatment.

LARVAE / SHAKE (
74
July Aug Sept Oct
SAMPLING PERIOD
Figure 4. Average numbers of small (up to 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and con
ventional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Averages of eight shakes
per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.

LARVAE /SHAKE ( f5
75
4.5-
4.0-
3.5-
3.0-
2.5-
2.0-
July Aug Sept
SAMPLING PERIOD
Figure 5. Average numbers of large (over 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and con
ventional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1978. Averages of eight shakes
per treatment.
: mo tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.

LARVAE/SHAKE (
76
July Aug Sept Oct
SAMPLING PERIOD
Figure 6. Average numbers of velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method
from no-tillage and conventional tillage "Cobb" soy
beans at Green Acres, Alachua Co., Fla., 1978. Aver
age of eight shakes per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.

LARVAE/SHAKE (LOG X)
77
SAMPLING PERIOD
Figure 7. Average numbers of small (up to 1.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method rrom no-tillage and conven
tional tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979. Averages of four shakes
per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.

LARVAE/SHAKE (
78
SAMPLING PERIOD
Figure 8. Average numbers of medium (1.6 2.5 cm) and large
(over 2.5 cm) velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method
from no-tillage and conventional tillage "Cobb"
soybeans at Green Acres, Alachua Co., Fla., 1S79.
Averages of four shakes per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.

LARVAE/SHAKE (LOG x )
79
Aug Sept Oct
SAMPLING PERIOD
Figure 9. Average numbers of velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method from
no-tillage and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1979. Average of
four shakes per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.

80
2.5-
April May June July
SAMPLING PERIOD
Figure 10. Average trap-week collections of Labidura riparia
nymphs from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla., April -
July, 1978. Four pitfall traps were placed in each
treatment.
conventional tillage
no tillage into rye stubble
no tillage into rye mulch

ADULTS/TRAP (LOG x)
81
2.5
2.0-
1.0-
0.5 -
r

i i i i i i i i i i i
25 2 9 16 23 30 6 13 20 27 4 II
Apr May June July
SAMPLING PERIOD
Figure 11. Average trap-week collections of Labidura riparia
adults from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla., April -
July, 1978. Four pitfall traps were placed in each
treatment.
: conventional tillage
: no tillage into rye stubble
: no tillage into rye mulch

NYMPHS + ADULTS/TRAP(LOG x)
82
2.5-
2.0-
1.5 -
1.0-
0.5-
25 2 9 ¡6 23 30 6 13 20 27 4 I!
April May June July
SAMPLING PERIOD
Figure 12. Average trap-week collections of Labidura riparia
(nymphs + adults) from no-tillage and conventional
tillage "Cobb" soybeans at Williston, Levy, Co.,
Fla., April July, 1978. Four pitfall traps were
set in each treatment.
: conventional tillage
: no tillage into rye stubble
O: no tillage into rye mulch

NYMPHS/TRAP (LOGx)
83
2.5 -
.5-
.0-1
I 1 1 1 ¡ I i 1 1
¡2 19 26 3 10 17 24 31 7 14
Sept Oct Nov
SAMPLING PERIOD
Figure 13. Average trap-week collections of Labidura riparia
nymphs from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla.,
September November, 1978. Averages of four
traps per treatment.
conventional tillage
no tillage into com stubble (after rye)
no tillage into corn mulch (after rye)

ADULTS/TRAP (LOGx )
84
0.5-r
¡2 19 26 3 10 17 24 31 7 14
Sept Oct Nov
SAMPLING PERIOD
Figure 14. Average trap-week collections of Labidura riparia
adults from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla.,
September November, 1978. Averages of four
traps per treatment.
conventional tillage
no tillage into com stubble (after rye)
no tillage into corn mulch (after rye)

NYMPHS + ADULTS/ TRAP (LOG x)
85
Sspt Oct Nov
SAMPLING PERIOD
Figure 15. Average trap-week collections of Labidura riparia
nymphs and adults from no-tillage and conventional
tillage "Cobb" soybeans at Williston, Levy Co.,
Fla., September November, 1978. Averages of four
traps per treatment.
: conventional tillage
: no tillage into com stubble (after rye)
: no tillage into corn mulch (after rye)

Figure 16. Weekly activity of Labidura riparia nymphs monitored by pitfall
traps in no-tillage and conventional tillage "Cobb" soybeans at
Green Acres, Alachua Co., Fla., 1978. Four traps were placed in
each treatment.
: no tillage into oat stubble
: conventional tillage

NYMPHS/TRAP (LOGx)
2.5-
0.5 -
CO
i i i i i t i i i i i i r
30 7 14 21 28 4 II 18 25 I 8 15 22 29
June July Aug Sept
SAMPLING PERIOD

Figure 17. Weekly activity of Labidura riparia adults monitored by pitfall
traps in no-tillage and conventional tillage "Cobb" soybeans at
Green Acres, Alachua Co., Fla., 1978. Four traps were placed
in each treatment.
: no tillage into oat stubble
: conventional tillage

ADULTS/TRAP (LOGx)
2.5-
( r | | i i | | i | r
30 7 14 21 28 4 II 18 25 I 8 15 22 29
June July Aug Sept
SAMPLING PERIOD

Figure 18. Weekly activity of Labidura riparia (nymphs + adults) monitored by
pitfall traps in no-tillage and conventional tillage "Cobb" soybeans
at Green Acres, Alachua Co., Fla., 1978. Four traps were placed in
each treatment.
: no tillage into oat stubble
: conventional tillate

NYMPHS + ADULTS/TRAP (LOG x )
2.5-
1 1 1 1 1 i 1 r i i i i r
30 7 14 21 28 4 II 18 25 I 8 15 22 29
June July Aug Sept
SAMPLING PERIOD

Figure 19. Weekly activity of Labidura riparia nymphs monitored by pitfall
traps (four in each treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua Co,, Fla,, 1979,
: no tillage into oat stubble
: conventional tillage

NYMPHS/TRAP(LOG x)
SAMPLING PERIOD

Figure 20. Weekly activity of Labidura riparia adults monitored by pitfall
traps (four in each treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua Co., Fla., 1979.
: no tillage into oat stubble
: conventional tillage

ADULTS/TRAP (LOG x )
SAMPLING PERIOD

Figure 21. Weekly activity of Labidura riparia nymphs and adults monitored by pitfall
traps (four in each treatment) in no-tillage and conventional tillage
"Cobb" soybeans at Green Acres, Alachua Co., Fla., 1979.
: no tillage into oat stubble
: conventional tillage

SAMPLING PERIOD
NYMPHS + ADULTS / TRAP (LOG x )
O r\> r\:
c_ ai 'o ai o cji
L 6

CHAPTER III
CORN CROP SYSTEMS
Materials and Methods
Cultural Practices
Vetch stubble experiment. Experiments on the effect
of no tillage practice on insects in com crop systems
were conducted in two different fields at Green Acres.
One field will be referred to as the vetch stubble
experiment and the other as the oat stubble experiment.
The vetch stubble experiment was run in a 92-m-long field
divided into eight plots and previously planted to "Hairy
vetch" (Vicia villosa Roth). Four tillage treatments
were compared in this experiment, namely no tillage into
vetch stubble, no tillage plus in-row subsoil into vetch
stubble, conventional tillage (vetch plowed under), and
conventional tillage plus in-row subsoil. Each treatment
was replicated four times in a randomized complete block
design.
The soil in the conventional tillage plots was prepared
with a moldboard plow (April 9, 1978) and a rototiller
(April 16, 1978), with vetch plowed under as green manure.
In no-tillage treatments com was seeded into the residues
of the vetch. On April 19, 1978, all the plots were planted
98

99
(using the Super-Seeder already mentioned) with "DeKalb
XL 78A" com in rows 76 cm apart. Paraquat (0.42 kg a.i./ha)
was used at planting, and 2,4-D (0.28 kg a.i./ha) and
atrazine (2.24 kg a.i./ha) after emergence, for weed control.
The entire field was fertilized at planting with 0-7.92-
29.88 (N,P,K) at the rate of 448 kg/ha. Additional appli
cations of N (28 kg/ha) were, made on April 22 and June 10,
1978. During the planting operation, the plots were treated
with carbofuran at the rate of 2.24 kg a.i./ha.
This experiment was repeated in the 1979 cropping
season with the same cultural practices, except that no
insecticide was used as soil treatment. The soil was
prepared in conventional tillage plots on March 30, 1979,
and corn (same hybrid) was planted on April 6, 1979.
Wheat stubble experiment. The effect of the no tillage
was also determined in corn seeded into wheat ("Holly")
stubble. The field (same size as in the vetch experiment)
was divided into eight plots in which the same tillage
treatments as above were displayed in a randomized complete
block design. The soil in the conventional tillage treat
ments was plowed and disked twice on June 2, 1978. On
June 3, all the plots were planted with "DeKalb XL 78A"
corn in 76 cm rows. The plots were treated with alachlor
(1,12 kg a.i./ha) and atrazine (1.68 kg a.i./ha) for weed
control. In addition to these two herbicides, no-tillage
plots were treated with paraquat (0.42 kg a.i./ha, plus

100
Ortho X-77 surfactant) on June 3, 1978. All the treatment
received 672.60 kg/ha of 5-4.4-12.5 (N,P,K) on June 3.
An additional application of 56 kg/ha of N was made in
all the plots on June 12, 1978. Half of the rows in each
plot were treated with carbofuran (2.24 kg a.i./ha) during
the planting operation. The other rows were not treated.
In 1979 the experiment was repeated without the carbo
furan application, but all other practices were the same
as in the 1978 season. Conventional tillage plots were
prepared on June 4, and com was planted on June 12, 1979.
Estimation of Insect Damage and Arthropod Populations
Soil arthropods. Damage to corn by soil insects
was assessed by randomly selecting two rows per replication
every week and counting the number of damaged plants.
Numbers of stunted, wilted or dead plants, characteristic
of the lesser cornstalk borer damage, as well as numbers
of cut, chewed plants (cutworms), were recorded. In the
wheat experiment, the total number of plants in the two
selected rows was recorded along with damaged plants in
order to estimate the percentages of damaged plants.
Populations of soil-inhabiting pest insects and arthropod
predators were monitored by means of pitfall traps as
described in the soybean section above. One trap was
placed in the middle row of each replication when com
was in stage 0.5 or stage 1 (Hanway, 1966). The traps
were kept in the field until corn was mature or until ears
were dry.

101
Above-ground insects. Fall armyworm and com earworm
damage was estimated by weekly visual observations. Two
rows were randomly chosen in each replication, and 15
consecutive plants were carefully observed in each row.
A total of 120 plants were thus examined weekly for each
treatment. The number of damaged plants (showing any
damage level, but whorl not destroyed) and the number
of plants with completely damaged whorl was recorded.
When com started tasseling (Stages 4 and 5, Hanway, 1966),
damage to the tassel was determined in the wheat stubble
experiment by recording the number of plants having at
least half of the tassel destroyed.
After ear shoots appeared, observations were no longer
made on the foliage, but only on ears. The combined damage
of Spcdoptera frugiperda (J. E. Smith) and Heliothis zea
(Bcddie) to com ears was estimated by counting and recording
the number of damaged ears on 30 plants randomly selected
from two rows in each replication (120 plants per treatment).
Two other rows were randomly chosen in each plot and the
number of damaged ears was recorded. Damage to ears was
also assessed at the harvest time. Each replication (plot)
was crossed diagonally and eight ears were collected.
A total of 32 ears were thus collected from each treatment.
The ears were placed in paper bags and brought into the
laboratory where the number of damaged ears (showing any
outside damage level) and the number of ears with a damaged area
extending to one or more centimeters within the kernel rows
were recorded.

102
Results and Discussion
Above-Ground Insects
Vetch stubble experiment. Damage to com foliage
and ears caused by Spodoptera frugiperda and Heliothis zea
in the 1978 vetch experiment is shown in Table 21. The
percent of plants with damaged foliage was 24.59 in the
no tillage and 30.83 in the conventional tillage; that
of ear damage was 50.78 in the conventional tillage plus
in-row subsoil and 44.32 in the no tillage. The difference
between treatments, however, were not significant. Damage
on ears was higher than on the foliage; 44% of the ears
in the no till and 43% in the conventional tillage were
damaged. Weekly damage levels on the foliage and ears
are shown in Figure 22.
The data were analyzed on a weekly basis, in addition
to the overall analysis, to detect any tillage effect
throughout the cropping season. Such an effect may disappear
as field conditions change during the season. No significant
differences were found between treatments on a weekly
basis for foliage damage (Fig. 22), but the percent of
infested ears was significantly higher in the no-tillage
corn than in the conventional tillage com during the
week when com plants were in the dent-physiologic maturity
stage (Hanway, 1966).
Infestations were comparatively low during the second
season. The 1979 data from the vetch experiment showed

103
that no-tillage practice did not significantly affect
frugiperda and H. zea damage to field com foliage
and ears, as compared to the conventional tillage corn
(Table 22). The weekly analysis of the data failed to
show any single week during which the difference between
treatment means was significant. Infestation levels in
the no till were 0.38 infested plants and 2.75 infested
ears per row-week; percent infestation was 1.5% infested
plants and 10.6% infested ears. In the conventional tillage
an average of 0.65 plants and 1.97 ears were infested
in each row every week. In terms of percent, 1.5% of
the plants and 5.4% of the ears were infested.
Wheat stubble experiment. Com in this experiment
was late planted in both 1978 and 1979, and Spodoptera-
Heliothis infestations were very high. Damage levels
were assessed on leaves, tassels, and ears in 1978. Table
23 contains the results. The average percent of plants
with infested foliage (but whorl not destroyed) and that
of plants with destroyed whorl were statistically the
same in all the treatments. Damage levels on tassel were
very high and appeared to be higher in the conventional
tillage plots than in the no-tillage plots, but the analysis
of the data did not detect any significant differences
among treatments. Differences between treatments also
were not significant for damage to ears. About 95% of
the plants observed in no till and 93% in conventional

104
till plots had a damaged whorl. Plant regrowth occurred,
but the stand reduction remained very high. Ears were
also very severely damaged in the late planted corn. More
than 86% of the ears in the no till, and 82% in the conven
tional till plots had Spodoptera-Heliothis damage.
Data collected in the second (1979) season from the
wheat experiment are in Table 24. Damage to the foliage
was estimated as average numbers of damaged plants per
row, percent of damaged plants calculated on a row basis,
and percent of infested plants calculated on the basis
of 120 plants observed per treatment and per week. The
analysis of the data showed that, whatever the method
used to estimate the damage, no-tillage cropping did not
have a significant impact on fall armyworm and corn earworm
infestations as compared to the conventional tillage (Table
24) .
The fall armyworm and corn earworm damage to ears
assessed at the harvest time is shown in Tables 25 and
26, respectively for the vetch stubble and wheat stubble
experiments. No significant differences were detected
between treatments in the two experiments.
No-till practice into vetch and wheat stubble did
not, in this study, significantly affect S^. frugiperda and
H. zea infestations on field com during the two years
of observation. Some above-ground insects such as the
armyworm (Pseudaletia unipuncta) are reported to cause
more severe damage to no-till corn than to the conventionally

105
tilled com (Musick and Suttle, 1973). These insects
are generally attracted by, and oviposit in, grassy areas
of the no-till com. The fall armyworm females usually
oviposit on green plants, and corn earworm females on
larval host plants (Metcalf et al., 1962). Crop residues
in no-tillage plots apparently did not attract female
moths to oviposit in these plots. If such an attraction
and concentration had occurred, more infested plants would
have been observed in no-till plots, especially during
the first weeks. Weekly, as well as overall analysis
of the data failed to show any significant preference
by female moths for the no-till com.
Conceivably, pest populations might have been higher
in the no till than in the conventional tillage and subse
quently reduced by higher predator populations in the
no-till plots. However, results obtained on ground predators
showed that predator numbers were lower in the no-till
plots than in conventional plots. It is believed that
female moths indiscriminately laid eggs on com plants
in all the plots because no-till plots did not provide
better above-ground conditions than those in the conventional
tillage plots.
Soil Insect Pests
Wireworms. Two species of wireworms (Elateridae),
Conoderus amplicollis (Gyll.) and C. falli Lane, were

106
collected in large numbers from the vetch and wheat stubble
expreiments. Of the two species, C. amplicollis was more
abundant than C. falli in both experiments. Conoderus spp.
are not important pests on com in Florida, but their
numbers were recorded in order to detect any tillage effect.
Data collected in 1979 from both experiments are
shown in Table 27. Statistical analysis of data showed
that no-tillage cropping, as well as in-row subsoil did
not affect significantly populations of Conoderus spp.
as compared to the conventional tillage. Wireworm popula
tions were highest toward the end of the crop season;
at the beginning of the season, when com could be in
the most susceptible (relative to these pests) stage,
wireworms were in low numbers.
Lesser cornstalk borer in vetch stubble. The average
numbers of damaged plants recorded from the vetch experiment
in 1978 and 1979 are shown in Table 28. Lesser cornstalk
borer infestations were relatively low in both seasons.
In the 1978 cropping season, infestations were significantly
(P=0.05) lower in the no-tillage corn than in the conven
tionally tilled com. The weekly average number of damaged
plants per row was 0.13 and 1.33, respectively in the
no-till and conventional till com (Table 28). The results
also showed that subsoiling into the furrows did not signif
icantly affect infestation levels in either no-tillage
or the conventional tillage treatments.

107
Table 28 shows lesser cornstalk borer infestations
recorded from the vetch stubble experiment in 1979. No
tillage did not affect E. lignosellus infestations in
com during the 1979 season. No significant differences
were found between treatment means. Average numbers of
damaged plants per row were 0.94 and 0.81, respectively,
in no-till and conventional till com.
Lesser cornstalk borer in wheat stubble. Com followed
wheat in this experiment and was seeded into wheat stubble
in no-till plots. In addition to counting only the number
of damaged plants as in the vetch stubble experiment,
the total number of com plants per row were recorded
along with damaged plants. Damage was thus estimated
as number of damaged plants per row and as percentage
of damaged plants. Tables 29 and 30 show the results
obtained, respectively, in 1978 and 1979. Lesser cornstalk
borer infestations, estimated as percent of damaged seedlings
or number of damaged seedlings per row, were significantly
(P=0.05) lower in the no-till corn than in the conventional
tillage com (Table 29). The average number of damaged
com seedlings was about three times higher in the conven
tional till than in the no-till treatment. About 1.5%
and 3.5% of the plants observed were damaged in no-till
and conventional till plots, respectively. In-row subsoiling
at planting significantly increased E. lignosellus damage
in the no-tillage plots, but not in the conventional tillage
plots.

108
When this experiment was repeated in the 1979 season,
no-tillage cropping did not significantly affect infestation
levels (Table 30), although the percentage of damaged
plants and the average number of infested plants per row
appeared to be slightly higher in conventionally tilled
plots than in untilled plots. In general, infestations
were higher during this season than in the previous season.
The average damage level for the whole field was only
2.89% of the plants infested in 1978, but 8.20% in 1979.
The results collected during the two years indicated
that E. lignosellus infestations were higher in the late
planted com (wheat stubble experiment) than in the early
planted com. The entire field in the vetch stubble experi
ment was treated with carbofuran at planting in 1978.
It was not possible, therefore, to determine whether the
low infestations observed in this field were due to the
insecticide or to the early planting (as reported by Leuck,
1966). Infestations might also have been naturally low
during that season. Half of the rows in the wheat stubble
experiment were treated, at planting, with carbofuran
in 1978. No significant differences in numbers of damaged
plants were found between treated and untreated rows within
a same tillage system. Carbofuran apparently did not
influence lesser cornstalk borer infestations. This may
be because infestation levels were naturally low during
the season.

109
No-tillage practice failed to significantly affect
lesser cornstalk borer infestations in the 1979 cropping
season when com was seeded into vetch or wheat stubble.
In the 1978 season, this practice significantly reduced
E. lignosellus infestations in both experiments. These
results agreed with those reported by All and Gallaher
(1977) and All et al. (1979). They found that lesser
cornstalk borer infestations were greatly reduced in no
tillage com as compared to com planted in conventionally
tilled blocks. Crop residues left on the ground in no
till systems were found to be the most important factor
contributing to these low infestations (Cheshire et al.,
1977; Cheshire and All, 1978). Crop residues reduce infes
tations by either providing food to the saprophagous larvae
or by disrupting the feeding behavior of the larvae through
odor or mechanical shielding of the host plants.
Cutworms in vetch and wheat stubble. During the
1978 season very few granulate cutworms [Feltia subterrnea
(Fab.)] were found in the traps in the vetch stubble and
wheat stubble experiments. One cutworm was collected
in 1979 in the wheat experiment. Cutworm populations
in the vetch experiment, however, were high in the 1979
season. The results recorded during that season are in
Table 31. Numbers of cutworms were significantly (P=0.05)
higher in the no-till corn than in the conventional till
corn. The no tillage plus subsoil also harbored more

110
cutworms than any of the conventional tillage treatments.
The weekly average numbers of cutworms per trap were 10.0
and 2.1, respectively, in the no-tillage and conventional
tillage plots. Subsoiling did not significantly increase
cutworm numbers within a same tillage system, although
the average number in no tillage plus subsoil was twice
higher than in the no tillage without subsoil (Table 31).
Although cutworm populations were high in the no
till plots, damage to corn seedlings was very low. Total
numbers of damaged plants recorded were one, zero, three
and one, respectively, from the conventional tillage,
conventional tillage plus subsoil, no tillage, and no
tillage plus subsoil. The corresponding plant population
was estimated in each treatment plot by randomly selecting
three rows per replication and counting the total number
of plants. The average numbers of plants per row were
26.5, 35.3, 38.0, and 38.0, for no till, no till plus
subsoil, conventional tillage, and conventional tillage
plus subsoil. Damage levels might have been underestimated
because some plants might have been infested but did not
fall down or were not completely cut. No noticeable cutworm
damage, however, was observed throughout the field.
It is not clear whether low cutworm numbers in 1978
were due to the carbofuran treatment of the soil. Cutworms
are known to vary greatly in numbers from one year to
another (Metcalf et al., 1962); populations are believed

Ill
to have been naturally low in the area in 1978, although
the insecticide might have had some effect. Cutworms
generally overwinter in the soil, under trash or clumps
of grasses, and female moths emerge from the soil in the
spring and oviposit on grasses and other plants. No
tillage systems provide an adequate environment for F.
subterrnea development because of the trash left on the
ground and the lack of soil tillage to destroy the larvae
and pupae.
That cutworms cause more severe damage to no-tillage
com than to the conventional tillage com has already
been documented (Musick, 1970b). It is not known, however,
why these relatively high cutworm populations caused prac
tically no damage to com seedlings in this experiment.
The same mechanism as that reported by Cheshire and All
(1978) for the lesser cornstalk borer may be involved
here. Crop residues in the no-till plots might have served
as food for the larvae, and prevented them from easily
locating com plants.
Soil-Inhabiting Predators
Ground dwelling spiders. The activity of ground
dwelling spiders was monitored in com in 1978 and 1979
in the vetch stubble experiment and in 1979 in wheat stubble.
Statistical analyses of data did not detect any significant
differences between the treatments. The weekly average
numbers were 1.30, 1.19, 1.28 and 1.47 spiders per trap

112
in no tillage, no tillage plus in-row subsoil, conventional
tillage and conventional tillage plus in-row subsoil,
respectively.
When the data were analyzed on a weekly basis, however,
they revealed significant differences among treatments
during the third, seventh and eighth weeks of the sampling
period. During the third week, the activity of the spiders
was significantly (P=0.01) higher in the no tillage than
in the conventional tillage. The average numbers were
2.5 and 0.25 spiders per trap, respectively in the no
tillage com and conventional tillage com. The activity
of the spiders was significantly (P=0.05) reduced in no
tillage plots during the seventh week but increased during
the eighth week.
In 1979 populations of ground spiders were very high
as compared to the 1978 crop season. The weekly averages
were 5.68, 7.66, 7.02 and 7.04 spiders per trap, respectively,
in no till, no till plus in-row subsoil, conventional
tillage and conventional tillage plus in-row subsoil. No
significant differences were found between these means.
The average numbers of spiders collected from the wheat
stubble experiment were 2.96, 3.50, 3.00 and 3.50 spiders
per trap, respectively in no tillage, no tillage plus
in-row subsoil, conventional tillage and conventional
tillage plus in-row subsoil. Spider populations were
not affected by the tillage method in corn crop systems.

113
Carabid beetles. Species and numbers of carabid
beetles collected in pitfall traps from the vetch stubble
experiment are in Tables 32 and 33, respectively for the
1978 and 1979 crop seasons. Five species were recorded
in the 1978 experiment, and all, except Galerita lecontei
(Dejean), were classified as very rare species, according
to Rivard's (1964) scale: "Very rare, 10 specimens or
less; Rare, 11 to 50; Common, 51 to 200; Abundant, over
200". Galerita lecontei was a rare species; 48.15% of
all the carabid predators collected were G. lecontei with
69.23% of the specimens being collected from the conventional
tillage plus in-row subsoil. None of the G. lecontei speci
mens was recorded from the no tillage, and only one specimen
was caught from the no tillage plus in-row subsoil (Table
32) .
In 1979, the number and species of carabids increased,
and 12 different species were recorded (Table 33). Only
G. lecontei, Harpalus pennsylvanicus DeGeer, and Selenophorus
pallia tus Fab. were rare species; the others were very
rare. About 47% of the carabids were collected from the
conventional tillage plus in-row subsoil; 30% were recorded
from the conventional tillage without subsoil. No till
and no till with subsoil harbored respectively 11.96 and
9.78% of the carabids collected.
The number of carabid beetles in the wheat experiment
was relatively low during the two cropping seasons. Twelve

114
specimens belonging to five species were recorded in 1978
(Table 34). All the species were very rare, and S. palliatus
accounted for about 50% of all the species collected.
Most of the carabids (42%) were collected from the no
tillage com. Selenophorus was also the most predominant
species in the 1979 season, but the activity of the beetles
was monitored for four weeks only in this experiment in
1979.
One species, G. lecontei, was active throughout the
season until the com was mature. The highest numbers
were recorded two to three weeks after ears appeared.
At this stage, a relatively high percent of the ears were
already infested by the Heliothis-Spodoptera complex.
Selenophorus palliatus was collected most often toward
the end of the season. Pasimachus spp. were more active
during the first five weeks of the sampling period, i.e.
six to seven weeks after com was planted. The catches
for other species were very erratic. These results agreed
with the report by Galvez (1979) who found that the activity
of the carabid beetles in com at Green Acres was inconsistent
during the entire study period, and that carabid fauna
generally was either rare or very rare. Carabid populations
were in such low numbers, and appeared so infrequently
that it is not believed that these predators played any
important role in regulating pest populations.
With respect to the tillage systems, the results
indicated a preference by the carabids to colonize conventional

115
tillage plots. Since pest populations in the conventional
tillage plots were not significantly higher than those
in the no-till plots, it may be assumed that the beetles
werse attracted by the more favorable edaphic conditions
in these plots rather than by pest populations. The absence
of carabid larvae (only four, not identified, were caught)
in the traps might indicate that most of the carabids
were originating from the neighboring wooded area or fields.
Striped earwig. Data on the foraging activity of
L. riparia are presented in graphs and analyzed on a weekly
basis (in addition to the overall analysis) in order to
show the effect of the tillage practice throughout the
cropping season. Figure 23 shows the weekly activity
of the earwig (all stages combined) in the vetch stubble
experiment in 1978. The overall analysis of the data
indicated that no-tillage practice, as compared to the
conventional tillage, did not significantly affect the
populations of earwigs.
The weekly analysis showed that during the second
week of the sampling period (about four weeks after com
was planted), the Labidura population was significantly
higher in the conventional tillage than in the no-tillage
com. During the third week a significant difference
between treatments was found only for the nymphal population
(not shown separately on the graph) which was higher in
the conventional tillage than in the no-tillage com.

116
The results obtained from the wheat stubble experiment
in both the 1978 and 1979 seasons are shown in Figures
25 and 26, respectively. In 1978, nymphal and adult Labidura
populations remained statistically the same in the no
tillage and conventional tillage com throughout the sampling
period, except during the eighth week when the nymphal
population was significantly (P=0.05) higher in the conven
tional tillage than in the no tillage.
In the 1979 season (Figure 26), the conventional
tillage com harbored significantly more earwig nymphs
during the first two weeks of the sampling period than
did the no-tillage com. During the fifth week, the adult
population was higher in the conventional tillage than
in the no-tillage com; at the end of the sampling period,
the total (nymphs and adults) population was significantly
(P=0.01) higher in the conventional tillage plots than
in the no-tillage plots. The difference between treatment
means (no till vs. conventional till) were highly significant
(P=0.01) for both the nymphal and the adult populations.
Data collected during the two years from silage corn
planted into either vetch or wheat stubble indicated that
the no-tillage com generally harbored lower L. riparia popu
lations than the conventional tillage corn. This trend
was more apparent for the nymphal population than for
the adult population. In fact, in most of the experiments
where no-tillage farming significantly affected the earwig
populations, numbers of nymphs were lower in no-tillage
plots than in the conventional tillage ones while the

117
numbers of adults remained statistically the same in all
the plots. Lower nymphal populations in untilled plots
may be an indication that adult earwigs preferentially
moved to the tilled plots to breed (to oviposit) while
they indiscriminately spread into all the treatment plots
for foraging activity.

118
Table 21. Foliage and ear damage caused by the fall army-
worm, Spodoptera frugiperda (J. E. Smith), and
the com earworm, Heliothis zea (Boddie), in
no-tillage and conventional tillage com at
Green Acres, Alachua Co., Fla., 1978. Numbers
are averages of 120 plants per treatment (each
week) for four weeks for foliage and three weeks
for ears.
% infestation*
Treatment
Foliage
Ears
No tillage into vetch stubble
No tillage plus in-row subsoil
24.59
44.32
into vetch stubble
37.46
38.40
Conventional tillage
30.83
43.25
Conventional tillage plus
in-row subsoil
22.71
50.78
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

119
Table 22. Damage caused by the fall armyworm, Spodoptera
frungiperda, and corn earworm, Heliothis zea, to
no-tillage and conventional tillage field com at
Green Acres, Alachua Co., Fla., 1979. Numbers are
averages of 120 plants per treatment (each week)
for five weeks for foliage and four weeks for ears.
Com infestation*
Treatment
Avg.
plants
No./row
ears
% infestation
plants ears
No tillage into vetch stubble
0.38
2.75
1.50
10.61
No tillage plus in-row subsoil
into vetch stubble
0.50
3.60
2.00
14.60
Conventional tillage
0.65
1.97
1.50
5.36
Conventional tillage plus
in-row subsoil
0.44
3.38
0.83
9.95
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

120
Table 23. Infestations of the fall armyworm, Spodoptera
frugiperda, and com earworm, Heliotnis zea ~in
no-tillage and conventional tillage field com
at Green Acres, Alachua Co., Fla., 1978. Average
based on 120 plants per treatment per week.
% infestation*
Plants with
destroyed
Treatment
Plants
Whorl
Tassel
Ears
No tillage into wheat stubble
77.50
94.58
74.16
86.86
No tillage plus in row sub
soil into wheat stubble
77.83
90.83
70.88
78.47
Conventional tillage
74.83
93.33
84.34
82.31
Conventional tillage plus
in-row subsoil
*
76.17
94.58
83.17
72.10
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

121
Table 24. Infestations of the fall armyworm, Spodoptera
frugiperda, and corn earworm, Heliothis zea, in
no-tillage and conventional tillage field com
at Green Acres, Alachua Co., Fla., 1979.
Inf
ested plants*
%
Treatment
Average
No./row
(on row
basis)
(on 120
plant basis)
No tillage into wheat stubble
31.42
68.94
91.67
No tillage plus in-row subsoil
into wheat stubble
35.25
71.80
92.09
Conventional tillage
26.96
60.30
87.50
Conventional tillage plus
in-row subsoil
30.71
64.54
88.75
a
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.

122
Table 25. Fall armyworm and corn earworm damage to the
conventional and no-tillage corn assessed at
the harvest time at Green Acres, Alachua Co.,
Fla., 1979. Thirty-
treatment.
-two
ears collected
per
Treatment
Damaged
Ears*
Ears with
Damaged
Kernels*
No.
%**
No.
%**
No tillage into vetch stubble
20
62.50
9
28.12
No tillage plus in-row
subsoil into vetch stubble
12
37.50
4
12.50
Conventional tillage
15
46.87
6
18.75
Conventional tillage plus
in-row subsoil
21
65.62
9
28.12
7? "
Damaged ears: ears with any outside damage level. Damaged
kernels: ears with a damaged area extending to one or
more centimeters within the kernel rows.
**In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's com
parisons were not made.

123
Table 26. Fall armyworm and corn earworm damage to the
conventional and no-tillage corn assessed at
the harvest time at Green Acres, Alachua Co.,
Fla., 1979. Forty ears were collected per
treatment.
Ears with
Damaged Damaged
Treatment Ears* Kernels*
No.
%**
No.
%**
No tillage into wheat stubble
38
95.0
31
77.50
No tillage plus in-row
subsoil into wheat stubble
33
82.50
27
67.50
Conventional tillage
39
97.50
34
85.0
Conventional tillage plus
in-row subsoil
39
97.50
37
92.50
Damaged ears: ears with any outside damage level. Damaged
kernels: ears with a damaged area extending to one or more
centimeters within the kernel rows.
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
not made.

124
Table 27. Number of Conoderus amplicollis (Gyll.) and C.
falli Lane (Elateridae) collected in pitfall
traps from conventional tillage and no-tillage
field com at Green Acres, Alachua Co., Fla.,
1979. Numbers are totals and averages of nine
weeks for vetch and six weeks for wheat with
four traps per treatment.
Total
Number
Average/trap*
Treatment
Vetch
stubble
Wheat
stubble
Vetch
stubble
Wheat
stubble
No tillage
466
150
12.94
6.25
No tillage plus
in-row subsoil
368
207
10.22
8.62
Conventional tillage
389
265
10.80
11.04
Conventional tillage
plus in-row subsoil
280
173
7.78
7.21
In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's com
parisons were not made.

125
Table 28. Lesser cornstalk borer,(Elasmopalpus lignosellus
(Zeller)), inf estations in no-tillage and conventional
tillage field com at Green Acres, Alachua Co., Fla.,
1978 -1979. Estimation is based on eight rows per
treatment examined each week for three weeks.
Treatment
Total
1978
Damaged plants
No. Average
1979 1978
No/row*
1979
No tillage into vetch stubble
3
15
0.13a
0.94c
No tillage plus in-row
subsoil into vetch stubble
2
13
0.08a
0.81c
Conventional tillage
32
3
1.33b
0.19c
Conventional tillage
plus in-row subsoil
TT
32
2
1.33b
0.12c
Means in each column not followed by the same letter are
significantly different at the 0.05 level by Duncan's new
multiple range test.

126
Table 29. Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus, in no-tillage and
conventional tillage field com at Green Acres,
Alachua Co., Fla., 1978.
Infestation*
No. plants
No.
Plants/
Treatment
observed
infested
l
row
No tillage into wheat
stubble
1987
31
1.56a
0.97c
No tillage plus in-row
subsoil into wheat stubble
2751
104
3.78b
3.25d
Conventional tillage
Conventional tillage plus
2507
88
3.51b
2.75d
in-row subsoil
m- -
2966
80
2.70b
2.50d
Values in each column not followed by the same letter are
significantly different at the 0.05 level by Duncan's new
multiple range test.

127
Table 30. Infestations of the lesser cornstalk borer,
Elasmopalpus lignosellus, in no-tillage and
conventional tillage field corn at Green Acres,
Alachua Co., Fla., 1979.
No. plants
Infestation*
Total
Number
Treatment
observed
infested
1
Avg/row
No tillage into wheat stubble
No tillage plus in-row
1138
90
7.91
3.75
subsoil into wheat stubble
1171
89
7.60
3.71
Conventional tillage
Conventional tillage plus
1160
109
9.40
4.54
in-row subsoil
1140
90
7.89
3.75
In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's
comparisons were not made.

128
Table 31. Activity of the granulated cutworm, Feltia
subterrnea (Fab.), monitored by nonbaited
pitfall traps in no-tillage and conventional
tillage com at Green Acres, Alachua Co., Fla.,
1979. Numbers are totals and average of four
traps per treatment for four weeks.
Treatment
Cutworm population
Tot. No. Avg./trap
No tillage into vetch stubble
160
10.0a*
No tillage plus in-row subsoil
into vetch stubble
345
21.6a
Conventional tillage
34
2.1b
Conventional tillage plus
in-row subsoil
5
0.3b
Values not followed by the same letter are significantly
different by Duncan's new multiple range test at the 0.05
level.

Table 32. Number and species of carabid predators collected in pitfall traps from
no-tillage and conventional tillage field corn at Green Acres, Alachua Co.,
Fla., May July, 1978. Numbers are totals of four traps per treatment.
Species
NVS
NVS+s
CT
CT+s
Tot
%
Index**
Calosoma sayi De/jean
0
0
1
0
1
1.09
VR
Chlaenius laticollis Say
0
0
0
1
1
1.09
VR
C. tomentosus Say
0
0
1
0
1
1.09
VR
Colliuris pennsylvanica (L.)
0
0
2
5
7
7.61
VR
Galerita lecontei De/jean
7
2
10
16
35
o
00
CO
R
G. /janus (Fab.)
1
1
2
0
4
4.35
VR
Harpalus caliginosus Fab.
1
0
0
0
1
1.09
VR
H. pennsylvanicus DeGeer
0
3
2
9
14
15.22
R
Pasimachus sublaevis Beauv.
2
0
0
1
3
3.26
VR
P. subsulcatus Say
0
0
0
1
1
1.09
VR
Scarites subterraneus (Fab.)
0
1
0
0
1
1.09
VR
Selenophorus palliatus Fab.
0
2
10
11
23
25.00
R
Total
11
9
28
44
92
1
11.96
9.78
30.43
47.83
*NVS: no tillage into vetch
s tubb1e;
NVS+s: No
tillage plus
in-
row subsoil into vetch
stubble; CT: conventional
tillage; CT+s: conventional tillage
plus in-
row subsoil.
**Rivard's scale: VR: very
rare; 10
specimens
or less
; R:
rare
, 11 to
50 specimens;
129

Table 33. Numbers and species of carabid predators collected in pitfall traps from
no-tillage and conventional tillage field corn at Green Acres, Alachua Co.,
Fla., April-July, 1979. Numbers are totals of four traps per treatment.
Species
NVS
Treatment
NVS+s CT
CT+s
Tot.
1
Index**
Calosoma sayi De/jean
0
0
1
1
2
7.4
VR
Colliuris pennsylvanica
(L.)
0
1
3
0
4
14.8
VR
Galerita lecontei
0
1
3
9
13
48.1
R
Harpalus pennsylvanicus
DeGeer
1
1
0
1
3
11.1
VR
Pasimachus sublaevis Beauv.
1
1
2
1
5
18.5
VR
Total
2
4
9
12
27
1
7.4
14.8
33.3
44.4
*NVS: no tillage into vetch stubble; NVS+s; no tillage plus in-row subsoil into
vetch stubble; CT: conventional tillage; CT+s: conventional tillage plus in-row
subsoil.
**VR: very rare, 10 specimens or less; R: rare 11 to 50 specimens (Rivard, 1964).
130

Table 34. Numbers and species of carabid predators collected in pitfall traps from
no-tillage and conventional tillage field corn at Green Acres, Alachua Co.,
Fla., July August, 1979.
Species
NWS
Treatment
NWS+s CT
CT+s
Tot.
%
Index**
Calosoma sayi De/jean
1
1
0
0
2
16.7
VR
Colliuris pennsylvanica (L.)
0
0
1
0
1
8.3
VR
Harpalus caliginosus Fab.
1
0
0
0
1
8.3
VR
Pasimachus sublaevis Beauv.
1
0
1
0
2
16.7
VR
Selenophorus palliatus Fab.
2
2
1
1
5
50.0
VR
Total
5
3
3
1
12
1
41.7
25.0
25.0
8.3
*NWS: no tillage into wheat stubble; NWS+s: no tillage plus in-row subsoil into wheat
stubble; CT: conventional tillage; CT+s : conventional tillage plus in-row subsoil.
**VR: very rare, 10 specimens or less; R: rare, 11 to 50 specimens (Rivard, 1964).
131

INFESTED PLANTS AND EARS
132
Damage On Foliage Damage On Ears
SAMPLING PERIOD
Figure 22. Weekly damage to field com foliage and ears
caused by Spodoptera frugiperda and Heliothis
zea at Green Acres, Alachua Co., Fla., 1978.
no tillage into vetch stubble
conventional tillage

AVERAGE NUMBER/TRAP(LOGx)
SAMPLING PERIOD
Figure 23. Weekly activity of Labidura riparia (nymphs + adults) monitored by pitfall
traps (4/treat.) in field corn at Green Acres, Alachua Co., Fla., 1978.
: no tillage into vetch stubble
: conventional tillage
133

AVERAGE NUMBER/TRAP(LOGx)
134
27 4 II 18 25 I 8 15 22 29 6
April May June July
SAMPLING PERIOD
Figure 24. Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field com at Green Acres, Alachua Co.,
Fla. 1979.
no tillage into vetch stubble
conventional tillage

AVERAGE NUMBER/TRAP (LOGx)
135
0.5J
i
0 -| j ¡ 1 j 1 1 1 1
23 30 7 14 21 28 4 II 18 25
June July August
SAMPLING PERIOD
Figure 25. Weekly activity of Lab idura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field com at Green Acres, Alachua Co.,
Fla., 1978.
no tillage into wheat stubble
conventional tillage

136
July August
SAMPLING PERIOD
Figure 26. Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla., 1979.
no tillage into wheat stubble
conventional tillage

GENERAL CONCLUSIONS
Soybean Crop Systems
According to their population levels, four insects, S.
festinus, P. includens, N. viridula and A. gemmatilis, were
the most important above-ground pests observed during the
two years. Populations of these insects, as well as injury
levels caused did not differ significantly in soybeans
grown in no-tillage and conventional tillage systems. How
ever, if serious infestations of E. lignosellus are to be
avoided, cultural practices must include applications of
a good soil insecticide, early planting and irrigation.
Com Crop Systems
Infestations due to S. frugiperda and H. zea, the most
important above-ground pests observed on corn, were more
severe in late planted than in early planted field corn,
but were not affected by the tillage methods. These pests
are not, according to the results, expected to cause more
damage in no-tillage corn than in conventionally tilled
com.
Wireworm populations were not affected by the no-tillage
practice. Although no tillage greatly increased cutworm
populations, no apparent damage was done to corn by these
insects. However, cutworms may be expected to cause more
137

138
damage to nontilled com than to the conventional tillage
corn. Therefore, a good program for weed control and insecti
cidal treatment of the soil must be considered as an important
part of the cropping procedure when no tillage is adopted
for corn production. No tillage reduced lesser cornstalk
borer damage to com seedlings. This practice may be used
in an integrated control program along with early planting,
irrigation and applications of a soil insecticide in order
to regulate Elasmopalpus infestations in com.
Arthropod Predators
No-tillage crop production did not affect ground spider
populations in either corn or soybean systems. Numbers of
spiders were very low when populations of most pests appeared
or were high. The striped earwig, L. riparia, was the most
abundant species collected in pitfall traps. The effect
of no tillage on the earwig was not consistent.
Fifteen species of carabid beetles belonging to eleven
genera were collected from both crop systems. However, in
numbers, none of the species exceeded the Rivard's 'rare'
category. In soybean systems the majority of carabids were
collected from no-till plots. Whereas, in corn systems most
carabids were recorded from conventional tillage treatments.
Corn and Soybean Yields
Com yields recorded from no-tillage systems were
statistically equal to those from the conventional tillage

139
(see Appendix C). Herbicide costs and fuel consumption,
in this case, determine net money returns from the no
tillage farming. If (no cost/benefit analysis was done)
herbicide costs exceeded the saving from reduced fuel
consumption, no-tillage resulted in decreased benefits
in this study.
No-tillage farming resulted in lower yields in soybean
crop systems (see Appendix D). Inadequate weed control
was believed to be the reason for lower yields recorded
from the no tillage. These results confirmed that good
weed control is a prerequisite to acceptable crop yields
from no-tillage systems.

APPENDIX A
CHEMICAL NAMES OF HERBICIDES MENTIONED OR USED
IN THE EXPERIMENTS
Common name
Chemical name
Alachlor
2-chloro-2',6'-diethyl-N-(methoxy-
methyl)-acetanilide
Atrazine
2-chloro-4-(ethylamino)-6-(isopro-
pylamino)-s-triazine
Linuron
3-(3,4-dichlorophenyl)-1-methoxy-
1-methylurea
Metribuzin
4-amino-6-tert-butyl-3-(methylthio)
as-triazine-5 (4H) one
Paraquat
(1,1'-dimethyl-4,4'-bipyridinium
ion)
Simazine
2-chloro-4,6-bis (ethylamino)-
s-triazine
2,4-D
(2,4-dichlorophenoxy) acetic acid
140

APPENDIX B
PREDATORY ACTIVITY OF LABIDURA
ON ANTICARSIA IMMATURES
The effectiveness of L. riparia as a predator on
A. gemmatilis immatures was assessed in the laboratory
by introducing one Labidura male into a cottage cheese cup
containing 5 or 15 Anticarsia larvae. Some cups (with larvae
and Labidura) were placed on a table for direct observations.
Others were kept in a growth chamber (temperature 28 C) for
24 hours. Predation on pupae was studied by placing three
pupae into each cup; the pupae were covered with 1 cm of
sand. One male Labidura was introduced into each cup and
the cups were kept in the growth chamber.
Direct observations indicated that small and medium
larvae (1-2.0 cm) were more easily caught and killed than
larger (over 2 cm) larvae. Large larvae were punctured after
a few minutes of struggle, but were not generally consumed.
Labidura were observed to kill five small larvae within two
minutes without completely consuming any or consumed only
one. An average of 5.2 minutes were required to consume a
small larva. These observations agreed with an earlier con
clusion by Bishara (1934, cited by Price and Shepard, 1977)
that L. riparia may kill more prey than it consumes.
141

142
Observations made after 24 hours also showed the effec
tiveness of L. riparia as a predator of Anticarsia immatures:
No. VBC
No. Labidura No. VBC No.VBC Consumed
VBC* size Tested Exposed Killed Totally Partially
Small (1-1.5 cm
9
71
64
32
6
Medium (1.6-2 cm)
8
46
40
8
15
Large (over 2 cm)
13
45
32
2
21
VBC: Velvetbean caterpillar (A. gemmatilis).
Averages calculated from the table above indicated that one
Labidura male killed (24 hours) 7.1, 5.0 and 2.4 small,
medium and large larvae, respectively, but consumed (totally)
only 3.5, 1.0 and 0.1 small, medium and large larvae. The
data also showed that the number of larvae killed or con
sumed by a single Labidura decreased as the age of the larvae
increased. Hassanein et al. (1968) came to the same conclu
sion when they exposed larvae of Frodenia litura Fab. to
L. riparia.
Thirty-two pupae were exposed to 11 Labidura for 24 hours
A total of 12 pupae were consumed. The earwig opened (usually
longitudinally) the pupal case of the prey and consumed the
contents. Each Labidura thus consumed an average of 1.1 pupae
The impact of L. riparia on A. gemmatilis larval popula
tions may be tremendous and important in regulating these pop
ulations in the field. The earwig kills many more prey than
it consumes and is generally observed in large numbers in the

143
fields. This impact, however, is believed to be less than
what was observed in confinement. Velvetbean caterpillars
wriggle vigorously and drop from the plant when disturbed.
Such a behavior prevents a predator from easily catching
the larvae. Moreover, L. riparia feeds on a variety of
prey and would "prefer" to prey on those small arthropods
it can easily kill.

APPENDIX C
YIELD OF "DEKALB XL 78 A" CORN
FROM GREEN ACRES
To estimate the yield, corn ears were collected from
all the plants in two center rows (6.10 m long) of each rep
lication in the vetch stubble experiment. In the wheat stubble
experiment, all the plants in the two rows were collected,
and the yield was estimated as dry matter (but not as
grain). The yield of corn recorded from the vetch stubble
experiment is shown below (yield reported at 15.5% moisture):
Avg.
Yield
(kg/ha)*
Treatment
1978
1979
Total
No tillage into vetch stubble
3031
5932
4472
No tillage plus in-row subsoil
2887
5932
4409
Conventional tillage
2464
3107
2785
Conventional tillage plus
in-row subsoil
*
2668
3562
3115
In the analysis of variance, no significant differences were
detected between the means. Therefore Duncan's comparisons
were not made.
The analysis of data revealed no significant differences
between treatments for yield either in 1978 or 1979.
Com yields (dry matter) from the wheat stubble experi
ment are shown in the table below (yield reported at 15.5%
moisture):
144

145
Treatment
Avg^_
1978
Yield
1979
(kg/ha)*
Total
No tillage into wheat stubble
5034
7253
6143
No tillage plus in-row subsoil
4892
7854
6373
Conventional tillage
5395
6053
5724
Conventional tillage plus
in-row subsoil
7C
5080
6844
5962
In the analysis of variance, no significant differences were
detected between the means. Therefore, Duncan's comparisons
were not made.
No tillage and conventional tillage produced 6143 and 5724 kg/ha
(average of two years), respectively, but these means were
not statistically different.
The no-tillage practice did not significantly affect
yields of corn seeded in either the vetch or wheat stubble.
Since yields of com were statistically the same in the
two tillage systems, the cost of herbicides and saving
in fuel consumption will determine net money returns.
Because if, for equal yields, costs of herbicides (used
in no tillage) exceed the saving due to reduced machinery
use, no-tillage farming will result in reduced net benefits.
Other factors such as soil protection against erosion,
possibility of two crops per year or per season when
no tillage is used, may also be considered when making
the decision to adopt the no-tillage farming.

APPENDIX D
AVERAGE YIELDS OF "COBB" SOYBEANS
Yield estimates were made at Green Acres in 1978
and 1979. Pods were harvested from two center rows (6.10 m
long) in each replication (four replications per treatment).
The yield, shown below, is reported at 13% moisture:
Treatment
Avg.-..
1978
Yield (kg/ha)
1979 Total
No tillage into oat stubble
1937*
975a**
1456a
No tillage plus in-row subsoil
1746
1379b
1563a
Conventional tillage
2304
1749b
2027b
Conventional tillage plus
in-row subsoil
H
2009
1614b
1812b
In the analysis of variance for 1978 data, no significant
differences were detected between the means. Therefore,
Duncan's comparisons were not made.
**
Values not followed by the same letter in each column are
significantly different at the 0.05 level by Duncan's new
multiple range test.
In 1978, conventional tillage and no-tillage soybeans
produced respectively 2304 and 1937 kg/ha. The statistical
analysis failed to detect any significant differences
between treatments. In the 1979 season, however, soybean
yields were significantly (P=0.05) lower in the no tillage
into oat stubble than in the conventional tillage. The
two-year average yields also were lower in the no tillage
than in the conventional tillage.
Higher lesser cornstalk borer damage to soybean
seedlings in the no tillage was not believed to be the reason
146

147
for lower yields in the no tillage. It is believed that
reduced yields recorded from the no tillage were due
to inadequate weed control, especially the bahiagrass
(Paspalum notaturn Flugge) which has colonized those plots
that were not tilled for three successive years. Several
workers (Triplett and Lytle, 1972; Griffith et al.,
1973) recorded lower crop yields from no-tillage systems
when weed control was not adequate. Although no cost/benefit
analysis was done, it is believed that this yield reduction
resulted in reduced net money returns.

LITERATURE CITED
Adeyemi, S. A. 0. 1969. The survival of stem borer popula
tion in maize stubble. Bull. Entomol. Soc. Nigeria.
2:16-22.
Adkisson, P. L., L. H. Wilkes, and B. J. Cochran. 1960.
Stalk shredding and plowing as methods for controlling
the pink-bollowrm, Pectinophora gossypiella. J. Econ.
Entomol. 53:436-9.
Afify, A. M., and H. T. Farghaly. 1970. Comparative labora
tory studies on the effectiveness of Lab idura riparia
Pall, and Coccinella undecimpunetata Reiche, as predators
of eggs and newly hatched larvae of Spodoptera littoralis
(Boisd.). Bull. Soc. Entomol. Egypte! 54:277-82.
All, J. N., and R. N. Gallaher. 1977. Detrimental impact of
no-tillage com cropping systems involving insecticides,
hybrids, and irrigation on lesser cornstalk borer infes
tations. J. Econ. Entomol. 70:361-5.
All, J. N., R. N. Gallaher, and M. D. Jellum. 1979. Influence
of planting date, preplanting weed control, irrigation,
and conservation tillage practices on efficacy of planting
time insecticide applications for control of lesser
cornstalk borer in field com. J. Econ. Entomol. 72:265-8.
All, J. N., C. W. Kuhn, R. N. Gallaher, M. D. Jellum, and
R. S. Hussey. 1977. Influence of no-tillage cropping,
carbofuran, and hybrid resistance on dynamics of maize
chlorotic dwarf and maize dwarf mosaic diseases of com.
J. Econ. Entomol. 70:221-5.
Ammar, E. D., and S. M. Farrag. 1974. Studies on the behavior
and biology of the earwig, Labidura riparia Pallas
(Dermaptera: Labiduridae). Z. Angew. Entomol. 75:189-96.
Anonymous. 1975. Soybeans highlights. Coop. Plant Pest
Rep. 25:188-91.
Bailey, J. C., L. B. Davis, and M. L. Laster. 1970. Stem
girdling by the 3-comered alfalfa hopper, and height
of soybean plants. J. Econ. Entomol. 63:647-8.
148

149
Barber, G. W., and F. F. Dicke. 1937. The effectiveness of
cultivation as a control for the com earworm. U. S.
D. A. Tech. Bull. 561, 16 pp.
Blatchley, W. S. 1910. An illustrated descriptive catalogue
of the Coleptera known to occur in Indiana. The Nature
Publ. Co., Indianapolis. 1386 pp.
Blickenstaff, C. C., and J. L. Huggans. 1962. Soybean
insects and related arthropods in Missouri. Mo. Agrie.
Exp. Stn. Res. Bull. 803, 51 pp.
Blevins, R. L., D. Cooks, S. H. Phillips, and R. E. Phillips.
1971. Influence of no-tillage on soil moisture. Agron.
J. 63:593-6.
Boosalis, M. G., and B. Doupnik, Jr. 1976. Management of
crop diseases in reduced tillage systems. Bull. Entomol.
Soc. Amer. 22:300-2.
Boyer, W. P. 1967. Survey method for three-cornered alfalfa
hopper (Spissistilus festinus) in soybeans in Arkansas.
Coop. Plant Pest Rep. 17 :324-5.
Brooks, D. H., and M. G. Dawson. 1968. Influence of direct-
drilling of winter wheat on incidence of take-all and
eyespot. Ann. Appl. Biol. 61:57-64.
Bums, E. E. 1973. Will conservation tillage increase the
incidence of plant disease? Ill. Res. 15:8-9.
Canerday, T. D., and F. S. Arant. 1966. Biology of Pseudo
plus ia includens and notes on biology of Trichoplusia
ni, Rachiplusia ou, and Autographa biloba. J. Econ.
Entomol. 60:870-1.
Caussanel, Cl. 1970. Principales exigences ecophysiologiques
du forficule des sables, Labidura riparia (Derm.
Labiduridae). Ann. Soc. Entomol. Fr. (N. S.). 6:589-
612.
Cheshire, J. M., Jr., and J. N. All. 1978. Monitoring lesser
cornstalk borer larval movement in no-tillage and con
ventional tillage com systems. Georgia Agrie. Res.
20:10-3.
Cheshire, J. M., Jr., J. Henningson, and J. N. All. 1977.
Radiolabeling lesser cornstalk borer larvae for
monitoring movement in soil habitats. J. Econ. Entomol.
70:578-80.

150
Clements, R. H. 1968. Important earwigs. Dermaptera, of
central and south Florida and the biology and control
of the primary species, Labidura riparia (Pallas)
under laboratory conditions. M. S. Thesis. Univ. of
Florida, Gainesville, 66 pp.
Curfs, H. P. F. 1976. Systems development in agricultural
mechanization with special reference to soil tillage
and weed control. Meded. Landbouwhogeschool Wageningen.
76, 179 pp.
Daft, G. G., and C. Leben. 1973. Bacterial blight of
soybeans: Field overwintered Pseudomonas glycinea or
possible primary inoculum. Plant Dis. Rep. 57:156-7.
Daugherty, D. M., M. H. Neustadt, C. W. Gehrke, L. E. Cavanah,
L. F. Williams, and D. E. Green. 1964. An evaluation
of damage to soybeans by brown and green stink bugs.
J. Econ. Entomol. 57:719-22.
Dean, H. A., and M. F. Schuster. 1958. Biological control
of Rhodesgrass scale in Texas. J. Econ. Entomol. 51:
363-6.
DeCoursey, R. M. ,- and C. 0. Esselbaugh. 1962. Description of
the nymphal stages of some North American Pentatomidae
(Hemiptera-Heteroptera). Entomol. Soc. Amer. Ann.
55:323-42.
Deitz, L. L., J. W. Van Duyn, J. R. Bradley, Jr., R. L. Rabb,
W. M. Brooks, and R. E. Stinner. 1976. A guide to the
identification and biology of soybean arthropods in
North Carolina. North Carolina Agrie. Exp. Stn. Tech.
Bull. 238, 264 pp.
Dempsey, A. H., and B. B. Brantley. 1953. Pimiento produc
tion in Georgia. Ga. Agrie. Exp. Stn. Bull. 277, 27 pp.
Doster, D. H. 1976. Economics of alternative tillage systems.
Bull. Entomol. Soc. Amer. 22:295-7.
Douglas, W. A. 1930. The velvetbean caterpillar as a pest
of soybeans in southern Louisiana and Texas. J. Econ.
Entomol. 23:684-90.
Doupnik, B., Jr., M. G. Boosalis, G. Wicks, and D. Smika.
1975. Ecofallow reduces stalk rot in grain sorghum.
Phytopathology. 65:1021-2.

151
Dupree, M. 1965. Observations on the life history of the
lesser cornstalk borer. J. Econ. Entomol. 58:1156-7.
Fehr, W. R., and C. E. Caviness. 1977. Stages of soybean
development. Iowa State Univ. Coop. Ext. Serv. Agrie.
Exp. Stn. Spec. Rep. 80. 11 pp.
Fenton, F. A., and W. L. Owen. 1953. The pink bollworm of
cotton in Texas. Texas Agrie. Exp. Stn. Mise. Publ.
100.
Fife, L. C., C. B. Cowan, Jr., and J. W. Davis. 1957.
Factors influencing pink bollowrm winter carry-over in
central Texas. J. Econ. Entomol. 50:642-4.
Fife, L. C., and H. M. Graham. 1966. Cultural control of
overwintering bollworm and tobacco budworm. J. Econ.
Entomol. 59:1123-5.
Frohlich, G., and W. Rodewald. 1970. Pests and diseases
of tropical crops and their control. Pergamon Press.
London, 371 pp.
Galvez, S. E. C. 1979. Seasonal abundance of pest and
beneficial arthropods in response to management strat
egies in corn. Dissertation, Univ. of Florida,
Gainesville. 128 pp.
Genung, W. G., and V. E. Green, Jr. 1965. Some stem boring
insects associated with soybeans in Florida. Fla.
Entomol. 48:29-33.
Graham, J. H. 1953. Overwintering of three bacterial
pathogens of soybean. Phytopathology 43:189-92.
Greene, G. L., J. C. Reid, V. N. Blount, and T. C. Riddle.
1973. Mating and oviposition behavior of the velvet-
bean caterpillar in soybeans. Environ. Entomol. 2:
1113-5.
Gregory, W. W., and G. J. Musick. 1976. Insect management
in reduced tillage systems. Bull. Entomol. Soc. Amer.
22:302-4.
Griffith, D. R., J. V. Mannering, H. M. Galloway, S. D.
Parsons, and C. B. Richey. 1973. Effect of eight
tillage-planting systems on soil temperature, percent
stand, plant growth and yield of com on five Indiana
soils. Agron. J. 65:321-6.

152
Hall, W. E. 1959. The effect of plowing methods and dates
of fertilizer application on the incidence of fusarium
root rot in Burt wheat. Plant Dis. Rep. 43:175-6.
Hanway, J. J. 1966. How a com plant develops. Iowa State
Univ. Coop. Ext. Serv. Agrie. Exp. Stn. Spec. Rep. 48.
17 pp.
Hardwick, D. F. 1965. The com earworm complex. Entomol.
Soc. Can. Memoirs 40, 247 pp.
Hassanein, M. H., A. M. Afify, and H. C. Farghaly. 1968.
Comparative laboratory studies of the efficiency of
Labidura riparia Pall, and Coccinella undecimpunetata
Reiche as cottonworm predators. Entomol. Rev. 47:271-3.
Hasse, W. L. 1971. Predaceous arthropods of Florida soybean
fields. M. S. Thesis. Univ. of Florida, Gainesville,
66 pp.
Hensley, S. D., L. D. Newsom, and J. Chapin. 1964. Obser
vations on the looper complex of the noctuid subfamily
Plusinnae. J. Econ. Entomol. 57:1006-7.
Herzog, D. C., J. W. Thomas, R. L. Jensen, and L. D. Newsom.
1975. Association of sclerotial blight with Spissistilus
festinus girdling in-jury on soybean. Environ. Entomol.
4:986-8.
Hill, D. S. 1975. Agricultural insect pests of the tropics
and their control. Cambridge Univ. Press, London,
516 pp.
Hinds, W. E., and B. A. Osterberger. 1931. The soybean
caterpillar in Louisiana. J. Econ. Entomol. 24:1168-73.
Holt, R. F., H. P. Johnson, and L. L. McDowell. 1973.
Surface water quality. Conservation tillage. Proc.
Nat. Conf. Soil Cons. Soc. Amer. Des Moines, Iowa,
pp. 141-56.
Isely, D., and F. D. Miner. 1944. The lesser cornstalk borer,
a pest of fall beans. J. Kans. Entomol. Soc. 17:51-7.
Janes, M. J. 1973. Com earworm and fall armyworm occurrence
and control on sweet com ears in south Florida. J.
Econ. Entomol. 66:973-4.
Jones, J. N., Jr., J. E. Moody, G. M. Shear, and W. W.
Moschler. 1968. The no-tillage system for com (Zea
mays L.). Agron. J. 60:17-20.

153
Jordan, C. R. 1965. Lesser cornstalk borer control on
beans, peas, soybeans, corn, sorghum and millet. Univ.
of Georgia Coll. Agrie, and U. S. D. A. Coop. Entomol.
Leaflet 22. Rev.
Kennedy, B. W. 1969. Detection and distribution of Pseudo
monas glycinea in soybean. Phytopathology 59 :1618-9 .
Keyworth, W. G. 1942. Verticillium wilt of the hop (Humulus
lupulus). Ann. Appl. Biol. 29:346-57.
King, D. R., J. A. Harding, and B. C. Langley. 1961. Peanut
insects in Texas. Texas Agrie. Exp. Stn. Mise. Publ.
550, 14 pp.
Lai, R. 1973. Soil erosion and shifting cultivation. FAO
Regional Sem. on Shifting Cultivation and Soil Cons, in
Africa. Ibadan, Nigeria, July 2-21.
Lai, R. 1979. Influence of six years of no-tillage and
conventional plowing on fertilizer response of maize
(Zea mays L.) on an alfisol in the tropics. Soil Sci.
Soc. Amer. J. 43:399-403.
Ledingham, R. J., R. J. Sallans, and A. Wennhardt. 1960.
Influence of culture practice on incidence of common
root rot of wheat. Can. J. Plant Sci. 40:310-6.
Lewis, W. M. 1970. No-tillage crop production in sod or
pasture. Nat. Conf. No-tillage Crop Prod., Univ. of
Kentucky, Lexington, pp. 52-4.
Leuck, D. B. 1966. Bioloby of the lesser cornstalk borer
in south Georgia. J. Econ. Entomol. 59:797-801.
Luginbill, P. 1928. The fall armyworm. U. S. D. A. Tech.
Bull. 34, 91 pp.
Luginbill, P., and G. G. Ainslie. 1917. The lesser cornstalk
borer. U. S. D. A. Bur. Entomol. Bull. 539, 27 pp.
McCalla, T. M. 1967. Effect of tillage on plant growth as
influenced by soil organisms. Conf. Proct. Tillage for
Greater Crop Prod., Detroit, Michigan. Amer. Soc.
Agrie. Eng., St. Joseph, Michigan, pp. 19-25.
Metcalf, C. L., W. P. Flint, and R. L. Metcalf. 1962.
Destructive and useful insects: Their habits and
control. 4th ed. McGraw-Hill, New York. 1087 pp.
Metcalf, Z. P. 1909. Insect enemies to tobacco. North
Carolina Dep. Agrie. Spec. Bull., 72 pp.
Miner, F. D. 1961. Stink bug damage to soybeans. Ark.
Farm Res. 10:12.

154
Miner, F. D. 1966. Biology and control of stink bugs on
soybeans. Ark. Agrie. Exp. Stn. Bull. 708, 40 pp.
Mitchell, E. R. 1967. Life history of Pseudoplusia
includens (Walker) (Lepidoptera: Noctuidae). J.
Georgia Entomol. Soc. 2:53-7.
Mitchell, W. C., and F. L. Mau. 1969. Sexual activity and
longevity of the southern green stink bug, Nezara
viridula. Entomol. Soc. Amer. Ann. 62:1246-7.
Moody, J. E., J. N. Jones, Jr., and J. H. Lillard. 1963.
Influence of straw mulch on soil moisture, soil
temperature and the growth of com. Soil Sci. Soc.
Amer. Proc. 27:700-3.
Morrill, W. L., and G. L. Green. 1973. Distribution of
fall armyworm larvae 1. Regions of field corn plants
infested by larvae. Environ. Entomol. 2:195-8.
Musick, G. J. 1970a. Insect problems associated with no
tillage corn production. Proc. Nat. No-tillage Res.
Conf. Univ. of Kentucky, Lexington, pp. 44-59.
Musick, G. J. 1970b. Problems with no-tillage crops.
Insects. Crops and Soils Magazine. 23:18-9.
Musick, G. J. 1973. Control of armyworm in no-tillage com.
Ohio Rep. 58:42-5.
Musick, G. J., and D. L. Collins. 1971. Northern corn
rootworm affected by tillage. Ohio Rep. 56:88-91.
Musick, G. J., and G. B. Petty. 1974. Insect control in
conservation tillage systems. Conservation tillage.
A handbook for farmers. Soil Cons. Soc. Amer., Ankeny,
Iowa. 52 pp.
Musick, G. J., and P. J. Suttle. 1973. Suppression of
armyworm damage to no-tillage corn with granular
carbofuran. J. Econ. Entomol. 66:735-7.
Neal, T. M. 1974. Predaceous arthropods in the Florida
soybean ecosystem. M. S. Thesis. Univ. of Florida,
Gainesville, 196 pp.
Nickels, C. B. 1926. An important outbreak of insects
infesting soybeans in lower South Carolina. J. Econ.
Entomol. 19:614-8.

155
Noble, L. W. 1955. Investigations of the pink bollworm and
hemipterous cotton insects in the El Paso area of Texas
1944-52. U. S. D. A. Circ. 957. 16 pp.
Parker, D. T., and W. C. Burrows. 1959. Root and stalk
rot in corn as affected by fertilizer and tillage
treatment. Agron. J. 51:414-7.
Peters, R. A. 1972. Control of weeds in no-tillage crops.
Proc. No-tillage Systems Sym. Ohio State Univ. Columbus,
pp. 132-9.
Phillips, W. J., and G. W. Barber. 1931. The corn earworm
as an enemy of field corn in the eastern states.
Farmers' Bull. 1651, 91 pp.
Price, J. F., and M. Shepard. 1977. Striped earwig, Labidura
riparia, colonization of soybean fields and response
to insecticides. Environ. Entomol. 6:679-83.
Price, J. F., and M. Shepard. 1978. Calosoma sayi:
Seasonal history and response to insecticides in
soybeans. Environ. Entomol. 7:359-63.
Rask, N., G. B. Triplett, Jr., and D. M. Van Doren, Jr.
1967. A cost analysis of no-tillage corn. Ohio Rep.
52:14-5.
Rivard, I. 1964. Carabid beetles (Coleptera: Carabidae)
from agricultural lands near Belleville, Ontario. Can.
Entomol. 96:517-20.
Rivers, R. L., K. S. Pike, and Z. B. Mayo. 1977. Influence
of insecticides and corn tillage systems on larval
control of Phyllophaga anxia. J. Econ. Entomol. 70:794-6.
Roane, C. W., R. L. Harrison, and C. F. Center. 1974.
Observations on gray leaf spot of maize in Virginia.
Plant Dis. Rep. 58:456-9.
Rolston, L. H., and R. L. Kendrick. 1961. Biology of the
brown stink bug, Euschistus servus Say. Kans. Entomol.
Soc. J. 34:151-7.
Schlinger, E. I., R. van den Bosch, and E. J. Dietrick.
1959. Biological notes on the predaceous earwigs,
Labidura riparia (Pallas), a recent immigrant to
California (Dermaptera: Labiduridae). J. Econ. Entomol.
52:247-9.

156
Shipley, J. L., and J. E. Osborn. 1973. Costs, input, and
returns in arid and semiarid areas. Nat. Cons. Tillage
Conf., Des Moines, Iowa. Soil Cons. Soc. Amer., Ankeny,
Iowa. pp. 168-79.
Sloderbeck, P. E., and C. R. Edwards. 1979. Effects of
soybean cropping practices on Mexican bean beetle and
redlegged grasshopper populations. J. Econ. Entomol.
72:850-3.
Stone, M. W. 1941. Life history of the sugar-beet wireworm
in south California. U. S. D. A. Tech. Bull. 744, 88 pp.
Strayer, J. R. 1973. Economic threshold studies and
sequential sampling for management of the velvetbean
caterpillar, Anticarsia gemmatilis Hubner, on soybeans.
Ph. D. Dissertation, Clemson Univ., N. C. 87 pp.
Strayer, J. R., and G. L. Green. 1974. Soybean insect
management. Florida Coop. Ext. Serv. Circ. 395. 15 pp.
Tawfik, M. F. S., S. Abul-Nasr, and M. M. El-Husseini. 1972.
The biology of Labidura riparia (Pallas). Bull. Soc.
Entomol. Egyptel 56:75-92.
Thiele, H. U. 1977. Carabid beetles in their environments:
A study on habitat selection by adaptations in physi
ology and behaviour. Springer-Verlag, New York. 369 pp.
Triplett, G. B., Jr. 1966. Herbicide systems for no-tillage
com (Zea mays L.) following sod. Agron. J. 58:157-9.
Triplett, G. B., Jr. 1976. Management of weeds in reduced
tillage systems. Bull. Entomol. Soc. Amer. 22:298-9.
Triplett, G. B., Jr., B. J. Conner, and W. M. Edwards. 1978.
Herbicide runoff from conventional and no-tillage
cornfields. Ohio Rep. 63:70-3.
Triplett, G. B., Jr., and G. D. Lyttle. 1972. Control and
ecology of weeds in continuous com grown without
tillage. Weed Sci. 20:453-7.
Triplett, G. B., Jr., and D. M. Van Doren, Jr. 1977.
Agriculture without tillage. Sci. Amer. 236:28-33.
Triplett, G. B., Jr., D. M. Van Doren, Jr., and B. L. Schmidt.
1968. Effect of corn (Zea mays L.) stover mulch on no
tillage corn yields and water infiltration. Agron. J.
60:236-9.

157
Tugwell, P., and F. D. Miner. 1967. Soybean injury by the
three-cornered alfalfa hopper. Ark. Farm Res. 16:12.
Turner, J. W. 1967. The nature of damage by Nezara
viridula (L.) to soybean seed. Queensland J. Agrie.
Anim. Sci. 24:105-7.
Turnipseed, S. G. 1973. Insects. Pp. 545-72. In Soybeans:
Improvement, production, and uses. B. E. Caldwell (ed.).
Amer. Soc. Agron., Inc. Madison, Wisconsin.
Unger, P. W., and R. E. Phillips. 1973. Soil water evapora
tion and storage. Conservation tillage. Proc. Nat.
Conf. Des Moines, Iowa. Soil Cons. Soc. Amer. Pp. 42-
54.
van den Bosch, R., and K. Hagan. 1966. Predaceous arthropods
in California cotton fields. Cali. Agrie. Exp. Stn. Bull.
820, 32 pp.
Walton, R. R., R. S. Matlock, and J. P. Boyd. 1964. Effect
of the lesser cornstalk borer on peanuts in Oklahoma.
Okla. State Univ. Exp. Stn. Processed Ser., 10 pp.
Watson, J. R. 1916. Life history of the velvetbean cater
pillar (Anticarsia gemmatilis Hubner). J. Econ. Entomol.
9:521-8.
Whitcomb, W. H., and K. Bell. 1964. Predaceous insects,
spiders and mites of Arkansas cotton fields. Ark.
Agrie. Exp. Stn. Bull. 690, 84 pp.
White, D. G., and J. L. Janney. 1978. Corn anthracnose
leaf blight and stalk rot spread into Illinois. Ill.
Res. 20:6-7.
Wiese, A. F., and D. W. Staniforth. 1973. Weed control in
conservation tillage. Cons. Tillage. Proc. Nat.
Tillage Conf. Des Moines, Iowa. Soil Cons. Soc. Amer.
Ankeny, Iowa. Pp. 108-14.
Wischmeier, W. H. 1973. Conservation tillage to control
water erosion. Cons. Tillage. Proc. Nat. Tillage Conf.
Des Moines, Iowa. Soil Cons. Soc. Amer. Ankeny, Iowa.
Pp. 133-41.
Wood, J. R. 1977. Survival of fall armyworm pupae buried
during the winter in Florida. M. S. Thesis, Univ. of
Florida, Gainesville, 68 pp.

158
Woodruff, N. P., and F. H. Siddoway. 1973. Wind erosion
control. Cons. Tillage. Proc. Nat. Conf., Des Moines,
Iowa. Soil Cons. Soc. Amer. Pp. 156-62.
Woodside, A. M. 1946. Life history studies of Euschistus
servus Say and E. tristigmus. J. Econ. Entomol.
39:161-3. ~
Yarham, D. J. 1975. The effect of non-ploughing on cereal
diseases. Outl. Agrie. 8:245-7.
Young, H. M. 1970. What is no-tillage. Proc. Nat. No-tillage
Res. Conf. Univ. of Kentucky, Lexington.

BIOGRAPHICAL SKETCH
Ki-Munseki Lema was bom on August 7, 1945, in Luvanga
(Kivulu), Bas-Zaire, a few miles away from Kinshasa,
capital of Zaire. He pursued his secondary education
at and was graduated with honors from the "Ecole Technique
Secondaire d'Agriculture" (Gombe-Matadi), in June 1967. In
December, 1967, he entered the "Universite Officielle du
Congo," now known as "Universite Nationale du Zaire, Campus
de Lubumbashi," and obtained the diploma of "Candidat en
Sciences Agronomiques." In November, 1969, he entered the
"Universite Lovanium" at Kinshasa (now Universite Nationale
du Zaire, Campus de Kinshasa) and received the degree of
"Ingenieur Agronome des Regions Tropicales," with distinc
tion, in June, 1972. Thereafter he joined the faculty of
agriculture at Kinshasa where he worked from 1972 to 1973
as Assistant Lecturer in Entomology.
In July, 1973, he was selected as a possible candidate
for a Rockefeller Foundation fellowship, and was sent to Ibadan,
Nigeria, for an intensive couse in English, after which he
entered the University of Florida and was awarded a Rockefeller
Foundation fellowship to pursue graduate studies in entomology.
He obtained the degree of Master of Science in December, 1976,
and the fellowship was extended for the Ph.D. program in
January, 1977.
159

160
The author is a member of the Florida Entomological
Society and the Entomological Society of America.
He is married to the former Lugwadio mi-Konde. They
are the parents of a wonderful four-year-old daughter,
Lukamba Nsunda, and a "troublesome" two-year-old son, Kapela.

I certify that I have read this study and that in
my opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.
Leece 1. Sailer, Chairman
Professor of Entomology
and Nematology
I certify that I have read this study and that in
my opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.
Donald C iferzg-,
Assistant Profess^
irman
Entomology and Nematology
I certify that I have read this study and that in
my opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.
Associate Professor of
Agronomy

This dissertation was submitted to the Graduate Faculty of the
College of Agriculture and to the Graduate Council, and was
accepted as partial fulfillment of the requirements for the
degree of Doctor of Philosophy.
March 1980
Dean, Graduate School



138
damage to nontilled com than to the conventional tillage
corn. Therefore, a good program for weed control and insecti
cidal treatment of the soil must be considered as an important
part of the cropping procedure when no tillage is adopted
for corn production. No tillage reduced lesser cornstalk
borer damage to com seedlings. This practice may be used
in an integrated control program along with early planting,
irrigation and applications of a soil insecticide in order
to regulate Elasmopalpus infestations in com.
Arthropod Predators
No-tillage crop production did not affect ground spider
populations in either corn or soybean systems. Numbers of
spiders were very low when populations of most pests appeared
or were high. The striped earwig, L. riparia, was the most
abundant species collected in pitfall traps. The effect
of no tillage on the earwig was not consistent.
Fifteen species of carabid beetles belonging to eleven
genera were collected from both crop systems. However, in
numbers, none of the species exceeded the Rivard's 'rare'
category. In soybean systems the majority of carabids were
collected from no-till plots. Whereas, in corn systems most
carabids were recorded from conventional tillage treatments.
Corn and Soybean Yields
Com yields recorded from no-tillage systems were
statistically equal to those from the conventional tillage


Page
Figure
19 Weekly activity of Labidura riparia nymphs
monitored by pitfall traps (four in each
treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979 93
20 Weekly activity of Labidura riparia adults
monitored by pitfall traps (four in each
treatment) in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres,
Alachua Co., Fla., 1979 95
21 Weekly activity of Labidura riparia nymphs
and adults monitored by pitfall traps (four
in each treatment) in no-tillage and con
ventional tillage "Cobb" soybeans at Green
Acres, Alachua Co., Fla., 1979 97
22 Weekly damage to field corn foliage and
ears caused by Spodoptera frugiperda and
Heliothis zea at Green Acres, Alachua Co.,
Fla. 1^78 132
23 Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field com at Green Acres, Alachua Co.,
Fla. 1978 133
24 Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla. 1979 134
25 Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field com at Green Acres, Alachua Co.,
Fla., 1978 135
26 Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla., 1979 136
xvii


136
July August
SAMPLING PERIOD
Figure 26. Weekly activity of Labidura riparia (nymphs +
adults) monitored by pitfall traps (4/treat.)
in field corn at Green Acres, Alachua Co.,
Fla., 1979.
no tillage into wheat stubble
conventional tillage


19
Soybean and Com Insect Pests in Florida
Soybean Insects
Three-cornered alfalfa hopper. The biology and descrip
tion of adults and nymphs of the three-cornered alfalfa
hopper, Spissistilus festinus (Say), may be found in Turnip-
seed (1973). Damage to soybeans is caused by adults and
nymphs that girdle the plants with their feeding punctures.
According to Bailey et al. (1970), S. festinus feeds mostly
on the lower portion of the stems, but on soybean plants
taller than 25.4 cm, the insect prefers to feed on leaf
petioles.
Girdled plants are weakened and may break over and
lodge during high wind or heavy rains. Plant lodging
may cause a stand reduction which may be associated with
yield loss. In South Carolina and Oklahoma (Anonymous,
1975), S^. festinus has caused economic damage to soybeans.
Tugwell and Miner (1967) in Arkansas found that the hoppers
girdled up to 55.2% of the plants, but caused no yield
loss.
In addition to plant girdling, S. festinus may also
indirectly affect soybean plants by transmitting or pre
disposing the plants to a fungal disease. The wounds
made by the hoppers through feeding punctures provide
entry for Sclerotium rolfsii Saccardo, the causal agent
of sclerotial blight (Herzog et al., 1975).


8
and spring plowing the most expensive system for com produc
tion. In one study (Doster, 1976) total costs (machinery,
herbicides, and part-time costs) were $62,49, $72.07, and
$48.05 in conventional fall plow, conventional spring plow,
and no tillage with coulter disc, respectively. The authors
also reported that herbicides were the most expensive item in
the no-tillage farming.
A tremendous saving in fuel results from reduced machin
ery use in no tillage. Triplett and Van Doren (1977) pointed
out that fuel consumption in untilled com was reduced by as
much as two-thirds of the amount consumed in the conventional
tillage.
Reports by various workers (Rask et al., 1967; Jones
et al., 1968; Triplett and Van Doren, 1977) showed that
yields from no tillage were 10-39% higher than those from
the conventional tillage. Higher yields combined with
reduced machinery costs and saving in labor results in
significantly higher net profits.
Young (1970) reported that net money returns from no
tillage farming were usually greater than with conventional
tillage systems. Doster (1976) evaluated net returns
for 243 ha of corn continuously grown in various tillage
systems in Indiana. He observed that spring plowing practiced
on Tracy silt loam yielded net returns of $76,000 while no
tillage with coulter gave a net return of $81,500. On
Runnymede loam, however, spring plowing and no-tillage coulter
yielded $94,000 and $68,000, respectively for the 243 ha.


64
Table 14. Activity of the striped earwig, Labidura riparia,
in no-tillage and conventional tillage late-
planted "Cobb" soybeans estimated by pitfall
traps at the Robinson farm, Williston, Levy Co.,
Fla., 1978. Numbers are averages of three traps
per treatment for ten weeks. Plots were treated
once with methomyl for the control of velvetbean
caterpillars.
Average/trap*
Treatment
Nymphs
Adults
Nymphs + Adults
No tillage into com stubble
122.03
107.60
229.63
No tillage plus in-row
subsoil into com stubble
117.57
105.87
223.43
No tillage into com mulch
125.03
101.50
226.53
No tillage plus in-row
subsoil into com mulch
136.40
109.37
245.77
Conventional tillage
into com stubble
118.20
111.13
234.13
Conventional tillage plus
in-row subsoil into com
s tubb1e
x
In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's comparisons
were not made.


6
increase of plant height as the amount of surface cover
increased in nontilled corn fields.
Runoff becomes a very important factor in the no tillage
because of large quantities of herbicides used in these
systems. Such runoff may increase the amount of soluble
chemicals in streams (Holt et al., 1973). According to Unger
and Phillips (1973), plant residues on untilled soil reduce
evaporation, runoff, and prevent crusting of the soil surface
The subject of soil erosion by water and wind has been
treated by a number of authors including Wischmeier (1973),
Woodruff and Siddoway (1973), and Triplett et al. (1978).
Soil erosion results in a tremendous loss of topsoils in
croplands. No-tillage practice greatly reduces soil erosion
because of the mulch that remains on the soil surface.
Triplett and Van Doren (1977) in Ohio observed that a 12.70
cm rainfall caused losses of up to 45 tons of soil/ha from
conventional tillage corn fields with slopes of 6-8% where
as a 20% slope watershed with no-tillage corn had a loss of
less than 112 kg/ha. Reduced and no-tillage systems can
decrease erosion potential as much as 50-fold (Triplett et al
1978) .
No-tillage cropping procedure is particularly important
for crop production on lands with slopes so steep that con
ventional tillage would cause unacceptable damage due to
erosion. This is especially true in tropical regions where
soils are highly erodible and rainfall intensities are
high (Curfs, 1976). Curfs (1976) recommended no-tillage and


CHAPTER I
LITERATURE REVIEW
No-Tillage Systems
Advantages and Disadvantages of No Tillage
Disadvantages Several disadvantages are associated
with the no-tillage practice. Musick (1970b) reported slower
com seed germination due to lower soil temperatures in
untilled fields. Early crop growth is also reported to be
depressed temporarily in no-tillage systems (Moody et al.,
1963). Late in the growing season, however, crop growth in
no tillage is faster than in tilled fields because of high
soil moisture associated with plant residues.
Plant density was observed to be generally lower in
no-tillage fields than in conventionally tilled fields.
This is due in part to the fact that some seeds do not get
into the furrow and are eaten by birds and rodents. Growers
in Illinois consider rodents to be important pests of crops
in no-till culture (Herzog, personal communication, 1980) .
Crop yields from no tillage may be lower than those
obtained from conventional tillage when no-tillage systems
are established on some types of soils. Griffith et al.
/
<4


40
Results obtained from the first season at Williston (rye
stubble experiment) showed that populations of the southern
green stink bug were significantly (P=0.05) lower in the
conventional tillage treatment than in any of the no-tillage
treatments (Table 5). An average of 1.32 stink bugs per
shake was collected weekly from the no-tillage soybeans, but
only 0.96 stink bugs were collected from the conventional
tillage. No significant differences were found between
the two no-tillage treatments or between the conventional
tillage and the conventional tillage plus in-row subsoil.
Stink bug populations were very low in the com stubbie
experiment at Williston.
Although N. viridula average population levels in the
1978 Green Acres experiment were 3.28 stink bugs per shake
in the no tillage into oat stubble and 2.61 stink bugs per
shake in the two conventional tillage treatments, analysis
of variance was not significant (Table 6). In the 1979
experiment, population levels were generally high, but
analysis of the data failed to show any significant differences
among treatment means (Table 7). The weekly average for
adult population was 4.94 and 4.88 stink bugs per shake,
respectively, in conventional tillage and no-tillage soybeans.
Stink bug damage to seed was assessed at the harvest time
during the two years, and the results obtained are in Tables
8 and 9. In 1978, damage appeared to be lower in the no tillage
with in-row subsoil than in all other treatments, but analysis


LITERATURE CITED
Adeyemi, S. A. 0. 1969. The survival of stem borer popula
tion in maize stubble. Bull. Entomol. Soc. Nigeria.
2:16-22.
Adkisson, P. L., L. H. Wilkes, and B. J. Cochran. 1960.
Stalk shredding and plowing as methods for controlling
the pink-bollowrm, Pectinophora gossypiella. J. Econ.
Entomol. 53:436-9.
Afify, A. M., and H. T. Farghaly. 1970. Comparative labora
tory studies on the effectiveness of Lab idura riparia
Pall, and Coccinella undecimpunetata Reiche, as predators
of eggs and newly hatched larvae of Spodoptera littoralis
(Boisd.). Bull. Soc. Entomol. Egypte! 54:277-82.
All, J. N., and R. N. Gallaher. 1977. Detrimental impact of
no-tillage com cropping systems involving insecticides,
hybrids, and irrigation on lesser cornstalk borer infes
tations. J. Econ. Entomol. 70:361-5.
All, J. N., R. N. Gallaher, and M. D. Jellum. 1979. Influence
of planting date, preplanting weed control, irrigation,
and conservation tillage practices on efficacy of planting
time insecticide applications for control of lesser
cornstalk borer in field com. J. Econ. Entomol. 72:265-8.
All, J. N., C. W. Kuhn, R. N. Gallaher, M. D. Jellum, and
R. S. Hussey. 1977. Influence of no-tillage cropping,
carbofuran, and hybrid resistance on dynamics of maize
chlorotic dwarf and maize dwarf mosaic diseases of com.
J. Econ. Entomol. 70:221-5.
Ammar, E. D., and S. M. Farrag. 1974. Studies on the behavior
and biology of the earwig, Labidura riparia Pallas
(Dermaptera: Labiduridae). Z. Angew. Entomol. 75:189-96.
Anonymous. 1975. Soybeans highlights. Coop. Plant Pest
Rep. 25:188-91.
Bailey, J. C., L. B. Davis, and M. L. Laster. 1970. Stem
girdling by the 3-comered alfalfa hopper, and height
of soybean plants. J. Econ. Entomol. 63:647-8.
148


107
Table 28 shows lesser cornstalk borer infestations
recorded from the vetch stubble experiment in 1979. No
tillage did not affect E. lignosellus infestations in
com during the 1979 season. No significant differences
were found between treatment means. Average numbers of
damaged plants per row were 0.94 and 0.81, respectively,
in no-till and conventional till com.
Lesser cornstalk borer in wheat stubble. Com followed
wheat in this experiment and was seeded into wheat stubble
in no-till plots. In addition to counting only the number
of damaged plants as in the vetch stubble experiment,
the total number of com plants per row were recorded
along with damaged plants. Damage was thus estimated
as number of damaged plants per row and as percentage
of damaged plants. Tables 29 and 30 show the results
obtained, respectively, in 1978 and 1979. Lesser cornstalk
borer infestations, estimated as percent of damaged seedlings
or number of damaged seedlings per row, were significantly
(P=0.05) lower in the no-till corn than in the conventional
tillage com (Table 29). The average number of damaged
com seedlings was about three times higher in the conven
tional till than in the no-till treatment. About 1.5%
and 3.5% of the plants observed were damaged in no-till
and conventional till plots, respectively. In-row subsoiling
at planting significantly increased E. lignosellus damage
in the no-tillage plots, but not in the conventional tillage
plots.


In soybeans, above-ground insect pests and the lesser
cornstalk borer, Elasmopalpus lignosellus (Zeller), were
generally unaffected by the no-tillage fanning. No tillage
did not significantly affect damage due to Spodoptera
frugiperda (J. E. Smith) and Heliothis zea (Boddie) or
populations of Conoderus spp. on com. The results also
indicated that no tillage greatly increased populations of
the granulate cutworm, Feltia subterrnea (Fab.), without
affecting cutworm damage to com seedlings. No tillage,
however, significantly reduced lesser cornstalk borer
damage in com.
Populations of ground-dwelling spiders were not affected
by the no-tillage practice, and the effect of this practice
on the dermapteran Labidura riparia (Pallas) was not consis
tent. In soybeans no tillage significantly increased the
activity of carabid beetles whereas in com most carabids
were collected from conventional tillage treatments.
Yields of soybeans were reduced in the no-tillage sys
tems as compared to the conventional tillage. Com yields,
however, were not affected by the no-tillage practice.
xxx


LARVAE/SHAKE (
76
July Aug Sept Oct
SAMPLING PERIOD
Figure 6. Average numbers of velvetbean caterpillars, Anticarsia
gemmatilis, collected by the plant shaking method
from no-tillage and conventional tillage "Cobb" soy
beans at Green Acres, Alachua Co., Fla., 1978. Aver
age of eight shakes per treatment.
: no tillage into oat stubble
: conventional tillage
Arrow indicates insecticidal treatment.


22
however, will consume the whole leaf leaving only the midrib
and large veins. When the infestations are high, the larvae
eat up all the leaves and attack the tender portions of the
stems, buds and small bean pods.
The velvetbean caterpillar is the most important defol
iator of soybeans in north and central Florida where popula
tions reach the peaks in late July, mid-August and early
September (Strayer, 1973). Outbreak infestations during
pod set and pod fill usually cause severe yield losses.
Brown and southern green stink bugs. Woodside (1946),
DeCoursey and Esselbough (1962), and Mitchell and Mau (1969)
described the stages and studied the biology of the brown
stink bug, Euschistus servus (Say), and the southern green
stink bug, Nezara viridula (L.).
Adult E. servus are grayish-yellow and measure 12.0-
15.0 mm long. The eggs measure 1.2-1.3 mm in height, and
hatch after 3-14 days in laboratory conditions (Rolston and
Kendrick, 1961). The N.viridula eggs hatched after an average
of 5.2 days in the laboratory. Both species pass through
five nymphal instars, and have at least two generations per
year. Hill (1975) reported three generations of N. viridula
during nine months in Egypt; there are probably three or
more in Florida (Sailer, personal communication, 1980).
The nature of stink bug damage to soybeans has been
studied by many workers (Miner, 1961 and 1966; Daugherty
et al., 1964; and Turner, 1967). Damage is caused when


57
Table 7. Number of Nezara viridula (Linn.) collected by the
plant shaking method in no-tillage and conventional
tillage "Cobb" soybeans at Green Acres, Alachua Co.,
Fla., 1979. Numbers are averages of four weekly
shakes per treatment for four weeks. The plots
were sprayed twice with acephate for insect control.
Average/shake
Treatment
Nymph
1-3**
Nymph
4-5
Adult
N 4-5 +
Adults
No tillage into oat stubble
2.94
1.69
4.88
6.56
No tillage plus in-row
subsoil into oat stubble
1.38
1.19
4.69
5.88
Conventional tillage
into oat stubble
1.06
1.50
4.94
6.44
Conventional tillage plus
in-row subsoil into oat
stubble
*
2.25
1.63
3.94
5.56
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.
1-5, first to fifth instars.


122
Table 25. Fall armyworm and corn earworm damage to the
conventional and no-tillage corn assessed at
the harvest time at Green Acres, Alachua Co.,
Fla., 1979. Thirty-
treatment.
-two
ears collected
per
Treatment
Damaged
Ears*
Ears with
Damaged
Kernels*
No.
%**
No.
%**
No tillage into vetch stubble
20
62.50
9
28.12
No tillage plus in-row
subsoil into vetch stubble
12
37.50
4
12.50
Conventional tillage
15
46.87
6
18.75
Conventional tillage plus
in-row subsoil
21
65.62
9
28.12
7? "
Damaged ears: ears with any outside damage level. Damaged
kernels: ears with a damaged area extending to one or
more centimeters within the kernel rows.
**In the analysis of variance, no significant differences
were detected among the means. Therefore, Duncan's com
parisons were not made.


60
Table 10. Effect of tillage practice on populations of the
velvetbean caterpillars, Anticarsia gemmatilis
Hubner, estimated by the plant shaking method in
"Cobb" soybeans at Williston, Levy Co., Fla.,
April July, 1978. Numbers are averages of four
weekly shakes per treatment for six weeks. Plots
were treated with methomyl (0.56 kg a.i./ha) on
September 27 for the control of velvetbean
caterpillars.
Average
Number
Larvae/shake"
Treatment
Small
Large
Small + Large
No tillage into com stubble
7.46
2.54
10.00
No tillage plus in-row
subsoil into com stubble
9.58
3.50
13.08
No tillage into com mulch
6.92
3.21
10.13
No tillage plus in-row
subsoil into com mulch
7.54
2.71
10.25
Conventional tillage
into com stubble
8.33
2.46
10.79
Conventional tillage plus
in-row subsoil into com
stubble
7.50
2.79
10.29
In the analysis of variance, no significant differences were
detected among the means. Therefore, Duncan's comparisons
were not made.


LARVAE /SHAKE (
72
SAMPLING PERIOD
Figure 2. Average numbers of large (over 2.5 cm) velvetbean
caterpillars, Anticarsia gemmatilis, collected by
the plant shaking method from no-tillage and con
ventional tillage "Cobb" soybeans at Williston,
Levy Co., Fla., 1978. Averages of eight shakes
per treatment.
: conventional tillage
: no tillage into corn stubble
O: no tillage into corn mulch
Arrow indicates insecticidal treatment


142
Observations made after 24 hours also showed the effec
tiveness of L. riparia as a predator of Anticarsia immatures:
No. VBC
No. Labidura No. VBC No.VBC Consumed
VBC* size Tested Exposed Killed Totally Partially
Small (1-1.5 cm
9
71
64
32
6
Medium (1.6-2 cm)
8
46
40
8
15
Large (over 2 cm)
13
45
32
2
21
VBC: Velvetbean caterpillar (A. gemmatilis).
Averages calculated from the table above indicated that one
Labidura male killed (24 hours) 7.1, 5.0 and 2.4 small,
medium and large larvae, respectively, but consumed (totally)
only 3.5, 1.0 and 0.1 small, medium and large larvae. The
data also showed that the number of larvae killed or con
sumed by a single Labidura decreased as the age of the larvae
increased. Hassanein et al. (1968) came to the same conclu
sion when they exposed larvae of Frodenia litura Fab. to
L. riparia.
Thirty-two pupae were exposed to 11 Labidura for 24 hours
A total of 12 pupae were consumed. The earwig opened (usually
longitudinally) the pupal case of the prey and consumed the
contents. Each Labidura thus consumed an average of 1.1 pupae
The impact of L. riparia on A. gemmatilis larval popula
tions may be tremendous and important in regulating these pop
ulations in the field. The earwig kills many more prey than
it consumes and is generally observed in large numbers in the


3
Doupnik et al. (1975) and All and Gallaher (1977)
observed that the conditions created in untilled fields were
not favorable to all pest species, and that no tillage may
have detrimental effects on some pest organisms. The lesser
cornstalk borer, Elasmopalpus lignosellus (Zeller), caused
less damage in no-tillage than in conventional tillage corn
(All and Gallaher, 1977), and stalk rot incidence of grain
sorghum,[Sorghum bicolor (L.) Moenck], was higher in conven
tionally tilled than in nontilled blocks in Nebraska (Doupnik
et al., 1975).
Because of the increasing adoption of no tillage as a
crop production procedure, detailed studies are needed to
better understand the biology and behavior of pest species,
and to assess the importance of pest problems in no-tillage
systems. Experiments were conducted in Alachua and Levy
counties, Florida, in order to discern the influence of no
tillage on the most important insect pests of com and soy
bean [Glycine max (L.) Merrill] ecosystems. Data were also
collected to determine the effects on soil-inhabiting arthro
pod predators.


158
Woodruff, N. P., and F. H. Siddoway. 1973. Wind erosion
control. Cons. Tillage. Proc. Nat. Conf., Des Moines,
Iowa. Soil Cons. Soc. Amer. Pp. 156-62.
Woodside, A. M. 1946. Life history studies of Euschistus
servus Say and E. tristigmus. J. Econ. Entomol.
39:161-3. ~
Yarham, D. J. 1975. The effect of non-ploughing on cereal
diseases. Outl. Agrie. 8:245-7.
Young, H. M. 1970. What is no-tillage. Proc. Nat. No-tillage
Res. Conf. Univ. of Kentucky, Lexington.


Table 32. Number and species of carabid predators collected in pitfall traps from
no-tillage and conventional tillage field corn at Green Acres, Alachua Co.,
Fla., May July, 1978. Numbers are totals of four traps per treatment.
Species
NVS
NVS+s
CT
CT+s
Tot
%
Index**
Calosoma sayi De/jean
0
0
1
0
1
1.09
VR
Chlaenius laticollis Say
0
0
0
1
1
1.09
VR
C. tomentosus Say
0
0
1
0
1
1.09
VR
Colliuris pennsylvanica (L.)
0
0
2
5
7
7.61
VR
Galerita lecontei De/jean
7
2
10
16
35
o
00
CO
R
G. /janus (Fab.)
1
1
2
0
4
4.35
VR
Harpalus caliginosus Fab.
1
0
0
0
1
1.09
VR
H. pennsylvanicus DeGeer
0
3
2
9
14
15.22
R
Pasimachus sublaevis Beauv.
2
0
0
1
3
3.26
VR
P. subsulcatus Say
0
0
0
1
1
1.09
VR
Scarites subterraneus (Fab.)
0
1
0
0
1
1.09
VR
Selenophorus palliatus Fab.
0
2
10
11
23
25.00
R
Total
11
9
28
44
92
1
11.96
9.78
30.43
47.83
*NVS: no tillage into vetch
s tubb1e;
NVS+s: No
tillage plus
in-
row subsoil into vetch
stubble; CT: conventional
tillage; CT+s: conventional tillage
plus in-
row subsoil.
**Rivard's scale: VR: very
rare; 10
specimens
or less
; R:
rare
, 11 to
50 specimens;
129


80
2.5-
April May June July
SAMPLING PERIOD
Figure 10. Average trap-week collections of Labidura riparia
nymphs from no-tillage and conventional tillage
"Cobb" soybeans at Williston, Levy Co., Fla., April -
July, 1978. Four pitfall traps were placed in each
treatment.
conventional tillage
no tillage into rye stubble
no tillage into rye mulch


LARVAE / SHAKE (
73
SAMPLING PERIOD
Figure 3. Average number of velvetbean caterpillars, Anticarsia
femmatilis, collected by the plant shaking method
rom no-tillage and conventional tillage "Cobb"
soybeans at Williston, Levy Co., Fla., 1978. Averages
of eight shakes per treatment.
: conventional tillage
: no tillage into com stubble
a: no tillage into corn mulch
Arrow indicates insecticidal treatment.


APPENDIX A
CHEMICAL NAMES OF HERBICIDES MENTIONED OR USED
IN THE EXPERIMENTS
Common name
Chemical name
Alachlor
2-chloro-2',6'-diethyl-N-(methoxy-
methyl)-acetanilide
Atrazine
2-chloro-4-(ethylamino)-6-(isopro-
pylamino)-s-triazine
Linuron
3-(3,4-dichlorophenyl)-1-methoxy-
1-methylurea
Metribuzin
4-amino-6-tert-butyl-3-(methylthio)
as-triazine-5 (4H) one
Paraquat
(1,1'-dimethyl-4,4'-bipyridinium
ion)
Simazine
2-chloro-4,6-bis (ethylamino)-
s-triazine
2,4-D
(2,4-dichlorophenoxy) acetic acid
140


APPENDIX D
AVERAGE YIELDS OF "COBB" SOYBEANS
Yield estimates were made at Green Acres in 1978
and 1979. Pods were harvested from two center rows (6.10 m
long) in each replication (four replications per treatment).
The yield, shown below, is reported at 13% moisture:
Treatment
Avg.-..
1978
Yield (kg/ha)
1979 Total
No tillage into oat stubble
1937*
975a**
1456a
No tillage plus in-row subsoil
1746
1379b
1563a
Conventional tillage
2304
1749b
2027b
Conventional tillage plus
in-row subsoil
H
2009
1614b
1812b
In the analysis of variance for 1978 data, no significant
differences were detected between the means. Therefore,
Duncan's comparisons were not made.
**
Values not followed by the same letter in each column are
significantly different at the 0.05 level by Duncan's new
multiple range test.
In 1978, conventional tillage and no-tillage soybeans
produced respectively 2304 and 1937 kg/ha. The statistical
analysis failed to detect any significant differences
between treatments. In the 1979 season, however, soybean
yields were significantly (P=0.05) lower in the no tillage
into oat stubble than in the conventional tillage. The
two-year average yields also were lower in the no tillage
than in the conventional tillage.
Higher lesser cornstalk borer damage to soybean
seedlings in the no tillage was not believed to be the reason
146


Table
Page
33 Numbers and species of carabid predators
collected in pitfall traps from no-tillage
and conventional tillage field corn at
Green Acres, Alachua Co., Fla., April -
July, 1979. Numbers are totals of four
traps per treatment 130
34 Numbers and species of carabid predators
collected in pitfall traps from no-tillage
and conventional tillage field corn at
Green Acres, Alachua Co., Fla., July -
August, 1979 131
xi n


SAMPLING PERIOD
NYMPHS + ADULTS / TRAP (LOG x )
O r\> r\:
c_ ai 'o ai o cji
L 6


125
Table 28. Lesser cornstalk borer,(Elasmopalpus lignosellus
(Zeller)), inf estations in no-tillage and conventional
tillage field com at Green Acres, Alachua Co., Fla.,
1978 -1979. Estimation is based on eight rows per
treatment examined each week for three weeks.
Treatment
Total
1978
Damaged plants
No. Average
1979 1978
No/row*
1979
No tillage into vetch stubble
3
15
0.13a
0.94c
No tillage plus in-row
subsoil into vetch stubble
2
13
0.08a
0.81c
Conventional tillage
32
3
1.33b
0.19c
Conventional tillage
plus in-row subsoil
TT
32
2
1.33b
0.12c
Means in each column not followed by the same letter are
significantly different at the 0.05 level by Duncan's new
multiple range test.


36
Developmental stages of the soybeans were recorded weekly
according to the method described by Fehr and Caviness
(1977).
Results and Discussion
Soil-Pest Insects
Lesser cornstalk borer infestations were not assessed
in the rye stubble experiment at Williston. Table 1 contains
the results obtained from the corn stubble experiment.
Although the weekly average number of infested plants per
row was 2.04 in the conventional tillage and 1.92 in the
no-tillage treatment, the analysis of variance was not
significant. The results also indicated that in-row sub
soiling did not affect E. lignosellus infestations, and
that com stubble was not statistically different from
com mulch with respect to lesser cornstalk borer infesta
tions .
In 1978 some plants were killed by paraquat in the no
tillage plots at Green Acres (oat stubble experiment); this
made observations difficult. Lesser cornstalk borer damage
was, therefore, estimated only in the 1979 season. The
results from the 1979 oat stubble experiment are shown in
Table 2. Damage levels were significantly (P=0.01) higher
in the no-tillage soybeans than in the conventional tillage
soybeans. The weekly average number of damaged plants per