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Population dynamics of the stinkbug (Hemiptera: Pentatomidae) complex on soybean and comparison of two relative methods of sampling

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Population dynamics of the stinkbug (Hemiptera: Pentatomidae) complex on soybean and comparison of two relative methods of sampling
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Stinkbug (Hemiptera: Pentatomidae)
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viii, 259 leaves : ill. ; 28 cm.

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Adult insects ( jstor )
Female animals ( jstor )
Instars ( jstor )
Nymphs ( jstor )
Planting ( jstor )
Planting date ( jstor )
Population growth ( jstor )
Soybeans ( jstor )
Species ( jstor )
Statistical analysis ( jstor )
Dissertations, Academic -- Entomology and Nematology -- UF
Entomology and Nematology thesis Ph. D
Pentatomidae ( lcsh )
Soybean -- Diseases and pests ( lcsh )
City of Quincy ( local )
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bibliography ( marcgt )
non-fiction ( marcgt )

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Thesis (Ph. D.)--University of Florida, 1981.
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Bibliography: leaves 252-258.
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Typescript.
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Vita.
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by Euripedes B. Menezes.

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POPULATION DYNAMICS OF THE STINKBUG
(HEMIPTERA: PENTATOMIDAE)
COMPLEX ON SOYBEAN AND COMPARISON OF TWO RELATIVE METHODS OF SAMPLING








BY

EURIPEDES B. MENEZES


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


1981




























TO

MY WIFE

AND

MY DAUGHTERS














ACKNOWLEDGMENTS


I am very grateful to my chairman, Dr. D. C. Herzog, and committee members, Drs. R. I. Sailer, D. H. Habeck, and E. B. Whitty, for their guidance, advice and criticism throughout the course of this work. I wish to thank Dr. D. R. Minnick, G. E. Smart, Jr., and S. H. Kerr for their invaluable assistance and for their marked interest in my Ph.D. program.

I wish to expres my gratitude to Coordenagao do Aperfegioamento de Pessoal de Nivel Superior (CAPES) and Programa de Ensino Agricola Superior (PEAS) for their financial support through a fellowship, and to the Universidade Federal Rural do Rio de Janeiro for making possible the obtainment of this fellowship.

I acknowledge the advice and assistance of Dr. G. E. Allen as former chairman of the supervisory committee. Thanks are also due to Mr. Andrew Brown, Mrs. Jill Y. Goreau, and Mr. Reginald L. Forehand for their help in my field work; Mr. Philip J. d'Almada for his assistance with statistics, and Mrs. Edna Larrick for her patience in typing this work.

A very special gratitude is extended to Mrs. Barbara Hollien and Mrs. Sheila Eldridge for their help and encouragement, and to my dear friends, Mr. Edilson B. Oliveira, Mr. Tom Brunson, and Miss Enizet Moreira, for their encouragement and comfort.

Last, but not least, my love and special gratitude is due to my wife, Elza M. Menezes, who always offered her support and devotion.

iii










I also extend my gratitude to my daughters, Caroline and Jacqueline, for having gone through the numerous upheavals associated with my studies.


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TABLE OF CONTENTS


ACKNOWLEDGMENTS . . . . . . . . -.

ABSTRACT . . . . . . . . - - .

INTRODUCTION . . . . . . . . . .

CHAPTER
I LITERATURE REVIEW . . . . . . .
The Main Species of Stinkbugs . . . .
Nature of Damage . . . . . . .
S a m p l i n g . . . * . . .
Population Dynamics . . . . . . .

II MATERIALS AND METHODS . . . . . .
General Experimental Procedures . . .
General Experiments in 1977, 1978, and 1979
Statistical Analyses . . . . . .

III EFFECTS OF SOYBEAN VARIETY AND PLANTING DATE
ON ABUNDANCE OF DEVELOPMENTAL STAGES OF
N. viridula, A. hilare, AND E. servus .
Results . . . . . . . . .
Discussion . . . . . . . .
Conclusions . . . . . . . .


Page



- -vi






. . 13

- . 19
- . 13 . . 17
. . 11 . . 17 . . 20



. . 22 . . 22
. . 117 . . 124


IV POPULATION DYNAMICS OF STINKBUG COMPLEX ON SOYBEANS .

Results . . . . . . . . . . . .
Discussion . . . . . . . . . . .

V COMPARISON OF TWO RELATIVE SAMPLING METHODS
FOR THE STINKBUG COMPLEX ON SOYBEAN . . . .
Results . . . . . . . . . . . .
Discussion . . . . . . . . . . .
Conclusions . . . . . . . . . . .

REFERENCES CITED . . . . . . . . . . . .

BIOGRAPHICAL SKETCH . . . . . . . . . . . .


v


125 125
141


154 154 156 157 252 259













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


POPULATION DYNAMICS OF THE STINKBUG
(Hemiptera: Pentatomidae)
ON SOYBEAN AND COMPARISON OF TWO RELATIVE METHODS OF SAMPLING By

Euripedes B. Menezes

March 1981

Chairman: Dr. Donald C. Herzog Major Department: Department of Entomology and Nematology

The objectives of this three-year study conducted at the University of Florida, Agricultural Research and Education Center, Quincy, Gadsden County, Florida, include: (1) to compare sweep net and ground cloth sampling methods of measuring populations of three stinkbug species: Nezara viridula, Acrosternwn hilare, and Euschistus servus; (2) to determine the distribution, species composition, and relative abundance of the pentatomids associated with soybeans in Florida; and (3) to determine the effect on stinkbug population dynamics of soybean varieties of different maturity planted on two dates.

Forrest and Bragg soybean varieties were used in 1977, Bragg and Cobb in 1978, and all three varieties in 1979.

Weekly samples of stinkbugs and other insects associated with those soybean varieties were taken by two methods: sweep net and ground cloth.


vi










In 1977, thirteen weekly samples were made with both methods,

sweep net and ground-cloth, from August through the beginning of November on each plot of Bragg and Forrest soybean variety.

In 1978, fifteen weekly samples were made with both methods on

Bragg and Cobb, and in 1979, fifteen weekly samples were made with both methods on each plot of Bragg, Cobb, and Forrest soybean variety. Results are shown in Tables 1 through 16 and Figs. 1 through 168

N. viridula was the most abundant species on all planting dates in all three years, and together with results of A. hilare, and E. servus adults characteristically colonized early plantings of early maturing varieties first and in greatest numbers. As the season progressed, later plantings and later-maturing varieties became more attractive to all species and in late season these plantings supported the largest populations of both adults and nymphs of all species. As earlymaturing varieties senesced, adults of all species studied moved to varieties of later maturity.

Results indicate that the trap cropping method of controlling

N. viridula developed in Louisiana may also be used against these species in Florida.

Adults of N. viridula were usually the first to colonize timed plantings of Forrest, Bragg and Cobb during the three years of this study. Left uncontrolled this species produced very large nymphal and subsequent adult populations. Because of the magnitude of populations and apparent overlap, numbers of generations produced in individual plantings were impossible to determine, but it is probable that two occurred in certain plantings.


vii










Adults of both A. hilare and E. servus were very low relative to N. viriduLa. Nymphal populations of these species likewise were low with the exception of 1979. Population trends of these two species on the times-varietal plantings appeared to be quite similar to that of N. viridua. Single nymphal generations were produced in 1977 and 1978, but two generations of each species occurred in some plantings in 1979.

In Florida, A. hilare and E. servus post little threat to soybean production of themselves, but as species components of the stinkbug pest complex they become significant because damage produced by members of the complex is similar and additive.

For all three species the magnitude of the regression coefficients usually increased as development proceeded. This is probably a function of the degree of aggregation of individual developmental stages.

Collections of adults and all nymphal stages of N. viridula,

A. hiZare, and E. servus by sweep net and ground cloth are significantly correlated. Data and regression analyses presented will allow the construction of coefficients for calibration between the methods for all development stages, on several varieties and planting dates.


viii














INTRODUCTION


Soybean, Glycine max (L.) Merrill, because of its high yield of oil and protein, is a major source of food for human and animal consumption. Although the crop is being grown in many countries around the world, the United States, China, and Brazil have become centers of production. Soybean production in the United States doubled from 1960 to 1973, with the greatest rate of increase in southern latitudes (Turnipseed and Kogan, 1976). Soybeans are now the third leading crop in both acreage and value in the United States, exceeded only by corn and wheat; and of the 16 major food crops worldwide, soybean ranks sixth in acreage, exceeded only by the cereal crops, wheat, rice, corn, barley, and millet (FAO, 1977). A continuous and rapid expansion of soybean acreage has been predicted, particularly for subtropical and tropical latitudes (Amer. Soybean Assoc., 1972). In Florida, for example, soybean acreage has increased 75-fold since 1949, to 450,000 A. in 1979 (Whitty, personal communication). Large increases in soybean acreage have altered the economic status of some insects; however, due to the length of the growing season and the nature of the crop, there are probably as many or more insects associated with soybean than with any other major crop produced in the U.S. Among these insect pests are the stinkbugs.

*
E. B. Whitty, Agronomy Dept., University of Florida, Gainesville,
Florida, 32611.


1






2



The objectives of this three-year study include: (1) to compare sweep net and ground cloth sampling methods of measuring populations of three stinkbug species: Nezara viridula, acrosternum hilare, and Euschistus servus; (2) to determine the distribution, species composition, and relative abundance of the pentatomids associated with soybeans in Florida; and (3) to determine the effect of soybean varieties of different maturity planted on two dates on stinkbug population dynamics.














CHAPTER I


LITERATURE REVIEW



According to Herzog et al. (1981) at least 40 species of stinkbugs occur worldwide on soybeans, but damage has actually been documented for only a few of these species. According to these authors, there is at least one important stinkbug pest species on the crop in every major soybean-producing region of the world.

The following species have been reported as pests of soybean: Nezara viridula (L.), Acrosternum hilare (Say), A. Acutum (Dallas), A. marginatun (Palisot de Beauvois), Piezodorus guidinii ) (Westwood), P. palZescens (Germar), Thyanta palZidovirens accera (Stal), custator (F.), T perditor (F.)-, Edessa meditabunda (F.), Euschistus servus (Say), E. tristigumus (Say), E. obscurus (Palisot de Beauvois), E. quadrator(Rolston), E. ictericus (L.) E. heros (F.), E. crenator

(F), and E. variolarius (Palisot de Beauvois). Based on its cosmopolitan distribution and the degree of feeding damage, the most serious species is N. viridula, commonly called the southern green stinkbug in the U.S.

Turnipseed and Kogan (1976) stated that the stinkbug complex and the corn earworm, HeZiothis zea (Boddie), are the most serious soybean pod feeders in the U.S. Turnipseed (1973) listed the northern green stinkbug, A hiZare, the southern green stinkbug, N. viriduZa, and the brown stinkbug, E. servus, as the three most important members of

3






4


the stinkbug complex attacking soybean. According to him the green stinkbug is found in the south and northward into Missouri and some midwestern states. The southern green stinkbug is confined primarily to the southern and southeastern states, extending as far west as Texas and as far north as Arkansas, Tennessee, and Virginia (DeWitt and Godfrey, 1972). According to Blatchley (1926), the brown stinkbug, also common in the south and southeast, has been reported as far north as Massachusetts and west to New Mexico.

Deitz et al. (1976) reported the green stinkbug, A. hilare to be the most abundant stinkbug pest in soybeans in North Carolina, and the brown stinkbug E. servus, was also present in low numbers. According to Nettles et al. (1970) N. viridula, A. hilare, and E. servus are the three main species which cause soybean injury in South Carolina. Jones and Sullivan (1978, 1979) reported the ratio of N. viridula, A. hiZare, and Euschistus spp. in experimental plots in South Carolina to be 52, 30, and 16%, respectively, in 1974; and 60, 19, and 20% in a 1975 test. Jones (1979) studied the distribution and abundance of pentatomids in soybeans in South Carolina, and based on sweep net and ground cloth samplings found that both the green stinkbug and the brown stinkbug occurred in all three areas of the state sampled. The southern green stinkbug was restricted primarily to the coastal plain, where it was usually the predominant species present in 1976. McPherson (1978) reported that N. viridula, A. hilare, and E. servus are the most abundant species in Louisiana.






5



The Main Species of Stinkbugs

A. The Southern Green Stinkbug, Nezara viridula (L.)

The life history of the southern green stinkbug, N. viridula has been studied by a number of workers in different parts of the world (Jones 1918, Drake 1920, Cumber 1949, Everett 1950, Kiritani and Hokyo 1962, Mitchell and Mau 1969, Corpuz 1969, Singh 1972, Harris and Todd 1979a, 1980a). The work of Jones (1918), Drake (1920), and Harris and Todd (1980a, b, c, d) in Louisiana, Florida, and Georgia, respectively, provide a broad data base for this species in the southern United States

(Herzog et al., 1981).

In the early spring, as the days begin to warm, the bugs emerge

from overwintering quarters in search of food. According to Drake (1920), mating begins almost immediately upon emergence from hibernation.

Corpuz (1969) observed 6-10 days and Mitchell and Mau (1969) 7 days for the premating period. The range of copulatory duration is 1-165h., with a mean of 37.25 31 h. (Harris and Todd, 1980a). These authors reported 1-6 matings prior to oviposition (mean 1.94), and

3 days post-mating/pre-oviposition, thus, a mean pre-oviposition period of 17.5 days. Jones (1918) and Wilson and Kelsheimer (1955) reported a pr-oviposition period of about 4 weeks. There is a distinct periodicity of oviposition with 75% of the eggs being laid in the last 3 hours of daylight. The pale yellow eggs are generally laid in hexagonally-shaped clusters, with individual eggs closely packed in regular rows and firmly glued to the substrate. The average incubation time is 5 days in the summer (Harris and Todd, 1980b).






6


Kiritani (1963) reported that females mated repeatedly and deposited 80 to 100 eggs per mass with increasing mass size in decreasing intervals (7 to 10 days) between successive ovipositions. The average incubation period of eggs was 4 to 5 days. As incubation proceeds, the eggs become a deeper yellow, then pinkish-yellow, with a red crescent-shaped spot appearing on the operculum and, by the time of hatch, they are a rich orange color (Herzog et al., 1981). During the summer, the period from egg to adult is 35-37 days, depending on temperature (Jones, 1918; Drake, 1920; Harris and Todd, 1980a).

Harris and Todd (1980a) studied the development of N. viridula

in the laboratory. In their study they used 75 egg masses laid by 20 females, and monitored development in the laboratory under controlled conditions of 25-28*C, 55-65% RH, and a 14 h. photophase. The mean nymphal development period (days) was 36.7, divided by stages as follows: egg,4.8; 1st instar, 3.8; 2nd instar, 5.2; 3rd instar, 4.5; 4th instar, 6.4; 5th instar, 11.9. They compared these observations with seven previous studies conducted in five countries, and they discussed inconsistencies among those studies concerning the possible effects of temperature, photoperiod, latitude, and rearing method.

According to Jones (1918) nymphal development was first instar,

3 days; second instar, 4 days; third instar, 5 days; fourth instar, 6 days; fifth instar, 7 days. (Kariya (1961) reported 200 to 30'C was the optimal temperature range for development. In the first instar, nymphs cluster on or near the egg mass and have not been observed to feed. Drake (1920) stated that the nymphs begin to disperse and feed, just before or subsequent to molting.






7


The tendency to aggregate carries through the third stage and is reported to have an effect on the rate of development and mortality (Kiritani, 1964a; Kiritani et al., 1965; Kiritani and Kimura, 1965, 1967). Rizzo (1968) studied this stinkbug in Argentina and according to him 7 to 20 days after mating the female lays eggs in variable numbers of from 55 to 105, rarely less than 55 eggs. The nymphal stage has five instars and they have the following scheme: first, 3-9 days; second, 4-12 days; third, 5-10 days; fourth, 6-13 days; and fifth, 7-16 days, depending upon the temperature. Kiritani et al. (1966) demonstrated that the mortality rate increased at adult emergence, leveled off at a constant rate until 60% mortality occurred, then suddenly increased thereafter. Jones (1918) reported an average male longevity of 44 days and female longevity of 51 days. Jones (1918) and Drake (1920) observed four generations per year in Louisiana and Florida, respectively, and according to Drake (1920) a fifth generation probably occurred in the southern portion of Florida. The nymphs, like the adults, are usually found upon those portions of the plant on which they prefer to feed, namely the tender growing shoot and especially the developing fruit (Herzog et al., 1981). B. The Green Stinkbug, Acrosternwn hilare

The green stinkbug, Acrosternum hilare, for a long time called the soldier bug, is one of those insects that may occasionally cause serious damage to widely different plants. In Utah, this species mated in mid-June, and oviposition extended from June to September, peaking during July (Sorenson and Anthon, 1936). Females laid from 6 to 114 eggs






8


averaging 41.5 (N=5). The incubation period ranged from 5-14 days. with an average of 8.1 days. The mean period of nymphal development per instar was: first, 5.06 days; second, 11.5 days; third 12.5 days; fourth, 16.5 days; and fifth, 20.7 days. Whitmarsh (1917) observed that green stinkbug females may deposit three clusters of eggs, with the first cluster always the largest, usually between 40 and 50 eggs. The normal period of incubation seems quite constant, as a rule, being 7-8 days. Underhill (1934) stated that in Virginia, the period of incubation of egg masses was 8.39 days; a female deposited 75-80 eggs. Nymphal development required (averages): first, 5.1 days; second, 5.9 days; third, 6.3 days; fourth, 7.2 days; and fifth 4.1 days. The average number of days from egg to adult was 38.5 days. Sailer (1953) reared A. hilare in confinement and speculated that more than one generation would occur in a season. The average time required for development was 55.2 days, with a minimum of 49 and a maximum of 81. C. The Brown Stinkbuq, Euschistus senrva

Woodside (1946) observed that the number of eggs per cluster varied from 1-28, the average being 16.3. The length of the incubation period was 8.7 days, and first instar, 5.5 days; second instar, 8.4 days; third instar, 9.0 days; fourth instar, 12.3 days; and fifth instar, 17.8 days. The total nymphal period was 53.2 days. Rolston and Kendrick (1961) working with this stinkbug in Arkansas, found an average of 21.1 eggs per cluster. The average incubation period was 5.4 days, ranging from 3-14, and the durations of nymphal stadia were: first, 3.7 days; 1-2,

8.8 days; 1-3, 13.7 days; 1-4,20.6 days; 1-5, 33.3 days. Nymphal






9


development time ranged from 23-63 days. The combined egg and nymphal stages were completed in an average of 38.1 days.


Nature of Damage


Several workers have described the effects of damage to soybeans by stinkbugs. According to Jones (1976), nymphal and adult stinkbugs damage soybeans by piercing the pod wall into the developing seed. Salivary enzymes are injected into the seed and the liquified tissues are then withdrawn through the stylets. They attack all parts of a plant including stems, foliage (particularly leaf veins), flowers, and fruit, but prefer the tender young growth and fruiting structures. The feeding punctures form minute, hard brownish or blackish spots on the seed. The loss of plant juices, the injection of powerful digestive enzymes, and the profusion of entry sites for pathogenic and decay organisms all contribute to crop injury. The extent of stinkbug damage to soybeans depends upon the stage of seed development at which feeding occurs. Feeding by stinkbugs during the early stage of seed formation can result in shriveled, deformed, and undersized seeds; whereas, feeding during later stages of endosperm development results in a weakened, deformed area with puncture marks where the stylets pierced the seedcoat. The flesh of the cotyledons is often shrunken and deformed beneath the seedcoat, with a whitish chalky area where the cell's contents have been removed. Frequently, a dark discoloration may be present around the punctured area and the inner membrane of the seedcoat may be fused to the cotyledons rather than being free as is






10


normal (Kilpatrick and Hartwig, 1955; Blickenstaff and Huggans, 1962; Daugherty et al., 1964; Miner, 1966; Turner, 1967; and Herzog et al., 1981).

Lower and Hankins (1960) and Miner (1966) indicated that high infestations of N. viridula could occur in maturing soybeans without any appreciable degree of yield reduction; however, stinkbugs could conceivably reduce yield through early infestations or in late maturing soybean varieties.

Soybean seeds damaged by southern green stinkbugs have a slightly higher protein content and a slightly lower oil content than non-damaged beans (Miner, 1961, 1966). As the severity of stinkbug damage increases,

linoleic, palmitic, stearic, and oleic acidsincrease, while linolec decreases (Todd et al., 1973). Seed damage can also reduce germination, emergence, and seedling vigor (Jensen and Newsom, 1972; Todd and Turnipseed, 1974; Thomas et al., 1974).

Stinkbug damage not only affects soybeans directly through

reduction in yield and quality, but also by providing entry sites for disease organisms such as the yeast spot disease, Nematospora coryi Peglion. In Florida stinkbugs in conjunction with wet weather may spread anthracnose, GZomereZla gZycines L. and W., and cercospora spot, Cercospora sp. (Genung et al., 1964). Ragsdale (1977) reported that the southern green stinkbug transmits the causal organisms of several bacterial diseases of soybean.

Economic threshold studies have been conducted with the southern green stinkbug by Miner (1966), Duncan and Walker (1968), Todd and Turnipseed (1974), and Thomas et al. (1974), and with the green






11


stinkbug by Blickenstaff and Huggans (1962), Daugherty et al. (1964), and Miner (1966). Their results show that one adult or large nymph per

3 row-ft. during seed enlargement and one bug per row-ft. after seeds are full size causes sufficient damage to justify treatment. McPherson et al. (1979), studying the stinkbug complex in Louisiana, reported similar results; however, their work revealed that late instar nymphs and adults of E. servus produced damage comparable to that of N. viriduLa and A. hilare when population densities were maintained at high levels. Miner (1966) compared the damage to soybean by the brown, green, and southern green stinkbugs in field cages. According to him the type and severity of damage by the green stinkbug was identical to damage by the southern green stinkbug. Field studies by Duncan and Walker (1968) revealed that 61.1, 45.6, and 33.1% damaged seeds were produced by densities of the southern green stinkbug of 2.5, 1.1, and 0.7/row-ft. when maintained over a 7-week period.


Sampling


The methods most commonly used to sample above ground populations

of arthropods are: (a) direct observations, (b) ground cloth, (c) sweep net, and (d) vacuum or suction net (usually a D-Vac). The direct observations and the ground cloth may approach absolute or direct population estimates for some species, while the other two are relative sampling methods.

Stinkbug sampling in soybeans i-s difficult due mainly to the clumped distribution early in the life cycle and a more nearly random distribution






12


in later stages at high population densities. Since stinkbug damage is not readily visible in the growing crop, actual counts must be made necessitating greater effort in order to determine stinkbug population levels adequately.

Absolute quantitative measurements of stinkbug populations are

best made utilizing the fumigation cage method (Marston et al., 1976). The ground cloth method of sampling so nearly approximates the absolute measurement of stinkbug populations that it may be considered as absolute and it is easy and quick (Todd and Herzog, 1980). Marston et al. (1976) compared three relative sampling methods with an "absolute" fumigation cage method. The fumigation cage and ground cloth methods collected significantly larger numbers of stinkbugs than did the vacuum net and sweep net methods.

Duncan (1968) comparing sweep net and ground cloth methods for

sampling of N. viridula, concluded that fourth and fifth nymphal instars and adults were sampled with equal efficiency by both techniques, while second and third nymphal instars were not sampled adequately with either method.

Rudd and Jensen (1977) compared sweep net and ground cloth sampling methods for N. viridula. They showed by regression analysis that numbers of stinkbugs captured by the two methods were highly correlated, ranging from r = 0.835 for N. viridula females to r = 0.982 for fourth instar N. viridula, with r = 0.998 for third, fourth and fifth instars and adults combined. They concluded that a larger number of samples are required to measure a population mean with the ground cloth than with the sweep net (Herzog et al., 1981).


L






13


The time required for acquisition of samples was reported by Rudd and Jensen (1977) as 21.2 and 48.3 seconds/sample for the sweep net (25 sweeps) and ground cloth (6 row-ft.) methods, respectively. Their data indicate that the sweep net was superior to the ground cloth for most sampling objectives based on time required per observation. Since this research was with N. viridula, it cannot be directly related to other phytophagous pentatomids. Behavior probably differs among species to such an extent that factors for calibrating between sampling methods, calculated from regression analyses, would be significantly different for other species. However, for pest management purposes in the southeastern United States where N. viridula is the predominant species, calibrations for this species may be used without incurring significant error (Herzog et al., 1981).

For over a century the sweep net has been the most widely used

tool for sampling arthropods on small grain, forage, and many row crops. One reason for this popularity, despite difficulties in standardizing the method for accurate population studies, is that no other method

can capture as many insects from vegetation per man hour and with as little damage to the crop and cost for equipment (Ruesink and Kogan, 1975).


Population Dynamics

Understanding the population dynamics of pest species is essential for development of sound pest management systems. Seasonal abundance of soybean insect pests and predators have been reported by Raney and Yeargan (1977), Wuensche (1976), Deitz et al. (1976), Kogan et al. (1974),










Corner et al. (1974), Shepard et al. (1974), Burleigh (1972), Pedigo et al. (1972), and Herzog (1968). Little information is available on the abundance and population dynamics of stinkbug pests of soybeans, however.

N. viriduZa has a complex population profile (Harris and Todd, 1980a). It is polyandrous, polygamous, multivoltine, and long lived as an adult, thus producing an overlap of generations (Kiritani, 1963; Harris and Todd, 1980b).

Weather, population density, food, and natural enemies have all been cited as factors which influence the population dynamics of N. viridula. Jones (1918) observed heavy mortality to adults in the winter months in Louisiana during sudden drops in temperature. According to Kiritani and Hokyo (1962), adverse weather conditions are major mortality factors for eggs and early nymphal instars.

In a five-year study, Kiritani (1964b) concluded that abundance of N. viridula was partly determined by the combination and relative abundance of host plants, and partly by climatic factors. He found winter to be the critical period for survival for this species with

habitat heterogeneity and hibernacula the only means of insuring winter survival.

Herzog et al. (1981) postulated that all developmental stages

are present on soybeans in Louisiana, Georgia, and Florida until harvest and may be collected from unharvested plants as late as mid-December. Bratley (1936, 1941) reported reduced populations of N. viridula in the spring in Florida following severe winters.






15


Although N. viridula often invades soybean fields in large numbers early in the season, it barely maintains its population level until pod formation when the population increases drastically (Newsom et al.,1975, Wuensche, 1976).

Kiritani (1965) found that local overpopulation tends to increase

mortality among immature N. viridula and decreases longevity, body weight, and fecundity of adults. He considered this a key factor in keeping populations in check.

Pitts (1977) observed that despite a reproductive diapause in N. viridula, overwinter survival is enhanced by the presence of succulent food. Adults often become active and feed during mild periods in the winter. The availability of cold-hardly plants, such as mustard, greatly increased survival of N. viriduZa by providing an excellent hibernaculum and a constant source of food.

The brown stinkbug, Euschistus servus, is an occasional pest of several vegetable crops in Arkansas (Rolston and Kendrick, 1961). Two generations occur in the northwestern section of the state, but few of the second generation nymphs become adults. The adults overwinter feed on common mullein in the spring before other hosts become available. They collected this species in small numbers on several field crops, none of which appeared to be particularly favored as a host.

As the weather begins to warm in spring, adults move into clover, early vegetables, corn, and tobacco where they feed or oviposit (Herzog et al., 1981). The resultant nymphs and adults constitute the first generation. Tomatoes, leguminous and cruciferous vegetables, and okra become attractivelin April, May, and June, and these provide the major


L_






16


food sources and oviposition sites during early and mid-summer. Although a few individuals can be found in soybeans throughout the growing season, they provide a suitable food only after flowering and podset. According to the authors, this usually occurs in late July and August. By then, third generation adults are present and immigrate into soybeans which provide the major source of food in late summer and early fall (late July through November). Soybeans are not the only source of food for these species in Central and North Florida during this period as the very abundant weeds Desmodium sp. and Crotalaria sp. are excellent hosts (Sailer, personal communication).


























*
Dr. R. I. Sailer, Entomology and Nematology Department, University of Florida, Gainesville, Florida 32611.













CHAPTER II


MATERIALS AND METHODS



General Experimental Procedures


Studies were conducted at the University of Florida, Agricultural Research and Education Center, Quincy, Gadsden County, Florida, using Forrest and Bragg soybean varieties in 1977, Bragg and Cobb in 1978, and Bragg, Cobb and Forrest in 1979.



General Experiments in 1977, 1978, and 1979

The soybeans were grown with the standard cultural practices described by Hinson (1967) and Whitty et al. (1971). The crop was planted at approximately 67 Kg/ha with a row spacing of 0.91 m. The herbicides trifluralin 4EC and metribuzin 70WP were incorporated into the soil prior to planting at rates of 0.56 and 0.29 Kg/ha, respectively. At cracking time, alachlor 4EC and dinitroamine 2EC were applied at rates of 2.25 and 0.37 Kg/ai/he, respectively.

Forrest (Maturity Group V) and Bragg (Maturity Group VII) soybean varieties were each planted on June 7, 1977, and June 22, 1977. Earlyplanted Forrest bloomed by July 17, and pod-fill began by August 10.

Early-planted Bragg bloomed by July 24, and pod-fill began by August 20. Late-planted Forrest bloomed by July 31 and pod-fill began by August 22. Late-planted Bragg bloomed by August 4 and pod-fill began by August 29.


17






18


Bragg and Cobb (Maturity Group VIII) soybean varieties were

planted on June 13 and June 30, 1978. Early-planted Bragg bloomed by July 29 and pod-fill began by August 22. Early-planted Cobb bloomed by August 5 and pod-fill began by September 4. Late-planted Bragg bloomed by August 10 and pod-fill began by September 3. Late-planted Bragg bloomed by August 10 and pod-fill began by September 3. Lateplanted Cobb bloomed by August 18 and pod-fill began by September 10.

All three varieties were planted again on June 12, 13, and 27,

1979. Early-planted Forrest bloomed by July 25 and pod-fill began by August 22; meanwhile, Bragg bloomed by August 2 and pod-fill began by August 25. Cobb bloomed by August 11 and pod-fill began by September 6. Late-planted Forrest bloomed by August 7 and pod-fill began by August 27; meanwhile, Bragg bloomed by August 10 and pod-fill began by September 1. Cobb bloomed by August 18 and pod-fill began by September 12.

Each plot consisted of 60 rows 24.38 m long; plots were arranged in a "split-plot" design. In each year the experiment was replicated two times.

Weekly samples of stinkbugs and other insects associated with those soybean varieties were taken by two methods: sweep net and ground cloth. In the ground cloth method the cloth was placed between two rows of soybean, so that it was located beneath undisturbed foliage (Boyer and Dumas, 1963, 1969). Approximately 0.61 row/m of soybeans on each side were then vigorously shaken over the cloth. The stinkbugs and other insects that fell onto the cloth were collected and transferred to a plastic bag and were counted and recorded later. All second-fifth instars as well as adult pentatomids were identified and






19


recorded. Sixteen samples per plot were taken along a diagonal, in order to sample the whole plot. Two rows were skipped between sampled rows.

A modification of the sweep net method described by DeLong (1932) was used. This was the one-row variation as described by Kogan and Pitre, Jr. (1980). Sweeps were taken while walking beside the row, holding the handle of a 38 cm diameter sweep net directly in front of the observer, with the opening of the net always facing the row of plants to be sampled. Sixteen samples consisting of 50 consecutive sweeps ca. 0.61 m apart from alternating sides of the row while walking beside it, were taken per plot. After 50 sweeps in a single row, contents of the net were transferred to a plastic bag, and later counted and recorded. Two rows were skipped between sampled rows.

In 1977, thirteen weekly samples were made with both methods, sweep net and ground cloth, from August through the beginning of November on each plot of Bragg and Forrest soybean varieties.

In 1978, fifteen weekly samples were made with both methods on Bragg and Cobb, and in 1979, fifteen weekly samples were made with both methods on each plot of Bragg, Cobb, and Forrest soybean varieties.






20


Statistical Analyses

Two statistical analyses were performed:

A. The model used for the 1977, 1978, and 1979 experiments was:


*ijk + + ii + aij + yk+ yik + jk + 'ijk + bijk

where

= overall population mean

a. = ith planting date effect

th variety effect

= ijth planting date x variety interaction effect

E. = jth main plot error

yk = kth week effect

aYik = ikth planting date x week interaction effect

-yjk = jk th variety x week interaction effect

a~yijk = ijkth planting date x variety x week interaction effect

Eijk = ijkth subplot error.
The design was a split plot arrangement of treatments in a completely randomized design for each of three years. In 1977 and 1978, a 2 x 2 factorial was used on the main plot; for 1979, a 2 x 3 factorial was used on the main plot. On the split plot, 13 sampling dates were used for 1977 and 15 each for 1978 and 1979. For each year, the analysis was run for each combination of two collection methods, 3 species and

6 stages of insect development (including instars 2 to 5 and the adults). B. The model used was:

Y = o + Xlil + 6






21


where

Y = ith stinkbug count by sweep net

X = i th stinkbug count by ground cloth

E = i th random error
6 = number of stinkbugs collectible by sweep net when no
stinkbugs are collected by ground cloth

l = changes in number of stinkbugs collected by sweep net
per unit increase in number collected by ground cloth.

For each of 3 years, the collection by ground cloth was regressed on the collection by sweep net. This was done for each combination of

(i) 2 planting dates, 2 (or 3) varieties, 3 species and 6 stages;

(ii) 3 species and 5 stages (instar 2 omitted); and

(iii) 3 species (instar 2 omitted); over all other factors.

ANOVA and summary of results tables were made for each species, stages, and methods studied.

Data presented in Figs. 1 84b represent mean numbers of each stage collected per plot, representing 16 samples per plot. Ground cloth samples consisted of 1.22 row/m, and sweep net samples 50 sweeps.

Therefore, data are figuredon a basis of 19.51 row/m or 800 sweeps per plot.














CHAPTER III


EFFECTS OF SOYBEAN VARIETY AND PLANTING DATE
ON ABUNDANCE OF DEVELOPMENTAL STAGES OF
N. viridula, A. hilare, AND E. servus



Results


Stinkbug populations were sampled weekly with ground cloth on two or three soybean varieties planted on two dates during 1977, 1978, and 1979. From initial analyses, significant first- and second-order interactions with week were detected. Since these interactions were expected, and in order to resolve the effect of the other factors above the week effect, it was decided to partition the experimental period. Due to the size of the data, the number of partitions should be fewer than the number of sampling dates. The intention of partition was based on overall relative population growth (first period), a second period of relative stability, and a third period of decline were determined. Sampling periods did not always encompass the same crop growth stages among varieties and planting dates. N. viriduLa Adults

Populations of N. viridula adults sampled from early and late

planting dates of Forrest and Bragg varieties in 1977, Bragg and Cobb in 1978, and Forrest, Bragg and Cobb in 1979 are shown in Figs. 1 through 14, respectively. Results of statistical analyses are shown in Table 1.


22










20 YEAR=77 METH=SC VTY=FORREST PLANTING DATE=E SPECIES=NEZ


MALE
16 FEMALE



12



IL1J 6 w -.










8/5 0/12 0/20 8/26 8/31 9/9 9/16 9/24 10/1 10/6 10/15 10/22 10/27 SAMPLING DATE
Fig. 1. Populations of N. viridula adults collected by ground cloth on earlyplanted Forrest variety. Quincy, Florida, 1977.










TERR=77 METH=SC


MALE
FEMALE


K


/
/
/
I
/
I
I
/
I a'
I

/1
/
/
2


'A--
7


8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24 10/1


SAMPLING


10/8 10/15 10122 10/27


DATE


Fig. 2. Populations of N. viridula adults collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida, 1977.


30


16


C-)


LuJ


0


PLANTING DATE=E


SPECIES=NEZ


VTT=BRAGG










25- YERR=77 METH=SC VTY=FORBEST PLANT[NG DRTE=L SPECIES=NEZ


-- MALE
FEMALE



z( 5 C-)
z
Cr:







I I I --i



8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/27 SAMPLING DATE Fig. 3. Populations of N. viridula adults collected by ground cloth on late
planted Forrest variety. Quincy, Florida, 1977.










j r


VEAR=77 METH=SC Vt 'I' B BR C G PLANTING DATE=L SPEC IES=NEZ






/
/
/
/
/





/
/
/
/
/
/


7


?0 [~


IS [


I 0 [


0


-- MALE
-- FE11ALE


8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24

SAMPLING DATE


Fig. 4. Populations of N. viridula adults collected by
planted Bragg variety. Quincy, Florida, 1977


10/1 10/8 10/15 10/22 10/27


ground cloth on late-


hi

w:


I |_


YEAB=77 METH=SC


VTY'=BRAGG


PLANTING DATE=L


SPECIES=NE?


I [






27


In 1977, there was a significant difference in adult populations in the first (female and male P<0.05) and third sampling periods (female P<0.01, male P<0.05) on Forrest and Bragg varieties. No significant differences (P<0.05) occurred in the second sampling period. Populations of both males and females differed significantly (P<0.1) between planting dates in the first sampling period, but no significant differences were

obtained in the second or third sampling periods. Variety times planting date interactions were significant (P<0.05) for both sexes in the first and second sampling periods, but were nonsignificant (P>0.05) in the third.

In 1978, no significant difference (P>0.05) N. viridula adult abundance was detected between Bragg and Cobb varieties. Both males and females differed significantly (P<0.01) between early and late planting dates during the first sampling period, but no such differences (P>0.05) were detected in the second or third sampling period. No significant (P>0.05) variety times planting date interactions

occurred.

In 1979, both sexes differed significantly among varieties in the second (P<0.05) and third (P<0.01) sampling periods, but no significant difference (P>0.05) was detected among varieties in the first sampling period. Adult populations differed significantly among planting dates in the first (P<0.05), second (P<0.01) and third sampling periods (female P<0.01, male P<0.05). No significant (P>0.05) variety times planting date interaction occurred.










lb




32


211 1


16i [


0


YEAR=78 METH=SC VTY=BRRGG


A
- MflLE
FEMALE I,,
/
/
/
/
I



/
/
I





/
I
/
N
N


7/26 8/1 8/8 8/15 8/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/24 11/1

SAMPLING OTE
Fig. 5. Populations of N. viridula adults collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida, 1978.


2::


PLANTING DATE=E


SPECIES=NEZ


8 1













MALE
-- FEMALE
















-


7/26 6/1 6/6 6/15 6/23 6/29 9/5 9/11 9/21 9/26

SAMPLING DATE
Fig. 6. Populations of N. viridula adults collected by
planted Cobb variety. Quincy, Florida, 1978.


ground cloth on early-


q60 [


36


U


24


12



0


N')


PLANTING DATE=E


YEAR=78 METH=SC VTY=COBB


SPECIES=NEZ


10/3 10/10 10/17 10/24 11/1










TERB=78 METH=SC VTY=BRAGG


PLANTING DATE=L


SPECIES=NEZ


36 211




12




0


- MPLE
[EM FILE





/
I
I
/
/
I
/
I
I
I

,2

7


7/26 8/1 8/8 8/15 8/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/24 11/1


SAMPLING DATE
Fig. 7. Populations of N. viriduZa adults collected by ground cloth on lateplanted Bragg variety. Quincy, Florida, 1978.


60


ID cLJ

,;7-


w-









YEAR=78 METH=SC VTY=COBB


PLANTING DATE=L


SPECIES=NEZ


- MFILE
FFIMRLE






/
/
/
/ x
/ I
/
/
/



/
/


7/26 8/1 8/8 8/15 8/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/24 11/1


SAMPLING DRTE
Fig. 8. Populations of N. viriduZa adults collected by ground cloth on lateplanted Cobb variety. Quincy, Florida, 1978.


411


C

LL]


33 I I




0


L.)









TEAR=79 METH=SC VT=FORREST PLANTING DATE=E


-- MALE
FEMALE


7/26 8/1 8/7 6/15 0/21 6/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DATE
Fig. 9. Populations of N. viridula adults collected by ground cloth on earlyplanted Forrest variety. Quincy, Florida, 1979.


55 r


'P1 [


33 i1


C
:2: CE [Ii


22


II



0


N-.)


SPECIES=NE?












TEfR=79 METH=SC


VTY=BRRGG


PLRNTING DATE=E


SPEC[ES=NEZ


MFILE
FEMALE 7'
/



/
/

/
/
/
/
/
I
/
/
I
/
/






p p


7/26 8/1 8/7 8/15 8/21 8/26 9/4 9/10 9/21 9/29 10/5 10/12 10/19 SAMPLING DRTE


Populations of N. viridula adults collected by ground planted Bragg variety.- Quincy, Florida, 1979.


cloth on early-


130


104


18


CD 2:

(-)

CE:


26 [


0


(A) C.-)


Fig.


10.


10/26 '11/1









176



136


7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING UATE
Fig. 11. Populations of N. viridula adults collected by ground cloth on earlyplanted Cobb variety. Quincy, Florida, 1979.


MALE FEMALE










,t


10?


CF: Lii


66 1


311



0


(A)


TEAB=79 METH=SC VTT=COBB


PLANT[NG DATE=E


SPEC-IES=NEZ









TERR=79 METH=SC VTY=FORREST PLANTING OATE=L


- MALE
---FEMAlLE




ol/


7/26 8/1 8/7 8/15 B/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DATE
Fig. 12. Populations of N. viridula adults collected by ground cloth on lateplanted Forrest variety. Quincy, Florida, 1979.


12


9


C



LU


6


3



0


Ln)


SPEC[ES=NEZ










YERR=79 METH=SC VTY=BRRGG


90 72


7/26 8/1 6/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19


10/26 11/1


SAMPLING DATE
Fig. 13. Populations of N. viridula adults collected by ground cloth on lateplanted Bragg variety. Quincy, Florida, 1979.


--MALE
---FEMALE s











-/

1 I i t i i i


:7

Uj


5II 36


CA 0*1


PLANTING DATE=L


SPECIES=NEZ












HO
112


56


28



0


YERR=79 METH=SC VTY=COBB


MALE
FEMALE












-


7/26 8/1 B/7 6/15 B/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SRMPLING DRTE
Fig. 14. Populations of N. viridula adults collected by ground cloth on lateplanted Cobb variety. Quincy, Florida, 1979.


I

ED
U

cr
Iii
x


PLANTING OATE=L


SPECIE5=NEZ






38


Table 1. Results of analyses of variance for N. viridula concerning variety and planting date effects and variety x planting
date interaction.

Year Period First Second Third

1977 Date 8/5 to 8/20 8/26 to 9/24 10/1 to 10/27

Stage P. date Vty PdxVty P. date Vty PdxVty P. date Vty Pd.xVty

Female ** NS NS NS ** NS
Male ** NS NS NS NS
Fifth NS NS NS NS NS NS NS
Fourth NS NS NS NS NS NS ** NS
Third NS NS NS NS NS NS NS NS
Second ** NS NS NS NS NS NS NS NS

1978 Date 7/26 to 8/23 8/29 to 9/26 10/3 to 11/1

Stage P. date Vty PdxVty P. date Vty PdxVty P. date Vty Pd.xVty

Female ** NS NS NS NS NS NS NS NS
Male ** NS NS NS NS NS NS NS NS
Fifth NS NS NS NS NS NS NS NS NS
Fourth NS NS NS NS NS NS NS NS NS
Third NS NS NS NS NS NS NS NS NS
Second NS NS NS NS NS NS NS NS NS

1979 Date 7/26 to 8/21 8/28 to 9/29 10/5 to 11/1

Stage P. date Vty PdxVty P. date Vty PdxVty P. date Vty PdxVty

Female NS NS ** NS ** ** NS
Male NS NS ** NS ** NS
Fifth NS NS ** NS NS NS ** NS
Fourth NS NS NS NS NS ** NS
Third ** NS NS NS NS NS NS NS NS
Second NS NS NS NS NS NS NS NS


NS = Nonsignificant (P> 0.05)

* = Significant (P < 0.05)

** = Highly significant (P < 0.01)






39


N. viridula Nymphs

Populations of N. viridula nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 15 through 28. Results of statistical analyses are shown in Table 1.

In 1977, no significant differences (P>0.05) were detected in

nymphal populations between Forrest and Bragg varieties, except in the third sampling period, when numbers of fourth and fifth instars differed significantly (P<0.01 and P<0.05, respectively). No significant differences (P>0.05) were detected in nymphal populations between planting dates, except in the first sampling period, when numbers of second and third through fifth instars differed significantly (P 0.01 and P<0.05, respectively). No significant (P>0.05) variety x planting-date interactions occurred.

In 1978, no significant differences (P>0.05) were detected in

nymphal populations between Bragg and Cobb varieties or between planting dates. No significant (P>0.05) variety x planting date interactions were detected.

In 1979, no significant differences (P>0.05) were detected in

nymphal populations between Forrest, Bragg and Cobb varieties, except in the third sampling period, when numbers of fourth and fifth instars differed significantly (P<0.01). In the first sampling period numbers of all nymphal stages sampled (second through fifth) differed significantly (P<0.05) for second, fourth and fifth, P<0.01 for third) between planting dates. In the second sampling period numbers of fourth and fifth instars only differed significantly (P<0.05 and P<0.01, respectively) between planting dates. In the third sampling period










3 EAR=77 METH=SC VTT=FORREST PLANTING DATE=E SPECIES=NEZ
2N INSTAR
---3HD INSTAR
qTH INSTRJ

28 - 5TH INSTAR




UU



c
LUU



LL\ ++









0/5 6/12 8/20 0/26 6/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/27

SAMPLING DATE Fig. 1 Populations of N. viridula nymphs collected by ground cloth on earlyplanted Forrest variety. Quincy, Florida, 1977.









35 fTERF=77 METH=SC VTT=BBRGG PLANT[NG DfTE=E SFECIES=NEZ
2'1 [NSTAR 3RD INSTAR 4TH I NSTAR
28 5TH I NSTAR



21
C)







+ 7z
+ \+


0

8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/27

SAMPLING DATE Fig. 16. Populations of N. viridula nymphs collected by ground cloth on early
planted Bragg variety. Quincy, Florida, 1977.











30 YEA=77 METH=5C VTY=FORREST PLANTING DATE=L SPECIES=NEZ
-+-+ 2"' INST AR ---- 3"0 INSTAR\
-- 4TH INST AR-- jrH IN5T AR








/+
I/ + +
18
















6/5 8/12 8/20 0/26 6/31 9/9 9/16 9/2q 10/1 10/6 W0/15 10/22 10/27

SAMPLING DATE Fig. 17., Populations of N. viridu?-a nymphs collected by ground cloth on lateplanted Forrest variety. Quincy, Florida, 1977.










YEAR=77 [ETH=SC VTY=BRAGG PLANTING DATE=L SPECIES=NEZ
2+-+ 2 INSTHR
3R( INSTAR
4TH IN5TAR
STH INSTARd






F



(1/
c.i











8/5 8/12 6/20 8/26 8/31 9/9 9/A6 9/24 10/1 10/8 10/15 10/22 10/27

SAMPLING DATE Fig. 18. Populations of N. viridula nymphs collected by ground cloth on lateplanted Bragg variety. Quincy, Florida 1977.










1o TEAH=78 METH=SC VTT=BRRGG PLANTING DRTE=E SPECIES=NEZ
21N0 INSfTAR
---- [ID INSTAR
41" INSTRR
ST INSTAR




UU
















7/26 8/1 8/8 8/15 8/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/24 11/1

SAMPLING DATE Fig.1 9. Populations of N. viridula nymphs collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida, 1978.










65 -'EAB=78 METH=SC VTY=COBB PLANTING DATE=E SPECIES=NEZ
2t( [NSTAR .
-- 3HD INSTRR
-4H [NSTR
511 [N1TAR





:D




+ \+











7/26 8/1 8/0 0/15 6/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/24 It/1

SAMPLING OATE Fig. 20. Populations of N. viridula nymphs collected by ground cloth on earlyplanted Cobb variety. Quincy, Florida, 1978.










YEAR=78 METH=SC VTY=BRAGG PLANTING DRTE=L SPECIES=NEZ
95
---+ 2N0 INSTAR --- 3f0 INSTAR
-4 T INSTAR
5T1 [NSTAR











-~ X ,+ +/

0N
CEI
/L 36



+ +









7/26 8/1 8/8 8/15 8/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/241 11/1

SAMPLING DATE Fig. 21 Populations of N. viridula nymphs collected by ground cloth on lateplanted Bragg variety.. Quincy, Florida, 1978.










'YEAR=78 METH=SC VTY=COBB PLANTING DATE=L SPEC[ES=NEZ
+ND [I NSTR 3R INST AR 4TH INSTAR
-- 51H INSTHR












LI-/


+/
\/
lI-. -: : + +

-i 4 1






7/26 8/1 8/8 6/15 8/23 6/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/24 11/1

SAMPLING ORTE Fig. 22,- Populations of N. viridula nymphs collected by ground cloth on lateplanted Cobb variety. Quincy, Florida, 1978.









YEAR=79 METH=SC VTT=FORREST PLANTING DATE=E
-+-+ 2ND INSTAR
3R INSTAR 4TH INSTAR


SPEC[ES=NEZ


* 1t INSTAR


7/26 6/1 8/17 6/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DATE
Fig. 23. Populations of N. viridula nymphs collected by ground cloth on earlyplanted Forrest variety.. Quincy, Florida, 1979.


1 F5


106 [


81 [


C-) 77


Lii


54 [


21



0


-









TEnR=79 METH=SC VTT=BRRGG PLRNTING DRTE=E SPECIES=NEZ
210 INSTAR
---- 3R0 NSTAH
4TH INSTR 5TH [NSTAR











+ N









7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING ORTE Fig. 24. Populations of N. viridula nymphs collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida, 1979.










YEAR=79 METH SC VTY=COBB PLANT[NG DATE=E SPECIES=NEZ
-+-+ 2"0 [NSTARB
-30 INSTAR
4H INSTAR
5TH INSTRR
196



US




CE
C-C)
L/












7/96 0/1 6/7 8/15 6/21 0/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 1D/26 11/1

SAMPLING OATE Fig. 25. Populations of N. viridula nymphs collected by ground cloth on earlyplanted Cobb variety.- Quincy, Florida, 1979.










TERR=79 fIETH=SC VTT=FORREST PLANTING DRTE=L
-++2N0 [NS TRR 3f0 INSTAR 4TH IN'STAR
- 5- 5TH INSTR





\ %


SPECIES=NEZ


12 1


0


)+



to +

tN


7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DR TE
Fig. 26.. Populations of N. viridula nymphs collected by-ground cloth on lateplanted Forrest variety. Quincy, Florida, 1979.


60 48


36 1


CD
)



CE LIJ
5c7


.2q [


U-1










195 YERR=79 METH=SC VTY=BRAGG PLANTING ORTE=L SPECIES=NEZ
+2N) [NS3TAR
---- 31 INSTAR I
4TH [ NSTAR ii
5H INSTRR








CE
+I +




iJ 9 + *\1
/ +










7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DATE Fig. 27. Populations of N. viridula nymphs collected by ground cloth on lateplanted-Bragg variety. Quincy., Florida, 1979.










230 VEAR=79 METH=SC VTY=COBB PLANTING DATE=L SPECIES=NEZ
-+-+ 24 [ NS TAR ---- 3R0 INSTAR
-- 4TH INSTAR
5TH INSTAR



F




/ /
92 42
+


+ + N
4N



0 I I

7/26 8/1 8/7 8/15 8/21 8/20 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1


SAMPLING DATE Fig. 28.. Populations of N. viridula nymnphs collected by ground cloth on lateplanted Cobb variety. Qui-ncy, Florida, 1979.






54


no significant differences (P 0.05) occurred between planting dates for any nymphal stage. No significant (P 0.05) variety x planting date interaction was detected.


A. hilare Adults

Populations of A. hilare females sampled in 1977, 1978, and 1979 are shown in Figs. 29 through 42. Results of statistical analyses are shown in Table 2.

In 1977, no significant differences (P>0.05) in adult populations were detected between Forrest and Bragg varieties in the first sampling period. However, significant varietal differences were detected in the second sampling period for females and males (P<0.01 and P<0.05, respectively) and in the third sampling period for both sexes (P<0.05). No significant (P>0.05) planting date effects or variety x planting date interactions were detected.

In 1979, significant differences (P<0.05) were observed for both sexes among Forrest, Bragg and Cobb varieties in all three sampling periods. Significant differences between planting dates were observed for both sexes in the first (P<0.01) and second sampling period (P<0.01 for females, P<0.05 for males). No significant planting date effects (P>0.05) were observed in the third sampling period. No significant (P>0.05) variety x planting date interactions occurred in any of the three sampling periods.










YEAR=77 METH=SC VTr=FORREST


PLANTING DATE=E


-- MALE
---- FEMALE


10




8


SPECIES=ACR


8/5 8/12 8/20 5/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/27

SAMPLING DATE
Fig. 29. Populations of A. hilare adults collected by ground cloth on earlyplanted Forrest variety. Quincy, Florida, 1977.


I
/
2


~ 'I


I /


/
/


I


L)

cr Lu


6 II


('I





(\ ~


u-i
Cyl


0


2 1











10 r


YERRr77 METHZSC VtY~BRRGG PLPNTING DflTE~E SPEC I ES=RCR
I
/










I a
a a
/
/ / /
a
a

a
a
a
a
a


- MAL E
FEMALE


8/5 8/12 8120


8/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10122 10/27


SAMPLING DRTE
Fig.30. Populations of A. hilare adults collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida 1977.


C

wi


I1I[


0


U,


. ... .a .. i i i i i i i I


YEAR=77 METH=SC VTY=BRAGG


PLANTING DATE=E


SPECIES=ACB










TEAB=77 METH=SC VTY=FORBEST PLANTING DATE=L


-- MALE
---- FEMALE


10




8


/
/ N
/ /
N
N
N
/
/
/


8/5 8/12 8120 8/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/27

SAMPLING DATE
Fig.31. Populations of A. hiZare adults collected by ground cloth on lateplanted Forrest variety. Quincy, Florida, 1977.


01


CE L)J
5ii


6 II


0


SPECIES=ACB


2 [











TERh=77 MET1=SC


- MALE
---- FEMALE


/

N.
N .1 N
/ \ .'




A -- A A


A


8/5 6/12 8/20 6/26 8/31 9/9 9/16 9/24 10/1

SAMPLING DATE
Fig. 32. Populations of A. hilare adults collected by ground
planted Bragg variety. Quincy, Florida, 1977.


10/8 10/15 10/22 10/27 cloth on late-


Is


I I




C-)
i CL: Lii


3 1


0


U1


PLANTING DATE=L


SPECIES=HCB


VTY=BBRGG









YEAR=78 METH=SC VTY=BRAGG PLANTING DATE=E SPECIES=RCR


MALE
FEMALE




















7/26 8/1 8/8 8/15 8/23 8/29 9/5 9/1L 9/21 9/26 10/3 10/10 10/17 10/24 11/1 SAMPLING OATE
Fig. 33. Populations of A. hilare adults collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida, 1978.










YEAR=78 METH=SC VTY=COBB


PLANTING DATE=E


SPEC[ES=RC


I0



8


7/26 6/1


6/0 8/15 6/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/2q 11/1


SAMPLING DATE
Fig. 34. Populations of A. hilare adults collected by ground cloth on earlyplanted Cobb variety. Quincy, Florida, 1978.


MALE FEMPLEI /


CD C-)


C7
LU


6



II



2



0









TERR=78 METH=SC VT=BRAGG PLANTING DATE=L SPECIES=ACR


MALE
FEMALE








CE
-L I




2





7/26 6/1 6/8 8/15 6/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/24 11/1 SAMPLING DA TE Fig. 35. Populations of A. hilare adults collected by ground cloth on lateplanted Bragg variety.. Quincy, Florida, 1978.









YEAR=78 METH=SC


-- MALE
FEMALE


7/26 8/1 8/8 8/15 8/23 8/29 9/5 9/11 9/21 9/26


SAMPLING


10/3 10/10 10/17 10/24


11/1


0ATE


Fig. 36. Populations of A hilare adults collected by ground cloth on lateplanted Cobb variety. Quincy, Florida, 1978.


10 r


Li
cu-


II


2



0


VTY=COBB


PLANTING DATE=L


SPECIES=ACR









TEfR=79 METH=SC VTT=FORREST PLANTING DATE=E


MALE
FEMALE


7/26 8/1 8/7 8/15 8/21 6126 9/4 9/10 9/21


9/29 10/5 10/12 10/19 10/26 It/]


SAMPLING DATE

Fig. 37. Populations of A. hilare adults collected by ground cloth on earlyplanted Forrest variety. Quincy, Florida, 1979.


20


CD LU


15 10


SF[


0


SPECIES=RCR









YEAR=79 METH=SC VTY=BRRGG PLANTING DATE=E SPECIES=RCR
L


MALE
FEMALE





CE













7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1 SAMPLING ORTE
Fig. 38. Populations of A. hiare adults collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida, 1979.









YEAR=?9 METH=SC VTY=COBB


PLANTING DATE=E


SPECIES=ACR


MALE
---- FEMALE


7/26 6/1 6/7 6/15 8/21 6/26 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DATE
Fig. 39. Populations of A. hilare adults collected by ground cloth on earlyplanted Cobb variety. Quincy, Florida, 1979.


25


20


C

ci LIi


is 10


0


U,









YEAR=79 METH=SC VTY=FORREST PLANTING DATE=L


SPECIES=ACR



- -


7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1


SAMPLING DATE


Fig. 40. Populations of A. hilare adults collected by ground cloth on lateplanted Forrest variety. Quincy, Florida, 1979.


15 r


12 [


CE
ciz
57


0


-MALE
- FEMALE











/ \










TERR=79 METH=SC VTT=BRAGG


PLANTING DATE=L


SPECIES=ACB


15




10


MOLE
FE MOLE




N
N
N
N
N





2
/ N
/
/
/
I-


7/26 6/1 6/7 0/15 6/21 8/26 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DATE
Fig. 41. Populations of A. hilare adults collected by ground cloth on lateplanted Bragg variety. Quincy, Florida, 1979.


25


20


CE

LiJ '5-









TEAR=70 METH=SC VTr=COBB PLANTING DATE=L SPECIES=ACR


MALE
FEMALE




-Z 12
















7/26 8/1 8/7 8/15 6/21 8/26 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1 SAMPLING DATE Fig. 42. Populations of A. hilare adults collected by ground cloth on lateplanted Cobb variety.' Quincy, Florida, 1979.






69


Table 2. Results of analyses of variance for A. hiLare concerning
variety and planting date effects and variety x planting
date interaction.

Year Period First Second Third

1977 Date 8/5 to 8/20 8/26 to 9/24 10/1 to 10/27

State P. date Vty PdxVty P. date Vty PdxVty P. date Vty Pd.xVty

Female NS NS NS NS ** ** NS NS
Male NS NS NS NS NS NS
Fifth NS NS NS NS ** NS NS
Fourth NS NS NS NS NS NS NS NS
Third NS NS NS NS NS NS NS NS
Second NS NS NS NS NS NS NS NS

1978 Date 7/26 to 8/23 8/29 to 9/26 10/3 to 11/1

Stage P. date Vty PdxVty P. date Vty PdxVty P. date Vty Pd.xVty

Female NS NS NS NS NS NS NS NS NS
Male NS NS NS NS NS NS NS NS NS
Fifth NS NS NS ** NS NS NS NS NS
Fourth ** ** ** ** NS NS NS NS NS
Third ** ** ** ** NS NS NS NS
Second ** ** ** ** NS NS NS NS

1979 Date 7/26 to 8/21 8/28 to 9/29 10/5 to 11/1

Stage P. date Vty PdxVty P. date Vty PdxVty P. Date Vty Pd.xVty

Female ** NS ** NS NS NS
Male ** NS NS Ns ** NS
Fifth NS NS ** NS NS ** NS
Fourth NS NS NS NS NS NS NS
Third NS NS NS NS NS NS NS
Second NS NS ** NS NS NS NS NS


NS = Nonsignificant (P > 0.05)

* = Significant (P < 0.05)

** = Highly significant (P < 0.01)










1 'EAR=77 METH=SC VTT=FORREST PLANTING DATE=E SPECIES=ACR
2N INSrTR
- 1] INSTHR
TH INSTARR
-5H INSTR +



9 I +I
/ +












SRMLIN t TE
3 ~











planted Forrest variety. Quincy, Florida, 1977.









YEAR=77 11ETH=SC VTY=BRAGG
2"0 INSTRR --3 INSTAR 4H INSTAR
--51H [NSTAR


PLANTING DATE=E


SPECIES=ACB


9


Is

/ U
U
U


I


6 1


Ii


+
++


L ~ j J A4 N,_


8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/27


SRMPLING DRTE
Fig. 44. Populations of A. hilare numphs collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida, 1977.


15 r


11 IL


H
z ZD



CL
LU


---L- I









YEAR=77 METH=SC VTT=FORREST PLANT[NG DATE=L SPECIES=ACR
2ND INSTAR 3R0 INSTAR -4T INSTAR
-S- 5TH INSTAH
12



4 6



I-- Ij \ +



L i I) I i N
3






8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/211 10/1 10/8 10/15 10122 10/27

SAMPLING ORTE Fig. 45. Populations of A. hiZare nymphs collected by ground cloth on lateplanted Forrest variety. Quincy, Florida, 1977.












iER~=77 METH=SC VTY=BRAGG


-30 INSTAB

-- 41" WNSTRH 4 +
- 5'" INSTAR t


PLANT[NG DATE=L


SPECI ES=ACR


IS


14
I,


I) ~ ~
I. if /



U \*
/


m


k


U
/
S


rS








N


6/5 /12 8/20 8/26 6/31 9/9 9/16 9/24 10/1 10/6


10/15 10/22 10/27


SAMPLING DATE Fig. 46. Populations of A. hilare mymphs collected by ground cloth on lateBragg variety. Quincy, Florida, 1977.


15 r


91[


CD




Lii









YEAR=78 METH=SC VTY=BRAGG PLANT[NG OATE=E SPECIES=RCR
-+-+ 2"0 INSTHR -- 3fl NSTflR 4TH INSTAR
5TH INSTAR.
20 1'





z+
) +

+ ~ I 1 m


0 -4 +







7/26 8/1 8/8 8/15 B/23 6/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/2411/M

SAMPLING DATE Fig. 47. Populations of A. hilare nymphs collected by ground cloth on earlyplanted Bragg variety.. Quincy, Florida, 1978.













)'ER=78 METfI=SC VTY=COBB

-+-+ 2ND INSTAR
---- 3R INST AR

1TH INST AR
--- 5TH [NSTRR


PLANTING DFTE=E


SPECIES=RCR


f


-


0


K
*-m -' + /
m
4.











4.
K
I
U I
+
+
+ N4.
4 -4
Ii


3






0


7/26 8/1 6/8 8/15.


8/23 6/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10121 1 /I


5RMPLING DATE

Fig. 48. Populations of A. hilare nymphs collected by ground cloth on earlyplanted Cobb variety. Quincy, Florida, 1978.


15 r


12 [






C-)

crJ 37


I I


'-1 ul


K

K






-, -4.
4.









is iEAR=78 METH=SC VTT=BRAGG PLANT[NG DATE=L SPECIES=ACR
-+- 20 NSTAB
--- 3RD INSTAR 4TH [NSTHR
-- SUH INSTAR








+//













7/26 8/1 0689/15 0/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/24 11/1

SAMPLING DATE Fig. 49. Populations of A hi7-are nymphs collected by ground cloth on lateplanted Bragg variety. Quincy, Florida, 1978.










YEAR=78 METH=SC VTr=COBB PLANTING DATE=L SPECIES=ACR
2N INSTAR
---- 3R0 [NSTAR
-I H INSTAR
---rnST INSTAR








a:a



[jj 6 /
+ \+






7/26 8/1 8/8 8/15 8/23 8/29 9/5 9/11 9/21 9/26 10/3 10/10 10/17 10/241 11/1

SAMPLING DATE Fiq. 50. Populations of A. hiZare nymphs collected by ground cloth on lateplanted Cobb variety. Quincy, Florida, 1978.









YERR=79 METH=SC VTY=FORREST PLANTING DRTE=E
-++2 10 INSTARR+ 3R) [NSTRR 4TH INSTAR


SPECIES=RCR


70 56


7/26 8/1 8/7 8/15 8/21 8/26 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DRTE
Fig. 51. Populations of A. hilare nymphs collected by ground cloth on earlyplanted Forrest variety. Quincy, Florida, 1979.


ST"f IN5Ri + I




+ + 4
-/
S




+ +

+ +
%NTR + t\




,+ t + +


//


4 2


(LJ 7z


14 [-


0


--A


- -










YEAR=79 METH=SC VTY=BRAGG PLANTING DATE=E SPECIES=ACR
210 INWT AR
---- 3f0 INSTAR --- 4TH INSTAR 36 STH INSTAH 3I6




+\



L \+


I








7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1 SAMPLING DATE Fig. 52. Populations of A. hiZ +are nymphs collected by ground cloth on earlyplanted Bragg variety. Quincy, Florida, 1979.









YEAR=79 METH=SC V.TY=COBB


PLANT[NG DATE=E


SPECIES=ACR


-+-


7/26 8/1 6/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DRTE
Fig. 53. Populations of A. hilare nymphs collected by ground cloth on earlyplanted Cobb variety. Quincy, Florida, 1979.


50 r


-3RD INSTAR 4T[jH INSTAR 51H INSTR






\+ t



/+B + B


110 [~


CD


LuJ


30 20


10 [~


0


CO









YEAfF=79 METH=SC VTY=FORfEST PLANTING DATE=L SPECIES=ACR
2 + "+ 2 INSTA R
3R0 INSTRR -11H INSTAR

20 5TH INSTAR









) \
4
4/ / s / + S











7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1

SAMPLING DATE Fig. 54. Populations of A. hilare nymphs collected by ground cloth on lateplanted Forrest variety. Quincy, Florida, 1979.













TEAR=79 METH=SC VTf=B

-+-+ 20 INSTAR
---- 3F1 [NSTFR

4T INSTAR
-- 5TH INSTAR


RRGG


PLANTING DATE=L


SPECIES=RCR


0
-u ~~~0 ~
0
0
/
0
/
0 3

-- 0


/ / N
/ \'
/ *\
a + I
/ N \\I
0 4.
,1 / \/ ~ 0
4 4.
V 0
0 N
/ +
0
I +
4.

4/
/
/4 +
- .~,
-4. -


7/26 6/1 8/7 6/15 8/21


8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1


SAMPLING DATE

Fig. 55. Populations of A. hilare nymphs collected by ground cloth on lateplanted Bragg variety. Quincy, Florida, 1979.


35 r


28 [~


21 [


CE
hiJ


Ii' 1


0


CO
rj












TEAR=79 METH=SC VTY=C
-+-+ 2ND INSTAR

3fD INSTAR

- TH INSTAR
---- STH INS TAR


OBB


PLANTING OATE=L


SPECIES=ACR


* / a


35







28


7/26 8/1 8/7 8/15 8/21 8/28 9/4 9/10 9/21 9/29 10/5 10/12 10/19 10/26 11/1 SAMPLING DATE


Fig. 56. Populations of A. hilare nymphs-collected by ground cloth on lateplanted Cobb variety. Quincy, Florida, 1979.


/ S

/
a
a
a
a K
/

/ a
a / a
/
/
/ / a
a /
/
a
4 .1.= ~
/ ~ \ a

I +-*~~~ 'a
/ + /
/ \ '
/ + +1

a '4'+
4, 4'
I, /

A
4
4/ 'a 1~
4/7 4
/
N.4


LiJ IE


21







111


0





84


A. hilare Nymphs

Populations of A. hiZare nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 43 through 56. Results of statistical analyses are shown in Table 2.

In 1977, no significant differences (P>0.05) were detected in

nymphal populations between varieties during the first sampling period. In the second sampling period only populations of the fifth instar differed significantly (P<0.05) among varieties. In the third sampling period populations of all nymphal stages differed significantly (P<0.05) among varieties. No significant (P>0.05) planting date effects were observed for any nymphal stage in any sampling period. Significant (P<0.05) variety times planting date interactions occurred only in the fifth instar nymphs during the second sampling period.

In 1978, no significant (P>0.05) differences were detected between varieties for any nymphal stage in the second or third sampling period. However, varietal differences were significant (P<0.01) for second, third, and fourth instars only in the first sampling period. In the first sampling period, only second, third, and fourth instars differed significantly (P<0.01) between planting dates. In the second sampling period all nymphal stages and in the third sampling period, second and third stage nymphs differed significantly (P<0.01 and P<0.05, respectively) between planting dates. Significant (P<0.01) variety x planting date interactions occurred only in the first sampling period for second, third, and fourth instars.

In 1979, no significant differences (P>0.05) among varieties were detected for any nymphal stage in the first sampling period. In the





85


second and third sampling periods, varietal differences occurred only for the fifth instar (P<0.05 and P<0.01, respectively). Significant (P<0.05) planting date differences occurred for all stages in the first sampling period. In the second sampling period, second and fifth stages, and third and fourth stages also differed significantly (P<0.01 and P<0.05, respectively) between planting dates. No significant (P>0.05) planting date differences were detected for any nymphal stage in the third sampling period. No significant (P>0.05) variety times planting date interaction occurred in any sampling period.


E. servus Adults

Populations of E. servus adults sampled in 1977, 1978, and 1979 are shown in Figs. 57 through 70. Results of statistical analyses are shown in Table 3.

No significant differences (P>0.05) in adult populations were detected between Forrest and Bragg varieties in the first, second, and third sampling periods, in 1977.

No significant differences (P>0.05) for both sexes, concerning planting date or variety x planting date interactions were found in 1977.

No significant variety or planting date effects or variety x planting date interactions were observed during the first sampling period in 1978. However, significant differences between planting dates were observed for both sexes in the second (P<0.05) and third sampling period (P<0.01). In the third sampling period, adult populations differed significantly (P<0.05) among varieties.





86


In 1979, significant differences between planting dates were observed for both sexes in the first sampling period (P<0.05), but no significant planting date effects (P>0.05) were observed in the second and third sampling periods.

Significant varietal differences for adult populations were

observed in the second (P<0.05) and third (P<0.01) sampling periods of 1979, but no significant (P>0.05) variety x planting date interactions occurred in any of the three sampling periods.


E. servus Nymphs

Populations of E. servus nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 71 through 84. Results of statistical analyses are presented in Table 3.

In 1977, no significant variety or planting date effects or

variety x planting date interactions were observed to the fifth nymphal stage. No significant differences (P>0.05) were detected in nymphal populations concerning the planting date effects or variety or variety x planting date interactions during the first sampling period. Planting date effects were observed for fourth, third (P<0.01) and second (P<0.05) instars during the second sampling period; however, it was not significant (P>0.05) in fourth, significant (P<0.05) in third, and significant (P<0.01) in second nymphal stages during the third sampling period.

Varietal differences were significant (P<0.05) for fourth and

highly significant (P<0.01) to third and second instars in the second sampling period, but it was highly significant (P<0.01) for the fourth





87


and second instars, and significant (P<0.05) for the third instar in the third sampling period of 1977.

No significant variety or planting date effects or variety x planting date interaction were found in nymphal populations in the first sampling period of 1978. Planting date effects were significant (P<0.05 to the fifth and P<0.01 in the third and fourth instars) except for the second (P>0.05) during the second sampling period. It was significant in all nymphal stages (P>0.05 for the second and third, and P<0.01 for the fourth and fifth instars) in the third sampling period. No significant differences (P>0.05) among varieties were observed for any nymphal stage in the second sampling period. It was detected for the fifth (P<0.05) and fourth (P<0.01) instars (second and third were not significant, P>0.05) in the third sampling period. No significant (P>0.05) variety x planting date interactions occurred in any sampling period.

In 1979, no significant differences (P>0.05) among varieties were detected for any nymphal stage in the first and second sampling period. In the third sampling period, significant differences were observed for the fifth (P<0.01) and for the fourth (P<0.05), but not for the second and third instars (P>0.05). In the first sampling period only the fourth and fifth instars differed significantly (P<0.05) between planting dates. In the second sampling period only the second and third instars differed significantly (P<0.01) between planting dates. There were no planting date effects for all nymphal stages in the third sampling period. No significant (P>0.05) variety x planting date interaction occurred in any of the three sampling periods.









TEAR=77 METH=SC VTY=FORREST PLANTING DATE=E SPECIES=EUS


MRLE
--FEMALE




















8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/23 SAMPLING OATE
Fig. 57. Populations of E. servus adults collected by ground cloth on earlyplanted Forrest variety. Quincy, Florida. 1977.










YEAH=77 METH=SC VTY=BRAGG


- MALE
--- FEMALE


/ I
/ / /
- N /


N


8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24 10/1

SAMPLING DATE
Fig.58. Populations of E. servus adults collected by ground
planted Bragg variety. Quincy, Florida, 1977.


10/8 10/15 10/22 10/27 cloth on early-


10 r


6I


CD) CE


0


00


PLANTING DATE=E


SPECIES=EUS


8 [


4 [










YEAR=77 METH=SC VTY=FORREST PLANTING DATE=L SPECIES=EUS


-- MALE
FEMALE





::D
C) -- - N
C-~)


Ui











8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/27 SAMPLING DATE Fig. 59. Populations of E. servus adults collected by ground cloth on lateplanted Forrest variety. Quincy, Florida, 1977.









YEAR=77 METH=SC VTY=BRAGG PLANTING DRTE=L SPECIES=EUS


MALE
FEMALE









LL










8/5 8/12 8/20 8/26 8/31 9/9 9/16 9/24 10/1 10/8 10/15 10/22 10/027 SAMPLING DATE Fig. 60. Populations of E. servus adults collected by ground cloth on lateplanted Bragg variety. Quincy, Florida 1977.









YEAR=78 METH=SC VTY=BRAGG


- MALE
FEMRLE




\ / \ /


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POPULATION DYNAMICS OF THE STINKBUG (HEMIPTERA: PENTATOMIDAE ) COMPLEX ON SOYBEAN AND COMPARISON OF TWO RELATIVE METHODS OF SAMPLING BY EURI PEDES B. MENEZES 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 1981

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TO MY WIFE AND MY DAUGHTERS

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ACKNOWLEDGMENTS I am very grateful to my chairman, Dr. D. C. Herzog, and committee members, Drs. R. I. Sailer, D. H. Habeck, and E. B. Whitty, for their guidance, advice and criticism throughout the course of this work. I wish to thank Dr. D. R. Minnick, G. E. Smart, Jr., and S. H. Kerr for their invaluable assistance and for their marked interest in my Ph.D. program. I wish to expres my gratitude to CoordenagHo do Aperfegioamento de Pessoal de Nivel Superior (CAPES) and Programa de Ensino Agricola Superior (PEAS) for their financial support through a fellowship, and to the Universidade Federal Rural do Rio de Janeiro for making possible the obtainment of this fellowship. I acknowledge the advice and assistance of Dr. G. E. Allen as former chairman of the supervisory committee. Thanks are also due to Mr. Andrew Brown, Mrs. Jill Y. Goreau, and Mr. Reginald L. Forehand for their help in my field work; Mr. Philip J. d'Almada for his assistance with statistics, and Mrs. Edna Larrick for her patience in typing this work. A very special gratitude is extended to Mrs. Barbara Hollien and Mrs. Sheila Eldridge for their help and encouragement, and to my dear friends, Mr. Edilson B. Oliveira, Mr. Tom Brunson, and Miss Enizet Moreira, for their encouragement and comfort. Last, but not least, my love and special gratitude is due to my wife, Elza M. Menezes, who always offered her support and devotion.

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I also extend my gratitude to my daughters, Caroline and Jacqueline, for having gone through the numerous upheavals associated with my studies. iv

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TABLE OF CONTENTS Page ACKNOWLEDGMENTS '"tt ABSTRACT INTRODUCTION CHAPTER I LITERATURE REVIEW 3 The Main Species of Stinkbugs 5 Nature of Damage 9 Sampling Population Dynamics 13 II MATERIALS AND METHODS 17 General Experimental Procedures 17 General Experiments in 1977, 1978, and 1979 17 Statistical Analyses 20 III EFFECTS OF SOYBEAN VARIETY AND PLANTING DATE ON ABUNDANCE OF DEVELOPMENTAL STAGES OF N. viridula, A. hilave, AND E. servus . . . 22 Results 22 Discussion 117 Conclusions 124 IV POPULATION DYNAMICS OF STINKBUG COMPLEX ON SOYBEANS 125 Results 125 Discussion 141 V COMPARISON OF TWO RELATIVE SAMPLING METHODS FOR THE STINKBUG COMPLEX ON SOYBEAN 154 Results 154 Discussion 156 Conclusions 157 REFERENCES CITED 252 BIOGRAPHICAL SKETCH 259 V

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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 POPULATION DYNAMICS OF THE STINKBUG (Hemiptera: Pentatomidae ) ON SOYBEAN AND COMPARISON OF TWO RELATIVE METHODS OF SAMPLING By Euri pedes B. Menezes March 1981 Chairman: Dr. Donald C. Herzog Major Department: Department of Entomology and Nematology The objectives of this three-year study conducted at the University of Florida, Agricultural Research and Education Center, Quincy, Gadsden County, Florida, include: (1) to compare sweep net and ground cloth sampling methods of measuring populations of three stinkbug species: Nezam vividula, Acvostemum hilave, and Euschistus servuss (2) to determine the distribution, species composition, and relative abundance of the pentatomids associated with soybeans in Florida; and (3) to determine the effect on stinkbug population dynamics of soybean varieties of different maturity planted on two dates. Forrest and Bragg soybean varieties were used in 1977, Bragg and Cobb in 1978, and all three varieties in 1979. Weekly samples of stinkbugs and other insects associated with those soybean varieties were taken by two methods: sweep net and ground cloth. vi

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In 1977, thirteen weekly samples were made with both methods, sweep net and ground-cloth, from August through the beginning of November on each plot of Bragg and Forrest soybean variety. In 1978, fifteen weekly samples were made with both methods on Bragg and Cobb, and in 1979, fifteen weekly samples were made with both methods on each plot of Bragg, Cobb, and Forrest soybean variety. Results are shown in Tables 1 through 16 and Figs. 1 through 168 N. viriduta was the most abundant species on all planting dates in all three years, and together with results of A. hilave, and E. serous adults characteristically colonized early plantings of early maturing varieties first and in greatest numbers. As the season progressed, later plantings and later-maturing varieties became more attractive to all species and in late season these plantings supported the largest populations of both adults and nymphs of all species. As earlymaturing varieties senesced, adults of all species studied moved to varieties of later maturity. Results indicate that the trap cropping method of controlling N. viriduta developed in Louisiana may also be used against these species in Florida. Adults of N. viriduta were usually the first to colonize timed plantings of Forrest, Bragg and Cobb during the three years of this study. Left uncontrolled this species produced very large nymphal and subsequent adult populations. Because of the magnitude of populations and apparent overlap, numbers of generations produced in individual plantings were impossible to determine, but it is probable that two occurred in certain plantings. vii

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Adults of both A. hilave and E, servus were very low relative to N. viridula. Nymphal populations of these species likewise were low with the exception of 1979. Population trends of these two species on the times-varietal plantings appeared to be quite similar to that of E. viridula. Single nymphal generations were produced in 1977 and 1978, but two generations of each species occurred in some plantings in 1979. In Florida, A. hilave and E. servus post little threat to soybean production of themselves, but as species components of the stinkbug pest complex they become significant because damage produced by members of the complex is similar and additive. For all three species the magnitude of the regression coefficients usually increased as development proceeded. This is probably a function of the degree of aggregation of individual developmental stages. Collections of adults and all nymphal stages of N. viridula, A. hilare, and E. servus by sweep net and ground cloth are significantly correlated. Data and regression analyses presented will allow the construction of coefficients for calibration between the methods for all development stages, on several varieties and planting dates.

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INTRODUCTION Soybean, Glycine max (L.) Merrill, because of its high yield of oil and protein, is a major source of food for human and animal consumption. Although the crop is being grown in many countries around the world, the United States, China, and Brazil have become centers of production. Soybean production in the United States doubled from 1960 to 1973, with the greatest rate of increase in southern latitudes (Turnipseed and Kogan, 1976). Soybeans are now the third leading crop in both acreage and value in the United States, exceeded only by corn and wheat; and of the 16 major food crops worldwide, soybean ranks sixth in acreage, exceeded only by the cereal crops, wheat, rice, corn, barley and millet (FAO, 1977). A continuous and rapid expansion of soybean acreage has been predicted, particularly for subtropical and tropical latitudes (Amer. Soybean Assoc., 1972). In Florida, for example, soybean acreage has increased 75-fold since 1949, to 450,000 A. in 1979 (Whitty, personal communication). Large increases in soybean acreage have altered the economic status of some insects; however, due to the length of the growing season and the nature of the crop, there are probably as many or more insects associated with soybean than with any other major crop produced in the U.S. Among these insect pests are the stinkbugs. E. B. Whitty, Agronomy Dept., University of Florida, Gainesville, Florida, 32611. 1

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2 The objectives of this three-year study include: (1) to compare sweep net and ground cloth sampling methods of measuring populations of three stinkbug species: Nezara vividula^ aarostemum hilare^ and Eusahistus serous; (2) to determine the distribution, species composition, and relative abundance of the pentatomids associated with soybeans in Florida; and (3) to determine the effect of soybean varieties of different maturity planted on two dates on stinkbug population dynamics.

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CHAPTER I LITERATURE REVIEW According to Herzog et al (1981) at least 40 species of stinkbugs occur worldwide on soybeans, but damage has actually been documented for only a few of these species. According to these authors, there is at least one important stinkbug pest species on the crop in every major soybean-producing region of the world. The following species have been reported as pests of soybean: Nezara vividula (L.), Aavostemvm hilare (Say), A. Aautwn (Dallas), A. marginatum (Palisot de Beauvois), Piezodorus guidinii ) (Westwood) P. pallesoens (Germar) Thyanta palHdovirens aaaera (Stal), austatov (F.), T. perditov (F.)', Edessa meditabunda (F.), Eusohistus servus (Say), E. tTistigumus [S^y) E. obsauvus (Palisot de Beauvois), E. quadratov {^o'\stor\) E. ictevicus (L.) E. heros (F.)_, E. crenator (F), and E. variolarius (Palisot de Beauvois). Based on its cosmopolitan distribution and the degree of feeding damage, the most serious species is N. viridula, commonly called the southern green stinkbug in the U.S. Turnipseed and Kogan (1976) stated that the stinkbug complex and the corn earworm, Eeliothis zea (Boddie), are the most serious soybean pod feeders in the U.S. Turnipseed (1973) listed the northern green stinkbug, A hilare, the southern green stinkbug, N. vividula, and the brown stinkbug, E. servus, as the three most important members of 3

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the stinkbug complex attacking soybean. According to him the green stinkbug is found in the south and northward into Missouri and some midwestern states. The southern green stinkbug is confined primarily to the southern and southeastern states, extending as far west as Texas and as far north as Arkansas, Tennessee, and Virginia (DeWitt and Godfrey, 1972). According to Blatchley (1926), the brown stinkbug, also common in the south and southeast, has been reported as far north as Massachusetts and west to New Mexico. Deitz et al (1976) reported the green stinkbug, A. hilave to be the most abundant stinkbug pest in soybeans in North Carolina, and the brown stinkbug E. sein)us, was also present in low numbers. According to Nettles et al (1970) N. vividula, A. hilave, and E. servus are the three main species which cause soybean injury in South Carolina. Jones and Sullivan (1978, 1979) reported the ratio of iV. vividula, A. hilave, and Eusohistus spp. in experimental plots in South Carolina to be 52, 30, and 16%, respectively, in 1974; and 60, 19, and 20% in a 1975 test. Jones (1979) studied the distribution and abundance of pentatomids in soybeans in South Carolina, and based on sweep net and ground cloth samplings found that both the green stinkbug and the brown stinkbug occurred in all three areas of the state sampled. The southern green stinkbug was restricted primarily to the coastal plain, where it was usually the predominant species present in 1976. McPherson (1978) reported that N. vividula, A. hilare, and E. sewus are the most abundant species in Louisiana.

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5 The Main Species of Stinkbugs A. Th e Southern Green Stinkbug. Nesara viriduta (L.) The life history of the southern green stinkbug, N. viriduta has been studied by a number of workers in different parts of the world (Jones 1918, Drake 1920, Cumber 1949, Everett 1950, Kiritani and Hokyo 1962, Mitchell and Mau 1969, Corpuz 1969, Singh 1972, Harris and Todd 1979a, 1980a). The work of Jones (1918), Drake (1920), and Harris and Todd (1980a, b, c, d) in Louisiana, Florida, and Georgia, respectively, provide a broad data base for this species in the southern United States (Herzog et al 1981). In the early spring, as the days begin to warm, the bugs emerge from overwintering quarters in search of food. According to Drake (1920), mating begins almost immediately upon emergence from hibernation. Corpuz (1969) observed 6-10 days and Mitchell and Mau (1969) 7 days for the premating period. The range of copulatory duration is l-165h., with a mean of 37.25 31 h. (Harris and Todd, 1980a). These authors reported 1-6 matings prior to oviposition (mean 1.94), and 3 days post-mating/pre-oviposition thus, a mean pre-oviposition period of 17.5 days. Jones (1918) and Wilson and Kelsheimer (1955) reported a pr-ovi position period of about 4 weeks. There is a distinct periodicity of oviposition with 75% of the eggs being laid in the last 3 hours of daylight. The pale yellow eggs are generally laid in hexagonal ly-shaped clusters, with individual eggs closely packed in regular rows and firmly glued to the substrate. The average incubation time is 5 days in the summer (Harris and Todd, 1980b).

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6 Kiritani (1963) reported that females mated repeatedly and deposited 80 to 100 eggs per mass with increasing mass size in decreasing intervals (7 to 10 days) between successive ovipositions. The average incubation period of eggs was 4 to 5 days. As incubation proceeds, the eggs become a deeper yellow, then pinkish-yellow, with a red crescent-shaped spot appearing on the operculum and, by the time of hatch, they are a rich orange color (Herzog et al., 1981). During the summer, the period from egg to adult is 35-37 days, depending on temperature (Jones, 1918; Drake, 1920; Harris and Todd, 1980a). Harris and Todd (1980a) studied the development of N. viHdula in the laboratory. In their study they used 75 egg masses laid by 20 females, and monitored development in the laboratory under controlled conditions of 25-28C, 55-65% RH, and a 14 h. photophase. The mean nymphal development period (days) was 36.7, divided by stages as follows: egg, 4.8; 1st instar, 3.8; 2nd instar, 5.2; 3rd instar, 4.5; 4th instar, 6.4; 5th instar, 11.9. They compared these observations with seven previous studies conducted in five countries, and they discussed inconsistencies among those studies concerning the possible effects of temperature, photoperiod, latitude, and rearing method. According to Jones (1918) nymphal development was first instar, 3 days; second instar, 4 days; third instar, 5 days; fourth instar, 6 days; fifth instar, 7 days. (Kariya (1961) reported 20 to 30C was the optimal temperature range for development. In the first instar, nymphs cluster on or near the egg mass and have not been observed to feed. Drake (1 920) stated that the nymphs begin to disperse and feed, just before or subsequent to molting.

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7 The tendency to aggregate carries through the third stage and is reported to have an effect on the rate of development and mortality (Kiritani, 1964a; Kiritani et al 1965; Kiritani and Kimura, 1965, 1967). Rizzo (1968) studied this stinkbug in Argentina and according to him 7 to 20 days after mating the female lays eggs in variable numbers of from 55 to 105, rarely less than 55 eggs. The nymphal stage has five instars and they have the following scheme: first, 3-9 days; second, 4-12 days; third, 5-10 days; fourth, 6-13 days; and fifth, 7-16 days, depending upon the temperature. Kiritani et al (1966) demonstrated that the mortality rate increased at adult emergence, leveled off at a constant rate until 60% mortality occurred, then suddenly increased thereafter. Jones (1918) reported an average male longevity of 44 days and female longevity of 51 days. Jones (1918) and Drake (1920) observed four generations per year in Louisiana and Florida, respectively, and according to Drake (1920) a fifth generation probably occurred in the southern portion of Florida. The nymphs, like the adults, are usually found upon those portions of the plant on which they prefer to feed, namely the tender growing shoot and especially the developing fruit (Herzog et al 1981). B. The Green Stinkbug, Aarostemum hilare The green stinkbug, Aarosternvm hilave, for a long time called the soldier bug, is one of those insects that may occasionally cause serious damage to widely different plants. In Utah, this species mated in midJune, and ovi position extended from June to September, peaking during July (Sorenson and Anthon, 1936). Females laid from 6 to 114 eggs

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8 averaging 41.5 (N=5). The incubation period ranged from 5-14 days, with an average of 8.1 days. The mean period of nymphal development per instar was: first, 5.06 days; second, 11.5 days; third 12.5 days; fourth, 16.5 days; and fifth, 20.7 days. Whitmarsh (1917) observed that green stinkbug females may deposit three clusters of eggs, with the first cluster always the largest, usually between 40 and 50 eggs. The normal period of incubation seems quite constant, as a rule, being 7-8 days. Underhill (1934) stated that in Virginia, the period of incubation of egg masses was 8.39 days; a female deposited 75-80 eggs. Nymphal development required (averages): first, 5.1 days; second, 5.9 days; third, 6.3 days; fourth, 7.2 days; and fifth 4.1 days. The average number of days from egg to adult was 38.5 days. Sailer (1953) reared A. hilave in confinement and speculated that more than one generation would occur in a season. The average time required for development was 55.2 days, with a minimum of 49 and a maximum of 81. C. The Brown Stinkbug. Eusahipstupi rgwus Woodside (1946) observed that the number of eggs per cluster varied from 1-28, the average being 16.3. The length of the incubation period was 8.7 days, and first instar, 5.5 days; second instar, 8.4 days; third instar, 9.0 days; fourth instar, 12.3 days; and fifth instar, 17.8 days. The total nymphal period was 53.2 days. Rolston and Kendrick (1961) working with this stinkbug in Arkansas, found an average of 21.1 eggs per cluster. The average incubation period was 5.4 days, ranging from 3-14, and the durations of nymphal stadia were: first, 3.7 days; 1-2, 8.8 days; 1-3, 13.7 days; 1-4.20.6 days; 1-5, 33.3 days. Nymphal

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9 development time ranged from 23-63 days. The combined egg and nymphal stages were completed in an average of 38.1 days. Nature of Damage Several workers have described the effects of damage to soybeans by stinkbugs. According to Jones (1976), nymphal and adult stinkbugs damage soybeans by piercing the pod wall into the developing seed. Salivary enzymes are injected into the seed and the liquified tissues are then withdrawn through the stylets. They attack all parts of a plant including stems, foliage (particularly leaf veins), flowers, and fruit, but prefer the tender young growth and fruiting structures. The feeding punctures form minute, hard brownish or blackish spots on the seed. The loss of plant juices, the injection of powerful digestive enzymes, and the profusion of entry sites for pathogenic and decay organisms all contribute to crop injury. The extent of stinkbug damage to soybeans depends upon the stage of seed development at which feeding occurs. Feeding by stinkbugs during the early stage of seed formation can result in shriveled, deformed, and undersized seeds; whereas, feeding during later stages of endosperm development results in a weakened, deformed area with puncture marks where the stylets pierced the seedcoat. The flesh of the cotyledons is often shrunken and deformed beneath the seedcoat, with a whitish chalky area where the cell's contents have been removed. Frequently, a dark discoloration may be present around the punctured area and the inner membrane of the seedcoat may be fused to the cotyledons rather than being free as is

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10 normal (Kilpatrick and Hartwig, 1955; Blickenstaff and Huggans, 1962; Daugherty et al., 1964; Miner, 1966; Turner, 1967; and Herzog et a1 1 981 ) Glower and Hankins (1960) and Miner (1966) indicated that high infestations of N. viridula could occur in maturing soybeans without any appreciable degree of yield reduction; however, stinkbugs could conceivably reduce yield through early infestations or in late maturing soybean varieties. Soybean seeds damaged by southern green stinkbugs have a slightly higher protein content and a slightly lower oil content than non-damaged beans (Miner, 1961, 1966). As the severity of stinkbug damage increases, linoleic palmitic, stearic, and oleic acids increase, while linolec decreases (Todd et al 1973). Seed damage can also reduce germination, emergence, and seedling vigor (Jensen and Newspm, 1972; Todd and Turnipseed, 1974; Thomas et al 1974). Stinkbug damage not only affects soybeans directly through reduction in yield and quality, but also by providing entry sites for disease organisms such as the yeast spot disease, Nematospora ooryli Peglion. In Florida stinkbugs in conjunction with wet weather may spread anthracnose, Glomevella glycines L. and W. and cercospora spot, Cevcospova sp, (Genung et al 1964). Ragsdale (1977) reported that the southern green stinkbug transmits the causal organisms of several bacterial diseases of soybean. Economic threshold studies have been conducted with the southern green stinkbug by Miner (1966), Duncan and Walker (1968), Todd and Turnipseed (1974), and Thomas et al (1974), and with the green

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11 stinkbug by Blickenstaff and Huggans (1962), Daugherty et al (1964), and Miner (1966). Their results show that one adult or large nymph per 3 row-ft. during seed enlargement and one bug per row-ft. after seeds are full size causes sufficient damage to justify treatment. McPherson et al. (1979), studying the stinkbug complex in Louisiana, reported similar results; however, their work revealed that late instar nymphs and adults of E. servus produced damage comparable to that of N. viridula and A. hilave when population densities were maintained at high levels. Miner (1966) compared the damage to soybean by the brown, green, and southern green stinkbugs in field cages. According to him the type and severity of damage by the green stinkbug was identical to damage by the southern green stinkbug. Field studies by Duncan and Walker (1968) revealed that 61.1, 45.6, and 33.1% damaged seeds were produced by densities of the southern green stinkbug of 2.5, 1.1, and 0.7/row-ft. when maintained over a 7-week period. Sampling The methods most commonly used to sample above ground populations of arthropods are: (a) direct observations, (b) ground cloth, (c) sweep net, and (d) vacuum or suction net (usually a D-Vac). The direct observations and the ground cloth may approach absolute or direct population estimates for some species, while the other two are relative sampling methods. Stinkbug sampling in soybeans is difficult due mainly to the clumped distribution early in the life cycle and a more nearly random distribution

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12 in later stages at high population densities. Since stinkbug damage is not readily visible in the growing crop, actual counts must be made necessitating greater effort in order to determine stinkbug population levels adequately. Absolute quantitative measurements of stinkbug populations are best made utilizing the fumigation cage method (Marston et al 1976). The ground cloth method of sampling so nearly approximates the absolute measurement of stinkbug populations that it may be considered as absolute and it is easy and quick (Todd and Herzog, 1980). Marston et al (1976) compared three relative sampling methods with an "absolute" fumigation cage method. The fumigation cage and ground cloth methods collected significantly larger numbers of stinkbugs than did the vacuum net and sweep net methods. Duncan (1968) comparing sweep net and ground cloth methods for sampling of N. viridula, concluded that fourth and fifth nymphal instars and adults were sampled with equal efficiency by both techniques, while second and third nymphal instars were not sampled adequately with either method. Rudd and Jensen (1977) compared sweep net and ground cloth sampling methods for N. viridula. They showed by regression analysis that numbers of stinkbugs captured by the two methods were highly correlated, ranging from r = 0.835 for il/. viridula females to r = 0.982 for fourth instar N. viridula, with r = 0.998 for third, fourth and fifth instars and adults combined. They concluded that a larger number of samples are required to measure a population mean with the ground cloth than with the sweep net (Herzog et al 1981).

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13 The time required for acquisition of samples v;as reported by Rudd and Jensen (1977) as 21.2 and 48.3 seconds/sample for the sweep net (25 sweeps) and ground cloth (6 row-ft.) methods, respectively. Their data indicate that the sweep net was superior to the ground cloth for most sampling objectives based on time required per observation. Since this research was with N. viridula, it cannot be directly related to other phytophagous pentatomids. Behavior probably differs among species to such an extent that factors for calibrating between sampling methods, calculated from regression analyses, would be significantly different for other species. However, for pest management purposes in the southeastern United States where N. viridula is the predominant species, calibrations for this species may be used without incurring significant error (Herzog et al 1981). For over a century the sweep net has been the most widely used tool for sampling arthropods on small grain, forage, and many row crops. One reason for this popularity, despite difficulties in standardizing the method for accurate population studies, is that no other method can capture as many insects from vegetation per man hour and with as little damage to the crop and cost for equipment (Ruesink and Kogan, 1975). Population Dynamics Understanding the population dynamics of pest species is essential for development of sound pest management systems. Seasonal abundance of soybean insect pests and predators have been reported by Raney and Yeargan (1977), Wuensche (1976), Deitz et al (1976), Kogan et al (1974),

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14 earner et al (1974), Shepard et al (1974). Burleigh (1972), Pedigo et al. (1972), and Herzog (1968). Little information is available on the abundance and population dynamics of stinkbug pests of soybeans, however. N. viridula has a complex population profile (Harris and Todd, 1980a). It is polyandrous, polygamous, mul tivoltine, and long lived as an adult, thus producing an overlap of generations (Kiritani, 1963; Harris and Todd, 1980b). Weather, population density, food, and natural enemies have all been cited as factors which influence the population dynamics of N. viridula. Jones (1918) observed heavy mortality to adults in the winter months in Louisiana during sudden drops in temperature. According to Kiritani and Hokyo (1962), adverse weather conditions are major mortality factors for eggs and early nymphal instars. In a five-year study, Kiritani (1964b) concluded that abundance of N. viridula was partly determined by the combination and relative abundance of host plants, and partly by climatic factors. He found winter to be the critical period for survival for this species with habitat heterogeneity and hibernacula the only means of insuring winter survival Herzog et al. (1981) postulated that all developmental stages are present on soybeans in Louisiana, Georgia, and Florida until harvest and may be collected from unharvested plants as late as mid-December. Bratley (1936, 1941) reported reduced populations of N. viridula in the spring in Florida following severe winters.

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15 Although N. vividula often invades soybean fields in large numbers early in the season, it barely maintains its population level until pod formation when the population increases drastically (Newson et al.,1975, Wuensche, 1976). Kiritani (1965) found that local overpopulation tends to increase mortality among immature vividula and decreases longevity, body weight, and fecundity of adults. He considered this a key factor in keeping populations in check. Pitts (1977) observed that despite a reproductive diapause in ff. vividula, overwinter survival is enhanced by the presence of succulent food. Adults often become active and feed during mild periods in the winter. The availability of cold-hardly plants, such as mustard, greatly increased survival of ff. vividula by providing an excellent hibernaculum and a constant source of food. The brown stinkbug, Eusahistus sewus, is an occasional pest of several vegetable crops in Arkansas (Rolston and Kendrick, 1961). Two generations occur in the northwestern section of the state, but few of the second generation nymphs become adults. The adults overwinter feed on common mullein in the spring before other hosts become available. They collected this species in small numbers on several field crops, none of which appeared to be particularly favored as a host. As the weather begins to warm in spring, adults move into clover, early vegetables, corn, and tobacco where they feed or oviposit (Herzog et al., 1981). The resultant nymphs and adults constitute the first generation. Tomatoes, leguminous and cruciferous vegetables, and okra become attractive! in April, May, and June, and these provide the major

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16 food sources and oviposition sites during early and mid-summer. Although a few individuals can be found in soybeans throughout the growing season, they provide a suitable food only after flowering and podset. According to the authors, this usually occurs in late July and August. By then, third generation adults are present and immigrate into soybeans which provide the major source of food in late summer and early fall (late July through November). Soybeans are not the only source of food for these species in Central and North Florida during this period as the very abundant weeds Besmodium sp. and Crotataria sp. are excellent hosts (Sailer, personal communication). *Dr. R. I. Sailer, Entomology and Hematology Department, University of Florida, Gainesville, Florida 32611.

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CHAPTER II MATERIALS AND METHODS General Experimental Procedures Studies were conducted at the University of Florida, Agricultural Research and Education Center, Quincy, Gadsden County, Florida, using Forrest and Bragg soybean varieties in 1977, Bragg and Cobb in 1978, and Bragg, Cobb and Forrest in 1979. General Experiments in 1977, 1978, and 1979 The soybeans were grown with the standard cultural practices described by Hinson (1967) and Whitty et al (1971). The crop was planted at approximately 67 Kg/ha with a row spacing of 0.91 m. The herbicides trifluralin 4EC and metribuzin 70WP were incorporated into the soil prior to planting at rates of 0.56 and 0.29 Kg/ha, respectively. At cracking time, alachlor 4EC and dinitroamine 2EC were applied at rates of 2.25 and 0.37 Kg/ai/he, respectively. Forrest (Maturity Group V) and Bragg (Maturity Group VII) soybean varieties were each planted on June 7, 1977, and June 22, 1977. Earlyplanted Forrest bloomed by July 17, and pod-fill began by August 10. Early-planted Bragg bloomed by July 24, and pod-fill began by August 20 Late-planted Forrest bloomed by July 31 and pod-fill began by August 22. Latepi anted Bragg bloomed by August 4 and pod-fill began by August 29. 17

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18 Bragg and Cobb (Maturity Group VIII) soybean varieties were planted on June 13 and June 30, 1978. Early-planted Bragg bloomed by July 29 and pod-fill began by August 22. Early-planted Cobb bloomed by August 5 and pod-fill began by September 4. Late-planted Bragg bloomed by August 10 and pod-fill began by September 3. Late-planted Bragg bloomed by August 10 and pod-fill began by September 3. Lateplanted Cobb bloomed by August 18 and pod-fill began by September 10. All three varieties were planted again on June 12, 13, and 27, 1979. Early-planted Forrest bloomed by July 25 and pod-fill began by August 22; meanwhile, Bragg bloomed by August 2 and pod-fill began by August 25. Cobb bloomed by August 11 and pod-fill began by September 6. Late-planted Forrest bloomed by August 7 and pod-fill began by August 27; meanwhile, Bragg bloomed by August 10 and pod-fill began by September 1. Cobb bloomed by August 18 and pod-fill began by September 12. Each plot consisted of 60 rows 24.38 m long; plots were arranged in a "split-plot" design. In each year the experiment was replicated two times. Weekly samples of stinkbugs and other insects associated with those soybean varieties were taken by two methods: sweep net and ground cloth. In the ground cloth method the cloth was placed between two rows of soybean, so that it was located beneath undisturbed foliage (Boyer and Dumas, 1963, 1969). Approximately 0.61 row/m of soybeans on each side were then vigorously shaken over the cloth. The stinkbugs and other insects that fell onto the cloth were collected and transferred to a plastic bag and were counted and recorded later. All second-fifth instars as well as adult pentatomids were identified and

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19 recorded. Sixteen samples per plot were taken along a diagonal, in order to sample the whole plot. Two rows were skipped between sampled rows. A modification of the sweep net method described by DeLong (1932) was used. This was the one-row variation as described by Kogan and Pitre, Jr. (1980). Sweeps were taken while walking beside the row, holding the handle of a 38 cm diameter sweep net directly in front of the observer, with the opening of the net always facing the row of plants to be sampled. Sixteen samples consisting of 50 consecutive sweeps ca. 0.61 m apart from alternating sides of the row while walking beside it, were taken per plot. After 50 sweeps in a single row, contents of the net were transferred to a plastic bag, and later counted and recorded. Two rows were skipped between sampled rows. In 1977, thirteen weekly samples were made with both methods, sweep net and ground cloth, from August through the beginning of November on each plot of Bragg and Forrest soybean varieties. In 1978, fifteen weekly samples were made with both methods on Bragg and Cobb, and in 1979, fifteen weekly samples were made with both methods on each plot of Bragg, Cobb, and Forrest soybean varieties.

PAGE 28

20 Statistical Analyses Two statistical analyses were performed: A. The model used for the 1977, 1978, and 1979 experiments was: ^ijk = ^ ^'i + ^ ^^ij Sij ^ ^k^^^^ik ^ ^jk ^ '^^•jk bijk where y = overall population mean i**^ planting date effect ^i J. u g. = j variety effect 3 ct3.. = ij^'^ planting date x variety interaction effect £.. = ij main plot error = k^*^ week effect ay^b = ik^*^ planting date x week interaction effect By^i, = jk^*^ variety x week interaction effect a^y..^^ = ijk**^ planting date x variety x week interaction effect e. .. = i jk subplot error. ^k ^ik ^jk ^•jk ijk The design was a split plot arrangement of treatments in a completely randomized design for each of three years. In 1977 and 1978, a 2 x 2 factorial was used on the main plot; for 1979, a 2 x 3 factorial was used on the main plot. On the split plot, 13 sampling dates were used for 1977 and 15 each for 1978 and 1979. For each year, the analysis was run for each combination of two collection methods, 3 species and 6 stages of insect development (including instars 2 to 5 and the adults). B. The model used was: Y. = 6, + B^X.^ + e.

PAGE 29

21 where Y^. = i^*^ stinkbug count by sweep net X. = i^^ stinkbug count by ground cloth e^. = i random error 3 = number of stinkbugs collectible by sweep net when no stinkbugs are collected by ground cloth 3, = changes in number of stinkbugs collected by sweep net per unit increase in number collected by ground cloth. For each of 3 years, the collection by ground cloth was regressed on the collection by sweep net. This was done for each combination of (i) 2 planting dates, 2 (or 3) varieties, 3 species and 6 stages; (ii) 3 species and 5 stages (instar 2 omitted); and (iii) 3 species (instar 2 omitted); over all other factors. ANOVA and summary of results tables were made for each species, stages, and methods studied. Data presented in Figs. 1 84b represent mean numbers of each stage collected per plot, representing 16 samples per plot. Ground cloth samples consisted of 1.22 row/m, and sweep net samples 50 sweeps. Therefore, data are figured on a basis of 19.51 row/m or 800 sweeps per plot.

PAGE 30

CHAPTER III EFFECTS OF SOYBEAN VARIETY AND PLANTING DATE ON ABUNDANCE OF DEVELOPMENTAL STAGES OF N. viridula, A. hilare, AND E. servus Results Stinkbug populations were sampled weekly with ground cloth on two or three soybean varieties planted on two dates during 1977, 1978, and 1979. From initial analyses, significant firstand second-order interactions with week were detected. Since these interactions were expected, and in order to resolve the effect of the other factors above the week effect, it was decided to partition the experimental period. Due to the size of the data, the number of partitions should be fewer than the number of sampling dates. The intention of partition was based on overall relative population growth (first period), a second period of relative stability, and a third period of decline were determined. Sampling periods did not always encompass the same crop growth stages among varieties and planting dates. N. viridvla Adults Populations of N. viridula adults sampled from early and late planting dates of Forrest and Bragg varieties in 1977, Bragg and Cobb in 1978, and Forrest, Bragg and Cobb in 1979 are shown in Figs. 1 through 14, respectively. Results of statistical analyses are shown in Table 1 22

PAGE 31

23 LiJ II (D LU O UJ D_ CO LU II LU ho: Q o oc _i LU CC OC o o CD II X I— LU II DC (T UJ LU _J UJ IX CC LU 2: a. 1=3 > s(O (U c 0 x: +j 0 0 •a c 0 sai J2 T3 > C T3 •r~ 3 o>> +J ?^ +-> CO 0
PAGE 32

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PAGE 33

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PAGE 34

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PAGE 35

27 In 1977, there was a significant difference in adult populations in the first (female and male P<0.05) and third sampling periods (female P<0.01, male P<0.05) on Forrest and Bragg varieties. No significant differences (P<0.05) occurred in the second sampling period. Populations of both males and females differed significantly (P<0.1) between planting dates in the first sampling period, but no significant differences were obtained in the second or third sampling periods. Variety times planting date interactions were significant (P<0.05) for both sexes in the first and second sampling periods, but were nonsignificant (P>0.05) in the third. In 1978, no significant difference (P>0.05) N. vividula adult abundance was detected between Bragg and Cobb varieties. Both males and females differed significantly (P<0.01) between early and late planting dates during the first sampling period, but no such differences (P>0.05) were detected in the second or third sampling period. No significant (P>0.05) variety times planting date interactions occurred. In 1979, both sexes differed significantly among varieties in the second (P<0.05) and third (P<0.01) sampling periods, but no significant difference (P>0.05) was detected among varieties in the first sampling period. Adult populations differed significantly among planting dates in the first (P<0.05), second (P<0.01) and third sampling period (female P<0.01, male P<0.05). No significant (P>0.05) variety times planting date interaction occurred.

PAGE 36

28 UJ •z. II tn O UJ II U t— CL O O CE QO O tr H II X UJ oo II 0= a UJ UJ _i UJ cr cr UJ C3 4D m CM OS in oo oo CO CO INnOD Nb3N

PAGE 37

29

PAGE 38

30 UJ II c: o •M O (J -o zs o s. a> >i • JD CO O) I— UJ -t^ cr-Q o o o '— 3 >, I -o U <^ ^ Q-r> OJ S(O > 4O cn (/)

PAGE 39

31 INnOO Nd3W

PAGE 40

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PAGE 41

33 I M UJ LD UJ (_> UJ 0. UJ II UJ I— GC O LD LD LD CZ oc m n H UJ II cc CE UJ UJ cc cr UJ I I CO OJ \ a a CM — CD LD — CD CM — CD QO rvj CO CO O) 1— +-> U LU — -a 1— 1 — *i — CE o su o Q 3 >, -o O fO c _J a 3 Qx: ^ cc CO > O D1 (/I (O C SO QQ -p -o (0 CU F— +J 3 C Q. ta O 1— Q. Q. U3 OJ US INnOG Nb3W

PAGE 42

34 u so u o o -o r+J r— o o o -o io to 1 — 4-> Uo >, c -r^ • +J > o (/) ^ c o o o +-> T3 (O (U I— -P 3 C O CL Q. CO

PAGE 43

iNnOG Nb3W

PAGE 44

36 LlJ II cn I— u cn II UJ I— cc a CD CE —I 0CE cc 03 II u CO II X I— UJ C71 II cc CE UJ UJ _l UJ a: cr LU CO CD OJ LPS C3 05 OJ OJ CD CX) OJ OJ LTS CO I +-> to cr cr CO o +-* o "o o c 3 o s. o> >> Jli 1^ •a at 0) (0 o o so o u_ +J ft 3 > -o o c cs cr >> M 0) •r— i. (0 > MO cn CP (/) fO C sO CQ -o (O 0) 4-> 3 c a. to o Q. CO CO iNn03 Nd3W

PAGE 45

37 rvi UJ o UJ a. cn N LlI I— oc a o -J m o o N O cn n UJ CD rII cc a: UJ UJ UJ cc cc LlJ U3 o o o in cn UJ O QD CO oo CD cr a cr cn CO UJ-5 +-> (0 C o +-) o o -a c O JCT/ >> T3 (U !-> > re u c •r— 3 3 cr >> (U •r™ s> O O o •r— 4-) T3 (T3 (U +-> C a. (O o a. Q. ^ Ll_ INnOO Nb3W

PAGE 46

38 Table 1. Results of analyses of variance for N. viridula concerning variety and planting date effects and variety x planting date interaction. Year Period First Second Third 1977 Date 8/5 to 8/20 8/26 to 9/24 10/1 to 10/27 Stage P. date Vty PdxVty P. date Vty PdxVty P. date Vty Pd.xVty Female * NS NS NS ** NS Male * NS NS NS NS Fifth X NS NS NS NS NS NS NS Fourth X NS NS NS NS NS NS ** NS Third X NS NS NS NS NS NS NS NS Second ** NS NS NS NS NS NS NS NS 1978 Date 7/26 to 8/23 8/29 to 9/26 10/3 to 11/1 Stage P. date Vty PdxVty P. date Vty PdxVty P. date Vty Pd.xVty Female 'k'k NS NS NS NS NS NS NS NS Male ick NS NS NS NS NS NS NS NS Fifth NS NS NS NS NS NS NS NS NS Fourth NS NS NS NS NS NS NS NS NS Third NS NS NS NS NS NS NS NS NS Second NS NS NS NS NS NS NS NS NS 1979 Date 7/26 to 8/21 8/28 to 9/29 10/5 to 11/1 Stage P. date Vty PdxVty P. date Vty PdxVty P. date Vty PdxVty Female NS NS NS ** ** NS Male NS NS ** NS ** NS Fifth NS NS ** NS NS NS ** NS Fourth NS NS NS NS NS ** NS Third ** NS NS NS NS NS NS NS NS Second NS NS NS NS NS NS NS NS NS = = ** = Nonsignificant (P>0.05) Significant (P < 0.05) Highly significant (P < 0.01)

PAGE 47

39 N. viridula Nymphs Populations of N. viridula nymphs sampled in 1977, 1978, and 1979 are shown in Figs, 15 through 28. Results of statistical analyses are shown in Table 1 In 1977, no significant differences (P>0.05) were detected in nymphal populations between Forrest and Bragg varieties, except in the third sampling period, when numbers of fourth and fifth instars differed significantly (P<0.01 and P<0.05, respectively). No significant differences (P>0.05) were detected in nymphal populations between planting dates, except in the first sampling period, when numbers of second and third through fifth instars differed significantly (P O.OT and P<0.05, respectively). No significant (P>0.05) variety x planting, date interactions occurred. In 1978, no significant differences (P>0.05) were detected in nymphal populations between Bragg and Cobb varieties or between planting dates. No significant (P>0.05) variety x planting date interactions were detected. In 1979, no significant differences (P>0.05) were detected in nymphal populations between Forrest, Bragg and Cobb varieties, except in the third sampling period, when numbers of fourth and fifth instars differed significantly (P<0.01). In the first sampling period numbers of all nymphal stages sampled (second through fifth) differed significantly (P<0.05) for second, fourth and fifth, P<0.01 for third) between planting dates. In the second sampling period numbers of fourth and fifth instars only differed significantly (P<0.05 and P<0.01, respectively) between planting dates. In the third sampling period

PAGE 48

40 INnOG NU3N

PAGE 49

41 INnOG NU3N

PAGE 50

42 rvi UJ II CO LU co ^ Q o cr LU cn az o LlH >o CO II ^ tr cc cc Qc HI cr cr d (X ^— \— y— ^— u~> (D if) in z z z z r" — — o rvj QO LO CO LO CM CO LO CO II S a X X. (C IlCC Pj CO 3* LO LU I >I I UJ (— cr Q CD CE CD I o o o T3 c O io> -o (U •> +-> ro o -o I— i. ro o I— U LL. -5 ^ E c E ZJ c >) z. to > -l-> l/t O
PAGE 51

43 M LlJ II I cc CC QC CC a d cc 1— 1— 1— 1— 00 0") a:) rx* z Q Q X X 1— OO =)< ru Ln CD ~ — UD 05 CO CO to OJ CO OJ Ln (O c o J= -(-> o u -o c o SC71 >1 ja u 0) (O XJ r— o s(J o Q. > 1. o C c 3 >> -M (U s> O cr> CO n3 e sO CQ •t" t-> T3 (O (U -!-> 3 Q. (0 O f-~ Q. 00 05 INnOQ Nb'3W

PAGE 52

44 c o jC 4-> O 1 — u o • J3 00 T3 CJ> 0) (O r— -O UJ 1 — 't — 1— O So o CE a Q. • CD i ?? >) O £ C •r 3 _J MP a: CO pi O (/) (O o ca +j -a ro OJ r— 4J 3 C Q. to o >— a. Q. IT) LiINRDD Nb3W

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46 LU II to • UJ bJ Q_ CO l' II UJ a o cc Q_ CD CD cr cc CD II CZ5 rvj CD U 0-1 II X (— UJ cr cr cc cr or a: cr cc (D (T) (T) (J-) CM Ln CO 03 II or cr UJ O Q nj cn oo CO INnOO Nb3W

PAGE 55

47 I c o -t-> o o D c o szn >> JD co -D M U (U -o O (J &o > C o c (3 S cr >> cu s^> o to J3 c O o O +-> X3 (0 O) M 3 c Q. O a. CJ cr, LL. INnOD Nb3W

PAGE 56

48 iNn03 Nb3N

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49 INnOG NU3N

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PAGE 60

52 UJ z II cn UJ u LU CL cr a cr -J 0o CE cc 1 J3 o> 0 CT> OJ M rs 0) 1 -M CU •r— i:^ > 0 to c: s0 CQ 1 -•-> T3 (0 3 c Q. (O 0 QCL CJ3 U-5 cr> INnOD Nb3W

PAGE 61

53 LU z II if) LU LU 0. CO H Ul HCC Q O -J 0. m CD o (-> n o CD II oc or Qc oc cr cr cc tx I— I— ^)— CO CO en CO 2 Z Z Z CD !l CC a: LU O Q z a: (\J (O o o o LO (=) „ LU oo CO cc CD o cr CO 0) 10 c o o I— u o c 3 o C7> >i £1 D CT> •(-> CTl O jQ to jQ C O O O +J T3 t— -M 3 £Z O.
PAGE 62

54 no significant differences (P 0.05) occurred between planting dates for any nymphal stage. No significant (P 0.05) variety x planting date interaction was detected. A. hilave Adults Populations of A. hilare females sampled in 1977, 1978, and 1979 are shown in Figs. 29 through 42 Results of statistical analyses are shown in Table 2. In 1977, no significant differences (P>0.05) in adult populations were detected between Forrest and Bragg varieties in the first sampling period. However, significant varietal differences were detected in the second sampling period for females and males (P<0.01 and P<0.05, respectively) and in the third sampling period for both sexes (P<0.05). No significant (P>0.05) planting date effects or variety x planting date interactions were detected. In 1979, significant differences (P<0.05) were observed for both sexes among Forrest, Bragg and Cobb varieties in all three sampling periods. Significant differences between planting dates were observed for both sexes in the first (P<0.01) and second sampling period (P<0.01 for females, P<0.05 for males). No significant planting date effects (P>0.05) were observed in the third sampling period. No significant (P>0.05) variety x planting date interactions occurred in any of the three sampling periods.

PAGE 63

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PAGE 64

56 II cc cr UJ >ru o LD oo C3 UJ _J cr UJ U3 CD cn 05 cn — oo U3 rvj rvj — oo rvj oo LTJ CO I >> s o o 3 O sUJ -o*" HOJ ^ 4J re Q ^ -r>— o CD O — -i u u. lice cn I/) 9% +J >> r— (J 3 C T3 re (3 r-^ >) !-> rs; 0) s^' re > *o O) (A re c s. O CQ 4-> -O re (U -M C Q. re O r— Q. Q. 1 o ro CD LU iNnOD NU3W

PAGE 65

57 o cr II > cn r— CO 1 1 r UJ to 1 — cn / 1 Q ~ — Q U • en > to 0 1 4J C CO ( — *f — Q_ ri 3 031 D or r>j en QO CO ^ • C3 nj r-^ OJ CO (O ru > oo 0 — Q. a. INnOG Nb9N

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PAGE 68

60 cc o (X II CD o I i. le 0) Clef) CD o T3 O O —I 0. CD CD O o 11 o CO II cc cr UJ LU _l UJ cr CX LU 05 (TJ ID CO QO QO (jO CM LU I — (X a: cn o 01 >)00 -a I— -o CD ,U r— l/l >1 3 O -D £= (O •>-. 'si +-> z (T3 M> O J3 V) ^ C O O O +J TJ (O
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61 a cr II CO UJ o lU Q. CO II LU I— a a o a: —I 0. o o cr cc CO II o
PAGE 70

62 cc cr II CO UJ o LU Q_ CO II UJ I— (T3 c O 4J O O o o sCD >>CXD ^ r-* -a <— 01 M O (O 0) TD I— SO O 0 r— UCO +- >5 Z3 U D != 03 -r01 Cr r +-> (U *f— ^ sro 4> O (/> ^ C O O O •M -a (O Ol I— 4J 3 £ Q. (O O 1— TO

PAGE 71

63 QC U CE II Si/) UJ O UJ Q_ to UJ CE D Z cc CD UJ OC QC O O in n UJ H OC CL UJ cr UJ u_ U3 o CD CM LD CD CM CM CO CO LD CO cc Q CO Q_ (X CO U3 >1 sOJ o o u -o c: rj o S>i 1 — j:^ n T3 >0 O) -o +-> u io lZ o o >> CO (J +-> 13 cy • ?^ (U > ^' +-> 4(/) O cu i. (/I sc o o u_ -t-> T3 (O OJ -M Q. O Q. 'q. r-v ro cn CSJ INnOG Nb3W

PAGE 72

64 CO OJ — CD ru C3 ru I s^ UJ ru — cn 1=3 C7> OS ru ru OD Ln — a cc CO oo to nj c o +-> o r— o T3 C 3 O so 0) U
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PAGE 74

66 CO o cr II cn <_) LlJ CD II UJ 1— cr Q a: _i a. cn UJ CO cc o u. II >cn II X I— LU cn II cr cr UJ LU _l UJ cr _i 2: cr LU U3 CM ru OJ CO LTJ 00 U3 ru cn 0) c o 4J o 0 c 3 0 >) •a re 4J sCU 0 Ll'0 J >> to 4-> C •r" 3 3 0 o>> -M 0) re > +0 (U st/1 c 0 0 U•t— -l-> -0 re
PAGE 75

67 O (T II in UJ u u II UJ I— cc Q O -J O CD CT CC CD II O CO II X II CE UJ UJ —I UJ • — CO 10 o o CT CTv T3 1 1 1 +J rtJ 0) T_J a: 1— o 3 c T3 -ro03 -1-) rs; Ln 0 oi 03 c s0 CO (D -M T3 (0 (U I— 4J 3 C 03 Q. (O 0 >— Ql CL CO CNJ cr.

PAGE 76

68 o cc II cn ijj o a. CO ,oi -a 1— (U O (O UJ a: u I— Q cc CD 10 +J >— >, 3 U T3 C cu ^ sta M> o c o o o +J T3 <0 0) t— (-> 3 C Q. (C O i— a. 0. CM D1 INnOG Nd3W

PAGE 77

69 Table 2. Results of analyses of variance for A. hilare concerning variety and planting date effects and variety x planting date interaction. Year Period First Second Third 1977 Date 8/5 to 8/20 8/26 tc ) 9/24 10/1 to 10/27 State P. date Vty PdxVty P date Vty PdxVty P date Vty Pd.xVty Female NS NS NS NS ** ** NS NS Male NS NS NS NS it NS NS Fifth NS NS NS NS ** NS NS Fourth NS NS NS NS NS NS NS NS Third NS NS NS NS NS NS NS NS Second NS NS NS NS NS NS NS NS 1978 Date 7/26 to 8/23 8/29 to 9/26 10/3 to 11/1 Stage P. date Vty PdxVty P date Vty PdxVty P date Vty Pd.xVty Female NS NS NS NS NS NS NS NS NS Male NS NS NS NS NS NS NS NS NS Fifth NS NS NS ** NS NS NS NS NS Fourth ** ** ** ** NS NS NS NS NS Third ** ** ** ** NS NS NS NS Second ** ** ** ** NS NS NS NS 1979 Date 7/26 to 8/21 8/28 to 9/29 10/5 to 11/1 Stage P. date Vty PdxVty P date Vty PdxVty P Date Vty Pd.xVty Female ** NS ** NS NS NS Male ** NS * NS Ns ** NS Fifth NS NS ** NS NS ** NS Fourth NS NS NS NS NS NS NS Third NS NS NS NS NS NS NS Second NS NS ** NS NS NS NS NS NS = Nonsignificant (P > 0.05) = Significant (P < 0.05) = Highly significant (P < 0.01)

PAGE 78

70 o II CO o UJ CO II LU t— (X a CD _j a. in UJ cc cc o u. II o cn n CC oc CC or cr CE d CE 1— ^CO 0CO CO a CC r\j 00 3" X — IT) c 1 — Sn c o SI -u 09 \ o t — 1 o T3 O O • air-=r cri fM >>'— LU CO CU T3 ^_ CC 4-) •.CJ S> (/I O (T) ^ c Q.Too Q_ LO cc ety. CO ITJ • > rvj +-> 4to oo O O) s(/) sc o o uCO Populati planted CO "idol iNn03 NU3W

PAGE 80

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PAGE 81

73 o a a X X E c: 1I— f\J 00 3* LO I o o T3 c O i. D1 >> "O LU ^ I— o Q I— CD O r— U O -C -o >— c Q. •(— -J i,^ C_ E;cr CO (J 3 o*. o >, +J I/) OJ C •!O J•I(C +-> > n3 >— cn 3 C7) Q. ro O SO. CO INnOG NU3W

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PAGE 83

75 o cz II CO UJ o a. co cc Q CD CD CO o CJ II CJ CD n cr d cr cc 2" I— t— I— 1— tr< CO CO CO CO I, a Q X :r 3 a: ItCC fvj CO ^ LT) S T ; 'T : O O m o ^ LU 5^ fCJ> Q„ a a5 CO 05 03 ro CO LT) CO oo CO CO CE CO I > sc o o u a c: o s. >iOO J2 o t-> o en T3 o to cr >> (U s+> o c o o o I/) M T3 I— +J Ql ro O I— a. o. 00 iNnOD NU3W

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76 DC (_) cc II CO LlI CJ LiJ Q_ cn I— az a o cr Q_ O O cr CO II o CO II X I — UJ 03 II cr LU or cc cc cc 'X cr cr a: I— f— t— I— 00 CO cn CO a a X X cc Vicu CO =r bi CD CD — CO ^ LU a5 CD — cn CD OJ m OJ — OS LTJ CO rvj cr CO I -M o +-> o c :3 o scn • 00 JD CTl -D (1) •> +-> (O CJ "D 0) f— s_ I— o o <— a Li_ in >i Q. u I, c •1" C 3 cr a >) cu •rS> O cn oi to (O c O CQ +-> -o c Q. O a. Q. CD INRDD Nd3N

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84 A. hilare Nymphs Populations of A. hilare nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 43 through 56., Results of statistical analyses are shown in Table 2. In 1977, no significant differences (P>0.05) were detected in nymphal populations between varieties during the first sampling period. In the second sampling period only populations of the fifth instar differed significantly (P<0.05) among varieties. In the third sampling period populations of all nymphal stages differed significantly (P<0.05) among varieties. No significant (P>0.05) planting date effects were observed for any nymphal stage in any sampling period. Significant (P<0.05) variety times planting date interactions occurred only in the fifth instar nymphs during the second sampling period. In 1978, no significant (P>0.05) differences were detected between varieties for any nymphal stage in the second or third sampling period. However, varietal differences were significant (P<0.01) for second, third, and fourth instars only in the first sampling period. In the first sampling period, only second, third, and fourth instars differed significantly (P<0.01) between planting dates. In the second sampling period all nymphal stages and in the third sampling period, second and third stage nymphs differed significantly (P<0.01 and P<0.05, respectively) between planting dates. Significant (P<0.01) variety x planting date interactions occurred only in the first sampling period for second, third, and fourth instars. In 1979, no significant differences (P>0.05) among varieties were detected for any nymphal stage in the first sampling period. In the

PAGE 93

85 second and third sampling periods, varietal differences occurred only for the fifth instar (P<0.05 and P<0.01, respectively). Significant (P<0.05) planting date differences occurred for all stages in the first sampling period. In the second sampling period, second and fifth stages, and third and fourth stages also differed significantly (P<0.01 and P<0.05, respectively) between planting dates. No significant (P>0.05) planting date differences were detected for any nymphal stage in the third sampling period. No significant {P>0.05) variety times planting date interaction occurred in any sampling period. E. servus Adults Populations of E. servus adults sampled in 1977, 1978, and 1979 are shown in Figs. 57 through 70. Results of statistical analyses are shown in Table 3. No significant differences (P>0.05) in adult populations were detected between Forrest and Bragg varieties in the first, second, and third sampling periods, in 1977. No significant differences (P>0.05) for both sexes, concerning planting date or variety x planting date interactions were found in 1977. No significant variety or planting date effects or variety x planting date interactions were observed during the first sampling period in 1978. However, significant differences between planting dates were observed for both sexes in the second (P<0.05) and third sampling period (P<0.01). In the third sampling period, adult populations differed significantly (P<0.05) among varieties.

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86 In 1979, significant differences between planting dates were observed for both sexes in the first sampling period (P<0.05), but no significant planting date effects (P>0.05) were observed in the second and third sampling periods. Significant varietal differences for adult populations were observed in the second (P<0.05) and third (P<0.01) sampling periods of 1979, but no significant (P>0.05) variety x planting date interactions occurred in any of the three sampling periods. E. servus Nymphs Populations of E. servus nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 71 through 84. Results of statistical analyses are presented in Table 3. In 1977, no significant variety or planting date effects or variety x planting date interactions were observed to the fifth nymphat stage. No significant differences (P>0.05) were detected in nymphal populations concerning the planting date effects or variety or variety X planting date interactions during the first sampling period. Planting date effects were observed for fourth, third (P<0.01) and second (P<0.05) instars during the second sampling period; however, it was not significant (P>0.05) in fourth, significant {P<0.05) in third, and significant (P<0.01) in second nymphal stages during the third sampling period. Varietal differences were significant (P<0.05) for fourth and highly significant (P<0.01) to third and second instars in the second sampling period, but it was highly significant (P<0.01) for the fourth

PAGE 95

87 and second instars, and significant (P<0.05) for the third instar in the third sampling period of 1977. No significant variety or planting date effects or variety x planting date interaction were found in nymphal populations in the first sampling period of 1978. Planting date effects were significant (P<0.05 to the fifth and P<0.01 in the third and fourth instars) except for the second (P>0.05) during the second sampling period. It was significant in all nymphal stages (P>0.05 for the second and third, and P<0.01 for the fourth and fifth instars) in the third sampling period. No significant differences {P>0.05) among varieties were observed for any nymphal stage in the second sampling period. It was detected for the fifth (P<0.05) and fourth (P<0.01) instars (second and third were not significant, P>0.05) in the third sampling period. No significant (P>0.05) variety x planting date interactions occurred in any sampling period. In 1979, no significant differences {P>0.05) among varieties were detected for any nymphal stage in the first and second sampling period. In the third sampling period, significant differences were observed for the fifth (P<0.01) and for the fourth (P<0.05), but not for the second and third instars (P>0.05). In the first sampling period only the fourth and fifth instars differed significantly (P<0.05) between planting dates. In the second sampling period only the second and third instars differed significantly (P<0.01) between planting dates. There were no planting date effects for all nymphal stages in the third sampling period. No significant (P>0.05) variety x planting date interaction occurred in any of the three sampling periods.

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93

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102 Table 3. Results of analyses of variance for E. sewus concerning variety and planting date effects and variety x planting date interaction. Year Period First Second Third 1977 Date 8/5 to 8/20 8/26 to 9/24 10/1 to 10/27 Stage P. date Vty PdxVty P, date Vty PdxVty P. date Vty PdxVty Female NS NS NS NS NS NS NS NS NS Male NS NS NS NS NS NS NS NS NS Fifth NS NS NS NS NS NS NS NS NS Fourth NS NS NS ** NS NS ** Third NS NS NS ** ** ** * •Me Second NS NS NS ** ** ** ** 1978 Date 7/26 to 8/23 8/29 to 9/26 10/3 to 11/1 Stage P. date Vty Pd.xVty P, date Vty PdxVty P. date Vty PdxVty Female NS NS NS NS NS ** NS Male NS NS NS NS NS ** NS Fifth NS NS NS NS NS ** NS Fourth NS NS NS ** NS NS ** NS Third NS NS NS ** NS NS NS NS Second NS NS NS NS NS NS NS NS 1979 Date 7/26 to 8/21 8/28 to 9/29 10/5 to 11/1 Stage P. date Vty PdxVty P, date Vty PdxVty P. date Vty PdxVty Female NS NS NS NS NS ** NS Male NS NS NS NS NS ** NS Fifth NS NS NS NS NS NS ** NS Fourth NS NS NS NS NS NS NS Third NS NS NS ** NS NS NS NS NS Second NS NS NS ** NS NS NS NS NS NS = Nonsignificant (P > 0.05) = Significant (P < 0.05) = Highly significant (P < 0.01)

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113 UJ H LU UJ t/5 LU n UJ I— cr o a: CD m o u o II X 1— UJ cc CE cc oc cr cr cc cr 1— (— 1— 1— cn cn CO cn z z 1— 1 Q o r a: I— 1— CM cn =f in CM O o o •CD Ol >>cr> x> 1^ o >— (U LU +-> OJ 1— CE CJ (O o) -a a .— sO o o U r— o LL. t/) ^ > =r \ Ol L I Q>> E u 5^ c C -r3 OD :c 05 O" CE s cn g < >, -l-> rj (U — oo • "r" fel s(C IT) 4> O 43 oo (/) ^ C O O O •rOS ulat n "f" orl II LcU Q. ITS oo O 1— Q. Q. CO INHGD NU3W

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117 Discussion N. viridula Adults Adults of N. viridula were not collected in any planting at the beginning of the first sampling period of 1977. By the end of the first sampling period on August 20, both sexes had invaded the early Forrest planting in sufficient numbers that statistical analyses indicated significantly larger numbers in the early date plantings and in the Forrest variety. In 1978, adults of this species were collected only in early-planted Bragg on the first sampling date. By the end of the first sampling period on August 23, sufficient numbers had invaded early plantings of both varieties that statistical analyses indicated significantly larger populations than in the later plantings. In 1979, no adults were collected in any planting on the first sampling date. Statistical analyses indicated that by the end of the first sampling period larger populations of both sexes were present in the earlier planting dates. In the second sampling period in 1977 adults continued to increase disproportionately in early-planted Forrest as compared to other plantings. Since the earlier Forrest planting set pods before either of the Bragg plantings or the late-planted Forrest, these results confirm those of Newsom and Herzog (1977). They reported that adults of N, viridula were attracted to soybean plantings on which developing pods were first available. They further reported that this behavioral characteristic allows early plantings of early-maturing varieties, such as Forrest, to be used as trap crops.

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118 In 1978 and 1979, adult populations continued to increase in the second sampling period. However, in 1978 no variety or planting date effects were detected. In 1979, both sexes were present in significantly greater numbers on Forrest than on either Bragg or Cobb, and on early than on late plantings. Early in the third sampling period of both 1977 and 1979 plantings of Forrest began to mature, resulting in dispersal of adults into plantings of later-maturing varieties (Bragg and Cobb). It is this movement of adults that is prevented by judiciously timed insecticidal applications to trap plantings (Newsom and Herzog, 1977). In 1977, both sexes were significantly higher in Bragg than in Forrest varieties. In 1978 no variety or planting date effects could be detected. In 1979, early plantings supported the largest populations of adults. Cobb supported significantly higher, Forrest significantly lower adult populations than Bragg. In 1977 adult populations peaked on September 24 in early-planted Forrest, October 1 (females) and October 8 (males) in late-planted Forrest, October 8 in early-planted Bragg, and October in late-planted Bragg; in 1978, October 3 in early-planted Bragg, October 10 in lateplanted Bragg and late-planted Cobb, and October 17 in early-planted Cobb; in 1979, September 29 in early-planted Forrest, September 29 (females) and October 5 (males) in late-planted Forrest, October 19 (females) and October 26 (males) in late-planted Bragg, and October 26 in early-planted Bragg and both plantings of Cobb. Examination of the adult population curves for many of the plantings in all three years of the study reveals an interesting difference in the

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119 behavior of females and males. In many cases, females invaded earlier and in larger numbers than did males. This confirms observations of Herzog (personal communication) and others that colonizing females are usually mated and probably begin ovipositing almost immediately. Likewise, females often disperse from a particular planting earlier and at a faster rate than males. N. viridula Nymphs In the first sampling period of 1977, no significant varietal effect was found on any of the nymphal stages. Significantly more nymphs of all stages were found in the early plantings of both the Forrest and Bragg varieties, resulting from earlier adult invasions of these plantings. In 1978, no significant varietal or planting date effects were detected on any nymphal stage. In 1979, however, as in 1977, significantly more nymphs, at all stages were collected in the early date plantings, resulting from early invaion of adults. In the second sampling periods of 1977 and 1978 no significant variety or planting date effects were detected on nymphs. In 1979,. significantly more fourth and fifth instar nymphs were collected from early than late plantings, but no differences were detected for second or third instars. In the third sampling period of 1978, no variety or planting date effects were evident. In 1977 and 1979, populations of fourth and fifth nymphal instars were significantly lower on Forrest than on the later-maturing Bragg or Cobb. This probably occurred because the earlier senescence (maturity) of Forrest results in Bragg and Cobb

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120 being more attractive and suitable for oviposition by females. Subsequent nymphal populations therefore were greater in the later maturing varieties. The very evident difference in results obtained in 1978 compared to 1977 and 1979 probably occurred because of the absence of the earlymaturing variety Forrest in the 1978 study. On September 9, 1977, and October 5, 1979, peaks in fifth nymphal instar occurred in late-planted Bragg which cannot be completely accounted for by subsequent increases in the adult population. This indicates movement of emerging adults into earlier plantings or earlier maturing varieties. The same phenomenon may be occurring with the prolonged fifth instar peak in the late Bragg planting in 1978. A, hilare Adults Adults of A. hilare were not collected on the first sampling date in 1977 or 1978 from any planting except early-planted Forrest. No variety or planting date effects were detected in either year in the first sampling period. In 1979, significantly more males and females were collected in the early plantings and in the earlier maturing Forrest and Bragg varieties. Although numbers were much smaller, the 1979 result is similar to that observed in E. viridula, indicating that A. hilare may be potentially controlled with trap crops. In the second sampling period in 1977, significantly more adults of both sexes were collected in Forrest than Bragg variety. In 1978 no variety or planting date effects were detected. In 1979, significantly more males and females were collected in the early plantings, and Forrest than in Bragg or Cobb varieties.

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121 In the third sampling period of 1977, significantly more males and females were collected from Bragg than from Forrest. In 1978, no significant variety or planting date effects were detected. Again in 1979, significantly fewer adults were collected from Forrest than from the later-maturing varieties. The results observed closely parallel those obtained with N. viridula. Apparently the earlier maturity of Forrest resulted in dispersal of adults into later maturing varieties. As was observed with N. vividula^ females of A. hilccre often invaded certain plantings earlier and in larger numbers than males. Likewise, they also often dispersed from a particular planting earlier than males. N. hilare Nymphs In the first sampling period of 1977, no significant variety or planting date effects were detected on any nymphal stage because no nymphs were collected from any planting on any of the three sampling dates. In 1978, however, second through fifth nymphal instars were collected on August 23, but only in the early Bragg planting. Only second through fourth instars were found in significantly greater numbers in the early plantings and Bragg variety. The significant variety x planting date interaction occurred by virtue of these stages occurring only in the early Bragg planting. In 1979, all nymphal stages occurred in greater numbers in early date plantings. In the second sampling period of 1977, significantly more fifth instars were collected in Bragg than Cobb varieties. Interestingly, however, a significant variety x planting date interaction occurred

PAGE 130

122 because the late Bragg planting supported more fifth instars than did the early Bragg planting, while the nymphal populations of both Forrest plantings were similar. In 1978, larger numbers of all nymphal stages were collected in early plantings. In 1979, fifth instars were significantly more abundant on Forrest than on later-maturing Bragg and Cobb. Second through fifth instars were more abundant in early plantings. During the third sampling period of 1977, all nymphal stages were more abundant on Bragg than on Forrest. In 1978, second and third instars only were more abundant in late than early plantings. In 1979, fifth instars only were more abundant on Bragg and Cobb than on Forrest. E. servus Adults At beginning of the first sampling periods of 1977 and 1979 on August 15 and July 26, respectively, adults of E. servus were collected only from early-planted Forrest. In 1978, a single adult female was collected on the first sampling date from early-planted Cobb. No variety or planting date effects were detected in either 1977 or 1978. In 1979, significantly more males and females were collected from early plantings. No significant variety or planting date effects were detected in the second sampling period of 1977. In 1978, however, significantly larger populations of both males and females were collected from early date plantings. In 1979, on the other hand, significantly more adults were collected from Forrest than from the later-maturing varieties of Bragg and Cobb.

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123 No significant variety or planting effects were detected in the third sampling period of 1977. In 1978, however, significantly more adults were collected from late-date plantings and from Cobb than from Bragg. In 1979, as Forrest plantings matured, adults dispersed to Bragg and Cobb which were still acceptable hosts. E. serous Nymphs No nymphs of any stage were collected in the first sampling period of either 1977 or 1978. In 1979, second through fifth nymphal instars were collected from both Forrest plantings and from early plantings of both Bragg and Cobb. Only fourth and fifth nymphal instars were significantly more abundant in the early plantings. In the second sampling period of 1977, second and fourth nymphal instars were more abundant in early-date plantings and on Forrest variety, while the reverse was true with third instars. The reason for this inconsistent result is unknown. In 1978, third, fourth and fifth nymphal instars were significantly more abundant in early plantings, which corresponds with the availability of developing pods as food. Likewise, in 1979, second and third instars were significantly more abundant in early plantings. In the third sampling period of 1977, second and third nymphal instars were more abundant in early plantings, and second, third and fourth instars were more abundant on Bragg than on Forrest. In 1978, nymphal stages were more numerous in late plantings, and fourth and fifth instars more numerous on Cobb than Bragg. In 1979, fourth and fifth instars were more abundant on Bragg and Cobb than on Forrest.

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124 Conci usions N. vividula was the most abundant species on all planting dates in all three years. Characteristically, i7. vividula, A. hilare, and E. servus adults colonized early plantings of early maturing varieties first and in greatest numbers. As the season progressed, later plantings and later-maturing varieties became more attractive to all species and in late season these plantings supported the largest populations of both adults and nymphs. As early-maturing varieties senesced, adults of all species studied moved to varieties of later maturity. Results indicate that the trap cropping method of controlling Ifl. viridula developed in Louisiana (Newsom and Herzog, 1977) may also be used against this species in Florida.

PAGE 133

CHAPTER IV POPULATION DYNAMICS OF STINKBUG COMPLEX ON SOYBEANS Results Three species of stinkbugs, besides others of minor importance, were sampled weekly by both ground cloth and sweep net methods on three different soybean varieties in Florida in 1977, 1978, and 1979. Nezara viridula Adults Populations of N. viridula adults sampled from early and late planting dates of Forrest and Bragg varieties in 1977, Bragg and Cobb in 1978, and Forrest, Bragg, and Cobb in 1979 are shown Figs. 1 through 14, respectively. Results of statistical analyses are shown in Table 4. Highly significant differences (P<0.01) in populations of both males and females through time were observed for all three periods of 1977. Planting date x week interactions were highly significant (P<0.01) for both sexes in the second sampling period, and significant (P<0.05) for females but nonsignificant (P>0.05) for males during the third sampling period of 1977. Variety x week interactions were not significant (P>0.05) for either males or females in the first and second sampling periods, but were highly significant (P<0.01) in the third period. No significant 125

PAGE 134

12$ (P>0.05) planting date x variety x week interactions occurred in 1977. Populations of both sexes differed (P<0.01) through time in all three sampling periods of 1978. Planting date x week interactions were significant (P<0.05) for females and highly significant (P<0.01) for males in the first sampling period, but were nonsignificant (P>0.05) in the second and third sampling periods. No significant (P>0.05) variety x week interactions occurred in the first, second and third sampling periods. No significant (P>0.05) planting date x week x variety interactions occurred in 1978. The week effect was significant (P<0.01) for males and females in the first, second, and third sampling periods of 1979. Planting date X week interactions were significant (P<0.05) for females but nonsignificant (P>0.05) for males in the first sampling period; however, these interactions were highly significant for both sexes in the second and third sampling periods. No significant variety x week interactions were observed for males or females in the first sampling period, but they were highly significant (P<0.01) for females in the second and third sampling periods. For males, this interaction was nonsignificant (P>0.05) in the second, but highly significant (P<0.01) in the third periods. No significant (P>0.05) planting date x variety X week interactions were detected. N. vividula Nymphs Populations of N. viridula nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 15 through 28. Results of statistical analyses are shown in Table 4.

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PAGE 136

128 o 4J o o 0) O) sfO (O -M Q. o en 1—1 X X X T3 Q. 3 > X ^ CVJ 3 X cr> >> T3 C o > o +j u X a. t— 4 CM 3 \ X 00 >> -M +J (/) o > S+J u_ U3 CM \ 3 X T3 Q. 3 00 00 oo 00 oo oo * * 00 00 K * z: z 00 oo 00 00 oo oo ****** ****** 00 00 00 00 00 to z z z z z z * 00 00 00 00 00 * 00 * * z ****** ****** c/^ oo 00 00 00 oo 00 oo z z * * 00 * * z * * ****** ****** a; ^ T3 iTJ V; c M a.o > 1/1 •r™ 1 x: E O •r•r" z OO II II II 00 * z

PAGE 137

129 In 1977, highly significant differences (P<0.01) were detected in nymphal populations (except the fifth instar, P>0.05) among weeks during the first sampling period. In the second and third sampling periods nymphal populations differed significantly (P<0.01) among weeks, except the second instar in the second sampling (P<0.05). Highly significant (P<0.01) planting date x week interactions occurred in the first sampling period, but were nonsignificant (P>0.05) for the fifth instar. In the second sampl ing period these interactions were significant (P<0.05) for the second and third instars and nonsignificant (P>0.05) for the fourth and fifth instars. In the third sampling period populations this interaction was nonsignificant (P>0.05) for all nymphal stages (except the fourth instar, P<0.05). In 1978, significant differences (P<0.01) were detected for all nymphal stages among weeks in the first sampling period. In the second and third sampling periods, this interaction was significant for (P<0.01) second, third, fourth and fifth (P<0.05) instars. No significant (P>0.05) planting date x week interactions was found for the fifth instar in the first sampling period; however this interaction was highly significant (P<0.01) for all other stages. In the second sampling period no significant (P>0.05) planting date x week interactions occurred for the third and fourth instars, but this interaction was significant (P<0.05) for the second and fifth instars. In the third sampling period that interaction was significant (P<0.05) only for the second instar. No significant (P>0.05) planting date x week or planting date x week x variety interactions were detected.

PAGE 138

130 In 1979, nymphal populations differed significantly {P<0.01) among weeks in the first, second, and third sampling periods. Planting date X week interactions were highly significant (P<0.01) for all nymphal stages in the first sampling period. In the second sampling period these interactions were significant (P<0.05) for second, third and fourth instars, but nonsignificant (P>0.Q5) for the fifth instar. No significant (P>0.05) planting date x week interaction occurred in the third sampling period. In the first sampling period, significant variety X week interactions occurred for second, third, fourth (P<0.05) and fifth (P<0.01) instars; however, this interaction was nonsignificant (P>0.05) for all nymphal stages in the second sampling period. In the third sampling period, this interaction was highly significant (P<0.01) for the fourth and fifth, but nonsignificant {P>0.05) for the second and third instars. No significant (P>0. 05) planting date x variety X week interactions occurred in any sampling period. A. hilccre Adults Populations of A. hilare adults sampled from early and late planting dates of Forrest and Bragg varieties in 1977, Bragg and Cobb in 1978, and Forrest, Bragg and Cobb in 1979 are shown in Figs. 29 through 42, respectively. Results of statistical analyses are shown in Table 5. In 1977, populations of both males and females differed significantly (P<0.01) among weeks in the first, second, and third sampling periods. Planting date x week interactions were nonsignificant (P>0.05) for males and females in the first and third sampling periods, but were

PAGE 139

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PAGE 140

132 3 > X a. j—l 2 1— I X >^ o M ^> Uf) 1— o — ^ X -o a. 3 3 X > X Q. C\J X CT> >> D O > o +-> o £ 2 2 X > X a. I— 1 CM 2 \ X 00 >> -(-> (/) o > S+J •r™ Ul£) CM \ 2 X T3 Q. ^ 2 T3 O +J fO (0 M Q. CI (13 CU en >1— 1 00 (/) 00 00 00 * 00 00 * -K -K OO K -X -K * * * -K (/) OO 00 00 00 00 tn 00 00 00 00 00 00 00 CO * Z Z Z Z -K -K -K * * -K * )( oo 00 00 oo 00 00 00 -K 00 oo Z Z z ) -K -K * -K -K ^{ * -x * 0) ^ -o re sz V
1 (/) 1 c x: c O) o •r~ z 00 31 II M II 00 * z

PAGE 141

133 highly significant (P<0.01) in the second. Variety x week interactions were nonsignificant (P>0.05) for both males and females in the first sampling period; they were significant (P<0.05 and P<0.01 for males and females, respectively) in the second, and highly significant (P<0.01) for both in the third. No significant planting date x variety X week interactions occurred in any sampling period. In 1978, the two sexes differed significantly (P<0.01) among weeks in the first, second, and third sampling period. No significant {P>0105) planting date x week interactions occurred in the first or second sampling periods, but this interaction was significant (P<0.05) for females and highly significant (P<0.01) for males in the third. Variety x week interactions were highly significant {P<0.01) for females and nonsignificant (P>0.05) for males in the first sampling period, but were nonsignif icant (P>0.05) for both in the second and third periods. No significant (P>0.05) planting date x week x variety interations occurred. In 1979, both sexes differed significantly (P<0.01) among weeks in the first, second, and third sampling periods. Planting date x week interactions were highly significant (P<0.01) for both sexes in the first sampling period, were highly significant (P<0.01) for females and nonsignificant (P>0.05) for males in the second, and significant (P<0.05) for females and highly significant (P<0.01) for males in the third. Variety x week interactions were highly significant (P<0.01) for females in the first sampling period, but significant (P<0.05) in the second and third. This interaction was nonsignificant (P>0.05) for males throughout the season. No significant (P>0.05) planting date X week x variety interactions occured.

PAGE 142

134 A. hilare Nymphs Populations of A hilare nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 43 through 56, Results of statistical analyses are shown in Table 5. In 1977, no significant differences (P>0.05) were detected in nymphal populations among weeks during the first sampling period, but differences (P<0.01) were observed for all nymphal stages in the second and third periods. Planting x week interactions were not significant (P>0.05) for all stages in the first and third sampling periods, but were highly significant (P<0.01) for second and third, nonsignificant {P>0.05) for fourth, and significant (P<0.05) for fifth nymphal instars. Variety x week interactions were nonsignificant (P>0.05) for all nymphal stages in the first sampling period, nonsignificant (P>0.05) for second and fifth instars but highly significant (P<0.01) for third and fourth in the second, and significant (P<0.05) for second and third, and highly significant (P<0.01) for fourth and fifth in the third sampling period. No significant (P>0.05) planting date x week x variety interactions occurred. In 1978, week effects observed were significant (P<0.01) for second, third, and fourth instars but nonsignificant (P>0.05) for fifth instars in the first sampling period. The week effect was highly significant (P<0.01) for all nymphal stages in the second and third sampling periods. Planting date x week interactions were highly significant (P<0.01) for second, third, and fourth instars, nonsignificant (P>0.05) for fifth instars in the first sampling period, but highly significant (P<0.01) for all nymphal stages in the third.

PAGE 143

135 Variety x week interactions were highly significant (P<0.01) for second, third, and fourth instars, but nonsignificant (P>0.05) for fifth instars in the first sampling period, highly significant (P<0.01) for second and third but nonsignificant (P>0.05) for fourth and fifth instars in the second, and nonsignificant (P>0.05) for all nymphal stages in the third. Planting date x week x variety interactions were highly significant (P<0.01) for the second, third, and fourth instars, but nonsignificant (P>0.05) for the fifth in the first sampling period. In the second period these interactions were highly significant (P<0.01) for the second and third instars, but nonsignificant (P>0.05) for the fourth and fifth instars, and in the third sampling period the threefactor interactions were nonsignificant (P>0.05) for all nymphal stages. In 1979, highly significant (P<0.01) week effects were observed for all nymphal stages in the first, second and third sampling periods. Planting date x week interactions were highly significant {P<0.01) for all stages in the first sampling period, but were nonsignificant (P>0.05), except for second instar (P<0.01) in the second, and were nonsignificant (P<0.05) for the second, significant (P<0.05) for third and fourth, and highly significant (P<0.01) for fifth instars in the third sampling period. Variety x week interactions were significant (P<0.05) for fourth and fifth instars but nonsignificant (P>0.05) for second and third in the first sampling period, but no significant interaction (P>0.05 was found for any stages in the second period. In the third sampling period, this interaction was significant (P<0.05) for fourth and fifth instars but nonsignificant (P>0.05) for second

PAGE 144

136 and third stage nymphs in the third sampling period. No significant (P>0.05) planting date x week x variety were observed for any nymphal stage in 1979. E. servus Adults Populations of E. servus adults sampled in 1977, 1978 and 1979 are shown in Figs. 57 through 70. Results of statistical analyses are shown in Table 6. In 1977 no significant differences (P>0.05) were detected in male populations among weeks, but female populations differed significantly (P<0.05) through time in the first sampling period. Week effects were highly significant (RO. 05) for both sexes in the second and third periods. No significant (P>0.05) planting date x week interactions occurred in any sampling period. Variety x week interactions were not significant (P>0.05) for the two sexes in the first and second sampling periods, but were highly significant (P<0.01) for males and nonsignif' icant (P>0.05) for females in the third. No significant (P>0.05) planting date X week x variety interactions occurred. In 1978, week effects were highly significant (P<0.01) for both sexes in the first, second, and third sampling periods. No significant (P>0.05) planting date x week interactions were detected for either sex in the first and second sampling periods, but these interactions were highly significant (P<0.01) for both sexes in the third. Variety x week interactions were nonsignificant (P>0.05) for both sexes in the first and second sampling periods, but were significant (P<0.05) in the third. No significant (P>0.05) planting date x week x variety interactions occurred.

PAGE 145

137 to n3 +J > u 0) MOl +J -o 0) (1) CD 2 c O) -M C sz •r" 03 c s"q. 0) (J -o c c o (0 o CO s (U 2 CO fel +J cu o c 0) O) s> X (U O 4J (O (/I T3 0) 1/5 cn >1 c (0 +-> c £ Q. o n +J (J =1 O) CO MO) MU3 -o CM o 4-> T3 O •r™ s_ +-> (0 la 4-> Q. o Sr-^ ta 1^ X X >> +-> X Q. 3 X > X ^ CM 3 \ X o (-) sz O > o +-> o 0) to CM 3 00 X T3 ^ 3 2 X > X O 3 CM X >^ M 00 4-> to > io •1— 4-> LL. Lf> 3 CO X T3 Q. -i^ 3 00 00 oo c/1 (/) 00 00 * -K * Z * * 00 00 00 00 * z z z z ^ -x •X. -K -X * -K )< * -X 00 00 00 00 00 00 CO CO oo -X 00 00 z z z -x z z 00 00 -x -x -x -x z z -x -x -x X -x -x -x -x X •* -x -x -x 00 00 oo 00 00 oo CO oo 00 00 00 CO 00 00 00 00 CO oo X oo 00 oo 00 CO OJ ^ -o (t3 Q CO X a. X X T3 a. X a. X +-> X -o a. X X >> -M X T3 a. -l-J oo CO oo CO CO 00 •X -X CO CO oo -x z z z -x X -x -x -x -x X -x -x -x -x X -X -x -x -x X -X -X -X -X -X 00 00 00 CO CO 00 00 00 00 00 00 00 00 00 00 oo -x -x z z z z -x -x X -X -X -X -x -x X -x -x -x -x -x 00 00 00 00 00 00 c/) 00 00 00 00 oo 00 00 00 CO 00 00 X -x X C/0 00 00 to OJ jz -a <— ^ 4J T3 C fO OJ +-> S_ S_ O E >— M3 •U
PAGE 146

138 3 X. > X Q_ I— I \ 3 I— 1 X >> o 4-> +-> > •run 1— o X -o a. 3 X a. CM 3 X cr> +J C o > o +j o X 1— I CM 3 \ X 00 >i M +J U. CM 3 X o Q. 3 o o. >o en 4-> 00 * oo oo 00 00 z.-z.-z.-z. * oo 00 * * oo -K •X -K -X -K ****** 00 00 00 00 00 00 00 00 oo 00 00 oo 00 00 00 oo * **)<*** ****** 00 CO 00 00 00 00 00 CO 00 00 00 oo -it ^< -K 4< * * ****** * * (O V (0 4-> o C Q. *rITJ <4O •r— •r— +-> C *t•r" (0 c o I/) cn •r" <+>> CO 1 cn O 'r— OO II II II 00 * 2:

PAGE 147

139 In 1979, week effects were highly significant (P<0.01) for both sexes in the first, second, and third sampling periods. No significant (P>0.05) planting date x week interactions were detected for either sex in the first and second sampling periods, but these interactions were highly significant (P<0.01) for both sexes in the third. Variety x week interactions were nonsignificant (P>0.05) for both sexes in the first and second sampling periods, but were highly significant (P<0.01) in the third. No significant (P>0.05) planting date x week x variety interactions occurred in the first and second sampling period, but were highly significant (P<0.01) for females and significant (P<0.05) for males in the third period. g. servus Nymphs Populations of E. servus nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 71 through ,84. Results of statistical analyses are shown in Table 6. In 1977, no significant differences (P>0.05) were found in nymphal populations among weeks in the first sampling perid. The week effect was highly significant (P<0.01) for all nymphal stages in the second and third periods. Planting date x week interactions were nonsignificant (P>0.05) for all nymphal stages in the first sampling period, but were significant (P<0.05) for fourth instar and highly significant (P<0.01) for second, third, and fifth instars in the second, and nonsignificant (P>0.05) for fourth, and fifth instars and highly significant (P<0.01) for second and third in the third period. Variety x week interactions were not significant (P>0.05) for nymphal

PAGE 148

140 populations in the first sampling period, but were highly significant (P<0.01) for fourth instar and nonsignificant (P>0.05) for the other nymphal stages in the second, and significant (P<0.05) for fifth and highly significant (P<0.01) for second, third, and fourth instars in the third sampling period. In 1978, no significant (P>0.05) week effects were observed for nymphal populations in the first sampling period; however, populations of all nymphal stages varied significantly (P<0.01) through time in the second and third. Planting date x week interactions were not significant (P>0.05) for any nymphal stages in the first sampling period, but were highly significant (P<0.01) for second and third and nonsignificant for fourth and fifth instars in the second, and highly significant (P<0.01) for all stages in the third. Variety x week interactions were nonsignificant (P>0.05) in nymphal populations in the first and second sampling periods, but were highly significant (P<0.01) in the second and third and nonsignificant (P>0.05) in the fourth and fifth instars in the third. No significant differences (P>0.05) were detected in nymphal populations among planting date x week x variety interactions in the first, second, and third sampling periods. In 1979, week effects were highly significant (P<0.01) for second, third,and fourth instars, and significant (P<0.05) for fifth instars in the first sampling period, but highly significant (P<0.01) for all stages in the second and third periods. Planting date x week interactions were significant (P<0.05) for second and third instars, and highly significant (P<0.01) for fourth and fifth in the first sampling period, nonsignificant (P>0.05) for fourth and fifth instars. and

PAGE 149

141 significant (P<0.05) for second and third in the second period, but nonsignificant (P>0.05) for fourth instar, significant {P<0.05) for fifth, and highly significant (P<0.01) for second and third in the third sampling period. Variety x week interactions were nonsignificant (P>0.05) in nymphal populations during the first and second sampling periods, but were highly significant (P<0.01) for second and third but nonsignificant (P>0.05) for fourth and fifth instars in the third. No significant (P>0.05) planting date x week x variety interactions were detected for any nymphal stage in any sampling period. Discussion Populations of N. viridula, A. hilave and E. serous were very low in 1977, increased somewhat in 1978 and were very high in 1979 on three soybean varieties in this study. The relatively cold winter season of 1976-77 probably contributed to low stinkbug populations in 1977. No insecticide was used for stinkbug control in the experimental plots surveyed in 1977, 1978 and 1979. In the following discussion emphasis will be given to adult populations as the stage in the life cycle capable of dispersal among soybean plantings and as such governs the timing and magnitude of nymphal populations in a particular planting. Discussions of nymphal populations will deal primarily with second and fifth stage nymphs as they relate to adult populations.

PAGE 150

142 N. viridula Adults Southern green stinkbug adults colonized early-planted Forrest and Bragg during the first sampling period (8/5 to 8/20) of 1977. Seasonal abundance of this species increased through time (week) and the significant interaction planting date with week indicates that adult populations increased more rapidly in early than in late plantings. During the second sampling period (8/26 to 9/24), population trends were similar in the two planting dates. Adult populations increased sharply during this period on early-planted Forrest, showing a strong preference for the earlyplanted, early-maturing variety. Adult populations increased on earlyplanted Bragg from August 20 to September 9, however, populations on late-planted Bragg became higher thereafter through September 24. Males and females were low on late-planted Forrest from August 26 to September 9, but the female population increased substantially thereafter, reached a peak on October 1, then decreased sharply. Meanwhile, male population behavior was quite different on this variety because populations increased from August 26 to October 8 at which time the peak occurred. Males and females increased sharply on the late planting date Bragg by September 24, reached their peak populations on October 15, and thereafter declined rapidly. By the end of the season (October 27) adult populations had declined to zero on both early and late planting date Forrest because these plantings had senesced; but a small number of adults still remained on early and late planting date Bragg at this time.

PAGE 151

143 It is important to note that the interaction of planting date with week was a significant factor during the first period (8/5 to 8/20) and during the third period (10/1 to 10/27), and that the interaction of variety with week was also significant by the end of the season (10/1 to 10/27). This emphasizes the ability of the adults to find plantings which furnish adequate food in the form of pods. After developing through one generation, adults then prefer the later-maturing varieties. Adults first colonized both early-planted Bragg and early-planted Cobb during the first period (7/26 to 8/23) of 1978 and increased most rapidly there during the second sampling period (8/29 to 9/26). Males and females reached their peak population levels on early-planted Bragg on October 3, but by that time populations were similar on early and late plantings of Cobb. Colonization of late-planted Bragg and Cobb proceeded at a low rate from August 23 to September 11, but from September 21 to October 10, populations of both sexes were higher on the Cobb planting. Peak populations occurred in both plantings on October 10, and then declined more rapidly in Bragg than Cobb as that variety matured. Adult populations increased rapidly on early planting date Cobb, reaching a peak on October 17, declining thereafter, while populations on Cobb peaked on October 10. Once more, it is important to note that the interaction of planting date X week was significant during the first sampling period (7/26 to (8/23). Males and females colonized on early planted Forrest in 1979 in a manner similar to that observed in 1977. Both sexes were significantly

PAGE 152

144 higher on this than on other plantings from August 21 to September 29, reaching a peak at this time. Numbers declined rapidly thereafter to zero on October 191. Although delayed by about three weeks, adult populations increase in early-planted Bragg was similar to that in earlyplanted Forrest, peak populations occurring on October 26. Few adults were collected from Cobb through September 29, but increased rapidly thereafter to a peak on October 26. As populations declined on earlyplanted Forrest, corresponding increases occurred on the early Bragg and Cobb plantings. Adult populations remained very low on late-planted Forrest throughout the 1979 sampling season. The "attractive" stages of this planting were apparently asynchronous with adult populations and thereby escaped infestation. Adults began to colonize late-planted Bragg by September 10 and increased slowly through September 29. Numbers then increased rapidly to a peak on October 29, declining rapidly the following week. Adult populations remained very low on late-planted Cobb through September 29. Thereafter population increase was very rapid, peaking October 29 and declining to November 1. N. viriduta Nymphs No nymphal populations were detected before August 20 and 31 of 1977 in early and late plantings, respectively, approximately one week after females were first collected in each planting. In early and late plantings of Forrest it is possible to detect distinct peak populations of second nymphal instars, occurring on August 31 and September 9, respectively. Second nymphal instar population peaks are not evident on either

PAGE 153

145 Bragg planting, indicating a more continuous influx of adults (females) as the season progressed. Nymphal development produced peak fifth nymphal instar populations on September 24, October 1, 8, and 15 in earlyand late-planted Forrest and Bragg, respectively. These peaks corresponded exactly to peak adult populations in the same plantings. The peaks occur at one-week intervals which closely correspond to the timing of plant reproductive events (pod set and pod fill) in the respective plantings. Nymphal collections in 1978 were first made from early plantings of Bragg and Cobb on August 23 and on September 5 and 11 from late plantings of Cobb and Bragg, respectively. Unlike 1977, no distinct peaks of second nymphal instars could be detected in the earlier plantings. This indicates a more or less continuous influx of adults into the early plantings from surrounding soybeans outside the experimental area (which included Forrest and other varieties of similar maturity). In the later plantings of both Bragg and Cobb, however, more or less distinct peaks occurred, indicating a more synchronous influx of adults. Maximum numbers of fifth instars occurred on September 21-26, October 3-10, and October 3 in earlyand late-planted Bragg and late-planted Cobb, respectively. An indistinct peak occurred in early-planted Cobb, from September 21 through October 17. Peak fifth instar populations in most cases preceded those of adults by one week. In 1979, nymphal populations were first detected on August 1,7, 15, 21, and September 4, on early Forrest and Bragg, late Forrest, early Cobb, and late Bragg and Cobb, respectively. Because of the extremely large poulation occurring in 1979, it is, in most cases, impossible

PAGE 154

146 to detect distinct first or subsequent generation peaks of second instars. Peak numbers of fifth instars occurred on October 5 (early and late Forrest), October 19 (early Bragg and early and late Cobb) and bimodal peaks on October 5 and 19 (late Bragg). A. hilare Adults Throughout the three-year study period adult populations of A. hilare remained very low. Consistent with the results obtained by McPherson et al. (1979) in Louisiana. In 1977, adults colonized Forrest variety more rapidly than Bragg, indicating that this species responds to the availability of developing pods in a manner similar toN. viridula. On early-planted Forrest, numbers increased sharply from August 5 to a peak on September 9, then declined before rising to a secondary peak on October 1. On late Forrest, population increase was delayed by approximately two weeks; with maximum numbers collected October 1. Thereafter populations declined on both Forrest plantings, disappearing completely by October 22 as the crop senesced. On the Bragg variety adults increased more gradually through the first and second sampling periods, reaching peak populations on both early and late plantings on October 8, and then declining sharply to the end of the season (10/27). While populations remained low in 1978, initial colonizers were more numerous than was the case in 1977. Although the shape of the population curves appears somewhat different, little numerical difference is evident among populations on early or late plantings of Bragg or Cobb. On early-planted Bragg the maximum number of adults was collected on October 3, declining to negligible levels by the following week. The peak of adult males on early-planted Cobb occurred on October 3, females

PAGE 155

147 on October 10 and on late-planted Cobb the peak occurred on October 24. The late Bragg population displayed bimodal peaks (9/26 and 10/17) analogous to that occurring on early Forrest in 1977. After October 3 it was evident that adults preferred the later plantings of Bragg and Cobb. During the first sampling period of 1979 (through 8/21) adults colonized only early Forrest and Bragg, negligible numbers being collected in other plantings. Population increase was rapid in the second sampling period in all plantings except late Bragg and Cobb, and peak numbers of adults were collected from the two Forrest plantings by the end of this period (9/29). Populations declined on early and late Forrest plantings during the third sampling period as the crop began to senesce. Meanwhile, maximum numbers were collected in the two Bragg plantings on October 5, and in early and late Cobb on October 12 and 19, respectively, after which time numbers declined to the end of the season. A. hilare Nymphs In 1977, no nymphs of A. hilare were collected during the first sampling period. By August 26, second instars were present in early plantings of both Forrest and Bragg, being more abundant on Forrest. On August 31, this stage was also collected from late plantings of the two varieties. The timing of occurrence of second-stage nymphs, indicative of oviposition timing, supports results obtained showing that adults first colonize early plantings. Peak populations of fifth stage nymphs occurred in both Forrest plantings on October! and on both Bragg plantings on October 8. Timing and shape of the population curves for second and fifth stage nymphs indicated that but a single generation occurred in soybean within this study in 1977.

PAGE 156

148 Second nymphal instars were collected during the first sampling period of 1978 only on early-planted Bragg (8/23), the peak abundance occurring August 23-29. On early Cobb, first detection and peak abundance occurred simultaneously on August 29. Second stage nymphs were first collected from late Bragg and Cobb on September 5, and population peaks occurred one and two weeks later, respectively. On late Bragg a secondary peak occurred on October 3. Maximum numbers of fifth stage nymphs occurred on early Bragg and Cobb on October 3, and on late Bragg and Cobb on October 17 and 24, respectively. Timing of peak abundance of second instars on early Bragg and the secondary peak on late Bragg (six weeks lag time) indicates the possibility that two generations may have occurred during the 1978 season, but probably not in the same planting. Nymphs of A. hilars were detected much earlier in the 1979 season than was the case in either 1977 or 1978. Second instars were first detected in the respective early and late plantings of Forrest, Bragg, and Cobb as follows: August 1, 7, 21, September 4, August 21, and September 4. On early Forrest populations peaked on August 21 with a second, larger peak occurring on September 29, while a single peak occurred on the late planting on September 5. On early Bragg an initial peak occurred on August 21 with a secondary on October 5, while peaks occurred on September 21 and October 5 on the later planting. Early Cobb supported peak populations on September 4 and September 29; the later planting displayed no distinct peak, populations remaining more or less stable from September 10 through October 19. Maximum numbers of fifth instars were collected from the respective early and late plantings of Forrest, Bragg and Cobb on September 21, 29, October 12, 19, 12,

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149 and 19. The timing of initial and secondary peaks of second ins tar abundance on early plantings of Forrest and Bragg indicate that two generations may have occurred in these plantings. However, timing of the peaks in early Cobb and late Forrest, Bragg and Cobb indicate that the secondary peaks probably originated from dispersal of first field generation females into these plantings from early Forrest and Bragg. In most cases population trends, if not magnitudes, were similar for A. hilare among plantings to those observed with vividula. Early plantings supported larger nymphal populations than did the later plantings, while the opposite was usually true of iV. viridula. E. serous Adults E. servus adults were not abundant in any of the three years of this study, consistent with the results obtained by McPherson et al (1979). Both males and females of this species colonized all plantings in low numbers during the first sampling period of 1977. During the second and third sampling periods, while the form of the population curves appears somewhat different among plantings, numerically there is little difference. Peak populations occurred in earlyand late-planted Forrest on October 1, in early Bragg on October 8, and in late Bragg on October 1-8. During the 1978 season, small numbers of adults colonized plantings of Cobb one to two weeks earlier than Bragg. This was an unusual situation which occurred only with this species and only in this year. In the second sampling period, populations on early Bragg peaked rapidly (although small numbers were present) on September 5, and produced

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150 a secondary peak on September 26. In early Cobb the peak was delayed until September 21-26. It was not until near the end of the third sampling period that peak populations occurred in late Bragg and Cobb, on October 17 and 24, respectively. In 1979, first colonizing adults were collected on August 1 in early plantings of Forrest and Bragg. By the end of the first sampling period on August 21, plantings ranked according to adult abundance as follows: early Forrest, Bragg and Cobb, and late Forrest, Bragg and Cobb. Numerical abundance increased sharply during the second sampling period in all plantings except early Cobb. Peak adult populations occurred on respective early and late plantings of Forrest, Bragg and Cobb as follows: October 5, September 29, October 12, 12, 12, and 19. On both Forrest plantings, populations declined as the crop senesced to zero by October 19, while active adult populations were still present in the remainder of the plantings when sampling was discontinued after November 1 E. servus Nymphs Like the adults of this species, nymphal populations were very low during the 1977 cropping season. No nymphal populations were detected during the first sampling period, but second instars were collected from early Forrest and Bragg on August 26, and on the late plantings on August 31. Second stage nymphs peaked rapidly and sharply in early-planted Forrest and late-planted Forrest and Bragg on August 31, September 9, and August 31. On early Bragg no distinct population peak occurred, and numbers remained relatively constant from August 26 through September 16, then declined slowly to the end of the season.

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151 Fifth nymphal instars produced distinct peaks in earlyand late-planted Forrest on October 1 and September 16, respectively. Populations of this developmental stage fluctuated more widely through time on Bragg, reaching maximum numbers on October 1 and 8 in late and early plantings, respectively. This species apparently produced but a single generation on soybean during the 1977 cropping season. As was the case in 1977, no E. servus nymphs were collected in the first sampling period of 1978. First second nymphal instars were collected from early plantings on August 29 and from late plantings of Cobb and Bragg on September 5 and 11, respectively. Peak populations occurred on early Bragg and Cobb and late Bragg on October 5, August 29, and September 11, respectively. Second instars produced no distinct population peak in late-planted Cobb, but remained relatively constant from September 5 through October 17. Fifth instars produced distinct single peaks only in late-planted Bragg on October 10. In early Bragg initial and secondary peaks occurred on September 11 and 26. In early Cobb, maximum numbers were collected on September 26. In early Cobb, maximum numbers were collected on September 26, preceded by a preliminary smaller peak on September 5. The situation on late-planted Cobb was very different. Fifth stage nymphs increased sharply from August 29 to September 21, then continued to increase gradually through October 24 before declining to the termination of the study on November 1. Only a single generation was apparent during 1978. Nymphal populations were much larger in 1979 than either the 1977 or 1978 studies, as well as occurring earlier in the season. Single peaks of second instar populations were produced only in late plantings

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152 of Forrest and Cobb, both occurring on September 10. Double peaks occurred in early Forrest (August 21 and September 21-29), early Cobb (September 4 and 29), and late Bragg (September 21 and October 12). Early-planted Forrest apparently produced three population peaks, on August 21, September 10, and October 5. Maximum abundance of fifth nymphal instars occurred in respective early and late plantings of Forrest and Cobb on September 21-29, September 10-21, October 12, and 5, respectively. Only in Bragg did apparent bimodal peaks occur, September 4 and October 12, in the early planting and September 19 and October 19 in the late planting. It is apparent that E. Servus produced two nymphal generations within the early Forrest and Bragg plantings. Piezodorus guildinii Jones (1979) was the first to report this species from soybean in the United States. He indicated that this important South American pest was able to withstand the cold winters of South Carolina. In 1977, a single female of this species was collected at Quincy within the experimental area of this study. In 1978 several additional specimens were collected. By the 1979 cropping season populations had increased substantially, and 219 adults and 164 nymphs were collected in the course of the sampling season. Subsequently, in 1980 this species was again collected at Quincy and in Madison Co. (D. C. Herzog, personal communication) and in several Georgia counties adjoining Florida (J. W. Todd, personal communication). D. C. Herzog, Entomology and Nematology Department, University of Florida, Gainesville, Florida, 32611. ** J. W. Todd, Department of Entomology and Fisheries, University of Seorgia, Tifton, Georgia, 31794.

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153 This species is rapidly increasing in abundance. This situation should be watched closely as a similar situation in Brazil resulted in the almost complete displacement of N. viridula by P. guildinii. Conclusions Adults of N. viridula were usually the first to colonize timed plantings of Forrest, Bragg and Cobb during the three years of this study. Left uncontrolled this species produced very large nymphal and subsequent generation adult populations. Because of the magnitude of populations and apparent overlap, the number of generations produced in individual plantings was impossible to determine, but it is probable that two occurred in certain plantings. Adults of both A. hilare and E. servus were very low relative to N. viridula. Nymphal populations of these species likewise were low with the exception of 1979. The dynamics of populations of these two species on the times varietal plantings appeared to be quite similar to that of N. viridula. Single nymphal generations were produced in 1977 and 1978, but two generations of each species occurred in some plantings in 1979. In Florida, A. hilare and E. servus pose little threat to soybean production themselves, but as species components of the stinkbug pest complex they become significant because damage produced by members of the complex is similar (McPherson 1978) and additive.

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CHAPTER V COMPARISON OF TWO RELATIVE SAMPLING METHODS FOR THE STINKBUG COMPLEX AND SOYBEAN Results Populations of N. vividula adults sampled by ground cloth method from early and late planting dates of Forrest and Bragg varieties in 1977, Bragg and Cobb in 1978, and Forrest, Bragg and Cobb in 1979 are shown in Figs. 1 through 14, respectively. Populations of N. viriduta nymphs sampled in 1977, 1978, and 1979 are shown in Figs. 15 through 28. Results of statistical analyses are shown in Tables 7 through 13. Populations of A. hilare adults sampled by ground cloth method in 1977, 1978, and 1979 are shown in Figs. 29 through 42; and nymphal populations sampled in those years, are shown in Figs. 43 through 56. • Results of statistical analyses are shown in Tables 7 through 13. Populations of E. servus adults sampled by ground cloth method in 1977, 1978, and 1979 are shown in Figs. 57 through 70, and itmiature populations are shown in Figs. 71 through 84. Results of statistical analyses are shown in Tables 7 through 13. Populations of N. viridula adults sampled by sweep net method from early and late planting dates of Forrest and Bragg varieties in 1977, Bragg and Cobb in 1978, and Forrest, Bragg and Cobb in 1979 are shown in Figs. 85 through 98, respectively. Populations of viridula 154

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155 nymphs sampled in those years are shown in Figs. 99 through 112. Results of statistical analyses are shown in Tables 7 through 13. Populations of A. hilare adults sampled by sweep net in 1977, 1978, and 1979 are shown in Figs. 113 through 126, and immature populations are shown in Figs. 127 through 140. Results of statistical analyses are shown in Tables 7 through 13. Populations of E. servus adults sampled in 1977, 1978, and 1979 are shown in Figs. 141 through 154, and nymphal populations are shown in Figs. 155 through 168. Results of statistical analyses are shown in Tables 7 through 13. Tables 14 through 16 show results of linear regression analyses of the data taken by the two methods. Regression analyses were computed relating the number of individual developmental stages of each species captured with the sweep net to numbers captured by means of the ground cloth within the early and late plantings of Forrest Bragg and Cobb. Results show that 6^ (the regression coefficient) is highly significant (P<0.01) for all cases except second instar ^. hilare on late-planted Cobb in 1979 (P<0.05) and ranges from 0.237 for third instar N. viridula on early-planted Forrest in 1979 to 3.307 for fifth instar E. servus on early-planted Forrest in 1979. In most cases 6 (the 0 Y-intercept) was not significantly different from 0; exceptions occurred primarily on early plantings, Bragg variety, and with various developmental stages of A. hilare. R^ values (coefficients of determination) expressed, in the tables as percentages, ranged from 21.4% for the third instar N. viridula on early-planted Bragg in 1978 to 99.3%

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156 for female and male E. servus on early-planted Bragg in 1977 [correlation coefficients (r) = 0.463 and 0.996, respectively]. Discussion Significant linear relationships between populations of second through fifth instars, males, females and combined populations of N. viridula collectd by sweep net and shake cloth were demonstrated by Rudd and Jensen (1977). However, until now no similar relationships had been demonstrated for populations of A. hilave and E. servus, or for combined populations of species comprising the stinkbug complex. Results presented here indicate that the mathematical relationships between paired sweep net and ground cloth samples differs not only among developmental stages, but among species, varieties and planting dates sampled, and among years. Factors for calibration of sweep net to ground cloth samples can be computed for each variety/planting date/ species/developmental stage combination presented in Tables 14 through 16. However, due to the variability of the regression coefficients, the utility of such a tabulation of calibration equations (factors) is questionable. Further research is necessary on this problem to adequately characterize these relationships and their utility. For all three species the magnitude of the regression coefficients usually increased as development proceeded. This is probably a function of the degree of aggregation of individual developmental stages as described by Todd and Herzog (1980) and Herzog et al (1981).

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157 Conclusions Collection of adults and all nymphal stages of N. viHdula, A. hilave, and E. servus by sweep net and ground cloth are significan correlated. Data and regression analyses presented will allow the construction of coefficients for calibration between the methods for all development stages, on several varieties and planting dates.

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PAGE 250

242 Table 7. Results of regression analyses comparing sweep net and ground cloth for three stinkbug species on Forrest variety. Quincy, Florida, 1977. PI anti ng Date Estimate H :B. 0 1 = 0 N 6 "^0 ^1 i=0 i=l {%) N. vividuZa Female early 0 .013 1 .420 NS ** 88 .8 late 0 .028 1 .363 NS ** 87 .4 Male earl v 0 .058 1 .133 NS ** 74 .0 late 0 .025 1 .465 NS ** 88 .5 Fi f th earl v -0 028 T .554 NS 91 .6 late -0 .014 1 .246 NS ** 96 .3 Fourth earl v -0 004 1 1 .108 NS ** 90 .3 late 0 015 0 .954 NS ** 86 .7 Third early -0 n .898 NS ** 91 5 late -0 017 0 .816 NS ** 88 .6 Second pari V -0 031 0 953 • J si \J NS 91 ? late -0 22 0 .702 NS 79 8 A hi Zdfs Female early 0 01 1 1 .491 NS ** 88 .2 late 0 01 7 1 .536 NS ** 88 .6 Male 0 047 1 1 1 Ml NS ** c late 0 .032 .344 NS ** 90 0 Fifth earl v -0 007 1 573 NS ** 95 n late 0 019 0 .989 NS ** 85 4 Fourth earl v -0 1 .131 NS ** 93 5 late 0 000 Q .945 NS ** 73 0 Third early -0 01 3 0 .781 NS JO n late -0 01 9 0 .709 NS 73 0 Second early -0 01 3 n .692 NS ** 87 5 late -0 .011 0 .716 NS ** 90 n E. sewus Female early 0 .151 1. ,712 ** 85 .5 late -0, .039 1. ,910 NS ** 94 .0 Male early 0, .124 1. ,787 ** 92 .1 late 0, .189 1. ,167 NS ** 38 .0 Fi f th early -0, .064 1. ,993 NS ** 97 .3 late 0, .015 1. ,896 NS ** 93 .4 Fourth early -0, .040 1. ,507 NS ** 86 .2 lare 0, .014 1. ,361 NS ** 84, .2 Third early -0, ,015 0. ,729 NS ** 62, .8 late 0. .046 0. ,843 NS 50. .4 Second early -0. ,019 0. 822 NS ** 90. ,5 late 0. ,009 0. 822 NS ** 77. .3 NS = Nonsignificant (P > 0.05) ** = Highly significant (P < 0.01) = Significant (P < 0.05)

PAGE 251

243 Table 8. Results of regression analyses comparing sweep net and ground cloth for three stinkbug species on Bragg variety. Quincy, Florida, 1977. Estimate H :6. = 0 N = Planting ^— Date e 6^ i=0 i=l (%) N. viriduta Female early 0, .059 1, .789 ** ** 98.6 late 0, .039 1 .688 NS ** 95.2 Male early 0. .038 1, .783 ** 98.1 late -0, .007 1 .576 NS ** 86.8 Fi f th early 0, .009 1 .907 NS ** 96.7 late -0, .024 1 .537 NS ** 89.7 Fourth early 0, .022 1 .136 NS ** 81.5 late 0, .027 1 .145 NS ** 90.0 Third early -0, .009 1 .042 NS ** 80.5 1 ate -U. uuy U / /U QQ 1 yo. 1 Second early -0. ,011 0 .842 NS ** 88.1 late -0, .011 0 .936 NS ** 94.1 A hi tare Female early 0, ,132 0 .875 ** ** 73.0 late 0, ,070 1, .390 ** 78.9 Male early 0, ,085 1, .425 ** ** 77.3 late 0, ,042 1, .618 NS ** 86.2 Fifth early 0, ,003 1, .176 NS ** 87.0 late -0, ,002 1, .722 NS ** 86.7 Fourth early 0, ,065 1, .617 NS ** 47.4 late 0. ,016 1 .546 NS ** 91.2 Third early 0. ,010 0, .767 NS ** 83.6 -f) U 1 *+ n 74d ** yQ c Second early -0. ,006 0, .764 NS ** 87.2 late -0. ,020 0, .853 NS ** 95.4 E. sewus Female early 0. ,014 1, .947 NS ** 99.3 late -0. ,049 1, ,950 NS ** 96.4 Male early 0. ,004 1. .922 NS ** 99.3 late -0. ,021 1, .923 NS ** 97.8 Fifth early -0. ,073 2, ,030 NS ** 98.1 late -0. ,093 2. ,053 NS ** 98.0 Fourth early -0. ,082 1, ,607 NS ** 82.6 late -0. 029 1. ,798 NS ** 89.4 Third early -0. 054 1. ,109 NS ** 43.6 late -0. 015 0. ,983 NS ** 76.7 Second early 0. 000 0. ,680 NS ** 52.3 late -0. 059 1. ,367 NS ** 73.6 NS = Nonsignificant (P > 0.05) ** = Highly significant (P < 0.01) = Significant (P < 0.05)

PAGE 252

244 Table 9. Results of regression analyses comparing sweep net and ground cloth for three stinkbug species on Bragg variety. Quincy, Florida, 1978. Planting Date Estimate H^:6. = 0 N = 0 1 i=0 i=l (%) N. viridula Female early 0, .197 1 .899 ** ** 59 .3 1 a Lc _n -u .006 1 NS ** O-i A H Male early 0, .249 1 .878 ** ** 59 .3 late 0, ,020 1 .649 NS ** 85 .8 Fifth early 0, .291 1 .766 ** ** 69 .2 late 0. • Oil 1 .705 NS ** 88 .7 Fourth early 0. ,041 1 .385 NS ** 80 .5 late -0. ,002 1 .560 NS ** 88 .6 Third early 0. ,204 0 .710 ** 21 .4 late 0. ,002 0 .892 NS ** 89 .0 Second early 0. ,152 0 .866 ** 50 .9 late -0. ,010 0 .738 NS ** 72 .3 A. hilar e Female early 0. ,206 1 .586 ** ** 47 .7 1 a tc n ,068 1 / OD NS ** / D o Male early 0. ,211 1 .385 ** ** 43 .8 late 0. ,047 1 .788 NS ** 83 .0 Fifth early 0. 236 2 .815 ** ** 61 .7 late 0. 020 1, .857 NS ** 87 .8 Fourth early 0. 155 2. .517 ** ** 65 .2 lare 0. Oil 1, .850 NS ** 94 .0 Third early 0. 156 0, .990 ** ** 35 .2 late -0. 006 1, .681 NS ** 93, .2 Second early 0. 114 0, .610 ** ** 31 .0 late -0. Oil 1, .842 NS ** 95 .3 E. servus Demale early -0. 053 2, ,207 NS ** 98, .8 1 a Lc 082 2, NS ** y/, J Male early -0. 091 2. ,251 NS ** 97, .5 late -0. 093 1. ,881 NS ** 97, .4 Fifth early -0. 615 2. ,176 NS ** 88, ,4 late 0. 268 1 ,540 NS ** 85. ,7 Fourth early -0. 342 1. ,793 NS ** 81, ,3 late 0. 129 1. ,131 NS ** 80. ,5 Third early -0. 322 1. 579 NS ** 61. ,3 late 0. 014 1. 158 NS ** 80. ,0 Second early 0. 162 0. 741 NS 48. 7 late 0. 207 0. 425 NS ** 36. 9 NS = Nonsignificant (P > 0.05) ** = Highly significant (P < 0.01) = Significant (P < 0.05)

PAGE 253

245 Table 10. Results of regression analyses comparing sweep net and ground cloth for three stinkbug species on Cobb variety. Quincy, Florida, 1978. Estimate N Planting Date 6 ^0 ^1 1 V i=l rx (%) N. viridula Female early 0. ,024 2 .029 NS ** 93 .2 1 O Lc -D ,008 1 .991 n Male early 0. ,010 1 .934 NS ** 93 .0 late -0. ,016 1 .988 NS ** 97 .6 Fifth early 0. ,019 1 .437 NS ** 95 .6 late 0. 004 2 .078 NS ** 99 .1 Fourth early 0. ,045 1 .210 NS ** 79 .0 late 0. 006 1 1 858 NS ** 97 .6 Third early 0. ,035 0 .878 NS ** 74 .9 late 0. 018 1 750 NS ** 94 .0 Second early -0. 024 0 705 NS ** 82 .6 late 0. 009 1 1 878 NS ** 90 .8 A. hilar e Female early 0. ,100 1 .391 ** ** 61 .1 1 a tc n 005 1 856 yO Male early 0. ,086 1 .340 ** ** 76 .9 late -0. 012 2 .031 NS ** 97 .4 Fifth early 0. 027 1 .441 NS ** 68 .6 late 0. 004 2 .059 NS ** 97 .0 Fourth early 0. 001 1 .336 NS ** 73 .3 late 0. 017 1 721 NS ** 84 .4 Third early 0. 004 0 .862 NS ** 77 .6 late 0. 026 1 621 NS ** 80 .1 Second early 0. 003 0 .623 NS ** 85 .0 late 0. 004 n U NS ** 60 .8 E. servus Female early -0. o o 032 1 964 NS ** 98 .8 late 0. 025 1 .831 NS ** JO 7 Male early -0. 042 1 .885 NS ** 98 .9 late 0. 031 1 .794 NS ** 98 .3 Fifth early -0. 073 1 .592 NS ** 87 .7 late -0. 237 2 .029 NS ** 92 .8 Fourth early 0. 089 1 .307 NS ** 84, .0 late -0. 245 1 .638 NS ** 86, .4 Third early 0. 002 1 .105 NS ** 73, .2 late 0. 191 0 .791 NS ** 49, .1 Second early 0. 018 0 .735 NS ** 50, .4 late 0. 094 0 .499 NS ** 75, .5 NS = Nonsignificant (P > 0.05) **= Highly significant (P < 0.01) = Significant (P < 0.05)

PAGE 254

246 Table 11. Results of regression analyses comparing sweep net and ground cloth for three stinkbug species on Forrest variety. Quincy, Florida, 1979. Planting Date Estimate H^:6^. =0 N — ^0 1 i=0 i=l N. viridula Female early -0, .063 1 .735 NS ** 87 .4 1 ate -0, .037 1 .791 NS 7 / Male early -0, .003 1 .601 NS ** 69 .8 late -0, .033 1 .752 NS ** 95 .0 Fi f th early 0, .134 1 .015 NS ** 67 .4 late 0, .093 0 .637 NS ** 63 .2 Fourth early 0. .134 0 .651 NS ** 67 .4 late 0, ,054 0 .475 NS ** 66 .1 Third early 0, .114 0 .237 NS ** 35 .0 late 0. ,036 0 .326 NS ** 42 .6 Second early 0. ,035 0 .259 NS 40 .6 late -U. U 1 1 0 .456 NS ** 66 .8 A hi lave Female early -0. ,048 1 .400 NS ** 86 .5 1 ate -0. ,036 1, .838 NS ** 86 7 7 Male early -0. ,257 1, .295 NS ** 87 .5 late -0. ,071 1, .962 NS ** 89 .1 Fifth early -0. ,776 0, .690 ** 73 .1 late 0. ,043 0, .750 NS ** 79 .3 Fourth early -0. 167 0, .502 NS ** 69 .1 late -0. 113 0, .566 NS ** 65 .7 Third early 0. 087 0. ,414 NS ** 64 .1 late -0. 042 0, .325 NS ** 48 .1 Second early -0. 145 0. .526 NS irk 65 .4 late -D ~ u 097 0, ,460 NS •k* 66 .2 E. servus Fema 1 e early -0. 048 2. ,092 NS ** 90, .0 late -0. 036 2. ,027 NS ** Q7 0 Male early -0. 257 2. ,374 NS ** 89, .3 late -0. 071 2, ,120 NS ** 91, .5 Fifth early -0. 776 3. 307 NS ** 57, .3 late 0. 043 1. 735 NS ** 46. .0 Fourth early -0. 167 1. 646 NS ** 79. ,1 late -0. 113 1. 311 NS ** 78. ,4 Third early 0. 087 0. 774 NS ** 80. ,5 late -0. 042 0. 602 NS ** 89. ,0 Second early -0. 145 0. 610 NS 83. ,0 late -0. 027 0. 591 NS ** 84. ,0 NS = Nonsignificant (P > 0.05) ** = Highly significant (P < 0.01) = Significant (P < 0.05)

PAGE 255

247 Table 12. Results of regression analyses comparing sweep net and ground cloth for three stinkbug species on Bragg variety. Quincy, Florida, 1979. Planting Date Estimate = 0 i M — N ^0 ^1 ^ —A 1 =0 1 =1 R {/o) N. viridula Female early 0. .096 1 .254 NS iric 74.0 late -0. 009 1 .477 NS ** 94.7 Male early 0. 064 1 .487 NS ** 63.1 late -0. 013 1 .496 NS 1, ilf 92.9 Fifth early -0. 062 0, .877 NS 1 1. 79 A late 0. 036 0, .851 NS 75.2 Fourth early -0. 023 0 .512 NS 70.4 late 0. 110 0 .534 NS "kic 61 .5 Third early 0. 070 0 .412 NS 44.0 late -0. 117 0, -3 J 0 NS "kit 36.3 Second early -0. 038 0, .449 NS 72.2 late 0. 066 0, .558 NS ick 45.4 A 1*1 A n^ lare rema le early 0. 151 1, .527 n 75.0 late -0. 061 1 .649 NS ** 88.3 Male early 0. 188 1 379 ** ** 74.7 late -0. 052 1 .686 NS 86.8 r1 tth early 0. 281 0, 765 NS 67.3 late 0. 117 0, .636 NS 1 1 67.3 Fourth early 0. 117 0, .696 NS 72.6 late 0. 107 0, ,519 74.6 Thi rd early 0. 103 0, .418 NS 1 1 A A 0 44.8 late 0. 066 0. ,435 NS ** 41 .4 Second early Q. 144 0, ,361 NO "kic 45.2 late 0. 091 0, ,520 NS ** 36.6 E. servus Female early 0. 821 0, ,473 NS ** 60.0 late 0. 108 0. ,396 NS ** 90.1 Male early 1. 136 0. ,870 NS ** 52.3 late -0. 062 0. ,532 NS ** 93.4 Fifth early 1. 917 1. ,317 NS ** 40.5 late -0. 263 1. ,714 NS ** 92.7 Fourth early 0. 270 1. 970 NS ** 40.3 late -0. 191 2. 057 NS ** 78.3 Third early 0. 165 1. 135 NS 32.8 late 0. 468 1 814 NS ** 60.0 Second early 0. 160 1. 104 NS ** 30.9 late 0. 180 1 907 NS ** 75.8 NS = Nonsignificant (P > 0.05) ** = Highly significant (P < 0.01) = Significant (P < 0.05)

PAGE 256

248 Table 13. Results of regression analyses comparing sweep net and ground cloth for three stinkbug species on Cobb variety. Quincy, Florida, 1979. Planting Date Estimate H^:6 i = 0 N = ^0 ^1 i=0 i=l R' ( %) N. viridula Female early 0. 136 0 .998 NS ** 40. 2 late -0. 029 1 .294 NS ** 79. 0 Male early 0. 153 1 012 NS ** 34. 8 late -0. 048 1 312 NS •Ms 80. 0 Fifth early 0. 106 0 .773 NS ** 52. 4 late 0. 071 0 554 NS 61. 6 Fourth early 0. 059 0 .533 NS ** 57. 6 late 0. 082 0 476 NS ** 65. 0 Third early 0. 068 0 279 NS ** 64. 5 late 0, 098 0 445 NS ** 46. 5 Second early 0. 019 0 .320 NS ** 70. 1 late 0. 150 0 .479 NS ** 35. 3 A. hilar e Female early 0. 004 1 .675 NS ** 71 0 late -0. 016 1 284 NS ** 69. 0 Male early 0. 073 1 288 NS •k* 68. 0 late -0. 038 1 305 NS k* 76. 2 Fifth early 0. 163 0 691 NS ** 51 7 late 0. 078 0 537 NS ** 64. 8 Fourth early 0. 081 0 506 NS ** 52. 5 late 0. 141 0 460 ** 60. 0 Third early -0. 001 0 427 NS 80. 2 late 0. 169 0 407 ** 22. 5 Second early -0. 019 0 462 NS 81. 5 late 0. 165 0 600 NS 20. 5 E. serous Female early -0. 016 2 146 NS ** 96. 4 late -0. 241 2. 338 NS ** 95. 3 Male early -0. 213 2. 257 NS ** 97. 9 late -0. 088 2. 243 NS ** 97. 6 Fi f th early 0. 607 2. 418 NS ** 85. 3 late 0. 749 2. 544 NS ** 85. 4 Fourth early -0. 153 2. 280 NS ** 73. 6 late -0. 013 2. 359 NS ** 75. 5 Third early 0. 087 0. 862 NS ** 70. 0 late 0. 553 0. 766 NS ** 57. 2 Second early -0. 126 0. 693 NS ** 85. 2 late 0. 340 0. 498 NS ** 64. 1 NS = Nonsignificant (P > 0.05) ** = Highly significant (P < 0.01) = Significant (P < 0.05)

PAGE 257

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REFERENCES CITED AMER. SOYBEAN ASSOC. 1972. Will the soybean crop move to the tropics? Soybean Dig. 32:40-42. BLATCHLEY, W. S. 1926. Heteroptera or true bugs of eastern North America. Nature Publ Co., Indianapolis. 1116 p. BLICKENSTAFF, C. C. and J.' L. HUGGANS. 1962. Soybean insects and related arthropods in Missouri. Missouri Agric. Exp. Sta Res. Bull. 803: 1-51. BOYER, W. P.,andB. A. DUMAS. 1963. Soybean insect survey as used in Arkansas. USDA Coop. Econ. Insect Rep. 13:91-92. BOYER, W. P., and B. A. DUMAS. 1969. Plant-shaking methods for soybean insect survey in Arkansas, pp. 92-94 in Survey methods for some economic insects. USDA ARS 81-31:140 p. BRATLEY, H. E. 1936. The larger plant bugs. Rep. Fla. Agr. Exp. Sta. for 1935/1936:65-66. BRATLEY, H. E. 1941. The larger plant bugs. Rep. Fla. Agr. Exp. Sta. for 1940/1941:72. BURLEIGH, J. G. 1972, Population dynamics and biotic controls of the soybean looper in Louisiana. Environ. Entomol 1:290-294. CARNER, G. R., M. SHEPPARD, and S. G. TURNIPSEED. 1974. Seasonal abundance of insect pests of soybeans. J. Econ. Entomol. 67: 487-493. CLOWER, D. F., and T. E. HANKINS. 1960. Stinkbugs, a new menace to Louisiana soybeans. Insect Conditions in La. 3:7-8. CORPUZ, L. R. 1969. The biology, host range, and natural enemies of Nezara virdula L. (Pentatomidae Hemiptera). Philippine Entomol. 1:225-239. CUMBER, R. A. 1949. The green vegetable bug Nezara viridula. N. Z. J. Agr. 79:563-564. DAUGHERTY, D. M. M. H. NEUSTADT, C. W. GEARKE, L. E. CAVANA6H, L. F. WILLIAMS, and D. E. GREEN'. 1964. An evaluation of damage to soybeans by brown and green stinkbugs. J. Econ. Entomol. 57:719-722. 252

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253 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 Agr. Exp. Sta. Tech. Bull. 238:264p. DeLONG, D. M. 1932. Some problems encountered in the estimation of insect populations by the sweeping method. Ann. Entomol Soc. Amer. 25:13-17. DeWITT, N. B., AND G. L. GODFREY. 1972. The literature of arthropods associated with soybeans. II. A bibliography of the southern green sti nkhuq Nezara viridula (L.) (Hemiptera: Pentatomidae) 111. Natur. Hist. Surv. Biol. Notes. 78:23p. DRAKE, E. J. 1920. The southern green stinkbug in Florida. Fla. State Plant. Bd. Quart. Bull. 4:41-94. DUNCAN, R. G. 1958. Feeding relationships of Nezara viridula (1.) (Hemiptera: Pentatomidae) on soybeans. M.S. Thesis, Louisiana State University. 52 pp. DUNCAN, R. H., and J. R. WALKER. 1968. Some effects of the southern green stinkbug on soybeans. Louisiana Agr. 12:10-11. EVERETT, P. 1950. Spread of green vegetable bug. N. Z. Dept. Agr. J. 80:145-146. F.A.O. 1977. Production yearbook. F.A.O.,Rome. 31:391p. GENUNG, W. G., V. E. GREEN, and E. WEHLBURG. 1964. International relationship of stinkbugs and diseases to Everglades soybean production. Proc. Soil Crop Sci Soc. Fla. 24:131-137. HARRIS, V. E. and J. W. TODD. 1980a. Temporal and numerical patterns of reproductive behavior in the southern green stinkbug. Nezara viridula (L.) (Hemiptera: Pentatomidae). Entomol. Exp. Appl 27:105-116. HARRIS, V. E., and J. W. TODD. 1980b. Comparative fecundity, egg fertiligy and hatch among wildtype and three laboratoryreared generations of the southern green stinkbug, Nezara viridula (L.) (Hemiptera: Pentatomidae). J. Ga. Entomol. Soc. 15(3) :245-252. HARRIS, V. E., and J. W. TODD. 1980c. Duration of the immature life stages of the southern green stinkbug, Nezara viridula (L.) with a comparative review of previous studies. J. Ga. Entomol. Soc. 15(2):114-124. HARRIS, V. E., and J. W. TODD. 1980d. Male-mediated aggregation of male, female and 5th instar southern green stinkbugs and concomitant attraction of a tachinid parasitoid, Triahopoda pennipes. Entomol. Exp. Appl. 27:117-126.

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254 HERZ06, D. C. 1968. Seasonal location, and sexual variation in the color pattern of the bean leaf beetle, Cevtcma trifureata (Forster). M.S. Thesis, Louisiana State University. 87 p. HERZOG, D. C, J. W. TODD, and R. M. McPHERSON. 1981. The stinkbug complex. In L. D. Newsom, ed. Integrated Pest Management of Insect Pest of Soybeans, Willey Interscience, New York. (In press ) HINSON, K. 1967. Soybeans in Florida. Univ. Fla. Agr. Exp. Sta. Bull. 716:121 p. JENSEN, R. L., and L. D. NEWSOM. 1972. Effect of stinkbug-damaged soybean seeds on germination, emergence, and yield. J. Econ. Entomol. 65:261-264. JONES, T. H. 1918. The southern green plant-bug. U.S. Dept. Agric. Bull. 689:1-27. JONES, W. A., JR. 1976. An evaluation of selectd soybean genotypes for resistance to stinkbugs. M.S. Thesis. Clemson University, Clemson, S.C. 54 p. JONES, W. A., JR. 1979. The distribution and ecology of pentatomid pests of soybeans in South Carolina. Ph.D. Dissertation. Clemson University. 108 p. JONES, W. A., and M. J. SULLIVAN. 1978. Susceptibility of certain soybean cultivars to damage by stinkbufs. J. Econ. Entomol. 71(3): 534-536. JONES, W. A., and M. J. SULLIVAN. 1979. Soybean resistance to the southern green stinkbug, Nezara viridula (L.). J, Econ. Entomol. 72(4): 628-632. KARIYA, H. 1961. Effect of temperature on the development and the mortality of the southern green stinkbug, Nezara viridula and the oriental green stinkbug, Nezara antennata. Jap. J. Appl. Entomol. Zool 5:191-196. KILPATRICK, R. A., and E. E. HARTWIG. 1955. Fungus infection of soybean seen as influenced by stinkbug injury. Plant Dis. Rep. 39:177-180. KIRITANI, K. 1963. Oviposition habit and effect of parental age upon the post-embrionic development in the southern green stinkbug, Nezara viridula. Jap. J. Ecol 13:88-96. KIRITANI, K. 1964a. The effect of colony size upon the survival of larvae of the southern green stinkbug, Nezara viridula. Jap. J. Appl. Entomol. Zool. 8:45-54. KIRITANI, K. 1964b. Natural control of populations of the southern green stinkbug, Nezara viridula. Res. Popul Ecol, 6:88-98.

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255 KIRITANI, K. 1965. The natural regulation of the population of the southern green stinkbug, Nezava vividula (L.). Hroc. Ail inti. Congr. Centomol London, 1964, 12:375. KIRITANI. K.. and H. HOKYO. 1962. Studies on the life table of the southern green stinkbug, Bezara vtrtdula. Jap. J. Appl. tntomoi. Zool. 6:124-140. KIRITANI, K., N. HOKYO, K. KIMURA, and F. NAKASUYI. 1965. Imaginal dispersal of the southern green stinkbug, Nezara vvmdula U-J* in relation to feeding and oviposition. Jap. J. Appl. Entomol Zool. 9:291-297. KIRITANI, K., and K. KIMURA. 1965. The effect of population density during nymphal and adult stages on the fecundity and other reproductive performances. Jap. J. Ecol 15:233-236. KIRITANI, K., and K. KIMURA. 1967. Effects of parental age in life cycle of the southern green stinkbug, Nezava viridula (L.) (Heteroptera: Pentatomidae) Jap. J. Appl. Entomol. Zool. 2:69-78.. KIRITANI, K., F. NAKASUYI, and N. HOKYO. 1966. The survival rate of eggs and larvae in relation to group size in the southern green stinkbug, Nezara viridula (L.). Jap. J. Appl. Entomol. Zool. 10:205-211. 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, eds. Sampling methods in soybean entomology. Springer-Verlag, New York, 587 p. KOGAN, M., W. G. RUESINK, and K. McDOWELL. 1974. Spatial and temporal distribution patterns of the bean leaf beetle, Certoma trifuroata (Forster) on soybeans in Illinois. Environ. Entomol. 3:607-617. MARSTON, N. L., C. E. MORGAN, G. D. THOMAS, C. M. IGNOFFO. 1976. Evaluation of four techniques for sampling soybean insects. J. Kans. Entomol. Soc. 49:389-400. McPHERSON, R. M. 1978. Population dynamics and damage evaluations of four stinkbug species of three genera affecting quality and yield of soybean in Louisiana. Ph.D. Dissertation, Luouisiana State University, Baton Rouge, 112p. McPHERSON, R. M. L. D. NEWSOM, and B. F. FARTHING. 1979. Evaluation of our stinkbug species from three genera affecting soybean yield and quality in Louisiana. J. Econ. Entomol. 72:188-194. MINER, F. D. 1961. Stink bug damage to soybeans. Ark. Farm Res. 10(3):12.

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256 MINER, F. D. 1966. Biology and control of stink bugs on soybeans. Ark. Agr. Exp. Sta. Bull. 708:1-40. MITCHELL, W. C, and R. F. L. MAU. 1969. Sexual activity and longevity of the southern green stink bug, Nezara viridula. Ann. Entomol Soc. Amer. 62:1246-1247. NETTLES, W. C, C. W. THOMAS, and F. H. SMITH. 1970. Soybean insects and diseases. S.C. Ext. Ser. Circ. 504. 24 p. NEWSOM, L. D., and D. C. HERZOG. 1977. Trap crops for control of soybean pest. La. Agr. 20(3):14-15. NEWSOM, L. D., R. L. JENSEN, D. C. HERZOG, and J. W. THOMAS. 1975. A pest management system for soybeans. La. Agr. 184:10-11. PEDIGO, L. P., G. L. LENTZ, J. G. STONE, and D. F. COS. 1972. Green cloverworm populations in Iowa soybeans with special reference to sampling procedure. J. Econ. Entomol. 65:414-421. PITTS, J. R. 1977. Effect of temperature and photoperiod on lUezava viridula (L.). M.S. Thesis, Louisiana State University, Baton Rouge. 48 p. RAGSDALE, D. W. 1977. Isolation and identification of bacteria and fungi transmitted during feeding and from various organs of Nezara viridula (L.). M.S. Thesis, Louisiana State University, Baton Rouge. 48 p. RANEY, H. G. and K. V. YEARGAN. 1977. Seasonal abundance of common phytophagous and predaceous insects in Kentucky soybeans. Trans. Ky Acad. Sci 38:83-87. RIZZO, H. F. E. 1968. Aspectos morfologicos y biologicos de Nezara viridula (L.). (Hemiptera: Pentatomidae) Agr. Trop. (Maracay) 18:249-274. ROLSTON, L. H., and R. L. KENDRICK. 1961. Biology of the brown stinkbug, Euschistus servis (Say). J. Kans. Entomol. Soc. 34:151-157. RUDD, W. G., and R. L. JENSEN. 1977. Sweep net and ground cloth sampling for insects in soybeans. J. Econ. Entomol. 70:301-304. RUESINK, W. G., and M. KOGAN. 1975. The quantittative basis of pest management: sampling and measurement, pp. 309-351, in R. L. Metcalf, and W. H. Luckmann, eds. Introduction to insect pest management. John Wiley and Sons, N. Y. 587 p. SAILER, R. I. 1953. A note on the bionomics of the green stinkbug. J. Kans, Entomol. Soc. 26:70-71.

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257 SHEPARD, M., G. R. CARNER, and S. G. TURNIPSEED. 1974. A comparison of three sampling methods for arthropods in soybeans. Environ. Entomol 3:227-232. SINGH, Z. 1972. Bionomics of the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae) in central India. Ph.D. Dissertation, University of Illinois, Urbana-Champaign. 136 p. SORENSON, C. J., and E. W. ANTHON. 1936. Preliminary studies of Aarostemum hilaris (Say) in Utah orchards. Utah Acad. Sci Arts and Letters Proc. 13: 229-232. THOMAS, G. D., C. M. IGNOFFO, C. E. MORGAN, and W. A. DICKERSON. 1974 Southern green stinkbug: Influence of yield and quality of soybeans J. Econ. Entomol. 67:501-503. TODD, J. W., and D. C. HERZOG. 1980. Sampling phytophagous pentatomidae in soybean, pp. 438-478, in M. Kogan and D. C. Herzog, eds. Sampling methods in soybean entomology. Springer-Verlag, New York, 587 p. TODD, J. W., and S. G. TURNIPSEED. 1974. Effects of southern green stinkbug damage on yield and quality of soybeans. J. Ecln. Entomol. 67(3):421-426. TODD, J. W., M. D. JELLUM, and D. B. LEUCK. 1973. Effects of southern green stink bug damage on fatty acid composition of soybean oil. Environ. Entomol. 2(4) :685-689. TURNER, J. W, 1967. The nature of damage by Nezara viridula (L.) to soy bean seed. Queensl. J. Agr. An. Sci. 24:105-107. TURNIPSEED, S. G. 1973. Insects, pp. 545-572 in B. E. Caldwell, ed. Soybeans: Improvement, production, and uses. Amer. Soc. Agron. Pub., Madison, Wisconsin, Agron. Ser. 16. 681 p. TURNIPSEED, S. G. and M. KOGAN. 1976. Soybean entomology. Annu. Rev. Entomol. 21:25-60. UNDERHILL, G. W. 1934. The green stinkbug. Va. Agr. Exp. Sta. Bull. 294:1-26. WHITMARSH, R. D. 1917. The green soldier bug. Ohio Agr. Exp. Sta. Bull. 310:1-34. WHITTY, E. B., W. L. CURREY, J. R. STRAYER, D. W. DICKSON, and T. A. KUCHAREK. 1971.Soybean production guide. Fla. Coop. Ext. Serv. Circ. 277c. 12 p.

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258 WILSON, J. W., and E. G. KELSHEIMER. 1955. Production of southern peas (cowpeas) in Florida. I. Cultural practices and varieties II. Insects and their control. Ill Nematodes and their control. Fla. Agr. Exp. Sta. Bull. 557. 28 p. WOODSIDE, A. M. 1946. Catfacing and dimpling in peaches. J. Econ. Entomol. 39:158-160. WUENSCHE, A. L. 1976. Relative abundance of seven pest species and three predaceous genera in three soybean ecosystems in Louisiana M.S. Thesis. Louisiana State Univ., Baton Rouge, La. 384 p.

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BIOGRAPHICAL SKETCH Euri pedes B. Menezes was born on August 11 1942, in Frutal Minas Gerais, Brazil. He is the first child of two children of Marcel ina Gonial ves Menezes and the late Ambrolino Menezes de Sauza. Following graduation from Col^gio Estadual "Brasilio Machado" (High School) in Sao Paulo, he attended the Universidade Federal Rural do Rio de Janeiro and received the Bachelor of Science degree with a major in agronomy, in December, 1971. He attended the Escola Superior de Agricultura "Luiz de Queiroz" (USP) and received the degree of Master of Science with a major in entomology in March, 1974. In June, 1974, he became a faculty member at Universidade Federal Rural do Rio de Janeiro, in the Department of Entomology. In June, 1976, he came to the United States and took a course in the English language at Michigan State University, East Lansing, Michigan. In January, 1977, he began the studies for his Ph.D. degree at the University of Florida, Gainesville, Florida. He is currently a candidate for the degree Doctor of Philosophy in the Department of Entomology and Nematology. He married Elza Machado Menezes in December, 1971. They have two daughters, Caroline and Jacqueline. 259

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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. Herzog, Chairman Associate Professor of Entomology 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. Dale H. Habeck Professor of Entomology 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. Reece I. Sailer Professor of Etomology

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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. '1 Elmo B. Whitty 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 1981 Dean/yCollege of Agricu^jEure Dean for Graduate Studies and Research


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