• TABLE OF CONTENTS
HIDE
 Title Page
 Main
 Reference














Group Title: Research report - North Florida Research and Education Center ; 89-5
Title: Soybean insect pest population dynamics in relation to preplant tillage
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00066075/00001
 Material Information
Title: Soybean insect pest population dynamics in relation to preplant tillage
Series Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Physical Description: 14 pages : ill. ; 28 cm.
Language: English
Creator: Funderburk, J. E ( Joseph E. ), 1954-
Wright, D. L ( David L )
Teare, I. D ( Iwan Dale ), 1931-
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Florida Research and Education Center
Place of Publication: Quincy Fla
Publication Date: 1989
 Subjects
Subject: Insect pests -- Control -- Florida   ( lcsh )
Soybean   ( lcsh )
Entomology -- Research   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
Statement of Responsibility: by J. E. Funderburk, D. L. Wright, and I. D. Teare.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00066075
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71144984

Table of Contents
    Title Page
        Page 1
    Main
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Reference
        Page 12
        Page 13
        Page 14
Full Text
foo



wr-S


Soybean Insect Pest Population Dynamics
in Relation to Preplant Tillage






J. E. Funderburk, D. L. Wright, and I. D. Teare






Central Science
Library

APR 27 1989

University of Florida












J. E. Funderburk, Entomology and Nematology Dep.; and D. L. Wright and I. D.
Teare, Agronomy Dep.; North Florida Research and Education Center. Contribu-
tion from the Institute of Food and Agricultural Sciences, University of
Florida, Route 3 Box 4370, Quincy, FL 32351. Research Report NF-89-5.










ABSTRACT

Tillage operations can modify soil and plant characteristics where many

insects reside during at least part of their life cycle. However, information

relating tillage and subsoiling to soybean insect pests is very scarce or

inconclusive. The objective of this study was to determine the effect of

tillage and subsoiling on population cycles and population densities of

soybean insect pests in soybean [Glycine max (L.) Merr.]. Soybean were grown

on a Norfolk sandy loam soil (fine-loamy siliceous, thermal Typic Paleudult)

and tillage treatments were disking to a depth of 0.15 m; disk plus subsoil to

a depth of 0.23 m; no till; and no till plus subsoil. Planting occurred

immediately after disking or in conjunction with no tillage with a 2-row cone

planter at a depth of 25 mm. Row width was 0.76 m.- Plots were sampled for

insects by beating the soybean plants on both sides of the row into a 0.9 m

square ground. cloth. Population densities of velvetbean caterpillar (VBC),

Anticarsia gemmatalis Hubner, increased at R4 and peaked at soybean growth

stage R5.5; green cloverworm (GCW), Plathypena scabra (Fabricius) in 1985 and

1986 were greatest at soybean growth stage R1 and R2.6, respectively, but

remained low in 1987. The population densities and cycles of southern green

stinkbug (SGSB), Nezara viridula (Linnaeus), were statistically similar for

each preplant tillage treatment in 1985, 1986, and 1987 for nymphs and adults.

Since preplant tillage treatments caused no gross effects on the population

dynamics of VBC, GCW, and SGSB; the modification of preplant tillage is a way

to increase insect predators and to optimize the benefits of biological

control without concomitant increase in these insect pests.








INTRODUCTION

Tillage and subsoiling effects upon soybean yield and soil resistance

(Brown et al., 1988) have been reported for the Southeast, but the outcome of

those cultural practices on soybean insect pests has only begun to be

documented. Tillage operations modify soil habitats where many insect pest

(Troxclair et. al., 1984) and natural enemies (beneficial insects; McPherson

et. al., 1982; and Funderburk et. al., 1988) reside during at least part of

their life cycle. These modifications can alter survival or development of

insects (Herzog and Funderburk, 1986). Troxclair et al., (1984) monitored

numerous pests and natural enemies by sweep nets for two years in conventional

and no till soybeans planted in narrow and wide row spacing at three locations

in Louisiana. At the three locations, the banded cucumber beetle, Diabrotica

balteata LeCante, was the only insect pest whose numbers consistently

benefitted by conventional tillage.' Southern green stink bugs (SGSB), Nezara

viridula (Linnaeus), were not affected by either tillage while velvetbean

caterpillar (VBC), Anticarsia gemmatalis Hubner, were inconsistently favored

by no tillage.

Funderburk et. al., (1988) measured the effects of tillage and subsoiling

on beneficial insects and found that disk tillage (conventional tillage) had

higher bigeyed bug nymphal and adult populations than no tillage treatments

for over 2 years. Disk tillage also significantly favored damsel bug

populations over no till without subsoiling in 1985.

Musick (1985) and Herzog and Funderburk (1986) concluded that each crop

and pest situation must be evaluated individually and control decisions made

for each specific geographical location. The primary purpose of this study

was to determine the effect of tillage and subsoiling on population cycles and

population densities of larval green cloverworm (GCW), Plathypena scabra








(Fabricius), larval VBC, and nymphal and adult SGSB in a subsequent soybean

crop following winter wheat and to determine if the tillage/subsoiling

practices that increased beneficial (Funderburk et al., 1988) would reduce or

not affect insect pests. Either finding should aid in implementation of

cultural control strategies in integrated pest management systems in soybean

fields in the southeastern U.S.
MATERIALS AND METHODS

Soybean [Glycine max (L.) Merr.] were grown on a Norfolk sandy loam soil

(fine-loamy siliceous, thermal Typic Paleudult) at Quincy, FL. Treatments

were (1) disk (gang disk in two directions, 0.15 m depth) and plant; (2) disk,

subsoil (chisel plow at a depth of 0.23 m) and plant; (3) no till plant; and

(4) no till, subsoil, and plant. A 2-row cone planter was used to plant the

soybean at 25 mm soil depth in all plots. In 1985, 'Cobb' soybean were
planted on 30 July in plots 7.6 x 30.4 m in size. In 1986, the cultivar was

changed to 'Kirby' soybean which was planted 11 June in plots 7.6 x 24.4 m in

size. In 1987, 'Cobb' cultivar soybean were planted in plots (7.6 x 24.4 m)

and fenced on 16 July to exclude the deer that were walking and feeding in

replication 4.

In all three years, the soybean planting rate was 45 kg ha- Irrigations

were scheduled with soil tensiometers placed at 0.15 m soil depth. No irri-

gation was needed or applied to the plots in 1985, but in 1986 and 1987 25 mm

water ha-l was applied preplant and at intervals during the growing season

when tensiometers reached 0.02 MPa.

Herbicide treatment in 1985 consisted of an initial broadcast post emer-

gence application (31 July) of Poast (2-[1-(ethoxyimino)-butyl]-5[2-(ethyl-

thio)-propyl]-3-hydroxy-2-cyclohexen-l-one) at 0.58 L ha-1 + Basagran {3-(1-

Methylethyl)-(1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide) at 1.75 L ha~ +








Paraquat {1,1'-Dimethyl-4,4'bipyridinium ion); present as the dichloride salt

(ICI/Chevron/Crystal) or dimethyl sulfate salt at 1.17 L ha1 + crop oil at
2.38 L ha'-. A second post directed herbicide treatment of Paraquat at 0.58 L
ha- + 2,4-DB {4-(2,4-diclorophenoxy) butyric acid) at 1.17 L ha-1 + X-77 at

0.23 L per 380 L of solution was applied on 5 Sept.
The initial 1986 herbicide treatment (13 June) was a tank mix broadcast

application of Sencor DF {4-Amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-

triazin-5(4H)-one) at 0.56 kg ha-1 + Surflan {3,5-Dinitro-N4 ,N4-dipropylsul-
fanilamide) at 1.75 L ha- + Paraquat at 1.75 L ha- + X-77 at 0.23 L per 380
L of solution. A second herbicide treatment for grass control was a broadcast

application of Fusilade {butyl(R S)-2-[4-[5-trifluoromethyl)-2-pyridinyl]oxy]-

phenoxy]propanoate) at 3.51 L ha- + X-77 at 0.23 L per 400 L of solution
applied on 22 July.

In 1987, the first herbicide treatment was a broadcast spray preplant

application of Prowl {N-(l-ethylpropyl)-3,4-dimethyl-2,6-dinitro-benzenamine}

@ 1.75 L ha- + Sencor DF @ 0.42 kg ha- + Poast at 1.16 L ha~ + Paraquat @
0.87 L ha'- + Soydex oil @ 1.16 L ha~ with 197 L water. Paraquat was broad-

cast sprayed on 17 and 24 July @ 0.87 L ha-I with 189 L of water. Insecti-
cides were not applied at any time during the three years.
Nymphal and adult population densities were estimated on 6 dates during

1985 (8-23, 9-4, 9-16, 9-28, 10-9, 11-6), on 5 dates in 1986 (7-3, 7-15, 7-29,

8-12, 8-28), and on 5 dates in 1987 (8-6, 8-19, 8-31, 9-10). The sixth
sampling date in 1986 was discontinued because of excessive lodging caused by

heavy rains and high winds. Sampling was begun at early vegetative stage (V4)

in all years and continued to the late pod fill stage (R7) of crop growth in

1985, until the middle podding stage (R4) in 1986, and middle plus podding

stage (R5) in 1986.








Insect sampling was carried out as described by Kogan and Pitre (1980).

All plots were sampled on each sampling date by beating the plants on both

sides of the row into a 0.9 m square ground cloth placed between the rows.

Three samples were taken per plot on each sampling date. Also, adjacent plant

bases and the soil surface were visually examined.

The influence of preplant tillage treatment on population densities and

population cycles of VBC larvae, GCW larvae, SGSB nymphs, and SGSB adults were

Evaluated by ANOVA. Data from each growing season were analyzed separately.

The design was a split plot with dates as whole plots and tillage treatment as

subplots. The main effect of tillage treatment compared the influence of

preplant tillage treatment on seasonal population density. Orthogonal

comparisons were used to define treatment differences. The interaction of

date treatment compared the influence of preplant tillage treatment on

seasonal population cycles. Conservative degrees of freedom were used in each

ANOVA as described by Weiner (1971), since the effect of date could not be

randomized.

RESULTS AND DISCUSSION

A description of plant growth in relation to planting date is given to

describe plant height, canopy closure, maturity, and expected yield between

the years of 1985, 1986, and 1987. Insecticides were not applied at any time

during the experiment to allow insect pests and beneficial to multiply

naturally. When this situation is allowed, one cannot expect to harvest a

crop for seed yield in our geographical location. 'Cobb' soybean were planted

on 30 July 1985 because it is a late maturing cultivar in Group VIII,

maximizes the growing season and produces a satisfactory yield when late

planted. 'Kirby' is an early cultivar of Group VIII, was selected and planted

on 11 June 1986 (the optimum time for planting soybean in North Florida). The








expected yield of 'Cobb' when planted on 30 July 85, 'Kirby' when planted on

11 June 86, and 'Cobb' when planted on 16 July 87 based on previous date of

planting research was 0.827, 2.554, and 2.016 Mg ha"-, respectively, in North

Florida (Herzog et al., 1988). The 'Cobb' soybean in 1985 obtained an average

height of 0.46 m and the canopy did not close; the 'Kirby' average height was

0.86 m in 1986 and the canopy closed at approximately R5.8; the 'Cobb' average

height was 0.71 m in 1987 and the canopy closed at approximately R6.0.

. Maturity dates for 'Cobb'-85, 'Kirby'-86, and 'Cobb'-87 were 21 Nov, 1 Nov,

and 21 Nov; respectively.

Seasonal population dynamics (population density and population cycles) of

larval VBC and GCW in the soybean plots are shown in Figure 1. Population

densities of VBC were very low each year until soybean growth stage R4.

Sample estimates were greatest in 1985 and 1987 during soybean growth stage

R5.5. In 1986, VBC density was greatest during soybean growth stage R4,

because sampling was discontinued after R4 for the remainder of the season due

to soybean lodging. Population density estimates of GCW were very low on all

sample dates during 1987. Sample estimates were greatest in 1985 at soybean

growth stage R1 and in 1986 during soybean growth stage R2.6.

Density estimates of VBC (Figure 1) sometimes exceeded economic thresholds

(12 larvae per meter of row) when control procedures are recommended in

production fields (Johnson et al. 1988). VBC estimates in all treatments were

greater than the economic threshold density on sample dates during soybean

growth stages R4 and R5 in 1985 and during soybean growth stages R3, R5, and

R6 in 1987. Population densities of VBC were not economically important on

any sample date in 1986. GCW population estimates in all treatments were












VELVETBEAN CATERPILLAR
V4 R1 R4 R5 R8.6


230 248 260 276 290 306
V4 V10 VI R2. R4
140
1986
120

100-

80
eo

40

.20 :
Cs'


180 190 200 210 220
V4 R2 R3 R5


GREEN CLOVERWORM
R1 R4 R5 R5.8


230 240 180 190 200
R6 V4 R2


210 220 230 240 260 260 270 210


210 220 230 240
R3 R5 R6


220 230 240 250 260 270


DAY OF YEAR

Figure 1. Population density of larval velvetbean caterpillars and green
cloverworms in relation to day of year (Days Julian, 1985, 1986, and 1987) and
physiological stage of soybean development (O represents no till, subsoil;
represents no till, no subsoil; O represents disk, subsoil; and represents
disk, no subsoil).


H.








-J

0U
0

07


1987
8


a6


4


'2

ap








below economic threshold levels (same as VBC) on all sample dates in 1985,

1986, and 1987.

The population densities of VBC (Figure 1) differed between preplant

tillage treatments in 1985 (F, = 14.1; P < 0.001). Orthogonal treatment

comparisons showed that density was significantly less in the no till without
subsoiling treatment than in the other three treatments (F1, = 13.5; P <

0.001). Other orthogonal comparisons were not significantly different (F,1g

.= 2.7). Population cycles differed between preplant tillage treatments in
1985 (Fs,,1 = 10.5; P < 0.001), because estimates were similar on sample dates

when densities were very low and not similar on other sample dates when densi-

ties were greater. The density of VBC was similar in all preplant tillage

treatments in 1986 and 1987 (F1,1 = 0.6 and Fi = 0.2, respectively). Popu-

lation cycles also were similar in 1986 and 1987 (F4,i5 = 0.8 and F4, = 1.2;

respectively). GCW population densities were similar in all preplant tillage

treatments in 1985, 1986, and 1987 (F1,18 = 0.9, F1 1 = 0.2, and F1 = 0.6;

respectively)'. Likewise, population cycles were similar in 1985, 1986, and

1987 (F5,18 = 1.5, F 4,s = 1.8, and F4, = 0.6; respectively).

Seasonal population dynamics of nymphal and adult SGSB in the soybean

plots are shown in Figure 2. Adults typically invade soybean fields and begin

reproducing during soybean growth stages R3 and R4 (Schumann and Todd 1982).

The soybean growth stage during each growing season when adults invaded the

tillage plots ranged from Vll in 1986 to R5.5 in 1985. Nymphs then were

present each year. Population density of nymphs was greatest on the last

sample date in 1985 and 1986. In 1987, population density of nymphs was

greatest during soybean growth stage R4, but population density was less on

the next sample date during R6, because most nymphs developed to adults. SGSB

estimates (nymphs & adults) exceeded the economic threshold (Johnson et al.








NYMPHS
R1 R4 R5 F


d
z


>-






O
z
0


a.


210 220 230 240 260 260
DAY


270 210 220
OF YEAR


230 240 250 260 270


Figure 2. Population density of nymphal and adult southern green stink bugs
in relation to day of year (Days Julian, 1985, 1986, and 1987) and physio-
logical stage of soybean development ( 0 represents no till, subsoil;
Represents no till, no subsoil; [represents disk, subsoil; and represents
disk, no subsoil).


ADULTS








1988) in at least some treatments during R7 in 1985, R2 and R4 in .1986, and R3
and R5 in 1987.

Populations of SGSB adult and early nymphal instars exhibit a clumped

dispersion (Todd and Herzog 1980). Sampling precision when estimating SGSB

density in the experimental plots (Figure 2) therefore was poor on some

individual sample dates, and any differences in estimates on these dates

apparently were the result of random sampling error, rather than preplant

S tillage treatment differences. Overall, the population densities of SGSB were

statistically similar in each preplant tillage treatment in 1985, 1986, and

1987 for nymphs (F ,8 = 0.2, F1,1 = 0.3, and F,8 = 0.8; respectively) and

for adults (F18 = 0.5, F,5 = 0.7, and F,8 = 0.8; respectively). Popu-

lation cycles also were similar in 1985, 1986, and 1987 for adults (fs,18 =

0.9, F4,1 = 0.7, and F48 = 1.0; respectively) and nymphs (Fs,1 0.4, F4,15

= 0.5, and FI = 1.5; respectively).

Preplant tillage practices of soybean in our study had little effect on

population densities or population cycles of VBC, GCW, and SGSB. The signifi-

cant effect on population dynamics of VBC in 1985 may relate to the very late

planting of the soybeans in that year. Plant growth was visibly retarded in

the no-till without subsoiling plots which had the lower population densities

of VBC compared to the other treatments. In 1986 and 1987, no differences in

VBC population density were noted between preplant tillage treatments.

Bigeyed bugs and damsel bugs are important insect predators on VBC, GCW,

and SGSB in soybean in the southeastern U.S. The amount of predation of

insect pests (viz., VBC, GCW, and SGSB) is a function of predator population

density (O'Neil 1984). Population densities of bigeyed bugs and damsel bugs

are enhanced by preplant disk tillage practices (Funderburk et al. 1988,

McPherson et al. 1982, Troxclair and Boethel 1984). Funderburk et al. (1988)








drew their conclusions from data collected in 1985 and 1986 in the same plots

as the present study.

Consequently, our results showing a lack of preplant tillage effects on

pest population dynamics are unexpected, but useful. Since preplant tillage

treatments caused no gross effects on the population dynamics of VBC, GCW, and

SGSB in our study, the modification of preplant tillage practices is useful as

a way to increase insect predators for biological control and should remain an

important consideration for integrated pest management programs of soybean.

Biological control is a desirable control tactic, and integrated pest manage-

ment programs are designed to optimize the benefits of natural biological con-

trol. Enhanced predator populations may provide unknown economic benefits to

pests that reach outbreak population levels less frequently than VBC or SGSB.

Additionally, it may be possible to combine other production modifications

(e.g., resistant cultivars) with preplant tillage practices to achieve reduced

pest injury.

REFERENCES

Brown, E., B.T. Kidd, and D.L. Wright, and I.D. Teare. 1988. Tillage

methods in relation to soil resistance and soybean yield. Univ. of

Florida, North Florida Res. and Educ. Ctr., Quincy, FL. Research Report

NF-88-8.

Elvin, M. K., J.L. Stimac, and W.H. Whitcomb. 1983. Estimating rates of

arthropod predation on velvetbean caterpillar larvae in soybeans. Fla.

Entomol. 66:319-330.

Funderburk, J.E., D.L. Wright, and I.D. Teare. 1988. Preplant tillage

effects on population dynamics of soybean insect predators. Crop Sci.

28(6):973-977.








Herzog, D.C. and J.E. Funderburk. 1986. Ecological bases for habitat manage-

ment and cultural control. In: M. Kogan (ed.) Ecological theory and

integrated pest management practice. Wiley interscience, N.Y. p. 217-250.

Herzog, D.C., D.L. Wright, and F.M. Shokes, and I.D. Teare. 1988. Planting

date influence on yield, height and harvest date of selected soybean

cultivars. Univ. of Florida, North Florida Res. and Educ. Ctr., Quincy,

FL. Research Report NF-88-9.

S Johnson, F.A., J.E. Funderburk, D.C. Herzog, and R.K. Sprenkel. 1988.

Soybean insect control. Univ. of Florida, North Florida Res. and Educ.

Ctr., Quincy, FL, Extension Entomology Report #58:1-27.

Kogan, M., and H. N. Pitre, Jr. 1980. General sampling methods for above-

ground populations of soybean arthropods, pp. 30-60. In: M. Kogan and D.

C. Herzog (ed.) Sampling Methods in Soybean Entomology. Springer-Verlag,

Inc. New York.

McPherson, R.M., J.C. Smith, and W.A. Allen. 1982. Incidence of arthropod

predators in different soybean cropping systems. Environ. Entomol.

11:685-689.

Musick, G.J. 1985. Management of arthropod pests in conservation-tillage

systems in the southeastern U.S. p. 191-204. In: W.L. Hargrove, F.C.

Boswell, and G.W. Langdale (ed.) Proceedings of the 1985 southern region

no-till conference. July 16-17, 1985. Griffin, Ga.

O'Neil, R.J. 1984. Measurement and analysis of arthropod predation on the

velvetbean caterpillar, Anticarsia gemmatalis Hubner. Ph.D. Diss., Univ.

of Florida, Gainesville, (Diss. Abstr. 84-21056).

Schumann, F.W., and J.W. Todd. 1982. Population dynamics of the southern

green stink bug (Heteroptera: Pentatomidae) in relation to soybean

phenology. J. Econ. Entomol. 75:748-753.








Todd, J.W., and D.C. Herzog. 1980. Sampling phytophagous pentatomidae in

soybean. In: M. Kogan and D.C. Herzog (ed.) Sampling Methods in Soybean

Entomology, Springer Verlag, Inc., New York.

Troxclair, N.N., Jr., and D.J. Boethel. 1984. Influence of tillage practices

and row spacing on soybean insect populations in Louisiana. J. Econ.

Entomol. 77:1571-1579.

Weiner, B.J. 1971. Statistical principles in experimental design. 2nd ed.

McGraw-Hill, NY p. 281.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs