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THE EFFECT OF INSECTICIDES ON DYNAMICS OF SOIL INSECT PESTS AND CARABID BEETLES (COLEOPTERA: CARABIDAE) IN CORN AGROECOSYSTEMS
DISSERTATION
Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University
By
Zhong-Zhao Chen, M.S.
*****
The Ohio State University
1997
Dissertation Committee;
Dr. Harold R. Willson, Advisor Approved by
Dr. David J. Horn
Dr. David J. Shetlar — Advisor Dr. Benjamin Stinner Department of Entomology UMI Number: 9731602
UMI Microform 9731602 Copyright 1997, by UMI Company. All rights reserved.
This microform edition is protected against unauthorized copying under Title 17, United States Code.
UMI 300 North Zeeh Road Ann Arhor, MI 48103 ABSTRACT
Effects of three insecticides on soil insect pests and nontarget carabids
were evaluated in a series of laboratory, microplot and field plot studies. In the field studies, granular formulations of chlorpyrifos and tefluthrin were applied as at planting treatment (APT), and permethrin was applied with broadcasting as post-emergence treatment (PET). APT prevented stand losses by black cutworm, Agrotis ipsilon
(Hufiiagel), and root injury by rootworms, Diabrotica spp., which occurred in plots receiving PET and untreated control (UC). As a result, yields of APT were significantly greater than that of PET or UC, especially when population of insect pests were at economic levels.
Laboratory bioassays using topical and soil contact exposure techniques demonstrated that the insecticides used were toxic to carabids. The toxic effects were also demonstrated in microplot studies, where adult carabids of Scarites substriatus
Haldeman were subjected to insecticide treatments in a contained environment.
The behavior of carabids in field plots treated and untreated were monitored using pitfall traps throughout the year of treatment and the year following treatment. Five carabid species, Harpaliis pensylvanicus Say, Pterostichus chalcites Say, S. substriatus
Haldeman, P. stygicus (Say), and Anisodactylus sanctaecrucis P., were the dominant species, representing >85% of the total carabid collections in three growing seasons in
ii two field plots. Direct effects of PET with permethrin was clearly demonstrated when a barrier pitfall technique was used to monitor directional movement of carabids in response to treatments. In contrast, the effects were not clearly demonstrated in weekly trappings throughout the growing seasons, although differences in early season carabid collections between treatments indicated enhanced activity. Additionally, indirect effects on carabids were demonstrated where the field habitats were altered by insecticide treatments.
Besides the direct and indirect effects of insecticides, variations of field habitats and weather conditions among years were considered other factors affecting carabid activity. Seasonal abundance of carabids exhibited species characteristics. H. pensylvanicus and P. stygicus appeared to be the later season species, while P. chalcites,
S. substriatus, and A. sanctaecrucis were the early season species. Seasonal abundance of these species suggests their role in the fluctuation of soil insect pests in com field.
However, activities of carabids varied in response to the heterogeneity of habitats.
Ill Dedicated to my parents and my son
IV ACKNOWLEDGMENTS
I would like to express my sincere appreciation to Dr. Harold R. Willson, for his support, guidance, and patience throughout my graduate studies. My appreciation extends to Drs. David Shetlar, David Horn and Benjamin Stinner for being my reading and examining committee.
My special thanks goes to Foster F. Purrington, who confirmed all the carabid species in this study. 1 thank James B. Eisley for his technical assistance both in and out of field, and thank Jim Jasinski and Curtis Young for their field technical assistance. I thank C. Renk and other personnel in the Western Branch of OARDC who supplied the field production service for this study. I thank personnel in Extension Entomology, Dr.
Celest Welty, Dr. Bill Lyon and Dr. Acie Waldron (deceased), Jacque, Jean and Jeannett, who have been so j&iendly and helpful to me.
I would like to thank my parents, my brother and sisters, for their early encouragements and supports in my science career. Finally, special thanks to my wife,
Yanting Liu and my son, Jason Xi Chen, for their endless patience, constant support throughout my studies. VTTA
January 24,1960...... Bom - Fujian, China
June 1991 - December 1993 ...... Graduate Research Associate,
The Ohio State University
December 1993 ...... M. S. Entomology,
The Ohio State University
1993 - Present ...... Graduate Research Associate,
The Ohio State University
FIELDS OF STUDY
Major Field: Entomology
Minor Field: Plant Pest Management.
VI TABLE OF CONTENTS
Page Abstract ...... ii
Dedication ...... iv
Acknowledgments...... v
Vita...... vi
List of Table...... x
List of Figures...... xii
Chapters:
1. Insecticides and their interactions with important soil pests, carabids and vegetation in com ecosystems — a literature review and general hypothesis ...... 1 1.1 Introduction...... 1 1 .2 Soil insect pests in Ohio com field ...... 2 1 .2.1 Com rootworms...... 2 1 .2.2 Black cutworm...... 4 1.3 Carabids ...... 8 1.3.1 Life history and population dynamics ...... 8 1.3.2 Carabids in their environments ...... 10 1.3.3 Carabids in arable fields ...... 11 1.3.4 Sampling method — pitfall trap ...... 12 1.3.5 Carabid as bénéficiais ...... 14 1.4 Interactions among insects,plants and insecticides ...... 17 1.4.1 Impacts of insecticides on carabids ...... 17 1.4.2 Carabids and vegetation ...... 19 1.5 General hypothesis ...... 22 References...... 26
2. Prevention of stand loss caused by black cutworm,Agrotis ipsilon (Hugnagel), in field corns ...... 37
vu 2.1 Introduction...... 37 2.2 Materials and Methods ...... 40 2.2.1 Field studies ...... 40 2.2.2 Microplot studies ...... 41 2.3 Results and Discussion...... 42 2.3.1 Field studies ...... 42 2.3.2 Microplot studies ...... 46 2.4 Summary...... 54 References...... 55
3. The impact of selected insecticides on carabids (Coleoptera: Carabidae) from com fields ...... 57 Abstract...... 57 3.1 Introduction...... 58 3.2 Materials and Methods ...... 60 3.2.1 Laboratory bioassay studies...... 60 3.2.2 Microplot studies ...... 62 3.2.3 Field studies ...... 63 3.3 Results...... 65 3.3.1 Laboratory bioassay studies...... 65 3.3.2 Microplot studies ...... 67 3.3.3 Field studies ...... 70 3.4 Discussion...... 74 3.4.1 Laboratory bioassay studies...... 74 3.4.2 Microplot studies ...... 80 3.4.3 Field studies ...... 80 References...... 84
4. Study of dispersion patterns of carabids(Coleoptera; Carabidae) in com ecosystem under the influence of insecticide applications with barrier-pitfall trap technique ...... 87 Abstract...... 87 4.1 Introduction...... 8 8 4.2 Materials and methods ...... 92 4.3 Results...... 97 4.3.1 Movement of carabids between treatments ...... 97 4.3.2 Movement of carabids on the plot border ...... 109 4.4 Discussion...... 122 References...... 128
5. The interaction of carabid activities, soil insect pests and field vegetation under the influence of insecticide applications ...... 131 Abstract...... 131
vm 5.1 Introduction...... 132 5.2 Materials and Methods ...... 133 5.3 Results and Discussion...... 136 5.3.1 Key pest variable ...... 136 5.3.2 Carabid activities ...... 142 5.3.3 Carry-over effects of insecticides on carabids ...... 145
6 . Temporal and spatial distribution of carabids in response to the heterogeneity of field habitats in com agroecosystems ...... 152 Abstract...... 152 6.1 Introduction...... 153 6.2 Materials and Methods ...... 155 6.3 Results and Discussion...... 157 6.3.1 Carabid abundance and assemblage in com agroecosystems .... 157 6.3.2 Spatial distribution of carabids ...... 162 6.3.3 Temporal distribution of carabids ...... 170
7. Summary...... 186
Bibliography ...... 192
IX LIST OF TABLES
Table Page
2.1 Comparison of com plant stands, root ratings, and yields between treatments in the field plots. Western Branch of OARDC, 1994 ...... 43
2.2 Comparison of com plant injury (%) caused by CRWs between treatments in the field plots. Western Branch of OARDC, 1994 ...... 44
2.3 Comparison of com stand counts, plant injury (%), root rating, and yields between treatments in field plots. Western Branch of OARDC, 1995 ...... 47
2.4 Comparison of com stand counts, root ratings and yields between treatments in the field plots, Westem Branch of OARDC, 1996 ...... 48
3.1 Toxicities (topical LDjq) of the selected insecticides on adult carabids of the dominant species, S. substriatus, P. chalcites and H. pensylvanicus, 1995-1996 ...... 6 6
3.2 Relative toxicities (LC50) of the selected insecticides on adult carabids of the dominant species. S', substriatus, P. chalcites and H. pensylvanicus, by contacting-poisoning in soil-insecticide medium with series doses from formulated insecticides, 1995-1996 ...... 6 8
3.3 Comparison of mortalities of carabids and number of other soil dwelling arthropods between treatments in microplots. Westem Branch of OARDC, 1995 and 1996 ...... 69
3.4 Comparison of com stand counts, root rating and weed cover between treatments in com plots, Westem Branch of OARDC, 1994 and 1995 ...... 73
4.1 Comparison of the total catch and mortality (%) of carabids in pitfall traps between the two sides of barrier related with treatments ...... 98
4.2 Comparison of total catch of carabids per trap and mortality between treatments following post-emergence treatment (PET) ...... 102
X 4.3 Comparison of mean catches of carabids between treatments for the on-border trap set prior to the post-emergence treatment (PET) ...... 110
4.4 Comparison of mean pitfall catches and mortalities in different trap sets for different treatments on the on-border set following the post-emergence treatment (PET) ...... 111
5.1 Comparison of key pest variables and carabid catches between treatments and between the treated year and the untreated year in field A, 1994-1995 ...... 137
5.2 Comparison of key pest variables and carabid catches between treatments and between the treated year and the untreated year in field B, 1995-1996 ...... 139
5.3 Comparison of mean values of key pest variables and carabid catches between the 1st and 2nd year in com field plots, 1994-1996 ...... 140
5.4 Significant relationships found among seasonal collection of dominant carabid species and the key pest variables of field A and B, Westem Branch of OARDC, 1994-1996 ...... 146
6 .1 Total catch of carabids, species presented, their percentages in pitfall traps, and indices of species diversity and evenness in each field and year. Westem Branch of OARDC, 1994-1996 ...... 158
6.2 Total catch of carabids, species presented, and their percentages in pitfall traps in each field. Westem Branch of OARDC, 1994-1996 ...... 160
6.3 Percentage of Similarity (PS, upper right) and Spearman’s coefficient of rank correlation (R, lower left) of total carabid catches in the two field plots in three years ...... 163
6.4 The value of Spearman’s coefficient of rank correlation (R) of the cumulative catches of dominant carabid species among the two field plots in different years ...... 142
6.5 The Indices of Dispersion (ED) of the dominant carabid species and the Chi-square test for significant departures of ID form 1.0 ...... 166
XI LIST OF FIGURES
Figure Page
1.1 The effect of insecticides on the target and nontarget insects, vegetation, and their interactions in the com agroecosystem ...... 24
2.1 Comparison of cumulative plant injury (%) caused by black cutworm between treatments in microplots, 1995 ...... 50
2.2 Comparison of cumulative plant injury (%) caused by black cutwonn between treatments in microplots, 1996 ...... 51
3.1 Comparison of total carabid catches between treatments in com plots at the Westem Branch of OARDC, 1994-1995 ...... 71
3.2 Comparison of the catches of dominant carabid species and the total catch per trap between treatments for each individual pitfall trapping at the Westem Branch of OARDC, 1994 ...... 75
3.3 Comparison of the catches of dominant carabid species and the total catch per trap between treatments for each individual pitfall trapping at the Westem Branch of OARDC, 1995 ...... 77
4.1 Experimental plot plan with the arrangement of barrier-pitfall trap sets in the com field plots. The figure includes two of the four blocks of the experimental plots (five plots per block) ...... 93
4.2 Design of the barrier-pitfall trap se t ...... 95
4.3 Comparison of total carabids caught in barrier-pitfall traps between treatments prior to the post-emergence treatments (PET), 13-17 June, 1996 ...... 103
4.4 Comparison of mean number of carabids caught and mortality (%) in barrier-pitfall traps between treatments following the post-emergence treatment (PET), 17-20 June 1996 ...... 104
XU 4.5 Comparison of mean number of carabids caught in barrier-pitfall traps between treatments following post-emergence treatment (PET), 17 June - 22 August, 1996 ...... 106
4.6 Comparison of mean number of carabids caught in barrier-pitfall traps of the on-border set prior to the post-emergence treatment, 13-17 June, 1996 ...... 113
4.7 Comparison of mean number of carabids caught and their mortality (%) between alley side and plot side in barrier-pitfall traps on the on-border set following the post-emergence treatment (PET), 17-20 June, 1996 ...... 115
4.8 Comparison of mean number of carabids caught in barrier-pitfall traps on the on-border set following post-emergence treatment (PET), 17 June - 22 August, 1996...... 117
4.9 Comparison of mean number of carabids and the percentage of the dominant species caught in barrier-pitfall traps, and total catch of carabids between the on-border and the inter-plot set for the whole study period, 13 June - 22 August, 1996 ...... 119
6 .1 Plot of Principal Component Analysis using Varimax normalized ordination ...... 168
6.2 Total catches of dominant carabid species and the total catch of carabid in field plots A. Westem Branch of OARDC, 1994 ...... 171
6.3 Total catches of dominant carabid species and the total catch of carabid in field plots A. Westem Branch of OARDC, 1995 ...... 173
6.4 Total catches of dominant carabid species and the total catch of carabid in field plots B. Westem Branch of OARDC, 1995 ...... 175
6.5 Total catches of dominant carabid species and the total catch of carabid in field plots B. Westem Branch of OARDC, 1996 ...... 177
xiu CHAPTER 1
INSECTICIDES AND THEIR INTERACTIONS WITH IMPORTANT SOIL PESTS,
CARABIDS AND VEGETATION IN CORN ECOSYSTEMS
- LITERATURE REVIEW AND GENERAL HYPOTHESIS
1.1 Introduction
Black cutwonn (BCW),Agrotis ipsilon (Hufiiagel) and com rootwonns (CRW),
Diabrotica spp., are important soil insect pests in the United States com belt (Chiang
1978, Shrrod et ai. 1979, Story et al 1983, Willson and Eisley 1992). Although
insecticides have provided effective control of these soil insect pests, their impacts on nontarget organisms and agroecosystems have been of increasing concem. Numerous studies have attempted to study the multiple effects of insecticide treatments in agroecosystems (Edwards and Thompson 1975, Chapman and Harris 1980, Floate et al.
1989, Reed et al. 1992, Stark and Wennergren 1995), but a poor understanding of these effects remains. Carabids are an important predator group in soil and considered to be greatly affected by the insecticide treatments. To evaluate the effect of insecticide treatments on target and non-target insects in the com agroecosystem, the effects of the insecticide applications on the important soil insect pests (BCW and CRWs) and nontarget carabid beetles, as well as the possible interactions of soil insect pests, carabids
and field vegetation under the influence of insecticide applications will be the primary
area of investigation.
In this chapter, the literature of BCW, CRWs, and carabids, and their interactions
with other components of the agroecosystem and insecticide treatments will be reviewed,
and the general hypothesis of the investigation will be established.
1.2 Soil Insect Pests in Ohio Corn Fields
Soil insects were defined by Lilly (1956) as "any insects, which during its growing
or feeding stages, lives on or beneath the soil surface." Com rootworms and cutworms
are typical soil insects in Ohio field com (Willson and Eisley 1987 & 1992) and other
areas of the U.S. com belt (Chiang 1973, Levine and Oloumi-Sadeghi 1991).
1.2.1 Com Rootworms
Com rootworms (CRW) are serious soil pests in field com in Northern America.
Westem com rootworm (WCR), Diabrotica virgifera virgifera LeConte, and northern
com rootworm (NCR), D. longicornis (Say), are the most serious insect pests of field
com in the major com-producing states of the north central area of the U.S. (Chiang
1973, Willson and Eisley 1992). CRWs also attack other types of com including pop,
flint, flour, and sweet com (Levine and Oloumi-Sadeghi 1991).
The distribution, biology, and management of CRWs have been extensively reviewed (Chiang 1973, Krysan and Miller 1986, and Levine and Oloumi-Sadeghi 1991).
Adults of CRWs present in com fields fi'om July through October, feeding on com pollen. silks, immature kernels, and foliage of other plants (Chiang 1973). Oviposition occurs
mainly in com field from late July through early September. Overwintered eggs begin to
hatch from late May and early June the following year. Larvae feed on the roots of com
and on the root system of a limited number of other plants. The feeding damage to the
root system by CRW larvae reduces the amount of water and nutrients supplied to
developing plants. Early severe root damage may kill plants while later damage causes
reduction in ear weight (Chiang 1973). Adult beetles cut and feed on silks (Chiang and
Raros 1968), and can transmit maize chlorotic mottle virus (Jenson 1985).
1 .2.1 .1 Cultural Control
Crop rotation with small grains, soybean or alfalfa has provided excellent control
of CRWs, since eggs are laid almost exclusively in com fields, and larvae must feed on com roots the following season to complete development (Chiang 1978, Levine and
Oloumi-Sadeghi 1991). However, CRW larval damage on the first year com following a soybean has recently been reported (Levine and Oloumi-Sadeghi 1988). The possible biological explanation for the failure of rotation is the extensive diapause of CRW eggs, which has been confirmed occurring in NCR, but not found in WCR (Krysan et al. 1984,
Levine et al. 1988). WRC oviposition has been found in soybean fields with increasing numbers in Northeastem Illinois and Northwest of Indiana since the late 1980's and
1990's (Spencer and Levine 1997, Bledsoe et al. 1997). Crop rotation may be a selective pressure on CRWs, and some populations of CRWs appeared to have adapted to crop rotation. Evidence that a new race of WCR may be established has been reported in minois (O’Neil et al. 1996, Spencer and Levine 1997) and in Indiana (Bledsoe et al.
1997).
Delayed planting generally results in decreased root damage due to the lower
availability of com roots to eclosing larvae. However, the late planted com often has a
greater potential for CRW oviposition than the early planted com (Krysan et al. 1984).
1.2.1.2 Chemical Control
Soil insecticides have been a dominant and effective management tactic for
controlling CRWs, especially in continuous com (Willson and Eisley 1987 & 1994). The
persistence of soil-applied insecticides is an important factor in CRW control (Ahmad et
al. 1979, Felsot et al. 1982). While soil insecticides do not necessarily eliminate entire
CRW larval populations, they adequately protect root systems from the injury (Bergman
1987, Sutter and Gustin 1989). An ideal soil insecticide should persist in soil for 6-10
wks, the approximate length of time from insecticide application to the end of extensive
larval feeding. Because band-applied soil insecticides protect com root system only in a
limited zone around the site of application, numerous larvae may survive and complete development on peripheral roots outside the treated band (Felsot 1990).
1.2.2 Black Cutworms
Black cutworm (BCW),Agrotis ipsilon (Hufdagel), is another important pests of field com in the U.S. com belt (Chiang 1978, Story et al. 1983). Although several other cutworm species occasionally cause damage, BCW is the most destructive pest of seedling com. Evidence of the importance of BCW is given in world-wide bibliographies by Rings et al. (1976). In Ohio, BCW is one of the key pest in com field (Willson and Eisley 1992). As 4th to 6-7th instar (cutting instar) larvae, BCW chews through the stems
of coleoptile to five-leaf stage com plants near the soil surface. This results in
unrecoverable stands and yield loss (Story et al. 1983). Another symptom of feeding is
tunneling into the com stalk. Incompletely severed plants and tunneled plants tend to
wilt. The overall effect of infestation is patchiness in the plant stand (Troester 1982,
Willson and Eisley 1987).
1.2.2.1 Biology and Ecology
Weeds are suitable hosts for survival of BCW (Sherrod et al. 1979). A food
source is not essential for oviposition, but definitely benefits BCW by increased fecundity
and longevity (Sherrod et al. 1979). By identifying the pollen attached to BCW, Hendrix
and Showers (1992) traced moth migration into Missouri firom within Mexico. Soybean
debris has been observed to be more attractive to BCW than com debris for oviposition
and food, and the infestation is more likely to occur in com fields with soybean debris
than with com residues (Metcalf and Luckman 1982, Johnson et al. 1984).
1.2.2.2 Economic Damages
Com is generally most susceptible to cutting from the time it emerges from the soil until it reaches the four-leaf growth stage (Archer and Musick 1977). The decrease in plant stands and yield is directly proportional to the increase in larval density (Showers et al. 1983). Showers et al. (1979) used an approach to simulate BCW damage to seedling com and reported that grain loss became significant when more than a 1 0 % stand loss occurred. Plants severed at progressively lower levels (e.g. above, at or below the soil surface) and at progressively late stages of development (e.g. one- to four-leaf stage) produced significantly lower yield than seedlings severed at higher levels and earlier in development (Levine et al. 1983, Showers et al. 1983). A larva of increasing instar will cut progressively fewer seedlings at each succeeding com growth stage (Clement and
McCartney 1982).
1.2.2.3 Cultural Control
Cultural control is of great value for preventing BCW injury. The incidence of
BCW infestation exceeding a potential action threshold increased as tillage was reduced, especially in no-tillage com (Johnson et al. 1984, Willson and Eisley 1992). For instance, land kept free of weeds, crops or crop residues during late summer is rarely infested.
Johnson et al. (1984) reported that damage was consistently lower in the mould-board plough treatments. BCW infestation is least likely to occur when com is grown continuously using mould-board ploughing. Complete soil turnover by mould-board ploughing seems to negate any attraction of crop residue to BCW oviposition (Johnson et al. 1984). Higher incidence of BCW in no-tillage com following soybean has been reported (Johnson et al. 1984). In contrast, Brust et al. (1985) reported that conventional tillage com following soybean system had significantly more cut plants caused by BCW and fewer predators than that of no-tillage com following soybean system. They emphasized that endemic soil predator complex is a major factor in reducing BCW damage in com agroecosystem.
1.2.2.4 Chemical Control
Commonly used soil insecticides, such as tefluthrin and chlorpyrifos effectively protected plants from injury when plant injury in the untreated com plots was as high as
6 50% (Willson and Eisley 1993 & 1994), even in years of lower BCW infestations
(Willson and Eisley 1995 & 1996).
It is very important that the treatment is applied when the larvae are still in early
stages of development since later instars of BCW are likely to be tolerant to most insecticides (Harris and Sveg 1968b). Various insecticides had significant differences in efficacy for controlling BCW, and insecticide activity could be greatly influenced to a much greater extent with the technical formulation employed (Harris and Sveg 1968a &
1986b).
BCW larvae that damage com seedlings are usually in the field before the seed is planted, which reflects reality of field observations and field problems (Sherrod et al.
1979). Harris and Sveg (1968a) stated that cutworm infestations were virtually impossible to predict, especially for the BCW. Sherrod et al. (1979) suggested that considerable additional information on biology, behavior, and field ecology of BCW will be needed before good detection and control programs can be refined. Many works have also done on the sampling and the prediction of BCW (Story and Keaster 1982, Story et al. 1983, Showers et al. 1979) for years. However, the criteria of sampling and prediction of BCW are still not well defined. As the trend toward no-tillage com in the U.S. com belt, the stand loss of field com fi’om BCW’s damage has caused attention of extension entomologists. Therefore, the prediction of occurrence and the timing of control are particularly critical in BCW control. 13 Carabids
Carabidae is the largest adephagan family and the one having the most species of beetles. It contains more than 40,000 described species classified into 8 6 tribes (Erwin
1985), including over 2,000 North America species (Bell 1970). Much of the available biological and ecological information on carabids was summarized by Thiele (1977) and
Lovei and Sunderland (1996). The taxonomic accounts of North American carabid species including ecological information were documented by Ball (1960) and Lindroth
(1961-1969).
1.3.1 Life Historv and Population Dynamics
In the temperate zone, most carabids have one generation per year, while few subarctic and arctic species, two or more years are required to reach sexual maturity.
Individual development can last up to four years under unfavorable environmental conditions, such as harsh climates or adverse food conditions (Lovei and Sunderland
1996).
In general, carabids develop fi’om egg to adult in less than one year, reproduce once. Carabids are homometabolous insects that usually lay their eggs singly. The typical carabid larva is free moving campodeiform and usually undergoes three instars before pupating in soil (Lovei and Sunderland 1996). Larvae of many species undergo diapause in the second or third stages, either hibernation or aestivation. Adult longevity can also exceed one season, but varies from species to species (Thiele 1977). Generally, long adult life span is more common in large species and species with winter larvae or autumn breeders than in ones with summer larvae or spring breeders. Obligatory
8 univoltism is apparently rare and occurs mainly in species of short longevity. Bi- and
multvoltinsm is usually found in species living in unfavorable environments, and
dynamic polyvariance is common (Lovei and Sunderland 1996).
Based on adult reproduction activity, carabids are commonly divided into two
groups, spring-breeders and autumn-breeders (Thiele 1977). Spring-breeders hibernate as
adults only, whereas autumn-breeders mainly hibernate as larvae. Their period of
reproduction is often, but not always, simultaneous with respective peak of occurrence of
adults within a certain habitat (Wallins 1985). From pitfall trapping studies, Thiele
(1977) concluded that the seasonal activity period of spring-breeders is generally
characterized by one peak in the late spring (May-June) and one in the autumn (August -
September), while autumn-breeders only exhibit a single peak in the middle of the
summer (July - August).
Based on the development of the hind wings, carabids can be divided into three
groups: macropterous species — all individuals have fully developed hind wings,
brachypterous species - all individuals have vestigial wings, and dimorphic species -
some individuals have fully developed hind wings and other species have vestigial ones.
Brachypterous species are mostly forest species and have much more limited dispersal abilities than do the macropterous species (Bell 1970). The dispersion power of carabids was well documented by den Boer (1969). Many carabids make a seasonal migration from a primary habitat to a winter refuge (Bell 1970). Adults of same species make frequent dispersal flights. These flights are nocturnal, and are reflected in the large numbers of carabids which are attracted to lights (van Huizen 1979). Generally, more carabids are nocturnal than diurnal, and the diurnal species are
smaller than nocturnal ones. Night-active species are usually dark and dull, while diurnal
species often display iridescent colors (Greenslade 1963a). Temperature, light intensity,
and humidity are important factors influencing the diel activity (Thiele 1977).
Additionally, activities of specialist predatory carabids could synchronize with that of
their prey (Alderweireldt and Desender 1990).
1.3.2 Carabids in Their Environments
Thiele (1977) presented a detailed review on carabid habitat selection by
adaptations in physiology and behavior. He specified that the influence of a preceding
crop on the carabid population was not the changeover from one type of crop to another.
Different groups of carabids may dominate different habitats that vary in biotic and
abiotic features. Furthermore, population levels and dynamics of carabids are likely to
be influenced by spatial and temporal patches of favorable and unfavorable habitats in the
agricultural landscape (Booij and den Nijs 1992). Variation in soil moisture is an
important determinant of carabid distribution mainly through effects on egg and larval
development (Thiele 1977, Althoff et al. 1994).
The causes of aggregated distribution of carabids within patches of similar habitat are not well understood (Luff 1986), but responses to micro-habitat differences and behavioral responses that lead to aggregations in pitfall traps have been proposed as explanations (Greenslade 1963b, Luff 1986). Carabid population density and prey population are likely to be the factors that motivate the activities and walking behavior of carabids (Mois 1979). Furthermore, Goulet (1974) found that subtle variation in
10 environmental factor is more important than are behavioral factors in determining the
within-habitat distribution of at least some forest carabid species. By testing the
aggregation of carabids using pitfall traps, Luff (1986) concluded that there may be three
possible behavioral mechanisms which could lead to "clustering" aggregation. 1) The
carabids may move around by group, so that a trap that catches one beetle may have a
likehood of catching other beetles of the same group; 2) beetles may tend to spend more
time within areas of high prey density, resulting from change in their movement pattern after feeding; 3) once a trap has caught a beetle, it becomes more likely to collect more, by becoming more attractive to them.
1.3.3 Carabids in Arable Fields
The distribution of carabids in arable fields has been a subject of many investigations. Activities and diversities of carabid beetles in com (Esau and Peters 1975,
Tonhasca and Stinner 1991), soybean (House and All 1981, Sprenkel et al. 1979,
McPherson et al. 1982), Alfalfa (Los and Allen 1983, Lester and Morrill 1989), and other croplands (Kirk 1971, Brust et al. 1986, Purrington et al. 1989) have been reported. It was reported that 176 species of Carabidae were found in various habitats in an agricultural area in Ontario (Rivard 1964, 1966). A total of 127 species of Carabidae were found in cultivated fields in South Dakota (Kirk 1971); 94 species of carabids were collected in Iowa com field (Esau and Peters 1975); 64 species were determined with pitfall traps during growing seasons of 1980 and 1981 in East-Central Minnesota (Epstein and Kulman 1990). Thirty four species were reported from Georgia soybean fields
(House and All 1981). In Ohio, 133 species of 59 genera were reported found in
11 Columbus and its vicinity by Everiy (1927), and 45 carabid species were found in a
soybean field (Chen and Willson 1996).
Some studies have confirmed the existence of an important duality between the
distribution of carabids in arable fields and the distribution in the surrounding habitats,
such as field borders and grassy border strips (Best et al. 1981, Coombes and Sotherton
1986). This applies especially to those carabid species that belong to the reproductive
group of spring-breeders, which hibernate in the adult stage. Based on this seasonal
dispersion behavior, Wratten (1988) suggested that field boundaries or undisturbed areas
were necessary for reservation of carabid population in crop agroecosystems.
The adult carabids in a given crop field may have moved in by crawling or flying
from distant fields or other habitats, or may have been present as adults or larvae during
the previous year and thus, are associated with the previous year's crops (Kirk 1971).
Therefore, agricultural practices not only affect the local activities and population density
of carabids, but also influence the carabid activities by changing the attraction of field
habitats to the immigrating carabids.
1.3.4 Sampling Method - Pitfall Trap
Pitfall traps {Barter traps) have been widely used for studying surface dwelling
arthropods in their habitats. Investigations of carabids have been performed mainly by
means of this technique. It is a modification of an open vessel that captures walking and crawling arthropods that attempt to traverse an area where the trap is placed (Price and
Shepard 1978). Excellent reviews of these traps were described by Greeslade (1964),
Gist and Crossley (1973), Muma (1975), Southwood (1978), Halsall (1988). Pitfall
12 trapping to sample carabid beetles has many advantages. Because pitfall traps are cheap
and require little labor, they have been used as a major sampling method to study the
cropland fauna (Kirk 1971, House and All 1981). The resulting data are useful for
quantitative analysis (Gist and Crossley 1973, Price and Shepard 1978). Data obtained
from this approach provided a reliable index of carabid population densities dining each
species' activity period (Kirk 1971). Desender and Maelfait (1986) found that enclosed
pitfall trapping gave ratios between the catch of the different species showing a much
better correlation with those from soil samples than the catch-ratios from open pitfall
trapping by using fenced pitfall traps. They also suggested that fenced pitfall trap method
was suitable to compare the relative abundance of a nmnber of carabid species in short
term investigation during periods of peak activities. The distribution of catches of some
carabid species in pitfall traps has been shown significantly aggregated (Greenslade
1963b, Luff 1986, den Boer 1979).
Unfortunately pitfall trapping also has its limits in the study of carabid population
densities (Morril et al. 1990). Several authors have questioned the reliability of the pitfall trap catch as relative density estimates and studied different disturbing factors. Briggs
(1961) found that the activity of arthropods, and thus collections in pitfall traps, may be affected by feeding, mating, and egg-laying activities. Other authors reported that other factors, such as soil moisture (Mitchell 1963), and time of day (Greenslade 1963a), affected the results as well. Furthermore, a small catch does not always mean a small population of carabids in a field, it does mean that only a few individuals were moving about on the surface of the soil (Kirk 1971). As pitfall catches vary with the amount of
13 locomotor activity shown by Carabidae, the catch should be influenced by weather, field
vegetation and species susceptibility to the traps (Greenslade 1964), and by feeding
behavior, dispersion pattern and duality of activity of carabids (Gist and Crossley 1973).
The effect of groimd vegetation may affect the carabid movements and thus reduce
catches; differential susceptibility of species to trapping may related with the species
habits and behavior (Greenslade 1964). The placement of the pitfall traps may be
another factor that causes the variation of catches. Greenslade (1964) noted that the level
of trap opening affected the catch of pitfall traps. For population estimation, pitfall
trapping method has been considered valid only for mark-capture studies (Turner and Gist
1965).
However, other sampling methods for carabid beetle study are available. A
portable radar system (harmonic radar) was used to detect the individual movement of
four carabid species in a cereal field (Willim and Ekbow 1988). Mark and recapture method is the one to use in absolute estimate of carabids. Quadrant counts of carabid beetle is another classic sampling approach. Suction apparatus and large Berlese funnel were sometimes used to sampled carabid beetles as well. Soil cores sampled with a golf cup cutter is another technique to sample larval population of carabids and other soil arthropods.
1.3.5 Carabids as Bénéficiais
Most carabids are polyphagous that consume animal and plant material. Feeding habits of larvae and adults may be different for some species (Lovei and Sunderland
1996). Adults of most carabids are primarily carnivorous, feeding on almost any small
14 animai of suitable size (Bell 1970). Many species feed extensively on dead or disabled arthropods, and thus act more as scavengers rather than as predators. Larvae of carabids are more carnivorous and restricted in food range (Lovei and Sunderland 1996).
Many carabids presumably find their food via random search, while several diurnal species hunt for prey by sight (Forsythe 1987). Chemical cues are found as indicators in search for prey, e.g. aphids, springtails or snails (Chiverton 1984, De Ruiter et al. 1989). The use of chemical cues is probably more common than the few reported cases would suggest Once prey is located, the beetles typically switch to a well-defined prey-catching behavior (Lovei and Sunderland 1996). Most carabids use their well- developed mandibles to kill prey and firagment prey into pieces. Specialist species attacking prey seem to paralyze their prey by biting (Pakarine 1994), and preventing the defense behaviors of prey. Many large species eject a fluid with digestive enzymes, then consume the liquid portion of their partially digested prey, sometimes as well as the undigested prey fragments (Forsythe 1987).
In general, carabids are regarded as predaceous and thus beneficial (Horror et al.
1989). A great number of investigations on the distribution of carabid beetles in different habitats have been carried out over the past decades. Many field and laboratory experiments have shown that carabid beetles possessed regulatory ability on certain pest insect population (Kirk 1982). Some carabids are known to feed on such insect pests as gypsy moths, Lymantria dispar L. (Craighead 1950, MacLean and Usis 1992), Red- backed cutworm,Euxoa ochrogaster Guenee, (Frank 1971), and BCW (Brust et al. 1985).
Larvae of most species are thought to feed on soft-bodied soil insects (Kirk 1971).
15 Willson and Eisley (1992) argued that the presence of predatory activity reduced the occurrence of severe levels of BCW stand injury. Food preferences of five concunon species of carabids in Iowa cornfield were tested by Best and Beegle (1977). They found that dead larvae of BCW were the most preferred food for all species tested. Three species of carabids, Pterostichus chalcites Say, Harpalus pensylvanicus DeGeer, and
Scarites substriatus Haldetnan, were trapped in high enough numbers to warrant their investigation as potential natural control agents for such soil-inhabiting pests as black cutworm,A. ipsilon (Hufiiagel), armywonn, Pseudaletia unipuntia (Haworth), and southern com rootworm, Diabrotica undecimpunctata howardi Barber (Esau and Peters
1975, Chen and Willson 1996). In the soybean agroecosystem, a number of carabid species are facultative predators and exhibit varying degree of entomophagy and phytophagy, and constitute a major part of the predatory complex (Best and Beegle 1977,
House and All 1981). Obviously, simultaneous occurrences of many carabid species with the peak infestation periods of number of soybean insect pests have been reported (Price and Shepard 1978, Chen and Willson 1996), such as the late season activity of
Pterosticus chalcites and Harpalus pensylvanicus coinciding with the peak oviposition period of adult western com rootworms (Kirk 1973 and 1975). This suggested that these predaceous carabid beetles have potential as natural pest-control agents.
The importance of carabid as predators of pest species in com field has been documented (Best and Beegle 1977, House and All 1981, Brust et al. 1986). Radio labeling studies suggest that some carabid are predators of CRW eggs and larvae (Tyler and Ellis 1979). However, carabids and CRWs may have different habits and rarely
16 encounter each other. Therefore, carabids may play an opportunistic rather than a definite predatory role in a com agroecosystem (Kirk 1982).
1.4 Interactions among Insects, Plants and Insecticides
1.4.1 Impacts of Insecticides on Carabids
Properties of an insecticide are of major importance in determining its biological effectiveness in soil (Felsot 1985). A key factor influencing the effectiveness of an insecticide in soil is the length of time over which it will remain biologically active
(Harris 1972). Different species of insects vary widely in their natural tolerance to insecticides even for closely related species. Different growth stages of a given species may also vary considerably in its tolerance to insecticides. Harris and Sveg (1968a) reported that black and darksided cutworms become increasingly tolerant to insecticides such as Dursban with each successive instar. In another study, Harris and Sveg (1968b) found that toxicity of insecticides varies markedly with the stage of cutworm development.
The behavior of insects in the soil influence the effectiveness of soil insecticides.
Mobile insects usually contact more insecticide residues. Therefore, conditions that influence the mobility of an insect will influence indirectly on the effectiveness, in part, of an insecticide in certain conditions (Harris 1972). Generally speaking, once larvae enter the soil they become less vulnerable to the insecticide. In contrast, adults are generally more susceptible to the insecticide and could offer a possible target.
17 Insecticide treatments have exhibited a negative effect on soil dwelling predators
(Critcheiy 1972a & 1972b, Edwards and Thompson 1975, Tomlin 1975). The overall effect of organochlorine insecticide (DDT) applied to cropland has been net reduction in the carabid population and a change in the species composition (Brown 1978, Brown et al. 1988). Application of DDT at 2.24 kg/h decreased the numbers of carabids in cropfield (Edwards and Thompson 1973). In Ontario peach orchards that received DDT application at 5.6 kg/h a year, the carabid populations were significantly reduced in the case of Pterostichus, but increased as compared to orchards without DDT application for
Anadaptus ssidAnisodactylus, while the other species maintained their numbers (Heme
1963).
Diazinon and disulfoton at 8.96 kg/h, and phorate at 4.48 kg/h were highly destructive to carabids, but parathion gave the severest reduction (Edwards et al. 1967).
Laboratory tests on six species of carabids in treated soil found the LCjo levels differ among chemicals, which were diazinon < thionazin < dieldrin < azinphosmethyl < chlorfenvinphos (Mowat and Coaker 1967). Residues of OP compounds have been found in carabids with various amounts, applications at 9 kg/h leading to residues ranging from
0 to 0.28 ppm with phorate, up to 0.55 ppm with diazinon, and up to 1.33 ppm with chlorfenvinphos (Edwards and Thompson 1973).
The other effect of insecticides on carabids is the motivation of carabids by contact with chemical residues causing hyper activities (Miller and Adams 1982).
Activities of carabids may also due to the hunger of individuals in search of lower prey population caused by insecticide treatments (Chiverton 1984). In addition, insecticides
18 used to control insect pests could indirectly alter the carabid species assemblage by
changing the vegetation composition, because the vegetation is the important cue for the
dispersal of carabids.
Effects of carry-over from previous crop with chemical control would appear most
pronounced on the BCW and CRW in field com. On CRWs, overwintering as eggs in
fields, and whose larvae are mainly on com roots in the fields for which eggs were
deposited the previous late-summer (Chiang 1973, Willson and Eisley 1987, Boetel et al.
1972). Com plant density of previous season, which is relevant to the effectiveness of
insecticide treatments, will be an factor to influence oviposition from com rootworm. For
black cutworm, soybean debris has been observed be more attractive to black cutworm
than com debris for oviposition, and infestation was more likely to occur in com fields
with soybean debris than with com residue (Metcalf and Luckman 1982, Johson et al,
1984). Furthermore, the weed population, which may also be a result of plant density
affected by the insecticide treatments of previous season, could be the most important
factor that attracts BCW month for oviposition in the early growing season. Although
long distance migration of some carabid species have been observed, the activity of carabid beetles may be locally varied by insecticides applications, and may be affected by weed population, plant density, prey population that could be altered by the pesticide treatments of previous season.
1.4.2 Carabids and Vegetation
Competition of crop and weeds may directly or indirectly influence the activities of carabids. Pest control practice that maintains the crop in as competitive condition as
19 possible can be considered as a beneficial practice in terms of weed management in crop
fields. Conversely allowing a crop to be defoliated, even partially, by an insect or
pathogen can substantially increase the severity of weed problem. Norris (1982)
demonstrated that uncontrolled alfalfa attacked by the Egyptian alfalfa weevil resulted in
an over 50% increase in the quantity of yellow foxtail harvested late in the season.
On a theoretical basis, it should be expected that any disease or insect attack that
weakens the crop plant will allow weeds to grow better. Therefore, control of insects and
disease that attack the crop will usually reduce weed population. As a result of the
chemical control, the species diversity in arable fields is generally decreased, and the carabids species assemblage will be changed (Edwards and Thompson 1973).
The numbers of carabids caught were found to be directly related to the frequency and density of Poa annua L. (annual meadow grass) the only abundant non-crop plant present in winter wheat (Speight and Lawton 1976). Rivard (1966) suggested that the weedy vegetation associated with cereals may influence the extent to which carabids are controlling agents for pest species. Pimentel (1961) stated that plant species diversity plays an important role in preventing insect population outbreaks on Brassica plants.
Weeds exert a direct biotic stress by competing for sunlight, moisture, and some nutrients, thus reducing crop yields (Altieri 1994). Thus weeds alter the availability of soil nutrients to plants which then modifies the appearance and nutritional value of the plant to herbivorous insects and the ability of the plant to tolerate insect attack. Weeds are the only pests that are primary producers and serve as food sources for both insect pests and natural enemies that attack the pest (Norris 1982). The change of the
20 microenvironment by weeds directly affects insect pests and their natural enemies and can indirectly affect herbivorous insects by altering the growth and development of their host plant. On the other hand, herbivore-natural enemy interactions occurring in a crop system can be influenced by the presence of associated weeds, or by the presence of herbivores on associated weed plants (Altieri and Letoumeau 1982).
Shephard and Dehlman (1988) pointed out that influences of plants on predators may be due to the chemistry or morphology of the plant. Stresses may impact on predators directly from the plant or indirectly via the prey. However, it is difficult to separate influences emanating from the plant itself or from those which are sequestered by the prey and later taken up by the predator.
An additional contributing factor to plant stress as a consequence of insecticide application might be an increased or protracted period of attractiveness of crops, due to more prolific or prolonged flowering induced by chemicals applied for pest control purposes (Riley 1988). Insects, particularly lepidopteran, attracted to the flowers for nectar and then ovipositing, may be more readily attracted to these crops and, once there, remain to feed and oviposit for a much longer period, resulting in a greater than usual number of developing larvae in the field. High prey population may thus attract more activities of predators.
The presence of weeds in crops affects both plant density and spacing patterns, factors known to significantly influence insect populations (Mayse 1983). Many herbivores respond specifically to plant density; some proliferate in close plantings, whereas others reach high numbers in open canopy crops. Predator populations tend to
21 be greater in high density plantings. Mayse (1983) suggests that the microclimate associated with canopy closure, which occurs earlier in dense plantings, may increase development rates of some predators and possible facilitate prey capture.
1.5 General Hypothesis
The general hypothesis of this thesis is that the application of chemical insecticides for control of cutworms and rootworms in a com ecosystem will have direct or indirect effects on carabid populations, which represent a significant component of the nontarget community of soil fauna. The direct effects of an insecticide treatment on carabids is based on the broadspectrum toxicological properties of many insecticides used on com. However, the effects of the treatments in the field may be limited due to the timing and methods of the applications in relation to the biology and behavior of carabids.
The indirect effects of an insecticide treatment on carabids may be related to a modification of the field habitat. When an insecticide treatment is applied, the environmental conditions of a treated com ecosystem may differ fi-om that of an untreated com ecosystem if a substantial level of pest injury is prevented by a treatment. For example, if substantial stand loss occurs due to cutworm activity, then a treated com habitat may differ fi*om an untreated com habitat if a substantial weed population develops as a result of a significant loss in com stand. Therefore, if an insecticide treatment has an effect on the establishment of a com stand and related weed population development, then the insecticide treatment may have an indirect effect on carabid populations having a preference for specific vegetational habitats that related to specific
22 prey or host populations. The potential direct and indirect effects that an insecticide
treatment may have on the interactions of target pests, nontarget populations, and
vegetation were illustrated in Figure 1.1.
Com fields with different insecticide treatments and without insecticide treatment
will, most likely, have completely different soil insect pest damage and will have
different carabid activities. The impact of insecticides on carabid activities in an
agroecosystem may not be solely from the direct toxicity of insecticides. Individual
component in the agroecosystem that may be afiected differently by insecticides could
become positive or negative factors influencing the carabid activity.
The response of target and nontarget insects to insecticide treatments should influence the com agroecosystem, especially the major components of the ecosystem, such as vegetation (weeds and crop plants), field physical conditions (soil type, soil moisture, soil nutrient contents, etc.), weather conditions and the population of other arthropods (herbivores as prey, parasitoids, etc.). Changes in the agroecosystem should in turn influence the activities of insects.
The effect of insecticides on carabids is most likely due to the direct toxicity of insecticides, as well as due to the indirect impacts in the com agroecosystem, e.g. the influence on the interactions of com plants and weeds, predatory carabids and prey population, herbivore carabids and weed population.
Insecticide treatments may change the abundance and distribution of insect pests as prey in several ways. Com fields with effective stand protection may attract more adult CRW to lay eggs, which can be carried over into the next growing season. On the
23 insecticides
Target pests Non target (BCW, CRWs) (Carabids)
(Q Corn Weed & % Plant residues
> i Yield
Target pests Non target (BCW, CRWs) (Carabids)
re
■o Corn Weeds oc o o Plant residues (O
Indicates impact; Indicates interaction.
Figure 1.1 The effect of insecticides on the target and nontarget insects, vegetation, and their interactions in the com agroecosystem 24 other hand, fields with uneffective stand protection may have more weed growth, which,
if carried over into the next growing season, may attract more BCW for laying eggs. The
change of vegetation may alter the species composition of carabid community. Weedy
field areas may become obstacles for the walking activities of some carabid species but
may attract more activities of herbivore species. The change of prey populations and
distribution between fields or within a field fi’om direct or indirect pesticide influence can
alter the distribution and activities of predatory carabids. In contrast, weed firee com
fields actually have more open areas on the ground surface for the activities of some
carabid species.
Different insecticide treatments may also be a factor that affects the activities of
carabids. For example, at planting treatments may cause less direct toxic effects on
carabids that dispersed into fields at a later time, while the post-emergence treatment may cause higher mortality of carabids by direct contact. T-band treatment technique may cover relatively less field surface with chemical residue comparing with the broadcast application technique, thus causing less mortality of carabids.
All these direct and indirect effects of insecticide treatments may be carried over into the following growing seasons due to the chemical residues, seasonal distribution, behavior of arthropods, species competition, and predation, etc.
To evaluate the general hypothesis that various insecticide treatments for control of soil insect pests in com ecosystem will have direct or indirect effects on carabid guild, a series of experiments are designed. Two insecticide application approaches, at planting treatments and post-emergence treatment with different insecticides, will be used to test
25 the efficacy on the prevention of the stand and yield losses from natural BCW
infestations. Laboratory bioassay and field microplot studies will be performed to
determine the direct contact and soil residue toxicity of commonly used insecticides on
carabids. Standard pitfall trap technique will be used to evaluate effects of different
insecticide applications on carabid activities in field plots. A special sampling technique,
barrier-pitfall trap, will be used to detect any activity related with responses of carabids to
the application of insecticides in field situations.
References
Althoff, G. -H., P. Hockmann, M. Kleimer, F. -J. Nieheus, and F. Weber. 1994. Dependence of running activity and net reproduction in Carabus auronitens on temperature, pp. 95-100. In K. Desender, M. Dufrene, M. Loreau, M. L. Luff, and J-P. Maelfait [eds], Carabid Beetles; Ecology and Evolution. Kluwer Academic Publishers, Dordrecht.
Ahmad, N., D. D. Walgenbach, and G. R. Sutter. 1979. Degradation rates of technical carbofriran and a granular formulation in four soils with known insecticide use history. Bull. Environ. Contam. Toxicol. 23: 572-74.
Alderweireldt, M. and K. Densender. 1990 Variation of carabid diel activity patterns in pastures and cultivated fields, pp 335-38. In N. E. Stork [ed]. The Role of Ground Beetles in Ecological and Environmental Studies. Intercept, Andover.
Altieri, M. A. 1994. Biodiversity and Pest Management in a Agroecosystems. Food Product Press. New York. 185pp.
Altieri, M. A. and D. K. Letoumeau. 1982. Vegetation management and biological control in agroecosystems. Crop Prot. 1:4 05-430.
Archer, T. L. and G. J. Musick. 1977. Gutting potential of the black cutworm on field com. J. Econ. Entomol. 70: 745-747.
Ball, G. E. 1960. Carabidae, pp. 55-127./n R. H. Amett, Jr. [ed.]. The Beetles of the United States. The Catholic University of America Press, Washington, D. C.
26 Bell, R. T. 1970. Insecta: Coleoptera: Carabidae, adults and larvae, pp. 1053-1092. In D. L. Dindal [éd.]. Soil Biology Guide. John Wiley and Sons, New York.
Bergman, M. 1987. Com rootworm control; do we have any new solutions? Proc. 111. Agric. Pestic. Conf. 87, pp. 41-49. Urbana-Champaign.
Best, R. L. and C. C. Beegle. 1977. Food preferences of five species of carabids commonly found in Iowa cornfields. Environ. Entomol. 6: 9-12
Best, R. L., C. C. Beegle, J. C. Owens, and M. Ortiz. 1981. Population density, dispersion, and dispersal estimates for Scarites substriatus, Pterostichus chalcites, and Harpalus pensylvanicus (Carabidae) in an Iowa cornfield. Environ. Entomol. 10: 847-856.
Bledsoe, L. W., P. J. Boeve, and C. R. Edwards. 1997. History of com rootworm larval damage to com following soybean in Indiana. Submitted Papers at The North Central ESA Meeting, Columbus, U.S.A., March 23-25, 1997.
Boetel, M. A., D. D. Walgenbach, G. L. Hein, B. W. Fuller, and M. E. Gray. 1972. Oviposition site selection of the northern com rootworm (Coleoptera: Chrysmelidae). J. Econ. Entomol. 85: 246-49.
Booij, C. J. H. and L. J. F. M. den Hijs. 1992. Agroecological infiastructure and dynamics of carabid beetles. Proc. Sect Exp. Appl. Entomol., Neth. Entomol. Soc. 3: 72-78.
Borror, D. J., C. A. Triplehom, and N. F. Johnson. 1989. An Introduction to the Study of Insects. 6th ed. Saunders College Publishing. 875pp.
Briggs, J. B. 1961. A comparison of pitfall trapping and soil sampling in assessing population of two species of ground beetles (Col: Carabidae). E. Mailing Res. Sta. Annu. Rep.1960:108-112.
Brown, R. W. A. 1978. Ecology of Pesticide. Jone and Wiley, 525pp.
Brown, R. A., J. A. White, and C. J. Everett 1988. How does an autumn pyrethroid affect the terrestrial arthropod community? pp. 137-146. In M. P. Greaves, B. D. Smith and P. W. Grieg-Smith [eds]. Field Methods for the Study of Environmental Effects of Pesticides. BCPC Monograph 40, BCPC Famham, Surrey.
Brust, G. B., B. R. Stinner, and D. A. McCartney. 1985. Tillage and soil insecticide effects on predator-black cutworm (Lepidoptera: Noctuidae) interactions in com agroecosystems. J. Econ. Entomol. 78:1389-1392.
27 1986. Predation by soil inhabiting arthropods in intercropped and monoculture agroecosystems. Agriculture, Ecosystems and Environment 18:145-154. Elsevier Science Publishers, B. V. Amsterdam.
Chapman, R. A. and C. R. Harris. 1980. Insecticidal activity and persistence of terbufos, terbufo sulfoxide and terbufos sulfone in soil. J. Econ. Entomol. 73:536-543.
Chen, Z. Z. and H. R. Willson. 1996. Species composition and seasonal distribution of carabids (Coleoptera: Carabidae) in an Ohio soybean field. J. Kans. Entomol. Soc. 69: 310-316.
Chiang, H. C. 1973. Bionomics of the western com rootworms. Annu. Rev. Entomol. 18: 47-73.
1978. Pest management in com. Ann. Rev. Entomol. 23: 101-23.
Chiang, H. C. and R. S. Raros. 1968. Effects on populations of com rootworms of aldrin residues in soil four years after application. J. Econ. Entomol. 61: 1204-8.
Chiverton, P. A. 1984. Pitfall trap catches of the carabid beetle Pterostichus melanarius in relation to gut contents and associated organs in the locust Entomologia Experimentalis et Applicata 36: 23-30.
Clement, S. L. and D. A. McCartney. 1982. Black cutworm (Lepidoptera: Noctuidae): measurement of larval feeding parameters on field com in the greenhouse. J. Econ. Entomol. 75:1005-1008.
Coombes, D. S. andN. W. Sotherton. 1986. The dispersal and distribution of polyphagous predatory Coleoptera in cereals. Ann. Appl. Biol. 108: 461-474.
Craighead, F. C. 1950. Insect enemies of eastem forests. USDA. Misc. Publ. 657, 679pp.
Critcheiy, B. R. 1972a. A laboratory study of the effects of some soil applied organophosphorus pesticide on Carabidae (Coleoptera). Bull. Ent. Res. 62: 229-242.
1972b. Field investigations on the effects of an organophosphorus pesticide, thionazin, on predacious Carabidae (Col.). Bull. Ent. Res. 62: 326-342.
De Ruiter, P. C., M. R. van Stralen, F. A. van Euwijik, W. Slob, J. J. M. Bedaux, and G. Emsting. 1989. Effects ofhunger and prey traces on the search activity of the predatory beetle Notiophilus biguttatus. Entomol Exp. Appl. 51: 87-95.
28 den Boer, p. J. 1969. On the significance of dispersal power for populations of carabid-beetles (Coleoptera, Carabidae). Oecologia (Berl.). 4:29-73.
1979. Populations of carabid beetles and individual behaviour, pp 145-9. In P. J. den Den Boer, H-U Thiele, and F. Weber, [eds]. On the Evolution of Behaviour in Carabid Beetles. Misc. Pap. Agric. Univ. Wageningen 18.
Desender, K. and J. Maelfait 1986. Pitfall trapping within enclosures: a method for estimating the relationship between the abundances of coexisting carabid species (Coleoptera: Carabidae). Holarctic Ecology. 9: 245-250.
Edwards, C. A. 1990. The importance of integration in lower input agricultural systems. Agriculture, Ecosystems and Environment 27: 25-35.
Edwards, C. A. and A. R. Thompson. 1973. Pesticides and the soil fauna. Residue Reviews. 45: 1-79.
1975. Some effects of insecticides on predatory beetles. Arm. Appl. Biol. 80: 132-135.
Edwards, C. A., A. R. Thompson, and J. R. Lofty. 1967. Changes in soil invertebrate populations caused by some OP insecticides. Proc. 4th. Br. Insectic. Fungic. Conf. 1: 48- 55.
Epstein, M. E. and H. M. Kulman. 1990. Habitat distribution and seasonal occurrence of carabid beetles in East-central Minnesota. Midi. Nat. 13: 09-225.
Erwin, T. L. 1985. The taxon pulse: a general pattern of lineage radiation and extinction among carabid beetles, pp. 437-72. In G. E. Ball [ed.], Taxonomy, Phylogeny and Zoogeography of Beetles and Ants. Dordrecht: Junk.
Esau, K. L. and D. C. Peters. 1975. Carabidae collected in pitfall trap in Iowa cornfields, fencerows, and prairies. Environ. Entomol. 4: 509-513.
Everiy, R. T. 1927. A check list of the Carabidae of Columbus, Ohio and vicinity. Ohio J. Sci. 27: 155-156.
Felsot, A. 1985. Factors affecting the bioactivity of soil insecticides. Proc. 37th 111. Custom Spray Oper. Train. Sch., pp. 134-38. Urbana-Champaign, IL: Univ. 111. r 1990. An assessment of insecticide rotations for long-term management of com rootworm feeding damage. Proc. 111. Agric. Pestic. Conf. 90, pp. 71- 80. Urbana- Champaign, IL: Univ. HI.
29 Felsot, A. S., J. G. Wilson, D. E. Kuhlman, and K. L. Steffey. 1982. Rapid dissipation of carbofuran as a limiting factor in com rootworm (Coleoptera: Chrysomelidae) control in fields with histories of continuous carbofuran use. J. Econ. Entomol. 75: 1098-103.
Floate, K. D., R. H. Elliott, J. F. Doane, and C. Gillott. 1989. Field bioassay to evaluate contact and residual toxicities of insecticides to carabid beetles (Coleoptera: Carabidae). J. Econ. Entomol. 82: 1543-1547.
Forsythe, T. G. 1987. Common ground beetles. Naturalists' Handbook 8. Richmond Publishing. 74pp.
Frank, J. H. 1971. Carabidae (Coleoptera) as predator of the red-backed cutworm (Lepidoptera: Noctuidae) in central Alberta. Can. Ent 103: 1039-1044.
Gist, C. S. and D. A. Crossley, Jr. 1973. A method for quantiJfying pitfall trapping. Environ. Entomol. 2: 951-952.
Goulet, H. 1974. Biology and relationships of Pterostichus adstrictus Eschscholtz and Pterostichus pensylvanicus LeConte (Coleoptera: Carabidae). Questiones Entomologicae. 10:3-33.
Greenslade, P. J. M. 1963a. Daily rhythms of locomotor activity in some Carabidae (Coleoptera). Ent. Exp. Appl. 6: 171-180.
1963b. Further notes on aggregation in Carabidae (Coleoptera) with especial reference to Nebria brevicollis (F.). Ent. Mon. Mag. 99: 109-114.
1964. Pitfall trapping as a method for studying populations of Carabidae (Coleoptera). J. Anim. Ecol. 2: 301-310.
Halsall, N. B. and S. D. Wratten. 1988. The efficiency of pitfall trapping for polyphagous predatory Carabidae. Ecological Entomology 13: 293-299.
Harris, C. R. 1972. Factors influencing the effectiveness of soil insecticides. Annu. Rev. Entomol. 17: 177-98.
Harris, C. R. and H. J. Sveg. 1968a. Toxicological studies on cutworms. I. Laboratory studies on the toxicity of insecticides to the dark-sided cutworm. J. Econ. Entomol. 61: 788-793.
1968b. Toxicological studies on cutworms. II. Field studies on the control of the dark-sided cutworm with soil insecticides. J. Econ. Entomol. 61: 961-965.
30 Hendrix W. H. and W. S. Showers. 1992. Tracing black cutworm and armywonn (Lepidoptera: Noctuidae) northward migration using Pithecellobium calliandra pollen. Environ. Entomol. 21: 1029-1096.
Heme, D. H. 1963. Carabids collected in a DDT-sprayed peach orchard in Ontario, Can. Entomol. 95: 357-362.
House, G. J. and J. N. All. 1981. Carabid beetles in soybean agroecosystems. Environ. Entomol. 10:194-196.
Jenson, S. G. 1985. Laboratory transmission of maize chlorotic mottle virus by three species of com rootworms. Plant Dis. 69: 864-68.
Johnson, T. B., F. T. Turpin, M. M. Schreiber, and D. R. Griffith. 1984. Effects of crop rotation, tillage, and weed management systems on black cutworm (Lepidoptera: Noctuidae) infestations in com. J. Econ. Entomol. 77:919-921.
Kirk, V. M. 1971. Ground beetles in cropland in South Dakota. Ann. Entomol. Soc. Am. 64: 238-241.
1973. Biology of a ground beetle, Harpalus pensylvanicus. Ann. Entomol. Soc. Am. 66: 513-517.
1975. Biology of Pterostichus chalcites, a ground beetle of cropland. Ann. Entomol. Soc. Am. 68: 855-858.
1982. Carabid beetles: minimal role in pest management of com rootworms. Environ. Entomol. 11:5-8.
Krysan, J. L., J. J. Jackson, and A. C. Lew. 1984. Field termination of egg diapause in Diabrotica with new evidence of extended diapause in Diabrotica (Coleoptera: Chrysomelidae). Environ. Entomol. 13: 1237-40.
Krysan, J. L. and T. A. Miller [eds.]. 1986. Methods for the Study of Pest Diabrotica. New York: Spninger-Verlag. 260pp.
Lester, D. G. and W. L. Morrill. 1989. Activity density of ground beetles (Coleoptera: Carabidae) in alfalfa and sainfoin. J. Agric. Entomol. 6: 71-76.
Levine, E., S. L. Clement, W. L. Rubink, and D. A. McCartney. 1983. Regrowth of com seedlings after injury at different growth stages by black cutworm, Agrotis ipsilon (Lepidoptera: Noctuidae) larvae. J. Econ. Entomol. 76: 389-391.
31 Levine, E., D. Kuhlman, K. Steffey, and H. Oloumi-Sadeghi. 1988. New developments regarding extended diapause in northern com rootworms: research and survey results. Proc. 111. Agric. Pestic. Conf. 88, pp. 145-53. Urbana-Champaign, IL: Univ. 111.
Levine, E. and H. Oloumi-Sadeghi. 1988. Larval damage to com following soybeans by the western com rootworm, Diabrotica virgifera virgifera, in east central Illinois. Abstr. 43rd. Annu. Meet. North Cen. Branch Entomol. Soc. Am. Denver Colo. Abstr. 98.
1991. Management of Diabroticite rootworms. Annu. Rev. Entomol. 36:229- 255.
Lilly, J. H. 1956. Soil insects and their control. Annu. Rev. Entomol. 1: 203-22.
Lindroth, C. H. 1961-1969. The ground-beetles (Coleoptera: Carabidae) of Canada and Alaska, Pt.1-6. Opusc. Entomol. Suppl. 20.24. 29. 33. 34.35, Lund. 1192pp.
Los, L. M. and W. A. Allen. 1983. Abundance and diversity of adult Carabidae in insecticide-treated and untreated alfalfa fields. Environ. Entomol. 12: 1068-1072.
Lovei, G. L. and K. D. Sunderland. 1996. Ecology and behavior of ground beetles (Coleoptera: Carabidae). Ann. Rev. Entomol. 41: 231-56.
Luff, M. L. 1986. Aggregation of some Carabidae in pitfall traps, pp. 385-397. /nP. J. den Boer, M. L. Luff, D. Mossakowski, and F. Weber, [eds.], Carabid beetles, their adaptions and dynamics. XVII International Congress of Entomology, Hamburg, 1984.
Maclean, D. B. and J. D. Usis. 1992. Ground beetles (Coleoptera: Carabidae) of eastem Ohio forests threatened by the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae). Ohio J. Sci. 92: 46-50.
Mayse, M. A. 1983. Cultural control in crop fields: a habitat maniement technique. Environ. Entomol. 7: 15-22.
McPherson, R. M., J. C. Smith, and W. A. Allen. 1982. Incidence of arthropod predators in different soybean cropping systems. Environ. Entomol. 11: 685-689.
Metcalf R.L. and W.H. Luckmann. 1982. Introduction to Pest Management. 2nd Edition, John Wiley and Sons, New York, 587pp.
Miller, T. A. and M. E. Adams. 1982. Mode of action of pyrethroids. pp 3-27, In J. R. Coats, Insecticide Mode of Action. Acdemic Press, New York.
32 Mitchell, B. 1963. Ecology of two carabid beetles, Bembidion lampros (Herbst) and Trechus quadristriatus (Schrank). H. Studies of populations of adults in the field, with special reference to the technique of pitfall trapping. J. Anim. Ecol. 32: 399-392.
Mois, P. J. M. 1979. Motivation and walking behaviour of the carabid beetle Pterostichus coerulescens L. at different densities and distributions of the prey, pp. 185- 98, den Boer P. J., H-U. Thiele and F. Weber [Eds], On the Evolution of Behaviour in Carabid Beetles. Misc. Pap. Agric. Univ. Wageningen. 18.
Morril, W. L., D. G. Lester, and A. E. Wrona. 1990. Factors affecting efficacy of pitfall traps for beetles (Coleoptera: Carabidae and Tenebrionidae). J. Entomol. Sci. 25: 284- 293.
Mowat, D. J. and T. H. Coaker. 1967. The toxicity of some soil insecticides to carabid predators of the cabbage root fly. Arm. Appl. Biol. 59: 349-354.
Muma, M. H. 1975. Comparison of ground-surface species in four central Florida ecosystems. Flo. Entomol. 56: 173-196.
Norris, R. F. 1982. Interactions between weeds and other pests in the agro-ecosystem, pp. 343-405. In J. L. Hatfield and G. J. Thomason [eds.], Biometocology in Integrated Pest Management. Academic Press, New York.
O'Neil, M., M. Gray, E. Levine, and K.Steffey. 1996. Western com rootworm damage to first-year com in east-central Illinois. Poster Display at ESA meeting, Louisville, U.S.A., December, 1996.
Pakarine, E. 1994. The importance of mucus as a defence gainst carabid beetles by the slugs Arion fasciatus and Deroceras reticulatum. J.Mollusc. Stud. 60: 149-55.
Pimentel, D. 1961. The influence of plant spatial patterns on insect population. Arm. Entomol. Soc. Am. 54: 61-69.
Price, J. F. and M. Shepard. 1978. Calosoma sayi: seasonal history and response to insecticides in soybeans. Environ. Entomol. 7:359-363.
Purrington, F. F., J. E. Bater, M. G. Paoletti, and B. R. Stinner. 1989. Ground beetles fi-oma remnant oak-maple-beech forest and its surroundings in northeastem Ohio (Coleoptera: Carabidae). The Great Lakes Entomol. 22: 105-110.
Reed, J. P., F. R. Hall, and H. R. Krueger. 1992. Contact and volatile toxicity of insecticides to black cutworm larvae (Lepidoptera: Noctuidae) and carabid beetles (Coleoptera: Carabidae) in soil. J. Econ. Entomol. 85: 256-261. Riley, T. J. 1988. Plant stress from arthropods: insecticide and acaricide effects on insect, mite, and host plant biology, pp. 168-187. In E. A. Heinrichs [ed.], Plant Stress- insect Interactions. John Wiley and Sons. New York.
Rings, R. W., F. J. Arnold, A. J. Keaster, and G. J. Musick. 1976. A worldwide, annonated bibliography of the black cutworm. Ohio Agric. Res. Dev. Ctr. Res. Circ. 198. 106pp.
Rivard, I. 1964. Carabid beetles (Coleoptera; Carabidae) from agricultural lands near Belleville, Ontario, Can. Entomol. 96: 517-520.
1966. Ground beetles (Coleoptera: Carabidae) in relation to agricultural crops. Can. Entomol. 98:189-195.
Shepherd, M. and D. L. Dahlman. 1988. Plant-induced stress as factors in natural enemy efBcacy, pp 363-379. In E. A. Heinrichs [ed.]. Plant Stress-insect Interactions. New York, John Wiley & Sons.
Sherrod, D.W., J. T.Shaw, and W. H. Luckmann. 1979. Concepts on black cutworm field biology in Illinois. Environ. Entomol. 8: 191-195.
Showers, W. B., L. V. Raster, and P. G. Mulder. 1983. Com seedling growth stage and black cutworm (Lepidoptera: Noctuidae) damage. Environ. Entomol. 12: 241-244.
Showers, W. B., R. E. Sechriest, F. T. Turpin, Z. B. Mayo, and G. Szatmari-Goodman. 1979. Stimulated black cutworm damage to seedling com. J. Econ. Entomol. 72: 432- 436.
Southwood, T. R. E. 1978. Ecological Methods with Particular Reference to the Study of Insect Populations, 2nd ed. Chapman and Hall. London.
Speight, M. and J. H. Lawton. 1976. The influence of weed cover on the mortality imposed on artificial prey by predatory ground beetles in cereal fields. Oecologia. 23 : 211-223.
Spencer, J. L. and E, Levine. 1997. “It’s not easy being green”: Westem com rootworms in soybeans. Submitted Papers at North Central ESA Meeting, Columbus, U.S.A., March 23-25, 1997.
Spemkel, R. K., W. M. Brooks, J. W. Van Duyn, and L. L. Deitz. 1979. The effects of tluree cultural variables on the incidence of Nomuraearileyi, phytophagous Lepidoptera, and their predators on soybeans. Environ. Entomol. 8: 334-339.
34 Stark, J. D. and U. Wennergren. 1995. Can population effects of pesticides be predicted from demographic toxicological studies? J. Econ. Entomol. 88: 1089-1096.
Story, R. N. and A. J. Keaster. 1982. Development and evaluation of a larval sampling technique for the black cutworm (Lepidoptera: Noctuidae). J. Econ. Entomol. 75: 604- 610.
Story, R. N., A. J. Keaster, W. B. Showers, J. T. Shaw and B. L. Wright. 1983. Economic-threshold dynamics of black and claybacked cutworms (Lepidoptera: Noctuidae) in field com. Environ. Entomol. 12:1718-1732.
Sutter, G. and R. Gustin. 1989. Environmental factors influencing com rootworm biology and control. Proc. IH Agric. Pestic. Conf. 89, pp. 43-48. Urbana-Champaign, H: Univ. m.
Thiele, H.-U. 1977. Carabid Beetles in Their Environments, A study on habitat selection. Springer-Verlag, Berlin, New York.
Tomlin, A. D. 1975. The toxicity of insecticides by contact and soil treatment to two species of ground beetles (Coleoptera: Carabidae). Can. Ent. 107: 529-532.
Tonhasca, A. Jr. and B. R. Stinner. 1991. Effects of strip intercroping and no-tillage on some pests and beneficial invertebrates of com in Ohio. Environ. Entomol. 20: 1251-1258.
Troester, S. J. 1982. Damage and yield reduction in field com due to black cutworm (Lepidaptera: Noctuidae) feeding: Results of a computer simulation study. J. Econ. Entomol. 75: 1125-1131.
Tumer, F. B. and C. S. Gist. 1965. Influences of a thermonuclear cratering device on close-in populations of lizards. Ecology. 46: 645-652.
Tyler, B. M. J. and C. R. Ellis. 1979. Ground beetles in three tillage plots in Ontario and observations on their importance as predators of the northem com rootworm, Diabrotica tongicomis (Coleoptera: Chrysomelidae). Proc. Entomol. Sac. Ont. 110: 65-73. van Huizen, H. H. P. 1979. Individual and environmental factors determining flight in carabid beetles, pp 199-21. In P. J. den Den Boer, H-U. Thiele, and F. Weber, [eds]. On the evolution of behaviour in carabid beetles. Misc. Pap. Agric. Univ. Wageningen.
Wallins, H. 1985. Spatial and temporal distribution of some abundant carabid beetles (Coleoptera: Carabidae) in cereal fields and adjacent habitats. Pedobiologia 28:19-34.
35 Willim, H. and B. S. Ekbow. 1988. Movements of carabid beetles (Coleoptera: Carabidae) inhabiting cereal fields: a field tracing study. Oecoiogia 77: 34-43.
Willson, H. R. and B. Eisley. 1987. Insect Pests of Field Crops. Ohio Cooperative Extension Service Bull. 545. 21p.
1992. Effects of tillage and prior crop on the incidence of five key pests on Ohio com. J. Econ. Entomol. 85: 853-858.
1993. Evaluation of soil insecticides on first year and continuous com in Ohio, 1992. Insecticide and Acaricide tests. 18:213.
1994. Evaluation of soil insecticides in Ohio, 1993. Insecticide and Acaricide tests. 19: 213-214.
1995. Evaluation of soil insecticides for stand protection of no-till first year com in Ohio, 1994. Insecticide and Acaricide tests. 20: 184.
1996. Evaluation of soil insecticides continuous com in Ohio, 1995. Insecticide and Acaricide tests. 21: 233-234.
Wratten, S. D. 1988. The role of field boundaries as reservoirs of beneficial insects, pp. 144-50. In J. R. Pard [ed.], Environmental Management in Agriculture: European Perspectives, EEC/Pinter Publishers Ltd. London.
36 CHAPTER 2
PREVENTION OF STAND LOSS CAUSED
BY BLACK CUTWORM, Agrotis ipsilon (Hufiiagel), IN FIELD CORN
2.1 Introduction
Black cutworm (BCW),Agrotis ipsilon (Hufiiagel), is an important insect pest of field com in the United States. Although several other cutworm species occasionally cause damage, BCW is the most destructive pest of com seedlings. Evidence of the importance of BCW is given in world-wide bibliographies by Rings et al. (1976). In
Ohio, BCW is a key pest of field com (Willson and Eisley 1992a). As 4th to 6-7th instars, BCW chews through the stems of coleoptile to five-leaf stage com plants near the soil surface, which results in unrecoverable stands and yield loss (Story et al. 1983). Com is most susceptible to cutting from the time it emerges from the soil until it reaches the four-leaf growth stage (Archer and Musick 1977). The decrease in plants and yield are directly proportional to the increase in larval density (Showers et al. 1983). Showers et al. (1979) presented an approach to simulate BCW damage to seedling com and reported that grain loss becomes significant with more than 10% stand loss. Plants severed at progressively lower levels, such as above (e.g. at or below the soil surface) and at
37 progressively late stages of development (e.g. one- to four-leaf stage) produced significantly lower yield than seedlings severed at higher levels and earlier in development (Levine et al. 1983, Showers et al. 1983). It is very important to ensure that the treatment is applied when the larvae are still in the early stages of development since the later instars of BCW are likely to be less susceptible to most insecticides treated
(Harris and Sveg 1968b). Various insecticides exhibit significant differences in efficacy of controlling BCW, and insecticide activity could be influenced to a much greater extent with the technical formulation employed (Harris and Sveg 1968a & 1968b, Willson and
Eisley 1992b & 1996).
BCW larvae are in the field before the seed is planted reflects reality of field observations and field problems for BCW prediction (Sherrod et al. 1979). Although cutworm infestations are virtually impossible to predict (Harris and Sveg 1968a), many works have attempted on sampling and prediction of BCW populations (Showers et al.
1979, Story and Keaster 1982, Story et al. 1983). Sherrod et al. (1979) suggested that additional information on biology, behavior and field ecology will be needed before good detection and control programs can be refined. As the adoption of no-tillage practice in
US com belt increases, the stand loss of field com due to BCW’s damage has generally increased attention by entomologists. Management of BCW has relied upon rescue treatment based on scouting and the use of insecticide as preventive treatments in conjunction with com rootworm treatments in continuous com. In the U.S. com belt, entomologists currently recommend the use of plant damage counts to determine the need for rescue treatment. Using an artificial BCW infestation, Oloumi-Sadeghi et al. ( 1992)
38 argued that rescue treatment with pyrethroids were more effective than planting-time.
However, when BCW has an epidemic year, rescue treatments may be ineffective on the
plant damage based on the evidence of BCW activity deducted from com plant damage.
First, plant damage is rarely observed until after com emergence. Second, cutworm
activity has been at an epidemic stage when observable plant damage occurs. Third,
cutworm larvae may already be in the late instars which could be less susceptible to
insecticide treatments. Therefore, in com production, the relative efiBcacy of the rescue
treatment, compared to preventive treatment, on BCW in protection of com stands may
be questioned. Although many studies has done on BCW prevention treatments, the
results may reflect partly the field situation. Because most of these studies were based on
the artificial introduction of BCW colony into field plots at the most susceptible com
growth stages. As a matter of fact, these criteria are actually the most important and
difficult ones that an field entomologist can obtain for decision making. Before the BCW predation is well defined, it is necessary to confirm the efficacy and balance the profits of
insecticide treatments. Efficacies of preventive and rescue treatments that based on the observable CBW activities could be varied when BCW is epidemic. The objective of this study was to evaluate the efficacy of preventive and rescue treatments on the damage of BCW of natural infestation on com stands.
39 2.2 Materials and Methods
2.2.1 Field studies
The study was carried out in reduced tillage continuous com at the Western
Branch of OARDC, the Ohio State University from 1994 to 1996. Three insecticide
treatments, tefluthrin 1.50 (Force, Zeneca), chlorpyrifos 15G/4EC (Lorsban, DowElanco)
and permethrin 3.2EC (Pounce, PMC Corporation), and an untreated control were
arranged into a randomized complete block design with four replications. Preventive
treatments of tefluthrin (@ 0.146 kg(AI)/h) and chlorpyrifos (Lorsban 150 @ 1.463
kg(AI)/h) were applied at planting as a band prior to closure by the press wheel using a 4
row John Deere 7000 planter equipped with Noble granular insecticide application equipment and calibrated to deliver the recommended rates. Rescue treatments with permethrin (@0.11 kg (AI)/h) and chlorpyrifos (Lorsban 4EC @1.12 kg(AI)/h, 1996 only) were applied with a boom sprayer equipped with flat spray nozzles and calibrated to deliver the desired dosage at 4.83 kmph.
In 1994, a field of 40 m x 200 m was divided into 4 blocks with a 1.5 m driveway between every two blocks. A block (40 m x 48.8 m) was then divided into 4 plots enabled planting 4x16 rows with width of 0.76 m (30 in.). Com (Zea mays L. variety
Pioneer 3293) was planted on 18 May with the application of the two granular insecticides. Permithrin was applied on 2 June following the first stand count when the com was in 2-3 leaf stage.
In 1995, a field of 95 m x 100 m was divided into four blocks of 40 m x 48.8 m.
Com {Zea mays L., variety Countrymark 369) was planted with 16 rows of 0.76 m (30
40 in.) in each plot. Permethrin was applied on 9 June after the first stand count on 6 June
when the com was in 2-3 leaf stage.
In 1996, a field of 45.7 m x 102 m was divided into four blocks of 23.4 m x
45.7.8 m, where five plots of size (23.4 m x 9.14 m) was then divided. Com iZea mays
L., variety Countrymark 369) was planted on 1 June with 12 rows with of 0.76 m (30 in.)
in each plot. Permethrin and chlorpyrifos were applied on 17 June at 2-3 leaf stage.
Stand loss and plant injury rate were used as indices to estimate the damage of
BCW on com. Number of com plants and number of plant injured in 200 ft. row were counted on 2, 9 and 16 June, 1994,2 and 14 June, 1995, and 15 and 28 June, 1996. The plant injury rates were categorized into above-ground and below-ground in 1994. The third stand count in 1995 was not conducted until 17 October, at which time no plant injury was evaluated. In 1996, the BCW injury was minimal so that the plant injury and the third stand count were not evaluated.
2.2.2 Microplot studies
Microplot studies were performed in 1995 and 1996. Twenty clear plastic boxes of Rubbermaid® (16 in. x 11 in. x 9 in.) were used as microplots adjacent to the field plots. Four holes of about 2 mm in diameter were made on the bottom of each box to enable draining. Boxes were buried into the soil with top about 5 cm higher than the field surface, and filled with soil which was taken firom the area where a box was buried. Four microplots, three insecticide treatments and an untreated control, were blocked in a randomize complete block design with 5 replications. Four com seedlings were transplanted into each microplot, with one close to each of the four comers. In addition,
41 five com seeds were sowed in the middle of each box with the application of the granular
insecticides at the recommended field rate (tefluthrin @0.146 kg(AI)/h, chlorpyrifos @
1.463 kg(AI)/h) in the way similar to the field application. Four BCW larvae, 4th instar
was used in 1995 and 3rd instar was used in 1996, were then introduced into each box.
Two adults of Scarites substriatus Haldeman were introduced into each boxes to simulate
natural enemy pressure. After 24 h, liquid formulated permethrin was diluted to an
approximately recommended field rate (@0.11 kg (AI)/h) and sprayed on the appropriate
plot using a Logical® Plant & Garden Sprayer with the nozzle adjusted to coarse-spray.
Injured com plants of the transplanted and the new emerged by BCW were counted every
24 h until no further plant injury was observed.
The BCW larvae were obtained from the Com Insect Research Unit at Iowa State
University. BCW larvae were individually maintained in a plastic vial with on “pinto
bean diet” before used in the test. Scarites substriatus were obtained by pitfall trapping
with dry-traps in the adjacent fields prior to the set up of this experiment.
2.2.3 Data Analysis
Data were transferred log(x+l) before analysis. ANOVA was used to test the
difference between the treatments for the com stand count and plant injury.
2 J Results and Discussion
2.3.1 Field studies
In 1994, all the three com stand counts in the preventive treatments were significantly higher (P < 0.05) than that in the rescue treatment and the untreated control (
42 Stand counts' Root Yield Treatment 2 June 9 June 16 June Rating (Bu/A) Stand^ Stand^ Stand^ ( 1 -6 )
Tefluthrin 147.89 (6.50)a 154.38(3.53)a 150.37(2.46)a 3.10(0.24)a 123.55(2.75)a Chlorpyrifos 134.12(11.05)ab 136.00(10.03)a 133.50(10.86)a 3.15(0.2 l)a 120.61(6.23)a Permethrin^ 95.87(17.77)bc 94.12(17.62)b 88.25(17.03)b 4.25(0.30)b 77.30(13.52)b Untreated 84.38(9.90)bc 69.87(10.18)b 59.13(3.82)b 4.48(0.24)b 49.84(7.90)c
1. Data on the same column followed by different letters indicates significant difference (P < 0.05), Data in the bracket is stand error. 2. Stand counts are based on the total plants in 100 row. 3. Rescue treatment was applied on 2 June when com was in 2-3 leaf stage.
Table 2.1 Comparison of com plant stands, root ratings and yields between treatments in the field plots, Western Branch of OARDC, 1994. Plant injury (%)'
Treatment 2 June 9 June 16 June Above Below Below Above Below Total Total Total ground ground ground ground ground ground
Tefluthrin 8.08(3.15)a 5.00 2.38 1.63(0.32)a 0.88 0.75 0.50(0.36)a 0 . 0 0 0.50
Chlorpyrifos 12.23(2.89)a 5.75 3.50 2.00(0.35)a 0.50 1.50 0.25(0.14)a 0 . 0 0 0.25 Permethrin^ 18.80(3.25)5 13.88 6.25 2.75(0.43)a 1.13 1.63 0.50(0.35)a 0.13 0.38
Untreated 19.11(3.85)5 14.25 8 . 8 8 5.88(4.23)5 1.38 5.75 4.25(1.76)5 1.38 2 . 8 8
1. Plants injured over the stand counts in 100 row A. Data on the same column followed by different letters indicates significant difference (P < 0.05), Data in the bracket is stand error. 2. Rescue treatment was applied on 2 June when corn was in 2-3 leaf stage.
Table 2.2 Comparison of com plant injury (%) caused by CRWs between treatments in the field plots, Western Branch of OARDC, 1994. Table 2.1). The plant injury rates in the two preventive treatments, sampled on 2 June
before the application of permethrin, were significantly lower than that of the two
untreated plots (F= 3.65, df = 3 ,f = 0.49; Table 2.2). After the application of
permethrin, no significant difference of the plant injury were found between the
insecticide treated plots {P < 0.05). This indicates that the rescue treatment with permethrin effectively controlled the cutworm activity. However, the stand loss in rescue treatment plots was not recovered due to the delay of BCW control. The yield firom plots with rescue treatment was significantly higher than that firom the untreated control, while the yield firom plots with preventive treatments were significantly higher than that fi’om the untreated control and the plots with preventive treatment. In addition, the difference of yields between the two preventive treatments, the rescue treatment and the untreated control could be partly due to the root damage by com rootworms for which the root rating (1-6 scales) in preventive treatments were significantly lower than the others (F =
12.08, df=3,f = 0.001; Table 2.1).
Differences of the above ground and below ground plant injury among the treatments are presented in Table 2.2. On the first stand count (2 June) before the application of permethrin, com seedlings were in the 2-3 leaf stage. The plant injury in the plots treated with tefluthrin and chlorpyrifos were significantly lower than that in the two untreated plots (P < 0.0001) for both above and below ground injury. The above ground plant injury appeared to be higher than the below ground plant injury. On the second stand count (following the application of permethrin), the com seedlings were in the 3-4 leaf stage. The above ground plant injury in the plots treated with chlorpyrifos
45 was significantly lower than that in plots treated with permethrin and the untreated (P <
0.05), while the below ground plant injury in the three treated plots were significantly
lower than that in the untreated plots (P < 0.0001). In general, the below ground plant
injury appeared to be higher than that of the above ground plant injury. On the third stand
count, when the com seedlings were in 4-5 leaf stage, the below ground plant injury in the
treated plots were significantly lower than that in the untreated plots (P < 0.0001),
however, the above ground plant injury was insufBcient for statistic analysis.
In 1995, no significant difference of plant injury rates was found between the preventive treatments and the untreated plots prior to the application of permethrin (P >
0.05; Table 2.3), indicating that the BCW pressure did not cause significant impact on the com seedlings. However, plant loss in plots treated with tefluthrin were significantly lower than that in the untreated plots (P < 0.05) in stand counts, and the plant injury rate in plots treated with tefluthrin observed on 14 June was significantly lower (F = 3.47, df
= 3, P = 0.05) than that of the untreated plots (Table 2.3). No significant difference of yields were found among treatments (F = 2.87, df = 3, P = 0.81).
In 1996, BCW injury was minimal, no significant differences of com stand counts were found among the treatments (P > 0.05; Table 2.4).
2.3.2 Microplot studies
In the 1995 study, analysis of variance found that the plant injury (%) in the untreated plots was significantly higher than that in insecticide treated plots (F= 4.03, df
= 3, P =0.026). In the case of transplanted com seedlings and the newly emerged com seedlings, plant injury in untreated control was significantly higher than that in the three
46 Stand loss and plant injury(%)^ Root Yield Treatment’ 7 June 14 June 17 October Rating (Bu/A) Stand Stand Injury Stand Injury ( 1 -6 )
Tefluthrin 142.00(3.63)a 7.01 (1.70) 139.88(3.31 )a 9.05(1.77)a 129.25(7.72)a 2.20(0.14) 95.55(4.19)
Chlorpyrifos 131.75(8.3 l)ab 10.11(1.90) 129.38(2.64)ab 11.57(1.22)ab 119.88(5.69)ab 2.15(0.09) 93.78(2.60) Permethrin^ 115.12(8.55)ab 14.50(1.60) 113.38(7.82)b 13.71(1.29)ab 106.63(6.12)b 2.15(0.05) 89.65(3.70) Untreated 126.12(2.34)ab 11.1(3.02) 116.88(4.16)b 16.51(2.30)b 99.38(6.95)b 2.05(0.05) 80.18(5.72)
1. Data on the same column followed by different letters indicates significant difference (P < 0.05), Data in the bracket is stand error. 2. Stand counts were based on the total plants in I O' ft row, plant injury (%) is the plants injured over the total plants counted in 100 ft. row. 3. Rescue treatment was applied on 9 June when com was in 2-3 leaf stage.
Table 2.3 Comparison of corn stand counts, plant injury (%), root rating and yields between treatmentas in field plots, Western Branch of OARDC, 1995. Com stand^ Root Yield Rating (Bu/A) Treatment' 16 June 28 June ( 1-6 )
Tefluthrin 28.25(4.68) 27.75(3.66) 2 .1 0 (0 .1 2 ) 97.30(11.04) Chlorpyrifos 30.06(3.49) 28.44(5.50) 2.15(0.10) 95.03(6.34)
Permethrin^ 27.63(5.49) 27.25(5.41) 2 . 1 0 (0 .1 2 ) 84.90(4.32)
Chlorpyrifos^ 27.88(5.80) 26.00(5.88) 2 .1 0 (0 .1 2 ) 90.60(10.18) 4^ oo Untreated 26.94(5.94) 28.43(5.47) 2.35(0.10) 88.68(2.18)
1. Data in the bracket is stand error. 2. Stand counts were based on the total plants in 100 ft row, plant injury (%) is the plants injured over the total plant counted in 100 ft. row. 3. Rescue treatment was applied on 17 June when com was in 2-3 leaf stage.
Table 2.4 Comparison of com stand counts, root ratings and yields between treatments in the field plots, Western Branch of OARDC, 1996. treated plots for the newly emerged com {F = 7.87, df=3, f = 0.002; Fig. 2.1b), while
no significant difference was found among the treatments for the transplanted com
seedlings ( f = 1.04, df=3, f = 0.40; Fig. 2.1a). Stand loss after the 8 th day and before
the 21st day was very low in all treatments. In addition, the feeding of BCW on com
plants exhibited a shift firom the transplanted com seedlings to newly emerged com
seedlings after day 3, indicating the BCW preferred younger com plants which agrees with Clement and McCartney (1982) and Whitford and Showers (1979).
In 1996, plant injury in untreated control was significantly higher than that in the treated plots for the total plant injury (F= 25.84, df = 3, ? < 0.0001). For the transplanted corns, no significant difference was found in the plant injury among the treatments {F= 1.79, df=3,f = 0.189; Fig. 2.2a). For the newly emerged com plants, the cumulative plant injury at the day 8 after the application of insecticides in the plots treated with granules were significantly lower than that in the untreated plots and the plots treated with permethrin (F = 22.67, df=3,?< 0.0001; Fig. 2.2b). The distinct aspect of the plant injury in 1996 is that BCW injury on both the transplanted com seedlings and the new-emergence com seedlings occurred at the same time. The BCW cutting activity, which caused as high as 92% of plant injury in untreated plots, lasted three more days than that in 1995.
Although the activity of BCW in the microplot study decreased after the application of insecticides, the efficacy of the insecticide among treatments was not significant. In a closed microplot of the size used, the activity of BCW should be inhibited by the insecticide (with the application of recommended rate) used in 24 h for
49 □Tefluthrin HChiorpyrifos □Permethrin □Untreated
100 a. Transplants 80
60
40
20
3
C 100 m Q. New seedings 0 > 80 1 3 E 60 3 o
40
20 a a
Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8 Observation day
Figure 2.1 Comparison of cumulative plant injury (%) caused by black cutworm between treatments in micropiots, 1995. a. The cumulative plant injury (%) on transplants, b. The cumulative plant injury (%) on new seedings.
50 EJTefluthrin BChlorpyrifos □Permethrin □Untreated
100 a. Transplants 80
60
40
20
Z3
C 100 (0 Q. New seedings 0) > 80 % 3 0 60 o
40
20
Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8 Day 9 Day 10 Observation day
Figure 2.2 Comparison of cumulative plant injury (%) caused by black cutworm between treatments in microplots, 1996. a. The cumulative plant injury (%) on transplants, b. The cumulative plant injury (%) on new seedings.
51 EC and 48 h for the other granules. The lower efiBcacy of BCW control indicates the
BCW was in a growth stage that is less susceptible to insecticides (Harris and Sveg
1968a). The coincidence of destructive instar of BCW and the young com of 2-4 leaf
stage will cause vital com stand loss. In the microplot study in 1995 in which BCWs of
4th instar were used, the injury was relatively lower comparing with that in 1996 in which
BCWs of 3rd instar were used. The longer the period of coincidence lasts, the higher the com stand loss results. This incident agrees with Clement and McCartney (1982) that a larva of increasing instar cut progressively fewer seedlings at each succeeding com growth stage. Besides, the toxicity of soil insecticides is influenced by soil moisture and temperature (Harris 1972).
In the field studies, granular insecticides prevented stand loss caused by BCW in the com seedling stage. In contrast, the rescue treatment did not prevent the stand loss which occurred prior to the suppression of BCW activity. In microplot test, no significant difference was found between these two application techniques. Therefore, the timing of field BCW control was the key factor that influenced the efficacy of BCW rescue treatment.
A comparison of above and below ground plant injury (1994) demonstrated a fact that activity of BCW gradually shifted firom the above ground to the below ground, which may be related to the dry soil condition and the increasing temperature in that stage of growing season. The feeding behavior of BCW was in response to the growth stage of com plants. When com plants become appropriate six leaf stage, BCW will start tuimeling into the com plants (Sherrod 1979). In most cases, com plant damage of the
52 below ground is unrecoverable. This also indicates that the difSculty of rescue treatments when the damage of BCW become evident and the target pest is predominately below ground.
The occurrence of BCW in this three-year study happened to represented three typical levels of BCW activity. The damage of BCW in 1994 represented an epidemic year of BCW when the preventive treatment favored of prevention of stand and yield losses. The population of BCW in 1996 represented an non-epidemic year of BCW, when the insecticide treatment was not necessary. In 1995, although BCW population was moderate, the preventive treatments appeared to result higher cumulative stand counts than the rescue treatment did.
To avoid stand and yield losses, rescue treatment is ineffective when BCW is epidemic. Studies based on artificial infestation of BCW evaluate the efficacy of insecticide control, but the result may not reflect the natural infestation circumstances. It is also important to point out that preventive treatment may not be needed if BCW is not epidemic. To decide to apply preventive treatment or rescue treatment, procedures for an effective and accurate prediction of BCW population should be established.
Preventive treatment ensures the effective prevention of BCW damage when
BCWs is in the early instar that is susceptible to the insecticides. On the other hand, it has been noted that rescue treatment after the infestation is less effective since in many cases the BCW larvae are in the later instars before damage becomes apparent (Harris and
Sveg 1968b). The incidence of BCW infestations exceeding a potential action threshold increases as tillage was reduced, especially in no-tillage com (Willson and Eisley 1992a).
53 From the economic and environmental stand point, it is acceptable with the continuous
com that preventive treatments are applied at planting time incorporated with CRW
control in the U.S. com belt. In the case of first year com, it seems that preventive
treatment is quite arbitrary. However, it is clear that BCW will cause significant yield
loss with or without rescue treatment if BCW is epidemic. Given the trend of no-till com
practice in US com belt, and before a reliable prediction procedure for BCW activity is
well defined, preventive treatment at planting time may be warranted in situations having
a high potential for stand loss.
2.4 Summary
Efficacy of preventive and rescue insecticide treatment to protect com stand loss
firom black cutworm,Agrotis ipsilon (Hufiiagel), were tested in three years of field studies
with field plots and microplots. Field plots studies demonstrated that only preventive treatments at planting effectively protect com stand loss firom the black cutworm damage, while rescue treatment lost its control when black cutworm is epidemic (e.g. 1994). In the year when black cutworm population is relatively low (e.g. 1996), no significant difference of efficacy was found among the treatments. Two years of microplot studies showed that both treatment at planting time and post-emergence significantly reduced the
BCW injury compared with that of the untreated control. When the cutting-instar of
BCW occurs coincidently with the new emerging com, the plant injury rate was as high as 92%. This study exhibited that post-emergence treatment is less effective to protect the com stand loss when BCW is epidemic. Given the trend of no-till com practice in US
54 com belt, and before a reliable prediction procedure for BCW activity is well defined,
preventive treatment at planting time may be warranted in situations having a high
potential for stand loss.
References
Clement, S. L. and D. A. McCartney. 1982. Black cutworm (Lepidoptera: Noctuidae): Measurement of larval feeding parameters on field com in the greenhouse. J. Econ. Entomol. 75: 1005-1008.
Harris, C. R. 1972. Factors influencing the effectiveness of soil insecticides. Annu. Rev. Entomol. 17: 177-98.
Harris, C. R. and H. J. Sveg. 1968a. Toxicological studies on cutworms. I. Laboratory studies on the toxicity of insecticides to the dark-sided cutworm. J. Econ. Entomol. 61 : 788-793.
19686. Toxicological studies on cutworms. H. Field studies on the control of the dark-sided cutworm with soil insecticides. J. Econ. Entomol. 61: 961-965.
Levine, E., S. L. Clement, W. L. Rubink, and D. A. McCartney. 1983. Regrowth of com seedlings after injury at different growth stages by black cutworm, Agrotis ipsilon (Lepidoptera: Noctuidae) larvae. J. Econ. Entomol. 76: 389-391.
Oloumi-Sadeghi, H., E. Levine, K. L. Steffey, and M. E. Gray. 1992. Black cutworm damage and recovery of com plants: influence of pyrethroid and organophosphate soil insecticide treatments. Crop Protection. Vol 11, August. 323-328.
Rings, R. W., F. J. Arnold, A. J. Keaster, and G. J. Musick. 1976. A worldwide, annonated bibliography of the black cutworm. Ohio Agric. Res. Dev. Ctr. Res. Circ. 198. 106 pp.
Sherrod, D. W., J. T. Show and W. H. Luckmann. 1979. Concepts of black cutworm field biology in Illinois. Environ. Entomol. 8 : 191-195.
Showers, W. B., R. E. Sechriest, F. T. Turpin, Z. B. Mayo, and G. Szatmari-Goodman. 1979. Stimulated black cutworm damage to seedling com. J. Econ. Entomol. 72: 432- 436.
55 Showers, W. B., L. V. Kaster, and P. G. Mulder. 1983. Com seedling growth stage and black cutworm (Lepidoptera: Noctuidae) damage. Environ. Entomol. 12: 241-244.
Story, R. N. and A. J. Keaster. 1982. Development and evaluation of a larval sampling technique foe the black cutworm (Lepidoptera: Noctuidae). J. Econ. Entomol. 75: 604- 610.
Story, R. N., A. J. Keaster, W. B. Showers, J. T. Shaw, and B. L. Wright 1983. Economic-Threshold dynamics of black and claybacked cutworms (Lepidoptera: Noctuidae) in field com. Environ. Entomol. 12:1718-1732.
Willson, H. R. and J. B. Eisley. 1992a. Effects of tillage and prior crop on the incidence of five key pests on Ohio com. J. Econ. Entomol. 85: 853-859.
1992b. Evaluation of soil insecticides on first year and continous com in OH, 1991. Insecticide & Acaricide Tests. 17:219.
1996. Evaluation of soil insecticides on com in Ohio, 1995. Insecticide & Acaricide Tests. 21: 233.
56 CHAPTERS
THE IMPACT OF SELECTED INSECTICIDES ON
C ARAB IDS (Coleoptera: Carabidae) FROM CORN FIELDS
Abstract Studies were performed to evaluate the impact of three insecticides on
carabids with laboratory bioassay, microplot and field plots studies. Laboratory bioassay
showed that insecticides used in this study are toxic to carabids. Microplot studies
showed that soil insecticides significantly increased the mortality of the introduced
Scarites substriatus, and reduced the survived soil-inhabiting arthropods, and it is likely
that the application of insecticides could greatly reduce the local carabid populations in
field conditions. Field studies were performed 2 years to determine the impact of
insecticides on carabid activities in com plots treated with chlorpyrifos (Lorsban 15G),
tefluthrin (Force 1.5G) and permethrin (Pounce 3.2 EC) and the untreated control. The
cumulative total carabid catches in the untreated plots were significantly higher ( f < 0.05) than that in plots treated with granules at planting time in 1994, but not in 1995.
Although the cumulative total carabid catches in the plots with permethrin post emergence treatment were significantly higher {P < 0.05) than that in plots treated with granules at planting time for both years, the differences are not considered due to the
57 direct effect of insecticides, but due to the weed population in the untreated plots
resulting from the low com stands or poor com plant growth caused by soil insect pest
damages. However, significant differences have rarely been observed in carabid catches between treatments in the individual pitfall trapping, even in the first trapping immediately following the insecticide treatment. A decline in total carabid activity was observed after the application of permethrin when com was in 2-3 leaf stage. To conclude, laboratory bioassay and microplot experiment demonstrated that insecticides used in this study are toxic to carabids and it is likely that the application of insecticides could reduce the carabid population in the field condition. We argue that the pitfall trap is not an appropriate sampling method to evaluate effect of insecticide on carabid population in the experimental plots. While the laboratory tests may indicate only the innate relative tolerance of carabid to insecticides, they can't always predict the impact on carabids in field situation. To evaluate the impact of insecticides on abundance of carabid in crop fields, intensive study and long term research project should be resumed by using absolute population estimation with evaluation of the important field factors, as well as laboratory and microplot tests. A single study on the impact of carabid activities in agroecosystems could result in mis-interpretatioiL
3.1 Introduction
Although insecticide use has contributed to an increase in agricultural production, undesirable side effects affecting agricultural ecosystems have been identified. The prevalent side effects have been; development of insecticide resistance, emergence of new
58 plant pests due to the suppression of natural enemies, and pesticide residues moving to other ecosystems. Beneficial insects in the com ecosystem, such as soil-dwelling arthropod predators, are most likely suppressed in the processes of chemical pest control.
Soil-dwelling arthropod predators have been identified as major factor reducing soil pest damage compared to tillage or direct insecticide application (Ernst et al. 1985).
Carabids, one of the important predator guilds, have been shown to be effective predators of black cutworms,Agrotis ipsilon (Hafiiagel), as well as other Lepidoptera and
Coleoptera (Kirk 1971, Best and Beegle 1977). Although carabids may only play an opportunitistic predator role in certain com fields (Kirk 1982), evidence of direct predation of eggs and larvae of com root worms, Diabrotica spp. by carabids has been demonstrated by radiolabeling studies (Tyler and Ellis 1979). The potential of carabids as significant biological control agents of com soil insect pests is an attractive topic in sustainable agriculture. Unfortunately, there are few pesticides selective enough to control a particular pest without affecting the nontarget arthropods (Edwards 1990). The effect of insecticides on carabid populations has been studied by many workers (Critchely
1972, Humphrey and Dahm 1976, Gholson et al. 1978, Hsin et al. 1979, Floate et al.
1989, Jepsen et al.l990, and Reed et al. 1992). Soil insecticides used to reduce damage by root feeding pests, e.g. rootworms, Diabrotica spp., and wireworms, Elateridae, can reduce soil-dwelling predatory arthropod densities (Wright et al. 1960, Brust et al. 1985).
While insecticides may have significantly different toxicities to a carabid species (Tomlin
1975, Gholson et al. 1978, Hsin et al. 1979, Hagley et al. 1980, Reed et al. 1992), carabid species may exhibit differential susceptibilities to a single insecticide (Tomlin 1975,
59 Gholsoa et al. 1978). Different applications may also influence the effect of an insecticide on carabids in field conditions. Chritchley (1972) concluded that broadcast of thionazin at 11.2 or 44.8 kg/h considerably reduced numbers of carabids for up to eight weeks after application. Lower catches occurred again six months later because of the exposure of carabids to thionazin residues which had leached into deeper layers of the soil. On the other hand, dosage of 2.24 or 8.96 kg/h applied in rows sometimes increased numbers of carabids caught in pitfall traps, possibly because of sublethal effects increasing locomotor activity. The influence of soil insecticides used in com ecosystems on the carabid guild is not yet well understood. The objective of this study was to determine the effect of some commonly used insecticides on the dominant carabid species in com ecosystems.
3 .2 Materials and Methods
3.2.1 Laboratory Bioassay Studies
Carabids used in this study were collected in dry pitfall traps (the same as plastic cups that were used in field studies but with 2 small holes to enable draining) within no tillage com field plots. Live beetles were collected every day or every other day and maintained in clear plastic boxes covered with fresh alfalfa stems and leaves to reduce exercised movement. The beetles were fed with dogfood (Pedigree*) and 0.5 x 0.5 cm cubes (pieces) of ham under room temperature (about 23 °C) with photoperiod of 12:12 h
(L;D) until being tested. Only active beetles were used in the tests. Two types of
60 bioassays, standard LD# bioassay and LC# bioassay, were used to test the toxicity of the
formulated insecticides.
3.2.1.1 Topical application bioassav and LD^ q
Harpaluspensylvanicus Say was initially used to determine a range of dosages
that would be used to determine LDjoS. Two types of active ingredients, technical
materials and extracts from formulated insecticides, were used in this study. For the
extracts, active ingredients were extracted from the Force 1.5 G (tefluthrin), Lorsban 15G
(chlorpyrifos) and Pounce 1.5G (permethrin) in appropriate volume of solvent (analytic
grade acetone) to make 1% (wt/v) stock solutions for each insecticide used. Serial
dilutions were made by diluting the stock solution (1%) with acetone control to the
highest concentration (based on the pre-test). For the technical materials, only permethrin
and chlorpyrifos were available. Stock solutions of 1% (wt/v) for each technical material
and serial dilutions were made in the way described above. H. pensylvanicus, S. substriatus and P. chalcites were used in the bioassay. The average body weight of each
carabid species tested was calculated by weighing 50 female adults before each test, and used to express dosage in ug/g (ppm). Depending on the number of individuals available,
80 to 200 beetles were used for each dosage. Individual beetles were treated topically on the prostemum with I ul insecticide-solvent solution. Topical application were applied by using a microapplicator (Serial 11380, Instrumentation Specialties Company, Inc.) fitted with a 250 ul syringe and No. 27 gauge hypodermic needle, which was calibrated to deliver 1 ul solution. Doses were applied in an ascending order. Treated beetles were kept in a Rubbermaid* clear plastic container (41 cm. x 28 cm. x 15 cm) covered with
61 fresh alfalfa leaves and stems, and maintained in a culture chamber of 23 °C with a
photoperiod of 12; 12 (L:D) h. Mortality was recorded in 24 h after the topical
application. Moribund beetles were scored as dead. If mortality in the control exceeded
1 0 %, the result were not included in the LDj^ estimation.
3.2.1 .2 Çomaçt-pQisoning biQassay.and LCs»in.sflil
Serial dosages ( 0 , 0.5, 1 , 2.5, 5, 10 g) of each of the three insecticides were
completely mked with 2,700 cm^ top-layer field soil (moisture of about 13.5%). H.
pensylvanicus, S. substriatus and P. chalcites were used in this bioassay with 50 to 80
individuals for each dosage of the three formulated chemicals. Beetles (5 P. chalcites or
2 S. substriatus) were introduced into each container (16 oz Fabri-Kal* container) filled
with about 20 cm^ soU-insecticide medium. The container with tested beetles were
maintained in the way described previously. The number of dead beetles were recorded
in 24 h. after the introduction. Mortalities were calculated and adjusted for natural
mortality with Abbot's formula (Abbot 1925). LDjq and LC# value were computed by
probit analysis (Trevors 1986).
3.2.2 Microplot Studies
Microplots were used to assess specific predator-prey-pesticide interactions in
1995 and 1996. Clear plastic boxes of Rubbermaid* (41 cm. x 28 cm. x 15 cm.) were used as enclosed microplots. Four holes of about 1.5 mm in diameter were made on the bottom of each plastic box to allow draining. Plastic boxes were buried into the ground with 5 cm of the box walls about the field surface, and filled with soil that was initially removed. Three insecticide treatments and an untreated control were arranged in a
62 randomize complete block design with five replications. Then five com seeds were
planted in the box with application of the three insecticides in appropriate plots.
Treatments of tefluthrin (@ 1 g/m^ of granules or 0.015 g(AI)/m^ and chlorpyrifos (@ I
g/m^ of granules or 0.15 g(AI)/m^ separately were applied "in furrow" at "planting" time
with com seeds in the middle line alongside the elongate wall of plastic box. Then, two
adults of Scantes substriatus Haldeman and four 3rd to 4th instar larvae of black
cutworm, Agrotis ipsilon (Hufiiagel), were introduced into each box. The permethrin
treatment (with a garden sprayer being calibrated to the desired rate) was applied 24 h
after the introduction of the tested organisms. Two micro-pitfall traps, (glass shell vials,
21 X 70 mm) were used to monitor the activity of the carabids beginning seven days after
the application of insecticides. Evaluation of microplots was conducted in three weeks in
1995 and four weeks in 1996 . Soil in each microplot was separated and visually
inspected in the field. The number of S. substriatus survived, com rootworms alive,
residential carabids, and other live soil arthropods present in the microplots were recorded.
Differences of mean numbers ofS. substriatus collected in the "micro-pitfall- trap", the mortality of S. substriatus, and the mean number of other residential soil arthropods among treatments were analyzed using ANOVA.
3.2.3 Field Plot Studies
The field plot studies were carried out at the Westem Branch of OARDC, South
Charleston, Ohio, in 1994 and 1995 . The effect of insecticides on the activities of carabids, as nontarget arthropods, was observed in the field plots originally designed to
63 evaluate the efficacy of insecticides on controlling black cutworm and rootworm damage.
Chemicals used were: tefluthrin (Force 1.5G, Zeneca) @0.15 kg(AI)/h, chropyrifos
(Lorsban 15G, DowElanco) @ 1.46 kg(AI)/h, permethrin (Pounce 3.2EC, PMC
Corporation) @ 0.11 kg(AI)/h. Granular formulations of tefluthrin and chlorpyrifos were
applied at planting as a band (18 cm) prior to closure by the press wheel using a four-row
John Deere planter equipped with Noble granular insecticide application equipments.
Emulsifiable concentrate was applied with a boom sprayer equipped with flat spray nozzles. Calibrations were conducted to deliver the desired dosage at 4.8 kmph (3 mph).
Three insecticide treated plots and an untreated control were arranged in a randomized complete block design with four replications. Field plots were about 13 m x 40 m in size, planted with 16 rows (76 cm row width) of com. Field plots used were reduced tillage continuous com proceeded by reduced tillage com, and soil type is silty clay loam. In
1994, com (Zea mays L. var. Pioneer 3293) was planted on 18 May, and in 1995, com
{Zea mays L., var. Country Mark 693) was planted on 23 May.
Pitfall traps were used to sample the carabid fauna. The pitfall traps were 300 ml plastic cups (top opening radius = 3.5 cm) that were buried in the soil with their rims even with soil surface. Diluted (about 1:1) commercial antifreeze (ethylene glycol) was used in each trap to preserve the beetles and to prevent escape. Four pitfall traps were set alongside the middle of the mid-two-row about 8 m apart from every two traps within a plot. Sampling at one week intervals began early May and ended in mid October (22 and
24 samplings for 1994 and 1995). Number of species and specimens were recorded for individual traps. For each trapping period, traps were allowed to remain in the field for
64 48 h. Carabids collected in the pitfall traps were taken to the lab and washed under tap water through a No. 18 standard sieve. Specimens were kept in alcohol and specimens were pinned for taxonomic referencing.
Data were transformed /og(X+l) before analysis. ANOVA was used to test for differences of total number of carabids per trap, total number of specimens per trap for dominant species which composed 85% of the total carabids collected between treatments for each sampling, cumulative total carabids per trap, and cumulative number of specimens of dominant carabid species.
3 .3 Results
3.3.1 Laboratory Bioassay Studies
Topic LDjo of the chemicals used in this study were low on the carabids. For the technical materials used, permethrin exhibited relatively higher LDjq on the two early season species, S. substriatus and P. chalcites, while it had a low LDjq on the late season species, H. pensylvanicus. The LD 50 of chlorpyrifos on P. chalcites was about three folds higher than that on S. substriatus and H. pensylvanicus (Table 3.1). For the extracted chemicals, chlorpyrifos exhibited a high LD 50 on P. chalcites, which was about six time higher than that on S. substriatus and H. pensylvanicus. Although LDjqS of the three extracted chemicals on P. chalcites varies, they were relatively consistent on S. substriatus and H. pensylvanicus (Table 3.1). When the LD 50 of the technical materials and the extracts were compared, it was found that the LD 50 of the two technical materials varied on different carabid species. On S. substriatus, the LD 50 of technical material of
65 Equation of s.e. of LDso in 24 h Avg. ^nemicais logrprobit line weight of regression line ug/beetle ug/g beetle (g)
Scarites substriatus Technical permethrin Y = 5.303 + 0.704X 0.188 0.371 1.349 0.2750 materials chlorpyrifos Y = 5.759 +0.93 8X 0.245 0.155 0.568 0.2730
Extracted permethrin Y = 5.332 + 1.552 X 0.263 0.111 0.414 0.2683 chlorpyrifos Y = 6.234 + 1.77IX 0.364 0.201 0.729 0.2758 tefluthrin Y = 5.918 + I.262X 0.207 0.187 0.679 0.2756
Pterostichus chalcites Technical permethrin Y = 6.129+1.I80X 0.487 0.110 2.965 0.0371 materials chlorpyrifos Y = 7.836 + 2.392X 0.795 0.065 1.743 0.0373
Extracted permethrin Y = 6.209 + 1.217X 0.289 0.102 2.720 0.0375 chlorpyrifos Y = 5.839 + 1.026X 0.288 0.152 4.086 0.0372 tefluthrin Y = 6.893 + 1.629X 0.463 0.069 1.860 0.0371
Harpalus pensylvanicus Technical permethrin Y = 8.200 + 2.367X 0.443 0.045 0.218 0.204 materials chlorpyrifos Y = 8.190 + 3.178X 0.713 0.099 0.481 0.206
Extracted permethrin Y = 6.789+ 1.713X 0.220 0.090 0.431 0.209 chlorpyrifos Y = 6.589 + 1.914X 0.654 0.148 0.715 0.207 tefluthrin Y = 6.208+ 1.353 0.224 0.127 0.621 0.206
Table 3.1 Toxicities (topical LDjq) of selected insecticides on adult carabids of the dominant species, S. substriatus, P. chalcites dnà H. pensylvanicus, 1995-1996.
66 permethrin was about three times higher than that of the extracted permethrin, while the
LDjo of the technical materials and the extracts of chlorpyrifos were similar. On P.
chalcites, the LDjo of the technical material of permethrin was almost the same with that
of extracted permethrin, while the LD# of the technical material of chlorpyrifos was
about 3 folds less than that of the extracted material (Table 3.1). On H. pensylvanicus,
LD50S of the technical materials of permethrin and chlorpyrifos were about two times
higher as that of extracted materials (Table 3.1).
In the contact-poisoning bioassay via soil medium, LC^s of tefluthrin and
permethrin were about 5 folds lower than that of chlorpyrifos on S. substriatus, P.
chalcites and H. pensylvanicus (Table 3.2). The LC% of permethrin on P. chalcites was
about three times higher than the LC%s of permethrin and tefluthrin on all carabid species
tested (Table 3.2).
3.3.2 Microplot Studies
The results fi'om the two years of microplot studies were similar. In 1995,
mortalities of the artificially introduced S. substriatus in insecticide-treated plots were
significantly higher than that in the untreated plots ( F = 4.40, df= 3, f = 0.019), while no
significant difference were found among the three insecticides {P > 0.05, Table 3.3).
Thus, all three insecticides significantly reduced the population of S. substriatus. The
number of naturally presented coleopterans and the number of live arthropods were
found to be significantly higher in the untreated plots than that in the treated plots
respectively (F= 5.03, df = 3, f = 0.014; 7^= 19.4, df = 3, f < 0.0001). In 1996, mortality of the artificially introduced S. substriatus and the total arthropods found in
67 Chemicals Equation of log:probit s.e. o f line LCjo (ug/cm^), regression line 24 h
Scarites substriatus
Permethrin Y = 7.298 + 1.322X 0.220 18.3
Chlorpyrifos Y = 8.340+4,818X 0.725 202.7
Tefluthrin Y = 7.912+l.732X 0.192 20.8
Pterostichus chalcites
Permethrin Y = 7.426 + 2.050X 0.183 65.5
Chlorpyrifos Y = 7.879 + 3.073X 1.213 115.7
Tefluthrin Y = 6.228 + 0.769X 0.121 25.2
Harpalus pensylvanicus
Permethrin Y = 8.477 + 1.967X 0.377 17.087
Chlorpyrifos Y = 6.963 +2.I63X 0.724 123.656
Tefluthrin Y = 7.834 + I.599X 0.195 16.861
Table 3.2 Relative toxicities (LC50) of the selected insecticides on adult carabids of the dominant species, S. substriatus, P. chalcites and H. pensylvanicus, by contact-poisoning in soil-insecticide medium with series doses from formulated chemicals. 1995-1996.
68 Treatments* Observed groups tefluthrin chropyrifos permethrin untreated f-value
1995
S. substriatus mortality (%) 50.00a 80.00a 60.00a 1 2 .0 0 b 0 .0 0 1
S. substriatus in micropitfall 0 . 2 0 0 . 0 0 0 . 2 0 0.60 0.251
Other Carabid Adults 0.40 0 . 2 0 0 . 2 0 0.80 0.163
Carabid Larvae 0.40a O.SOab 0.60a 1.60b 0 . 0 1 2
Total coleopterans alive 1 .0 0 a 1.25a 0.60a 2.40b 0.014
Total Arthropods alive 3.00a 2.60a 2.50a 6.80b <0 .0 0 0 1
1996
S. substriatus mortality (%) 70.00a 60.00a 70.00a 1 0 .0 0 b 0.019
S. substriatus in micropitfall 0 . 2 0 0.40 0 . 2 0 0.60 0.547
Other Carabid Adults 0 . 0 0 0 . 2 0 0 . 2 0 0.40 0.247
Carabid Larvae 0.60 0 . 2 0 0 . 2 0 0.80 0.129
Total coleopterans alive 1.40 1.60 0.80 2 . 0 0 0.249 Total Arthropods alive 2.60a 3.00a 1.60a 5.20b 0.004
* Data followed by different latters on the same row indicate significant difference {P < 0.05), df = 3. Number of insects in the microplots were evaluated by visual observation in the field.
Table 3.3 Comparison of mortalities of carabids and number of other soil dwelling arthropods between treatments in microplots. Westem Branch of OARDC, 1995 and 1996.
69 insecticide treated plots were significantly higher than that in the untreated plots (F =
4.40, df = 3 ,P = 0.019; F = 6.78, df = 3 ,P = 0.004), while no significant differences were found among the insecticides (P > 0.05, Table 3.3). The results indicate that the use of insecticides decreased the soil arthropod populations. The number (in the bracket) of the live arthropods were: in 1995, carabid adults: A. sanctaecrucis F. [1 ], H. pensylvanicus
DeGeer [2], P. chalcites Say [2, one of the two found in micro-pitfall-trap],
Cyclotrachelus sodalis (LeConte) [3], and adults [2] and larvae/pupae [28] of Diabrotica spp.; in 1996, carabid adults:^4. sanctaecrucis^. [2], H.pensylvanicus [3], P. chalcites
[1], and larvae/pupae [14] and new adult [ 1 ] o f Diabrotica spp. An adult S. substriatus was observed chewing a live Diabrotica larva in the process of microplot final evaluation in 1995.
3.3.3 Field Studies
Five species, H. pensylvanicus, P. chalcites, S. substriatus, P. stygicus, and A. sancteacrucis, were identified as the dominant species representing 87.75% of the total number of carabids collected in the com plots. In 1994, analysis of variances showed that the cumulative total carabid catch in the untreated plots was significantly higher than that in the plots treated at planting with granular insecticides, while there was no significant difference of total catches between plots treated with permethrin and the untreated plots
(F= 3.04, df = 3, f = 0.036) (Fig. 3.1a). The total catch o f pensylvanicus va. the plots treated with permethrin and in the untreated control were significantly higher (F = 3.30, df=3 f = 0.026) (Fig. 3.1a) than that in the plots treated at planting. In 1995, the cumulative total carabid catches in plots treated with permethrin were significant higher
70 Figure 3.1 Comparison of total carabid catches between treatments in corn plots at the Westem Branch of OARDC, 1994-1995. a. total catches in 1994; b. total catches in 1995.
71 □ P. chalcites E3 A. sanctaecrucis a S. substriatus O P. stygicus E3 H. pensylvanicus E3 Total catch
100
s 5* ô E & n (0 ai c 3 (S Tefluthrin Chlorpyrifos Permethrin Untreated o- e S Ê Treatment 1994 0 o 01 •o S“ o 3 " 100 S s j: (B 0
1 50
40
30
20
10 N
0 Tefluthrin Chlorpyrifos Permethrin Untreated Treatment 1995
Figure 3.1 72 Treatment* tvey vanaoies tefluthrin chlorpyrifos permethrin untreated
1994 First stand count (6/02) 149.88a 134.13a 95.88ab 84.38b Last stand count (6/16) 150.38a 133.50ab 88.25bc 59.13c Root rating® 3.10a 3.15a 4.24b 4.25b Weeds cover^ 55.94a 53.75a 61.56ab 70.62b
Yield 124.00a 1 2 1 .0 0 a 77.00b . 50.00b 1995 First stand count (6/12) 142.00a 131.75ab 115.12ab 126.12ab Last stand count (10/07) 129.25a 119.88ab 106.63b 99.38b
Root rating 2 . 2 0 2.45 2.150 2.05 Weeds cover 24.13 30.12 22.94 16.19 Yield 63.93 54.70 71.18 54.80 * Different letters on the same row indicates significant difference (P < 0.05). ’’ Com stand counts per 100 ft row. ' Root rating was based on the 1-6 scale root rating system where I indicates non damage and 6 the highest degree of damage on com root system. '* Percentage of field surface covered by weeds per square meter.
Table 3.4 Comparison of com stand counts, root rating and weed cover between treatments in com plots, Westem Branch of OARDC, 1994 and 1995.
73 than that in the untreated plots while no significant difiference was found among the
treated plots (F = 3.11, df= 3, P = 0.033) (Fig. 3. lb). The total catch of P. chalcites in
the plots treated with permethrin were significantly higher than that in the plots treated
with tefluthrin and the untreated control (P= 4.32, df = 3, P = 0.008) (Fig. 3. lb). The
total catch of P. stygicus in the plots treated with tefluthrin and chlorpyrifos were
significantly higher than that in the plots treated with permethrin and the untreated control
in both years (1994: F =2.19, df= 3, P = 0.049; 1995: P = 4.91, df = 3, P = 0.004) (Fig.
3.1). Besides the direct effect of insecticides on carabids, the differences of com stands,
and weed population between treatments (Table 3.4) which resulted fi’om the insecticide
treatments on cutworms and com rootworms, could be the other important factor
indirectly affect the activities of carabids in the field plots.
Data analysis showed no significant differences in total carabid catch or total
catch of the five dominant species among treatments for the individual pitfall trap
sampling in both years. However, the total carabid catch declined following the application of permethrin in either years (Fig. 3.2 & 3.3).
3.4 Discussion
3.4.1 Laboratory Bioassay Studies
In general, P. chalcites appeared to be tolerant to the insecticide treatments in this study. Reed et al. (1992) estimated that LDjq of chlorpyrifos on P. chalcites was 1.4 ug/g
(24 h). Pterostichus chalcites was found to be highly resistant to dieldrin (LDj^ = 3357,
48 h) in an Iowa study in 1974 (Humphrey and Dahm 1976). This may be due to the
74 Figure 3.2 Comparison of the catches of dominant carabid species and the total catch per trap between treatments for each individual pitfall trapping at the Westem Branch of OARDC, 1994.
75 HTefluthrin EJChropyrifos El Permethrin ElUntreated EZ3Total
p. chaates
p. stygicus 150 —
100 ri
200 = s. substnabis 150 5?
S S E ta
H. pensytvanicus
mm
All carabids
^ ^ ^ ^ ^ ^ ^ ^ <#’ 4> # Sampling Date
Figure 3.2 76 Figure 3.3 Comparison of catches of dominant carabid species and the total catch per trap between treatments for each individual pitfall trapping at the Westem Branch of OARDC, 1995.
77 HTefluthrin ElChropyrifos E3Permethrin ElUntreated EDTotal
P .ch aates
A. san ctaeavas
P. stygicus
S. suMtnatus
100 â
r ^ - - ^ 1 1 1 1 - T
H. pensylvanicus
Al carabids
é ^ ^ ^ ^ ^ ^ ^ ^ ^ 4 ^ 4 ^ é 4^ # Sampling Date
Figure 3.3 78 innate tolerance developed from the frequent exposure to these insecticides. S. substriatus was relatively susceptible to the three chemicals compared with the other early season species, such as P. chalcites. The body weight of S. substriatus is about ten times higher than that of P. chalcites. The lower body-weight and body surface ratio may explain the poor tolerance of S. substriatus. Harpalus pensylvanicus and P. stygicus showed relative high susceptibilities to the 3 insecticides. These two species are typical late season breeders, and their activity may have avoided the selective pressure from the insecticide application early in the season and thus are relative more susceptible to the insecticides.
Although the LCjo of chlorpyrifos was 10 times lower than the other two insecticides, the field application rate of its formulated insecticide, Lorsban 15G formulation, which contains 15% of active ingredients could cause as same mortality on the carabid species as that by formulated tefluthrin (Force 1.5G) and permethrin (Pounce
I.5G) which contain 1.5% of active ingredients.
The inconsistency of LDjo and LC% observed for each chemical may be due to the dose transfer via contact poisoning in soil. Soil moisture is important in dose transfer for the granular insecticides. The soils used in the laboratory tests may have been relatively drier than that in the field conditions so that the release of active ingredients of the granular insecticides into the soil medium was delayed. However, the variations of the toxicity results tested by different methods or during different time periods is not unexpected because that the field-collected tested beetles were from mid-June and mid-
September and probably varied widely in physiological conditions and ages.
79 3.4.2 Microplot Studies
The microplot technique was used to study the specific interaction of insecticides on carabids under the natural weather and soil conditions. The reduction of the introduced carabids and the total survival of soil-dwelling arthropods in the treated plots indicated that the insecticides used in this study may have significant impact on soil dwelling arthropods, which agreed with the results that the three insecticides used in this study were toxic to carabids in the laboratory bioassay. Although the differences of carabid catches in the micro-pitM traps were not significant among the treatments, it is likely that the catches in the untreated control plots were higher than that in the plots treated with chemicals.
3.4.3 Field Studies
It was clear that the total activity of carabids were represented by the activities of dominant species. Differences in the cumulative total catches between treatments were due to the difference of the cumulative catches of the dominant carabid species. In 1994, the most abundant species was H, pensylvanicus, which was collected in the late season.
In 1995, the most abundant species was P. chalcites, which was primarily collected prior to the application of permethrin Since the catch of carabids dramatically declined after the application of permethrin, the activity of the early season carabid species may be affected by the toxic effect of insecticides. The activity of the late season carabid species may be stimulated indirectly by the insecticide applications.
Insecticide treatments indirectly influence the activity of carabids by altering the plant abundance and distribution in com field and reducing the prey populations. The
80 application of insecticides, especially the granular insecticides ^plied at planting,
significantly protected the com plants firom cutworm damage and reduced the rootworm
injury on the root systems, especially in 1994 (Table 3.4). Vigorous growth of com plant
reduced the weed population development. In contrast, higher weed populations
developed in the untreated plots with the low com plant density reduced by the cutworms
(Table 3.4). As a result, the carabid activities could response to the vegetation of com
plots with dififerent treatments due to weed growth associated with com plant densities.
H. stygicus is a late season breeder and prefers open areas (Chen and Willson
1996). Higher catches fi'om the plots treated with granules may be due to the aggregation
of H. stygicus in the plots with more com stands having relatively low weed population.
The increase in total carabid catch in late season 1994 was due to the high activity of H. pensylvanicus. This species is a late season species whose adult activity may have
avoided the effect of insecticides. In addition, this species is an omnivorous carabid, preferring weedy fields, especially where foxtails, Setaria spp., are abundant (Kirk 1973).
High population of foxtails in the study plot in the late season, especially in the untreated plots, could have been the in^ortant factor that influenced the activity of H. pensylvanicus.
It is not unexpected that there were not significant difference of the carabid catches in pitfall traps among the treatments in the individual pit 6 ll trapping, even for the trapping period immediately following the permethrin treatment. Several workers have even noted that increases in carabid activity following applications of insecticide
(Edwards and Thompson 1975, Chiverton 1984, Heneghan 1992), and laboratory studies
81 have confirmed that the sub-lethal dosages can have a short term stim ulating efiect
(Critchley, 1972). Lack of detection of the insecticide impact on carabid activities in the
field studies could be caused by various factors. First, carabids are highly locomotive
arthropods, and the number of carabids collected in pitM traps could thus be influenced
by the dispersion. It was observed that the affected carabid population in the insecticide
treated plots can quickly recover due to the relative small size of the experiment plots and
lack of control over the movement of the carabids between adjacent plots and untreated
area. One week trapping intervals could be long enough for the dispersion of the carabids
over the field plots that masked any of treatment effects. Secondly, carabids are basically
polyphagous and the larval and adult stages of some carabid species may feed on different
things. The searching of various food sources and the different feeding habits of different
developing stages of a carabid may be another factor. Third, sublethal dosages of
organophosphate and pyrethroid insecticides could initiate hyperactivities (Miller and
Adams 1982). The excited activity results in a higher catch of carabids in insecticide
treated plots than that in the untreated plots (Edwards and Thompson 1975, Chiverton
1984, Heneghan 1992). Finally, the mortality of soil arthropods in the insecticide treated
plots could become a strong attraction to certain predaceous carabid species, which could
be caught in pit&ll traps while searching for the dead bodies of soil arthropods and before they were subsequently poisoned to death. In addition, Chiverton (1984) argued that reducing prey populations by insecticides can result in hungrier predators with, consequently, higher activity. Therefore, until the field evaluation on carabid population is earned out with large com fields incorporated with effective experimental design and
82 effective sampling approaches, conclusions about the impact of these insecticides on
carabid activities sampled with pitfall traps in com ecosystems would be premature.
Although permethrin may be toxic to the late season species, H. pensylvanicus, it
is relative less toxic to the early season species. Force 1.5G was relatively lower in
toxicity comparing with the other two formulated chemicals. No significant difference of
mortality of carabids was found between insecticides in both microplot studies and
contact-poisoning tests, which suggests none of the three insecticides provides selectivity
to be of benefit in Integrated Pest Management program for soil pests control with less
impact on soil predatory carabids in com ecosystems.
In term of carabid species, H. pensylvanicus and P. stygicus are more herbivorous
than predatory, while P. chalcites and S. substriatus are general considered important soil predators in com fields. P. chalcites and S. substriatus are most abundant in the early season synchronized with the important soil insect pests, such as cutworms and
Diabrotica. Pitfall trap catches of these two early season species were abundant before the post-emergence application of permethrin and their roles as predators of soil insect pests may not be affected by post-emergence application if the timing is appropriately adjusted. Pitfall trap catch of H. pensylvanicus and P. stygicus are abundant in the later season, and are most likely in response to the weed population rather than the permethrin treatment. Therefore, the differences in pitfall trap of total carabids among treatments may not reflect the direct effect of the insecticide treatments on the carabid fauna in the field conditions. To evaluate the effect of insecticides on carabids, it is important to consider the effect of insecticides on individual carabid species. However, the difference
83 in carabid catches may be attributed indirectly to the treatments since the weed growth
associated with carabid abundance was due to differences of com plant density resulting
from significant differences in cutworm control.
The laboratory tests may indicate only innate relative tolerance of carabids to the
insecticides, and they caimot always predict their impact of insecticides on carabid
populations in the field. The microplot test may indicate the effect of insecticides under
the natural weather conditions, but the enclosure environment may not reflect the effects
of insecticide under the open field conditions regarding the soil moisture and dispersion
activities of carabids. To evaluate the impact of insecticide on abundance of carabids in
crop fields, the intensive study should be resumed by using absolute population
estimation with evaluation of important field factors, and incorporated with laboratory
and semi-field studies. A single study on the impact of carabid activities in
agroecosystem could result in mis-interpretation.
References
Abbott, W. S. 1925. A method for computing the effectiveness of an insecticide. J. Econ. EntomoL 18: 265-267.
Best, R. L. and C. C. Beegle. 1977. Food preferences of five species of carabid beetles commonly found in Iowa cornfields. Environ. Entomol. 6 : 9-12.
Bmst, G. E., B. R. Stinner, and D. A. McCartney. 1985. Tillage and soil insecticide effects on predator-black cutworm (Lepidoptera: Noctuidae) interactions in com agroecosystems. J. Econ. Entomol. 78: 1389-1392.
Chen, Z. Z. and H. R. Wilson. 1996. Species composition and seasonal distribution of carabids (Coleoptera: Carabidae) in an Ohio soybean field. J. Kans. Entomol. Soc. 69: 310-316.
84 Chiverton, P. A. 1984. Pitfall trap catches of the carabid beetle Pterostichus melanarius in relation to gut contents and associated organs in the locust. Entomoiogia Expeiimentalis et ^plicata 36; 23-30.
Critchely, B. R. 1972. A laboratory study of the effects of some soil applied organophosphorus pesticide on Carabidae (Coleoptera). Bull. Ent. Res. 62: 229-242.
Edwards, C. A. 1990. The importance of integration in lower input agricultural systems. Agriculture, Ecosystems and Environment. 27: 25-35.
Edwards, C. A. and Thompson. 1975. Some effects on insecticides on predatory beetles. Ann. ^ p l. Bio. 80: 132-135.
Floate, K. D ., R. H. Elliott, J. F. Doane, and C. Gillott. 1989. Field bioassay to evaluate contact and residual toxicities of insecticides to carabid beetles (Coleoptera: Carabidae). J. Econ. Entomol. 82: 1543-1547.
Gholson, L. E., C. C. Beegle, R. L. Best, and J. C. Owen. 1978. Effects of several commonly used insecticides on cornfield carabids in Iowa. J. Econ. Entomol. 71:416- 418.
Hagl^, E. A. C. D. J. Pree, and N. J. Holiday. 1980. Toxicity of insecticides to some orchard carabids (Coleoptera: Carabidae). Can. Ent. 112: 457-462.
Heneghan, P. A. 1992. Assessing the effects on an insecticide on the activity of predatory ground beetles, pp. 113-120. In Interpretation of Pesticide Effects on Beneficial Arthropods. Association of Applied Biologists.
Hsin, C-Y., L.G. Sellers, and P.A. Dahm. 1979. Carabids and the toxicity of carbofuran and X&b\iîos to Pterostichus chalcites. EnviroiL Entomol. 8: 154-159.
Humphrey, B. J. and P. A. Dahm. 1976. Chlorinated hydrocarbon insecticide residues in Carabidae and the toxicity of dieldrin to Pterostichus chalcites. Environ. Entomol. 5 : 729-734.
Jepson, P. C., S. J. DufSeld, J. R. M. Thacker, C. F. G. Thamas, and J. A. Eiles. 1990. Predicting the side-effect of pesticides on beneficial invertebrates. Brighton Crop Protection Conference - Pests and Diseases 1990, pp 957-962.
Kirk, V. M. 1973. Biology of a ground beetle, Harpalus pensylvanicus. Ann. Entomol. Soc. Am. 66: 513-517
85 1982. Carabids: minimal role in pest management of com rootworms. Environ. Entomol. 11:5-8.
NfiUer, T. A. and M. E. Adams. 1982. Mode of action of pyrethroids, pp3-27. In R. Coats [ed.]. Insecticide Mode of Action. Academic Press, New York.
Reed, J. P. F. R. Hall, and H. R. Krueger. 1992. Contact and volatile toxicity of insecticides to black cutworm larvae (Lepidoptera: Noctuidae) and carabid beetles (Coleoptera: Carabidae) in soil. J. Econ. Entomol. 85: 256-261.
Tomlin, A. D. 1975. The toxicity of insecticides by contact and soil treatment to two species of ground beetles (Coleoptera: Carabidae). Can. Ent. 107: 529-532.
Trevors, J. T. 1986. A BASIC program for estimation LD% values using the IBM-PC. Bull. Environ. Contam. Toxicity. 37: 18-26
Tyler, B. M. J. and C. R. Ellis. 1979. Ground beetles in three tillage plots in Ontario and observations on their importance as predators of the northern com rootworm, Diabrotica /ongicom/j (Coleoptera: Chiysomelidae). Proc. Entomol. Soc. Ont. 110: 65-73.
Wright, D. W., R_ D. Hughes, and J. Worrall. 1960. The effect of certain predators on the numbers of cabbage root fly (Erioischia brassica Bouche) and on the subsequent damage caused by the pest. Ann. Appl. Biol. 48: 756-763.
86 CHAPTER 4
STUDY OF DISPERSION PATTERNS OF CARABIDS (Coleoptera: Carabidae) IN
THE CORN ECOSYSTEM UNDER THE INSECTICIDE APPLICATIONS WITH
BARRIER-PITFALL TRAP TECHNIQUE
Abstract A barrier-pitfall trap technique was used to determine the movement pattern
of carabids in response to insecticide treatments in com plots. Treatments included:
granular formulations of tefluthrin and chlorpyrifos applied at planting (AP), liquid
formulations of permethrin and chlorpyrifos applied post-emergence (PE), and an
untreated control. A pattern of movement in which carabids became more active and
moved out of the plots with PE treatments was observed in the first 3 d following the PE
treatment. This response was believed to be motivated by contact with insecticide residue
causing hyperactivity. For the plots with PE treatment, the mortality of carabids caught on the way moving out was significantly higher than that moving into the plots. The mortality data suggests that the insecticide treatment caused a great reduction in local carabid populations. Scarites substriatus and Harpalus pensylvanicus, which represented more than 90% of the total catch, were the dominate species in the early and late season respectively in the com plots. S. substriatus suffered a high mortality in the plots with PE
87 treatments, while H. pensylvanicus exhibited a trend of dispersing from the grassy alley, and gradually into the com plots. Additionally, this study demonstrated that the barrier- pitfall trap technique is effective for detection of movement of the activated carabids exposed to insecticide treatments. Modification of the trapping technique is suggested to enable the effectively detection of the directional movement of carabids.
4.1 Introduction
Carabids have been considered to be important soil-inhabiting predators of soil pests, such as black cutworm,Agrotis ipsilon (Hufiiagel), and com rootworms,
Diabrotica spp. In field com (Brust et al. 1985, Best and Beegle, 1977). In the U.S. com belt, soil insecticides are routinely used to control com rootworms and black cutworms.
The long and short term effects of insecticides on these predators are therefore important considerations when designing integrated pest management programs. For most of the conventional agriculture with intensive use of insecticides, carabids have been studied as nontarget arthropods (Edwards and Thompson 1975, Reed et al. 1992, Ricdick and Mills
1995). The destructive impact of pesticides on carabid populations has been reported
(Critchley 1972, Edwards and Thompson 1975, Tomlin 1975 and Gholson et at. 1978).
However, the effect of insecticides on carabid activities evaluated with pitfall trapping have been conflicting. Numbers of carabids caught in pitfall trap in plots treated with insecticide can be lower than (Edwards and Thompson 1975, Powell et al. 1985), higher than (Edwards and Thompson 1975, Chiverton 1984), or not different from (Powell et al.
1985) those in untreated plots. Explanations focus mostly on the plot size, with or
88 without barriers, behaviors of carabids, environment factors and the efficacy of trapping
techniques.
Carabids are highly locomotive arthropods. By summarizing several studies,
Thiele (1977) stated that the average speed of dispersal for some carabid species was a
few meters per 24 h. Best et al. (1981) reported that dispersal of Pterostichus chalcites
and Scarites substriatus were 8.5 and 12.2 m per day respectively, but without any clue of
whether these carabids actually dispersed into or out of the field. In a field study, the
number of the carabids trapped could be influenced by the dispersion 6om adjacent areas
and the quick recovery of carabid populations in insecticide treated plots. This may be
due to relatively small size of plots and lack of control between adjacent plots and
untreated areas. The gradual invasion of carabids firom outside the field will be another
factor that could cause the negative results in a large field study. Coombes and Sotherton
(1986) reported that the greater the distance into treated fields, the greater the time taken
for recovery of populations to equilibrium levels with untreated areas.
Chiverton (1984) has shown that pesticides could increase carabid activities either through a direct stimulating effect, or by increased activity in search of low number of prey. The sublethal dose may thus increase the pitfall catch of carabids in chemical treated plots. Heneghan (1992) found that field application of a pyrethroid insecticide caused a change in carabid activity, which alters with the duration of exposure ~ initially high activity and subsequently great reduction in pitfall catches. In addition, Chiverton
(1984) argued that reducing prey populations by application of insecticides results in
89 decrease of arthropod prey population and hungrier carabids with subsequently higher
activity.
Dispersion patterns of carabids are mostly aggregated (den Boer 1979, Luff 1986).
Best at al. (1981) argued that aggregated dispersion pattern may be in response to the
environmental conditions rather than true contagion between individuals, because that the
aggregations observed were never very dense, and they covered fairly large and relatively
consistent areas of the grid. The aggregation of carabids will also be in response to the agrégation of the prey which may in turn respond to the chemical application. By studying Pterostichus coerulescens L., Mois (1979) described walking behavior of carabids that can be divided into two types depending on the degree of hunger. Hungry carabids showed a more directed walking pattern compared to a walking pattern with a higher frequency of turning movements following feeding. In addition, the more hungry the carabids were, the faster the recapture rates in pitfall traps, which indicates a higher mobility in hungry carabids (Grum 1971, Baars 1979b).
A common assumption in studies on the effect of pesticides on carabids is that pesticides are toxic to the target pests, and may influence the non-target arthropods at the same time. Such assumption may be true if the pesticides used have a broad spectrum of action. Carabids, as other beneficial arthropods, have thus been intensively studied as nontarget soil-inhabiting arthropods. In most cases, negative effects of pesticides were
"logically" assumed when pitfall-trap catches of carabids in treated plots were lower than those in untreated controls (Chiverton 1984). However, when the pitfall catches of carabids in treated plots were higher than those in the imtreated ones, investigators have
90 speculated various correlations to explain the situation. It should be emphasized that carabids catches in pitfall traps are determined by numerous factors, such as pesticide stimulation, hunger, age, local topography and weather conditions. It is also important to note that pitfall trap catch is a measure of effective abundance and determined by both activity and population size (den Boer 1977). The various local dispersion or random walking of carabids between treated and untreated, either in large field or small experimental plots, may mask the full impact of pesticides.
The dispersal and survival capability of carabids has been well described by den
Boer (1977). Studies have been conducted to detect the dispersion of carabids in crop fields. Best et al. (1981) designed a trial using trapping grid and traps around the grid field plot with capture-recapture technique, and found that Pterostichus chalcites and
Scarites substriatus preferred com and that the dispersion may be mostly limited within a field, while Harpalus pensylvanicus preferred edge of com field and dispersed from field border into field during early to mid-August. With the similar technique, Coombes and
Sotherton (1986) found that different species of carabids dispersed by walking or flying into cereals field with different penetration capability at different times during the growing season. However, few studies were able to describe the movement pattem of carabids between treated and untreated plots. The objectives of this study were to detect the possible movement patterns of carabids between insecticide treated and untreated plots, to determine the dispersal pattem of carabids on the plot border, and the effect of application methods on carabid activities.
91 4.2 Materials and Methods
This study was conducted in a reduced tillage com field at the Western Branch of
Ohio Agricultural Research and Development Center located in South Charleston, Ohio,
1996. Plot size was about 9.1 m x 18.3 m planting with 12 row (76 cm row width) (Fig.
4.1). Four insecticide treatments with two application methods and an untreated control were arranged in a randomized complete block design with four replications. Granular formulations of tefluthrin (Force 1.5G @0.15 kg(AI)/h) and chlorpyrifos (Lorsban 15G
@ 1.46 kg(AI)/h) were applied at planting (AP) on 1 June as a band prior to closure by the press wheel using a two-row John Deere planter equipped with Noble granular insecticide application equipments and calibrated to deliver the desired field rates at 3 mph. Emulsifiable formulations of permethrin (Pounce 3.2EC @ 0.11 kg (AI)/h) and chlorpyrifos (Lorsban 4EC @ 1.12 kg (AI)/h) were applied at three-leaf stage on 17 June with a boom sprayer equipped with fiat spray nozzles and calibrated to deliver the desired dosages at 4.81 kmph.
To determine the dispersion pattem of carabids between treatment plots and along plot borders, a barrier-pitfall trap design was used, which included a polyethylene barrier of 50 cm in length and 15 cm above field surface with one pitfall trap on each side of the barrier (Fig. 4.2). Each pitfall trap of the barrier-pitfall trap set was set up by burying a plastic cup, volume of 298 ml, and with three holes of about 1.5 mm in diameter on the bottom for draining, with the rim even with the soil surface. The theory for using this
92 Figure 4.1 Experimental plot plan with the arrangement of barrier-pitfall trap sets in the com field plots. The figure includes two of the four blocks of the experimental plots (five plots per block).
93 B Bare alley ground
S' Grass Alley O n
, 914 m ^ 45.7 m <
Figure 4. i 7cm
3cm 3cm
7cm Barrier
■ ■ ■ I * ! ! ! 15cm ./ y ' y f y y y y y-yiryy-ry-ry
50 cm
Figure 4.2 Design of the barrier-pitfeU trap set
95 barrier-pitfall trap design is that beetles will most likely be caught in the trap on the side
of to another plot Therefore, comparison of carabid catches from traps on one side to the
traps on the other side of a barrier should indicate the directional movement. At the same
time, it is assumed that traps on both side of barrier will have the same opportunity to
catch the beetles walking in the directions that are parallel or nearly parallel with the
barrier, or the beetles that randomly walk around the trap station area. Two dispersal
measurements were used at the same time to determine the movement patterns of
carabids between treatment plots and on the plot border that were next to the grassy alley
respectively. The trap stations of the inter-plot set were set up between treatment plots, for which two trap stations were set up between every two treatment plots. For each trap station for the inter-plot set, trap sets were set up in the middle between the edge rows of every two treatment plots with the barrier paralleled with the row direction and with a distance of about 6 m between the two barriers and about 6 m from the plot edges (Fig.
4.1). Two trap stations of the on-border set were set up on the plot border between the plot and the grassy alley for each plot. Each trap station was set up on the com row about
1.5 m from the plot edge, about 3 m between the two barriers, and about 3 m from the edge rows of both sides of a plot Due to the wet weather, pitfall traps were not set up until 12 June. Pitfall trap catches were counted and traps were emptied every morning to avoid heat exposure, and every two-three days after 20 June when the canopy covered about 60% area of the field. Beetles were counted and then released into the middle area of the plots or to the grassy alley where the beetles were assumedly heading to, to
"‘resume” the natural dispersion pattem. The number of adult carabids per trap for the
96 dominant species in this field (Chen and Willson 1996), Scarites substriatus, Pterostichus
chalcites, P. stygicus and Harpalus pensylvanicus were recorded to each trap. In
addition, the number of dead beetles and total catches were recorded per trap at 24 h intervals for the first 3 trapping days following the PE treatment.
Data were transferred log (X+1) before analysis. ANOVA was used to analyze the difference between treatment plots and Tukey multiple comparison procedure was used to separate the means of the groups of treatments. General Linear Model (GLM) was used to analyze the differences between numbers of carabids that on alley side and that on plot side under different chemical applications. Carabid mortalities firom the two experiments were calculated and analyzed with the tow techniques mentioned above.
Original data was presented with mean number per trap-day, representing the mean number of carabids caught in a trap in 24 hours for the same data group.
4J Results
4.3.1 Movement o f carabids between treatments
For the inter-plot set, catch of a trap was catalogued into groups based on a treatment side the trap was on and a treatment side the trap was next to. In a comparison of the total catches between each of the groups (of that each treatment was compared with the other four treatments), no significant difference of total catches and mortalities (%) was observed among these groups before or after the PE treatments (Table 4.1).
97 Table 4.1 Comparison of the total catch and mortality (%) of carabids in pitfall traps between the two sides of the barrier related to the treatments.
98 Side A SideB DataPoint Treatments Catch per trap Treatments Catch per trap
Total catch of carabids before PE treatment (June 13-17) 11.50 Chlorpyrifos AP 5.00 2 Tefluthrin AP 5.67 Untreated 1.50 10
Chlorpyrifos AP 5.88 Tefluthrin AP 3.50 2 4.75 Untreated 4.84 10
Total catch of carabids after PE treatment (June 17-20) 2.00 Chlorpyrifos AP 1.50 2 1.25 Chlorpyrifos PE 1.72 4 Telflutherin AP 0.75 Permethrin PE 3.75 4 0.00 Untreated 0.00 2
1.88 Permethrin PE 2.50 8 Chlorpyrifos AP 0.50 Chlorpyrifos PE 3.50 2
Chlorpyrifos PE 3.50 1.50 6 Untreated Permethrin PE 3.67 1.83 4
Mortality (%) of carabids after PE treatments (June 17-20) 0.00 Chlorpyrifos AP 0.00 2 43.75 Chlorpyrifos PE 62.50 4 Telflutherin AP 0.00 Permethrin PE 59.72 4 0.00 Untreated 0.00 2
53.12 Permethrin PE 48.54 8 Chlorpyrifos AP 50.00 Chlorpyrifos PE 45.83 2
Chlorpyrifos PE 58.33 25.00 6 Untreated Permethrin PE 72.22 8.33 4
Table 4.1 (continued) 99 Table 4.1 (continued)
Total catch after PE treatment (June 20-30) 2.50 Chlorpyrifos AP 0.50 2 4.00 Chlorpyrifos PE 5.75 4 Telflutherin AP 1.00 Permethrin PE 4.75 4 2.50 Untreated 3.00 2
3.13 Permethrin PE 5.00 8 Chlorpyrifos AP 0.00 Chlorpyrifos PE 3.50 2
Chlorpyrifos PE 4.25 2.50 6 Untreated Permethrin PE 5.67 4.67 4
Total catch after PE treatment (June 17 to August 22) 27.50 Chlorpyrifos AP 0.50 2 26.00 Chlorpyrifos PE 5.75 4 Telflutherin AP 59.50 Permethrin PE 4.75 4
20.00 Untreated 3.00 2
33.25 Permethrin PE 31.75 8 Chlorpyrifos AP 31.00 Chlorpyrifos PE 20.00 2
Chlorpyrifos PE 40.25 37.25 6 Untreated Permethrin PE 49.33 67.17 4
100 For the daily carabid catches before PE treatments, data were pooled and analyzed
with the factors of treated and untreated, where treated factor includes the two treatments
applied at planting time, while the untreated includes the two treatment plots designed for
PE treatment and the untreated control. ANOVA analysis showed that mean carabid
catches in traps from trap stations having at least one side with treated plot and the other
side without treatment were significantly higher (P < 0.05) than that from trap-sets with
both sides treated on the trapping period of 12 to 13 June, and 16 to 17 June. No
significant difference of mean carabid catches was observed between traps from trap
stations with both sides treated or with both sides untreated (P > 0.05, Fig. 4.3). This
implies that carabids moved around more often in plots with AP treatments than that in
plots without treatments during.
After the PE treatment, the number of carabid per trap-day from the traps in the
plots with PE treatment and next to plots without PE treatment was significantly higher
(P < 0.05) than that in the traps between plots treated at planting time or that in the
untreated control plots for the sampling dates of 18 and 20 June (Fig. 4.4a). Comparing
total catches and mortalities between traps of untreated control, treatments at planting and
PE treatments of sampling period of 17-20 June, found that traps in plots with PE treatments and in combination with any other treatments always caught significantly more carabids than other traps (Table 4.2). It is important to note that the mortality of carabids caught in the traps in the plots with PE treatments was significantly higher (P = 0.0003) than that from the traps in the plots without PE treatments (Table 4.2). The mortality of carabids from traps in the plots without PE treatment and next to plots with PE treatments
101 Treatment* untreated control treatment at planting post-emergence the trap on (CK) (APT) treatment (PET) Treatment AP PET CK APT PET CK APT the trap next to
Data Points (N) 2 1 0 2 4 18 1 0 18
Mortality(%) 0 .2 0 a 15.00b 0.50a 0.20a 38.89b 66.67c 53.83c 6/17-20 df= 6 , F = 3.65, P = 0.032
Total catch 0 . 1 0 a 1.70ab 0.10a 1.75ab 1.33ab 3.60b 2.72b
6/17-20 d f= 6 , F = 3.4, P = 0.006
Total catch 3.00 3.80 2.50 1.50 2.50 5.10 4.90 6/20- 30 d f= 6 ,F = 1.073, P = 0.123
Total catch 1 1 . 0 0 55.00 20.00 29.50 37.22 45.70 29.78 6/17-8/22 d f= 6 ,F = 1.04, P = 0.408 * APT indicates treatment at planting, PET indicates post-emergency treatment.
Table 4.2 Comparison of total catch of carabids per trap and mortality between treatments after post-emergence treatment (PET).
102 E3 On untreated side El On treated side OT E3 Both sides treated Q. B Both sides untreated CO = 3 S. I I
6/13-14 6/14-15 6/15-16 6/16-17 Sampling date
Figure 4.3 Coisparison of total carabids caught in barrier-pitAil traps between treatments prior to post-emergence treatment (PET), 13-17 June, 1996.
103 Figure 4.4 Comparison of mean number of carabids caught and mortality (%) in barrier- pitfall traps between treatments following the post-emergence treatment (PET), 17-20 June, 1996. a. catches between the PET and non PET plots; b. mortalities between the PET and non PET plots; c. catches between treated and untreated plots; d. mortalities between treated and untreated plots.
104 El Both sides without PET E] On non-PET piot & next to PET piot B On PET piots and next to non-PET plots 100
80
60
40
i 20 a I a o 0) o. E3 between treated & I E3treated->Untreated E 3 C ^ Untreated->treated C 3 5
8 /17-18 8 /18-19 8 /19-20 6/17-18 6/18-19 6/19-20 Sampling date
Figure 4.4
105 Figure 4.5 Comparison of mean number of carabids caught in barrier-pitfall traps between treatments following the post-emergence treatment (PET), 17 June - 22 August, 1996. a. catches between treated and untreated plots; b. catches between PET and non PET plots.
106 • Both sides untreated $ On treated side & next to the untreated ▲ On untreated side & next to the treated
Im
0) Q. 0) o E 3 • Both sides with PET C 3 ♦ On non-PET side & next to PET plot C n A On PET side & next non-PET plot 0) 2
1
0 20 22 24 26 28 30 2 4 7 9 11 14 16 19 21 23 25 27 29 1 4 6 8 10 13 15 17 20 22 June July August Sampling date
Figure 4.5 was significantly higher than that firom traps in plots with both sides without PE
treatments (P = 0.0008), but was significantly lower than that firom traps in plots with PE
treatments and next to plots without PE treatments (P = 0.017) during the trapping period
of the day 1 to day 3 following PE treatment (Fig. 4.4b). This indicates that carabids
firom plots with PE treatments had significantly higher mortality than that firom other
plots, and significantly more carabids moved firom plots with PE treatments to other plots
without the PE treatments than the movement of opposite direction during the first 3 d
following the PE treatments. Because mortalities of carabids in traps between the plots
without PE treatments were very low, the higher mortality firom traps in plots without PE
treatments and that next to the plots with PE treatments indicates that carabids walked
around the barrier and dispersed to other plots after being exposed to the insecticides. No
significant difference (P > 0.05) was found on the mean number of carabid caught,
neither the mortalities, among comparison groups of treated plots (including the four
insecticide treatments) and untreated control (Fig. 4.4c&d).
For the daily collections, no significant difference was found among mean number of carabids caught in traps per group after 20 June (Fig. 4.5). However, relatively fewer carabids were caught in the traps between plots treated (either AP or PE) than that in the other traps in the last week of the trapping period (Fig. 4.5a). This indicates that fewer carabids were likely moving firom plots treated with insecticides to the untreated plots than that from plots untreated to the treated plots.
108 4.3.2 Movement o f carabids on the plot border
During the trapping period before the PE treatment (13 to 17 June), no significant
difference of the mean number of carabids per trap-day was found between plots treated
with different insecticides (Table 4.3). No significant difference of the number of
carabids per trap-day was found between the treated and the untreated plots. No
significant difference of the mean number of carabids per trap-day was found between
that firom traps on the alley side and that on the plot side (Fig. 4.6).
After the PE treatment, no significant difference of total catches was found among
the five treatments during trapping period of first 3 d the following the PE treatment
(Table 4.4). Mortalities of the carabids collected from traps in the plots with PE
treatments were significantly higher than that in the imtreated plots and that in the plots
treated at planting for both sides (alley side and plot side) during the trapping period of
first 3 d following PE treatments (Table 4.4). The mortality of carabids caught in traps on
the plot side was significantly higher than that on the alley side during the trapping period
of the first 3 d following PE treatments (Table 4.4).
Comparison of total catches and mortalities between traps for the untreated control, treatment at planting and of PE for the sampling period of the first 3 d following
PE treatments, no significant difference was found between mean number of carabids caught in the traps on alley side and on plot side in the plots treated at planting time (Fig.
4.7a) or in the plots with PE treatments (Fig. 4.7b). The mean number of carabids in traps on alley side was found to be significantly higher than that in the traps on plot side during the sampling of 17 to 18 June {P = 0.04, Fig. 4.7e). In regard to mean carabid
109 Date Treatments* Pitfall trap Mean in PE treatments setting AP treatments untreated catch June telfluthrin chlorpyrifos oermethrin chlorpyrifos control
13-14 Alley side 4.25 2.88 3.38 3.25 1.38 3.03 Plot side 4.13 2.25 2.75 3.38 2.63 3.03 Mean 4.19 2.56 3.06 3.31 2.00
14-15 Alley side 0.13 0.38 0.38 1.75 0.38 0.60 Plot side 0.63 0.50 1.00 0.63 0.13 0.58 Mean 0.38 0.44 0.69 1.19 0.25
15-16 Alley side 0.88 0.25 2.13 1.88 0.63 1.15 Plot side 2.63 2.38 0.25 1.50 1.75 1.70 Mean 1.75 1.31 1.19 1.69 1.19
16-17 Alley side 1.63 0.63 0.88 3.50 1.38 1.60 Plot side 0.50 2.25 2.00 2.50 2.63 1.98 Mean 1.06 1.44 1.44 3.00 2.00
Mean Alley side 1.72 1.03 1.69 2.59 0.94 1.78 Plot side 1.97 1.84 1.50 2.00 1.78 1.82 Mean 1.84 1.44 1.59 2.30 1.36 1.80 AP = at planting, PE = post-emergence.
Table 4.3 Comparison of mean catches of carabid between treatments for the on-border trap set prior to the post-emergence treatment (PET).
no Table 4.4 Comparison of mean pitfall catches and mortalities between different trap sets for different treatments of the on-border set following the post-emergence (PE) treatments, 17-19 June.
Ill Date AP treatments* PE treatments* Mean in Trap sets untreated caKh June telfluthrin chlorpyrifos permethrin chlorpyrifos
17-18 Alley catch 0.75 0.63 0.75 1.50 1.38 1.00 side moit% 0.00a** 0.00a 29.17b 60.41b 2.00a 18.42 A Plot catch 1.13 1.75 1.25 1.75 1.38 1.45 side [Qort% 0.000a 12.50a 62.50b 75.00b 25.00a 35.00B
Mean catch 0.94 1.19 1.00 1.63 1.38 mort% 0.000a 6.25a 45.83b 67.70b 13.75a
18-19 Alley catch 0.25 1.00 0.63 0.13 0.13 0.43 side mort% 12.50 9.38 18.75 0.00 0.00 8.13 Plot catch 0.75 1.88 0.63 1.38 0.38 1.00 side mort% 4.17 6.25 18.75 52.08 0.00 16.25
Mean catch 0.50 1.44 0.63 0.75 0.25 mort% 8.33 7.81 18.75 26.04 0.00
19-20 Alley catch 1.00 0.13 0.13 0.13 0.50 0.38 side mort% 2.00 0.00 6.25 0.00 0.00 1.65 A Plot catch 0.75 0.50 1.63 0.88 0.50 0.85 side niort% 0.00a 12.50a 60.42b 62.50b 0.00a 27.08B
Mean catch 0.88 0.31 0.88 0.50 0.50 mort% 0.00a 6.25a 30.22b 31.25b 0.00a
Mean Alley catch 0.67 0.58 0.58 0.58 0.67 0.60 side niort% 4.17 3.13 15.97 20.14 0.83 8.85A Plot catch 0.88 1.38 1.17 1.33 0.75 I.IO side ixiort% 1.39a 10.42a 47.22b 63.19b 8.33a 26.IIB
Mean catch 0.77 0.98 0.83 0.96 0.71 mort% 2.78a 6.77a 31.60b 4 1.67b 4.58a
* AP = at planting, PE = post-emcrgcncc. Mort% = mortality (%). ** Data on the same row followed with different lower-case letters indicate significant difference (P < 0.05). Data on the same column followed with different uppcr-case letters indicate significant difference (P < 0.05). And mort% represents mortality (%).
Table 4.4 112 Figure 4.6 Comparison of mean number of carabids caught in barrier-pitfail traps of the on-border set prior to the post-emergence treatment (PE), 13-17 June, 1996. a. between treated and untreated plots on the on-border set; b. between alley side and plot side on the on-border set; c. between alley side and plot side for the treated plots; d. between alley side and plot side for the untreated plots.
113 Total on plot bortef Total on both side of trap-set □Treated plots □ On alley side □ On plot side □Untreated plots
I S' s. I E 4 On treated plot border On untreated plot border e □On alley side □On alley side s □O n plot side □On plot side ______s 3
2 1
1
0 6/13-14 6/14-15 6/15-16 6/16-17 6/13-14 6/14-15 6/15-16 6/16-17 Sampling date
Figure 4.6
114 Figure 4.7 Comparison of mean number of carabids caught and their mortality (%) between the alley side and the plot side in barrier-pitfail traps of the on-border set following the post-emergence treatment (PET), 17-20 June, 1996. a. catches for plots treated at planting; b. mortality for plots treated at planting; c. catches for plots with post emergence treatment; d. mortality for plots with post-emergence treatment; e. catches for the untreated plots; f. mortality for the untreated plots.
115 On alley side ^ On plot side
100 Treated at planting Treated at planting
0
100 Post-emergence treatment Post-emergence treatment a 2 II II i
Untreated Untreated 80
60 a 40
0.5 2 0 i 6/17-18 6/18-19 6/19-20 6/17-18 6/18-19 6/19-20 Sampling date
Figure 4.7 116 Figure 4.8 Comparison of mean number of carabids caught in barrier-pitfail traps of the on-border set following the post-emergence treatment (PET), 17 June - 22 August, 1996. a. for plots treated at planting; b. for plots with post-emergence treatment; c. for the untreated plots; d. for the total catches.
117 4 Catch on alley side O Catch on plot side 12 10 8 a. Treated at planting 6 4 2 A A () 0 5 4 jg) Post emergence treatment / ♦ I 3 S 2 P , _ ...... () I 1 0 I 5 oo * 4 C. U n treated Q / \ 3 S 2 O ♦ '"A G J ; s Q () 1 , 0 Î 0 5 4 Total catch 3 2 O ■Q G () 1 $)- O 0 8 — 20 22 24 26 28 30 2 4 7 9 11 14 16 19 21 23 25 27 29 1 4 6 8 10 13 15 17 20 22 June July Sampling date August
Figure 4.8 Figure 4.9 Comparison of mean number of carabids and the percentage of the dominant species caught in barrier-pitfail traps, and total catches of carabids between the on-border set and the inter-plot set for the whole study period, 13 June - 22 August, 1996. a. for the inter-plot set; b. for the on-border set; c. for the total catches.
119 100 > -♦ -♦-♦-H ► (A u —« .2 80 g a 10 60 Between treatments c 40 a. • s. substriatus 2c ♦ H. pensylvanicus 20 Ë o ■o 0 0 5 100 « 80 O) 1 60 On plot border s. substriatus I 40 pensylvanicus (O 6 20 o 0 n I 4 3 C. The two trap sets I E3 On plot border d Between treatments E 2 3 C C 1 S s 0 a m m t 13 15 16 17 18 19 20 22 24 26 28 30 2 4 7 9 11 14 16 19 21 23 25 27 29 1 4 6 8 10 13 15 17 20 22 June July August Sampling date
Figure 4.9 catches for 17 to 18 June sampling, mortality of carabids in the traps on the plot side was significantly higher than that in the traps on alley side in the plots with PE treatments {P <
0.05, Fig. 4.7d). For the trapping period of 19-20 June, none of the carabids were found dead in the traps on alley side while the mortality of the carabids in traps on the plot side was about 80% (Fig. 4.7e) for the plots with PE treatments. The mortality of carabids caught in the traps in the untreated control plots was very low (Fig. 4.7f) during the first 3 d sampling following the PE treatment.
After 20 June, no significant difference was found between mean number of carabids caught in traps on plot side and alley side of the barrier (Fig. 4.8). However, on the plots with PE treatment, relatively more carabids were caught in the traps on alley side than that in the traps on the plot side during the last week of the sampling (Fig. 4.8b).
During the sampling period, S. substriatus and H. pensylvanicus were the two dominant species. Very few individuals of P. chalcites and P. stygicus were caught in the pitfall traps (about 3% of total catches respectively). During the early season, S. substriatus represented at least 70% of the total carabid catches, while H. pensylvanicus represented more than 80% of the total carabid catches at almost all of the trappings after mid July (Fig. 4.9). The shift of the dominant species in the traps between treatments
(Fig. 4.9a) appeared to be the same with that in the traps on the plot border (Fig. 4.9b).
However, during the sampling period of 10 to 17 August, mean number of carabids per trap-day from the on-border set appeared to be higher than that from the inter-plot set
(Fig. 4.9c).
121 4.4 Discussion
The effect of granules applied at planting on the carabid movement could not be evaluated due to the wet weather that delayed the setup of the pitfall trap stations.
However, during the sampling period of the 4 days prior to the PE treatment, the effect of granular insecticides on carabid activity was demonstrated by that higher carabid catches in the pitfall traps of the treated plots than that in the untreated plots. Granules applied on row sometimes increase numbers of carabids trapped, possibly because of sublethal effects increasing locomotor activity (Heneghan 1992). Reed et al. (1992) found that significant more carabids died on the field surface where granules were applied in 48 h following the insecticide application than that in the untreated control plots.
The measurement of both inter-plot set and on-border set demonstrated the movement of carabids from plots treated with insecticides to the untreated plots, especially in the first 1 to 3 days immediately following the PE treatments. The mortalities of carabids in the pitfall traps demonstrated further the pattern that carabids moving from the plots with PE treatments to the plots without PE treatments following the PE treatment. The walk velocity and pattern of carabid adults varied with both the motivation of individuals and the external stimulations (Mois 1979). The active movement of carabids under the influence of insecticides may be initiated by various factors, such as superexciting effects from the sublethal dosaging (Miller and Adams
1982), or prey population shortage (Chiverton 1984).
It appeared that permethrin and chlorpyrifos caused superexcitement and initiated the frequent movement of carabids in the plots with PE treatments. The insecticides used
122 in this study, organophosphate and pyrethroid, are the neuroactive insecticides, which
could cause the hyperactivity of insects (Miller and Adams 1982). Laboratory work has confirmed that sub-lethal dosages can have a short term stimulatory efTect on insects
(Critchley 1972). Dempster (1968) also reported an increases in carabid activity following applications of pesticides.
Traps on the side of a plot with insecticide treatment should have a greater probability to catch the carabids firom the plot than that from other plots. Thus mortality in these traps could reflect the mortality caused by the insecticide applied in this plot.
This was indicated by the high mortality of the carabid in the pitfall traps during the first three days sampling following the PE treatment. Those carabids stimulated by pesticides could walk faster with less turnings, thus may pick up more chemical residuals from the soil surface and eventually die. The high mortality of carabids appearing in the traps in the plots with PE treatments suggests that the mortality was caused by the direct contact to the chemical residues. Similar increases in carabid activity after pesticide application have been noted by Dempster (1968), Chiverton (1984) and Heneghan (1992). In addition, Critchley (1972) reported that broadcast of thionazin considerably reduced numbers of carabids for up to eight weeks after application, but the efiect was not detected after the third day following insecticide treatment.
The frequent movement of carabids between the treated and the untreated plots may reflect a lack of prey population in the insecticide treated plot, which could have motivated carabid individuals to a less random walk pattern with higher speed in search of prey. Prey population may occur aggregated in certain microhabitats depending on
123 their preferences. Other studies indicated that predators can react to their preys by
concentrating in the most profitable sites (Hassell and May 1974). Chiverton (1984)
found that significant increases in pitfall trap catches of carabids were observed in the
treated plots compared to the untreated control, and corresponding decreases were
observed in prey populations following insecticide application. By comparing gut
contents of carabids, Chiverton (1984) stated that individual female Pterostichns
melanarius from insecticide treated plots had significantly fewer of their gut areas full of
solid arthropod food when compared to those firom untreated plots. Baars (1979a &
1979b) described two types of individual carabid movement — random walk and directed
movement. The latter was found more firequently in the hungry individuals within a
population. Mois (1972) also concluded that if no prey is encountered, carabid walking
tends to be in more or less random pattern, while firequently turning movements occurs
mostly often following feeding, the latter of which is similar to the pattern of other predators and parasites described by Mitchell (1963), and Hassell and May (1974).
Data fi’om the first 3 d of trapping period following the PE treatment exhibited a dispersal pattern that beetles moving out of treated plots. But most of the data of carabid catches firom the traps on the both sides of barrier after the 3 d after PE treatments did not show such a pattern. The dispersion of carabids could be determined by other environmental factors other than insecticide influence. The walking pattern and its velocity depends on external factors such as the surface structure, vegetation, temperature, and also on the motivation state of the carabids (Mois 1978). During the sampling period around the days of PE treatment, the com canopy cover was thin.
124 Carabids may have avoided the relative bare fields and been in search of better shelter.
The movement of carabids could direct to the grassy alley. However, the grassy alley may not represent the best site for the food resource of the predatory carabids, and those beetles may have wondered around the border of the plots. The consequent result of this activity is that the detection of the movement direction was masked by the back and forth walking behavior of carabids on the plot border. Although carabids walk in an almost continuously changing direction (Mois 1978), those walk around the barrier could be trapped in the traps on both sides of the barrier. When this happens, the difference of mean number per trap-day of carabids between the traps in two sides of barrier should also indicate the trend of movement directions.
Data demonstrated that the activities of S. substriatus was abundant in the early season but declined after 4 July, while the activities of H. pensylvanicus appeared after 7
July and continued to be the most abundant species in the late season. The shift of these two dominant species agrees with Best et al. (1981). Carabid assemblages are moderately species rich (Lovei and Sunderland 1996). Usually, about 10-40 species are active in a habitat in the same season (Thiele 1977). Two species dominated about 90% of pitfall trap catches, which is different fi-om the previous studies that 4 to 5 dominant species that consisted of about 80% of pitfall trap catches in the same field (Chen and Willson 1996).
The efficiency of the pitfall traps without preserving facility, such as adding diluted ethylene glycol, may have influenced carabid species sampling. However, it is not strange that carabid catch could be more than 10 per trap-day in one field, but less than
0.5 per trap-day in an adjacent field on the same trapping day (Chen unpublished data).
125 Higher carabid activity, of which dominated by H pensylvanicus, observed on the
plot border than that between treatment plots in the late season, although not significant,
indicated that H. pensylvanicus prefers field border and the dispersion of this species was
from plot border to the center of the field plots. This dispersal pattern was similar to that
described by Combos and Sotherton (1986). Harpalus pensylvanicus, the dominant
species in the late season, may have dispersed and evidently moved into the field plots
from the border during the early to mid-August in com field (Best et al. 1981)..
The high standard deviation is another factor that affected the detection of the
movement pattern of carabids. In this study, it was common that more than 10 specimens
of S. substriatus or more than 30 specimens of H. pensylvanicus could be caught in a
single trap in early or late season respectively, while very few individuals or none were
caught in other traps. Environmental conditions, such as soil type (Harris 1964a &
1964b), moisture and temperature (Mitchell 1963, Harris 1964b, Monke and Mayo 1990),
are important to the dose transfer of soil insecticides and their toxicities to insects, and
could be the critical factor (Mois, 1978) influencing the walking velocity of carabids.
Catches of pitfall traps are determined not only by the population, but also the locomotor
activity of carabids. Therefore, the environmental conditions could directly or indirectly
influence the pitfall trap catches. However, den Boer remarked (1979) "a pitfall estimates
the fluctuations in composition and of numbers of the interaction group of which it
automatically forms the center; therefore pitfalls in different localities of the same more or less continually inhabited area, together give a reliable picture of the heterogeneity in the relevant conditions".
126 Numerous data sets supported the hypothesis that carabids move in a direction facing the barrier will mostly be trapped in the trap in front of the barrier. Those data sets include the data of the carabid movement from treated to untreated plots before spraying application, and the data of the carabid movement from sprayed plots to other plots, the significant higher mortality rate of carabids caught in the way moving out of plots 3 days immediately following the PE treatment. This study demonstrated that the barrier-pitfail trap technique could detect the movement direction of carabids in 1 to 3 d immediately after insecticide treatments. Modification of the barrier-pitfail trap with more effective directional control may refine the detection of carabid movements.
Although soil insecticides used were very toxic to the dominant carabid species studied (Chen unpublished data), the mortality of carabids in the field condition may vary in response to insecticide application methods. The boom spraying delivery of insecticides evenly across the soil surface could cause high mortality physically if weather and soil conditions favor the walking activity of carabids. On the other hand, the rise of soil temperature and moisture could increase the mortality of carabids physiologically
(Critchley 1972). Granular insecticides applied at planting and placed in a relatively smaller area on the field surface may have a relative lower rate of contact to carabids.
Some granular insecticide treatments are designed to control the subterraneous pests, the toxic exposure of adult carabids, which are most active on the soil surface, may be less compared with the spray application. Given the high mortality of carabids from the sprayed plots, concern is expressed in regard to how carabids can survive the killing of insecticides and how S. substriatus could resume its population in the coming season.
127 Carabids dispersed from the plots treated with insecticides into the untreated plots
or grassy field boundary. This indicates that adjacent fields or habitats without
insecticide use could be the refuge of carabids in the com ecosystem with conventional
agriculture. It is rather evident that H. pensylvanicus have dispersed into field from the
borders. Although S. substriatus was found primarily in the cornfield and not fencerows
(Esau and Peters 1975), Best et al. (1981) stated that this species may occupy the field margins if conditions in the field become unfavorable. Therefore, the untreated adjacent fields or habitats may be important shelters for carabids at certain times during the year.
References
Baars, M. A. 1979a Catches in pitfall traps in relation to mean densities of carabid beetles. Oecologia (Berl.) 41:25-46.
1979b. Patterns of movement of radioactive carabid beetles. Oecologia (Bel.) 44: 125-140.
Best, R. L. and C. C. Beegle. 1977. Food preferences of five species of carabids commonly found in Iowa com fields. Environ. Entomol. 6: 9-12.
Best, R. L., C. C. Beegle, J. C. Owens, and M. Ortiz. 1981. Population density, dispersion, and dispersal estimates for Scarites substriatus, Pterostichus chalcites, and Harpalus pensylvanicus (Carabidae) in an Iowa cornfield. Environ. Entomol. 10: 847- 856.
Brust, G. B., B. R. Stinner, and D. A. McCartney. 1985. Tillage and soil insecticide effects on predator-black cutworm (Lepidoptera: Noctuidae) interactions in com agroecosystems. J. Econ. Entomol. 78: 1389-1392.
Chen, Z. Z. and H. R. Willson. 1996. Species composition and seasonal distribution of carabids (Coleoptera: Carabidae) in an Ohio soybean field. J. Kans. Entomol. Soc. 69: 310-316.
128 Coombes, D.S. and N. W. Sotherton. 1986. The dispersal and distribution of polyphagous predatory Coleoptera in cereals. Ann. Appl. Biol. 108:461-474.
Chiverton, P. A. 1984. Pitfall-trap of the carabid beetle Pterostichus melanarius, in relation to gut contents and prey densities, in insecticide treated and untreated spring barley. Entomol. Exp. Appl. 36: 23-30.
Critchley, B. R. 1972. Field investigations on the effects of an organophosphorus pesticide, thionazin, on predacious Carabidae (Col.). Bull. Ent Res. 62: 229-242.
Dempster, J. P. 1968. The sub-lethal effect of DDT on the rate of feeding by the ground beetle Harpalus rufipes. Ent Exp. Appl. 11: 51-54.
den Boer, P. J. 1977. Dispersal power and survival — Carabids in a cultivated countryside (with a mathematical appendix by J. Reddingius). Misc. Pap. Landbouwhogesch. Wageningen 14: 1-190.
1979. Populations of carabid beetles and individual behaviour, general aspects, pp.145-9. In P.J. den Boer, H-U Thiele, and F. Weber [Eds.], On the Evolution of Behaviour in Carabid Beetles. Misc. Pap. Agric. Univ. Wageningen.
Edward, C. A. and A. R. Thompson. 1975. Some efkcts of insecticides on predatory beetles. Ann. Appl. Biol. 80: 132-135.
Esau, R. L. and D. C. Peters. 1975. Carabidae collected in pitfall trap in Iowa cornfields, fencerows, and prairies. Environ. Entomol. 4: 509-513.
Gholson, L. E., C. C. Beegle, R. L. Best, and J. C. Owen. 1978. Effects of several commonly used insecticides on cornfield carabids in Iowa. J. Econ. Entomol. 71; 416- 418.
Harris, C.R. 1964a. Influence of soil type on the activity of insecticides in soil. J. Econ. Entomol. 59: 1221-25.
1964b. Influence of soil type and soil moisture on the toxicity of insecticides in soils to insects. Nature (London) 202: 724-7.
Hassell, M. P. and R. M. May. 1974. Aggregation of predators and insect parasites and its effect on stability. J. Anim. Ecol. 43: 567-594.
Heneghan, P. A. 1992. Assessing the effects on an insecticide on the activity of predatory ground beetles. Aspects of Applied Biology, 31:113-120.
129 Lovei, G. L. and K. D. Sunderland. 1996. Ecology and behavior of ground beetles (Coleoptera: Carabidae). Annu. Rev. Entomol. 41: 231-56.
Luff, M. L. 1986. Aggregation of some Carabidae in pitfall traps, pp. 385-397. In P. L. den Boer, M. L. Lufif, D. Mossakowski, and F. Weber [eds.], Carabid Beetles, Their Adaptions and Dynamics. XVII Intematonal Congress of Entomology, Hamburg, 1984.
Miller, T. A. and M.E. Adams. 1982. Mode of Action of Pyrethroids, pp 3-27. In J. R. Coats [ed.]. Insecticide Mode of Action. Academic Press. New York.
Mitchell, B. 1963. Ecology of two carabid beetles, Bembidion lampros (Herbst) and Trechus quadristriatns (Schrank). H. Studies on populations of adults in the field, with special reference to the technique of pitfall trapping. J. Anim. Ecol. 32: 377-92.
Mois, P. J. M. 1979. Motivation and walking behaviour of the carabid beetle Pterostichus coerulescens L. at different densities and distributions of the prey, pp 185- 98. /n P. J. den Boer, H-U Thiele, F. Weber [Eds.], On the Evolution of Behaviour in Carabid Beetles. Misc. Pap. Agric. Univ. Wageningen.
Monke, B. J. and Z. B. Mayo. 1990. Influence of edaphological factors on residual activity of selected insecticide in laboratory studies with emphasis on soil moisture and temperature. J. Econ. Entomol. 83: 226-233.
Powell, W., G. J. Dean, and R. Bardner. 1985. Effects of pirimicarb, dimethoate and benomul on natural enemies of cereal aphids in winter wheat. Ann. Appl. biol. 106:235- 42.
Reed. J.P., F.R. Hall, and H.R. Krueger. 1992. Contact and volatile toxicity of insecticides to black cutworm larvae (Lepidoptera: Noctuidae) and carabid beetles (Coleoptera: Carabidae) in soil. J. Econ. Entomol. 85:256-61.
Riddick, E. W. and N.J. Mills. 1995. Seasonal activity of carabids (Coleoptera: Carabidae) affected by microbial and oil insecticides in an apple orchard in California. Environ. Entomol. 24:361-366.
Thiele, H.U. 1977. Carabid beetles in their environments. Springer-Verlz^. New York. 369pp.
Tomlin, A. D. 1975. The toxicity of insecticides by contact and soil treatment to two species of ground beetles. (Coleoptera: Carabidae). Can. Entomol. 107: 529-32.
130 CHAPTERS
THE INTERACTION OF
CARABID ACTIVITIES, SOIL INSECT PESTS AND FIELD VEGETATION
UNDER THE INFLUENCE OF INSECTICIDE APPLICATIONS
Abstract Interactions of carabid activities, soil insect pests, com plant growth and the
insecticide applications were observed in a field plot study for insecticide efBcacy. Two
field trials were initiated in 1994 and 1995 separately with the same insecticide
treatments. The same field plots were planted with com the following growing season,
but were not treated with any insecticides. Dominant carabid species responded
differently to the insecticide applications and field habitats. Field plots with low com
stands developed high weed populations, which carried over to the following year.
Variations of carabid activities appeared to be related to the insecticide applications were observed, especially where the weed and com population differences resulted firom the insecticide treatments. Activities of Anisodactylus sanctaecrucis, Pterostichus chalcites, and Harpalus pensylvanicus significantly correlated with the weed cover. P. chalcites was the early season species and its population was suppressed by the application of insecticide, while H. pensylvanicus and A. sanctaecrucis responded to the weed
131 population that related to the insecticide control on BCW damage. The activities of P.
chalcites and Scarites substriatus, in the 2nd year significantly correlated with the root
ratings in the 1st year for both fields indicating either enhanced predation on preys or hyper activities of carabids stimulated by remaining treatment residues. Interactions found among carabid populations, soil insect pests and vegetation influenced by
insecticide applications are expressions of species behavior attributed to individual species within the carabid community. Carry-over effects of insecticide treatments on carabid activities into a second year may result from the direct effect of toxicity on population behavior and the indirect effect of the treatments on the field habitats.
5.1 Introduction
Western com rootworm (WCR), Diabrotica virgifera virgifera LeConte, northern com rootworm (NCR), D. longicornis (Say), and black cutworm (BCW),Agrotis ipsilon
(Hufiiagel) are major soil insect pests of Ohio com (Willson and Eisley 1992).
Insecticide applications effectively control these soil insect pests, but their undesirable side effects including the impact of nontargeted animals, the suppression of natural enemies, and the residue of pesticide in the ecosystems, have been reported (Edwards and
Thompson 1975, Brown et al. 1988). Carabids, an important predatory group of arthropods, have been examined as predators of BCW, other lepidopterans and coleopterans (Best and Beegle 1977, Brust et al. 1986). Unfortunately, these predators may be as susceptible to insecticide treatments as their prey, and there are few pesticides selective enough to kill a particular pest without affecting its predators (Edwards 1990).
132 Insecticides used to reduce damage by root feeding pests (e.g. rootworms and wireworms) can reduce soil predatory arthropod densities (Wright et al. I960, McPherson et al. 1981).
The effect of insecticides on soil dwelling arthropods, including predatory carabids, is related to field physical factors, such as soil type, soil moisture, soil temperature (Harris, 1972), and vegetation. Although the effect of insecticides on carabid population has been studied by many workers (Edwards and Thompson 1975, Hsin et al.
1979, Reed et al. 1992), few studies have focused on the effect of interactions of the component complex of the com agroecosystem with insecticide treatments. The objectives of this study are to determine the interactions among the field vegetation, soil insect pests, carabid activities imder the influence of soil insecticide applications in the com ecosystem.
5.2 Materials and Methods
Studies were carried out an the Westem Branch of The Ohio Agricultural
Research and Development Center, 1994-1996. Two sets of field plots of reduced tillage continuous corns were used. Three insecticides: tefluthrin (Force 1.5G, Zeneca), chlorpyrifos (Lorsban 150, DowElanco), permethrin (Pounce 3.2EC, PMC Corporation) and an untreated control were arranged into a randomized complete block design with four replications. The granular formulations were applied at planting (AP) as a band prior to closure by the press wheel using a 4 row John Deere planter equipped with Noble granular insecticide application equipments and calibrated to deliver the recommended rates (tefluthrin @0.146 kg/h, chlorpyrifos @ 1.463 kg/h) at 3 mph. The post-emergence
133 (PE) treatment of permethrin was applied with a boom sprayer equipped with flat spray
nozzles and calibrated to deliver the desired dosage (@ 0.11 kg/h) at 4.83 kmph. In 1994,
the study area was a field (field A) of 40 m x 200 m which was divided into 4 blocks. A
plot was 40 m in length and 16 rows width with row spacing of 0.76 m (30 in.). Com
(Zea mays L. variety Pioneer 3293) was planted on 18 May with the application of the
two granular insecticides. The permethrin PE treatment was applied on 2 June. In 1995,
field A was planted with com without insecticide treatments with minimum tillage. Field
B was a new field of 95 m x 100 m which was divided into four blocks of 42.6 m x 48.8.
Com {Zea mays L., variety Country Mark 693) was planted with 16 rows width in a row spacing of 0.76 m (30 in.) on 24 May. The permethrin PE treatment was applied on 9
June in field B. In 1996, field B was planted with com without insecticide treatment on 1
June.
Evaluation o f black cutworms Com stand counts used as an estimate of com plant density and plant injury were taken in each year as an index of BCW activity. The number of com plants and injured plants per 200 ft. of row were counted to determine the com plant density and plant injury caused by BCW. Stand counts were conducted three times on 2, 9, 16 June in 1994 in field A; 7, 14 June and 17 October in 1995 in field A and B; 16,28 June 1996 in field B. Only the stand coimts on 4-5 leaf stage were used in this study.
Evaluation o f Corn rootworm Soil core sampling technique was applied to estimate the immature population of CRWs. Four soil cores were sampled from each plot using a 10 cm golf cup cutter with the height set to 10 cm. Samplings were conducted on 6-7 June
134 1994,6-8 June 1995, and 3 July 1996. Soil cores were visually inspected in field by both separating the soil and by immersing soil in water. Number of larvae and pupae found were recorded for each soil core.
Adult activities of CRWs were sampled with yellow sticky traps. Traps were set up in the mid-rows on ear level about 10 ft. inside each plot from the plot border and allowed to remain in the field for 48 h with one week interval to determine the relative adult activity of com rootwonns. Numbers of WCR and NCR were counted and recorded. Trapping was initiated when the new adult WCRs were observed and continued until the beetle number on traps were significantly low, of which 26 July to 30 August in
1994; 27 July to 24 August 1995; 4 August - 6 September 1996.
Root rating waw conducted when newly emerged western com rootwonns were observed. Five plant roots were randomly selected in each plot, cleaned, and rated according to Iowa 1-6 scale root rating system (Hill and Peters 1971). Root ratings were conducted on 8 July 1994, 6 July 1995, and 6 August 1996.
Weeds coverage evaluation The ground surface covered by weeds was used as an index of weed population. The weed cover was evaluated by visually estimating the percentage of ground covered by weeds within a 1 frame which was set up with the pitfall trap station in the middle of the frame. Weed cover was evaluated at every pitfall station in late season in 1994 and twice (late-May and mid-September) during the growing seasons of 1995 in fields A and B, and of 1996 in field B.
Carabid sampling. Pitfall trapping was used to monitor activities of carabid populations.
Pitfall traps were set up by burying a plastic cup with a volume of 280 cm^ (top radius =
135 3.5 cm, depth =10 cm) in soil with the rim even with the soil surface. Diluted formulations of commercial antifreeze (ethylene glycol) in water were used in each trap to preserve the caught beetles and to prevent escape of trapped specimens from the container. Four pitfall traps were set in the middle of mid-two-row at about 10 m interval between every two traps within a plot. Sampling began in early May and ended up in mid
October with one week interval (about 22 to 24 samplings). The number of specimens per species were recorded for individual traps. For each trapping period, traps were allowed to remain in the field for 48 h. Carabid beetles collected were identified to species for each trap station.
Data analysis Data was transformed (/ogX+l) before analysis. ANOVA was use to analyze differences of total catch of carabids per trap, cumulative catch per trap for dominant species, which presented 85% of total carabids collected, plant injury, stand counts, root rating, larval/pupal population of CRWs and yields between treatments.
Relationships between carabid activities and the key variables were determined by correlation coefficient analysis for cumulative catches of dominant species of carabids.
Mean catches of the dominant species were based on the catches in 21 samples (mid-May to mid October) in each field and year.
5.3 Results and Discussion
5.3.1 Key Pest Variables
For field A in 1994, com stand counts in the AP treatments were significantly higher {P < 0.05) than that of the PE treatments and the untreated plots (Table 5.1). Root
136 Table 5.1 Comparison of key pest variables and carabid catches between treatments and between treated year and the untreated year, in field A, 1994-1995.
137 Treatments rD Key variables' tefluthrin chiorpyrifos peimethrin untreated @ planting @ planting rescue check
1224 Stand count/100 f t . 149.87a 134.12a 95.87b 84.38b 0.007
CRW larvae & pupae^ 2.50 2 . 0 0 2.06 1.43 0.560 Root rating^ 3.10b 3.15b 4.25a 4.85a 0.001 CRW on yellow traps'* 61.58a 65.30a 46.99b 36.15b 0.000 Weed cover (%f 55.94b 53.75b 61.56a 70.62a 0.001 Yield (bu/ac) 123.55a 120.61a 77.30b 49.84b 0.000
P. chalcites 4.50 b 4.00b 8.00a 9.00a 0.048 A. sanctaecrucis 2.50 2.88 3.88 4.64 0.201 S. substiatus 10.94 11.50 12.38 13.71 0.536 P. stygicus 12.44a 12.88a 7.75b 6.79b 0.050 H. pensylvanicns 37.81b 33.38b 51.69a 51.43a 0.042 Total Carabids 75.00 b 73.13ba 93.44a 92.07a 0.045
1995 /all plots untreated! Com stand count 118.50 117.88 117.88 117.00 1.000 CRW larvae & pupae* • 1.31 0.94 1.19 0.75 0.660 Root rating' 2.30 2.45 2.40 2.90 0.380 CRW on yellow traps* 24.28 28.25 22.30 28.50 0.640 Weed cover {%Y 58.44 58.94 62.50 69.56 0.850 Yield (bu/ac) 63.92ab 54.71b 71.18a 54.80b 0.040
P. chalcites 8.75 11.68 11.31 7.44 0.307 A. sanctaecrucis 2.25b 2.88b 5.88a 4.75ab 0.015 S. substiatus 10.94 10.88 11.81 9.25 0.599 P. stygicus 4.38 5.69 5.25 3.50 0.242 H pensylvanicus 49.00b 66.31a 53.81ab 60.38ab 0.014 Total Carabids 89.44b 119.06a 102.38ab 97.44ab 0.001
2 Mean number of CRW larvae and pupae per soil core of 10 cm golf cup cutter. 3 Iowa 1-6 scale root rating system were used. 4 Mean number of CRW adults caught on the yellow sticky traps. 5 Mean of weed cover (%) in 1 ground surface around the pitfall trap stations.
Table 5.1 138 Table 5.2 Comparison of the key pest variables and carabid catches between treatments and between treated year and the untreated year, in field B, 1995-1996.
139 Treatments Key variables' tefluthrin chiorpyrifos permethrin untreated P @ planting @ planting rescue check
m i Stand count/100 ft. 142.00a 131.75ab 115.12ab 126.12b 0.011 CRW larvae & pupae^ 0.50 0.44 0.56 0.63 0.860 Root rating' 2.15 2.05 0.07 2.25 0.449 CRW on yellow traps'* 28.83 35.52 38.98 38.40 0.550 Weed cover (%)* 9.37 11.87 14.38 13.44 0.788 Yield (bu/ac) 95.55 93.78 89.65 80.18 0.081
P. chalcites 17.37b 28.8 lab 35.12a 22.2 lab 0.010 A. sanctaecrucis 2.25b 2.88b 5.88a 5.07a 0.012 S. substiatus 6.44 7.06 7.13 8.07 0.612 P. stygicus 7.00a 3.88ab 4.00ab 1.93b 0.005 H. pensylvanicus 14.13 14.06 15.13 12.71 0.674 Total Carabids 51.50ab 58.19ab 67.13a 48.12b 0.046
1996/All Plots Untreated) Stand count/100 ft. 99.75 86.00 95.25 94.00 0.800 CRW larvae & pupae^ 0.50 0.65 0.55 0.65 0.960 Root rating' 2.10 2.05 0.12 2.15 0.090 CRW on yellow traps'* 9.21 8.43 11.93 8.86 0.400 Weed cover (%)^ 18.25 31.31 37.19 35.63 0.790 Yield (bu/ac) 64.57 59.58 62.43 52.98 0.740
P. chalcites 23.94 26.87 30.25 20.31 0.186 A. sanctaecrucis 11.00 10.87 9.50 8.81 0.437 S. substiatus 10.63 10.25 8.75 8.19 0.294 P. stygicus 0.13 0.19 0.44 0.19 0.294 H pensylvanicus 2.52 1.31 2.38 3.00 3.38 Total Carabids 45.78 48.44 53.50 40.12 0.215 1 Carabid catches are the mean catch per trap station. 2 Mean number of CRW larvae and pupae per soil core of 10 cm golf cup cutter. 3 Iowa 1 - 6 scale root rating system were used. 4 Mean number of CRW adults caught on the yellow sticky traps. 5 Mean of weed cover (%) in 1 m^ ground surface around the pitfall trap stations.
Table 5.2 140 rating in AP treatments were significantly lower than that in the PE treatment plots and the untreated control (P < 0.05, Table 5.1). The combination of stand loss and rootworm injury resulted in significant differences in yields between treatments (P < 0.05, Table
5.1).
For field A in 1995, no significant difference of com stand counts, root rating, larval/pupal populations and yellow trap catch of CRW, were found between the treatments (P > 0.05, Table 5.1). However, the yield in the plots with PE treatment of previous year exhibited significantly higher than that in the plots treated with chiorpyrifos and the untreated control of the previous year (Table 5.1). The cause of this difference is unknown.
Weed cover in plots of AP treatment were found to be significantly lower than that in the PE treatment and the untreated plots in field A in 1994 (Table 5.1). It is important to note that significant stand loss due to cutworm injury in 1994 resulting in differences in weed cover in 1994, carried over into 1995, although differences in weed cover were not statistically significant (Table 5.1).
For field B, com stands in the plots treated with tefluthrin was significantly higher than that of the untreated control in 1995, but no significant difference of root rating,
CRW larval/pupal population and yellow trap catch of CRWs, weed cover, and yield were found between treatments in both years (Table 5.2). Although the effect of cutworm injury and rootworm activities were low in 1995 and 1996, the relationship of stand counts and yields per treatment in 1995 were similar to that of field A.
141 5.3.2 Carabid Activities
For field A in 1994, cumulative catches of P. chalcites, H. pensylvanicus and total
catch in plots with PE treatment and the untreated plots were significantly higher than
that in the plots with AP treatments (P < 0.05). In contrast, cumulative catches ofP.
stygicus in the AP treatments were significantly higher than that of the untreated controls
and the PE treatment (Table 5.1). For field A in 1995, the cumulative catch of H.
pensylvanicus in plots treated with chiorpyrifos was significantly higher than that in plots
treated with tefluthrin, while the catch of A. sanctaecrucis in plots treated with
permethrin was significantly higher than that in plots with AP treatments (Table 5.1).
For field B in 1995, the cumulative catch of P. chalcites in plots treated with
permethrin was significantly higher than that in plots treated with tefluthrin, while the
cumulative catch of A. sanctaecrucis in plots with PE treatment and the untreated plots
were significantly higher than that in plots with AP treatments {P < 0.05; Table 5.2), and
the catch of P. stygicus in plots treated with tefluthrin was found significantly higher than that in the untreated control. For field B in 1996, no significant difference of carabid catches were found among treatments (JP > 0.05; Table 5.2).
It is should be pointed out that the changes of dominant carabid species between field habitats were common, and the activity of specific carabid species may vary firom one field habitat to another (Thiele 1977). For example, the mean catch (in two years) of
P. chalcites in field B was about 3 times higher than that in field A, while the H. pensylvanicus and P. stygicus in field A were more than 3 times higher than that in field
B (Table 5.3). The variation of carabid activities between fields may be due to the
142 Field A Field B Groups 1994 1995 P 1995 1996 P Key pest variables Stand coimts/100 ft. 116.10 117.8 0.860 128.75 93.5 0.00 CRW larvae & pupae' 2.00 1.05 0.010 0.53 0.60 0.620 Root rating^ 3.84 2.51 0.00 2.14 2.14 1.000 Plant injury^ 14.55 0.16 0.00 0.11 1.34 0.00 CRW on yellow trap^ 52.51 25.84 0.00 35.42 9.61 0.00 Weed cover(%)^ 60.47 62.36 0.640 12.27 30.59 0.004 Yield (bu/acr) 92.82 61.15 0.004 89.79 59.89 0.00 Carabids* P. chalcites 1.22 1.97 0.004 4.95 4.83 0.780 A. sancreat 1.20 1.82 0.037 0.69 0.48 0.028 S. substriatus 3.08 3.48 0.225 1.68 1.91 0.260 P. stygicus 1.73 0.84 0.003 0.74 0.06 0.00 H pensylvanicus 6.95 9.87 0.001 1.91 0.19 0.00 1 Mean number of CRW larvae and pupae per soil core of 10 cm golf cup cutter. 2 Iowa 1-6 scale root rating system were used. 3 Percentage of plant injured by cutworms. 4 Mean number of CRW adults caught on the yellow sticky traps. 5 Mean of weed cover (%) in 1 m^ ground surface around the pitfall trap stations. 6 Carabid catches — the mean catch per trap station.
Table 5.3 Comparison of mean values of key pest variables and carabid catches between the 1st and 2nd year in com field plots, 1994-1996.
143 heterogeneity of field habitats which are relevant to the species assemblage (Thiele 1977,
Luff 1986), or the weather conditions varied among years that may temporally influence the abundance of carabids (Thiele 1977).
Activities of dominant carabid species responded to the insecticide treatments differently. P. chalcites and H. pensylvanicus were most abundant in treatments where com stand coimts were low with high weed cover. Pterostichm chalcites is an early season species (Kirk 1975, Chen and Willson 1996), and the activity was significantly suppressed by the application of insecticides in field A in 1994 and field B in 1995. In contrast, H. pensylvanicus is a late season species preferring weedy habitats. This species appeared to be very active in the plots with poor com stands and high weed cover in the treatment year for both fields. Cumulative catch of H pensylvanicus was found significantly correlated with the weed cover in the 1st year for both fields (Table 5.4). H. pensylvanicus is a seed feeder, especially on foxtails (Kirk 1971&1973). The weed cover, which indirectly corresponded to the effectiveness of insecticide control on cutworm in the field influenced the activity of this herbivorous species. Pterostichus stygicus prefers open areas (Lindroth 1961-69). This species was most abimdant in the plots where com stands were high. Fields with good com stands had less weed cover, thus had relatively open field surface for the activity of P. stygicus. In the case of A. sanctaecrucis, the activity correlated with the weed cover (Table 5.4), but occurred in relatively low numbers during the early season. This species may have been adversely affected by the soil insecticide treatments, which controlled cutworms, caused less stand loss and subsequently less weed cover.
144 5.3.3 Carry-over Effects o f Insecticides on Carabids
Analysis of variance found that the mean catch of P. chalcites and H. pensylvanicus in the 1st year were significantly lower than that in the 2nd year, while the mean catch of P. stygicus in the 1st year was significantly higher than that in the 2nd year in field A(P< 0.05; Table 5.3). In field B, the mean catch of A. sanctaecrucis and S. substriatus in the 1st year were significantly higher than that in the 2nd year, while the mean catch of P. stygicus, H pensylvanicus and the total catch in the 1st year were significantly lower than that in the 2nd year (JP < 0.05; Table 5.3). Such differences in carabid activity may reflect the toxic effect of insecticide applications, or may be related to the response of individual carabid species to the changes in environmental conditions related to insecticide treatments.
The mean catches of P. chalcites and S. substriatus in the 2nd year were significantly correlated negatively with the root damage caused mainly by CRWs in the
1st year for both fields (Table 5.4). Both P. chalcites and S. substriatus are regarded potential predators of soil insect pests in com fields (Kirk 1975, Best et al. 1981). Best and Beegle (1977) demonstrated that large carabids are capable of consuming large numbers of lepidopterous pest larvae in a 24-hour period. By using lepidopterous larvae
(black cutworm, armyworms, stalk borers and European com borer) and carabid activities, Brust et al. (1986) found significant correlation of the larvae consumed and the predator activity (number attacks by predators in larvae), and number of larvae consumed and absolute density estimates of predators and predator activity. The relationship of P. chalcites and S. substriatus populations and the damage mainly caused by CRWs
145 Table 5.4 Significant relationships found among seasonal collection of dominant carabid species and the key pest variables of field A and B, Western Branch of OARDC, 1994-1996.
146 p. chalcites A. sanctaecrucis S. substriatus P. stygicus slope P slope r^ P slope r^ P slope r» P slope 7 p Carabid catch vs. kev pest variable - Field A. 1994 94 stand count -0.14 26.3 0.04 94 weed cover 0.63 31.5 0.02 4.47 58.5 0.00 94 root rating 5.90 22.7 0.06 28.61 19.8 0.08
Carabid catch vs kev pest variable - Field A. 1995 94 stand count -0.27 51.90 0.00 94 weed cover 94 root rating -8.22 31.20 0.04 8.33 23.5 0.06 -1.77 29.60 0.04 95 stand count 95 weed cover 0.11 62.10 0.00 95 root rating 0.18 22.60 0.06
Carabid catch vs. key pest variable - Field B. 1995 95 stand count -2.48 52.70 0.00 95 weed cover 0.96 54.70 0.00 0.76 67.60 0.00 95 root rating -151.26 21.70 0.07
Carabid catch vs. kev pest variable - Field B. 1996 95 stand count 0.76 23.00 0.06 95 weed cover 95 root rating -166.00 44.00 0.01 -40.20 31.50 0.02 96 stand count 96 weed cover 0.15 53.50 0.00 96 root rating
Fig. 5.4 indicates a potential predation. Chemical AP treatments effectively reduced rootworm
injury, but sufBcient chemical residue may have remained into the following season that
resulted in the sub-lethal exposure of prey the following season (Brown 1978). When this
happened, an increase of predator activity could be seen. Another possible explanation is
that the sub-lethal chemical may have caused hyper activity of carabids leading an
increase catch in pitfall traps (Miller and Adams 1982).
Mean catches of A. sanctaecrucis significantly correlated with the com plant density in the 1st year for both fields and the weed cover in the 2nd year in the field B.
The mean catch of P. stygicus significantly correlated with the com plant density for the
1st year in field B, while the mean catch of S. substriatus correlated with the weed cover in the 2nd year in field A. Therefore, it is very likely that the insecticide treatments may reduce population activities of some carabid species, and increase the activities of other carabid species as a result of direst toxic effect and the indirect effect caused by the insecticide treatment on the field habitat.
Carry-over effects of insecticide applications on carabid activity are due to both the direct toxic reduction of populations, and the indirect change in habitat conditions, such as weed cover, resulting from the insecticide treatments. In the case of changes in habitat conditions, patterns in carabid activities could be related to species specific behavior. Vegetation is an important field factor that influences carabid activities (Rivard
1966, Speight and Lawton 1976, Norris 1982). When stand loss is prevented by insecticide treatments, development of a good com density competes with the weed growth and thus, field plots having a high com plant density actually results an open area
148 on the field surface that is attractive for activities of some carabids, while the field plots
having a high weed cover inhibits activities of some carabid species and attracts more
herbivorous carabids. The activities of H pensylvanicus and A sanctaecrucis
significantly correlated with weed cover, indicating the species innate characteristics of
weed feeding which could be possible factors that cause aggregation of these species.
Other aspects of the influence of insecticide treatments on carabids may be related to the
predation capabilities of carabid species. For example, P. chalcites and S. substriatus are
a predatory species (Kirk 1975, Best etal. 1981) and have been reported to feed on other
insects (Best and beegle 1977), and abundance of P. chalcites was reported significantly
correlated with the population of BCW (Brust et al. 1986). The activity of these
predatory carabids may individually respond to insecticide applications which affected
prey populations.
Interactions found among carabid populations, soil insect pests and vegetation
influenced by insecticide applications are expressions of species behavior attributed to
individual species within carabid community. These interactions could be varied due to
changes of other factor, such as weather condition, other agricultural practices. Carry over effects of insecticide treatments on carabid activities into a second year may result firom direct effect of chemical toxicity on population behavior or the indirect effect of treatments on the field habitat resulting firom the prevention of stand loss due to cutworms.
149 References
Best, R. L. and C. C. Beegle. 1977. Food preferences of j5ve species of Carabid beetles commonly found in Iowa cornfields. Environ. Entomol. 6: 9-12.
Best, R. L., C. C. Beegle, J. C. Owens, and M. Ortiz. 1981. Population density, dispersion, and estimates for Scarites substriatus, Pterostichus chalcites, and Harpalus pensy/vonicitf (Carabidae) in an Iowa cornfield. Environ. Entomol. 10:847-856.
Brown, R. W. A. 1978. Ecology of Pesticides. Jone & Wiley, New York, 525pp.
Brown, R. A., J. A. White, and C. J. Everett. 1988. How does an autumn pyrethroid afiect the terrestrial arthropod community? pp. 137-146. In M. P. Greaves, B. D. Smith and P. W. Grieg-Smith [eds.]. Field methods for the study of environmental effects of pesticides. BCPC Monograph 40, BCPC Famham, Surrey.
Brust, G. E., B. R. Stinner, and D. A. McCartney. 1986. Predator activity and predation in com agroecosystems. Environ. Entomol. 15: 1017-21.
Chen, Z. Z. and H. R. Willson. 1996. Species composition and seasonal distribution of carabids (Coleoptera: Carabidae) in an Ohio soybean field. J. Kans. Entomol. Soc. 69: 310-316.
Edwards, C. A. and A. R. Thompson. 1975. Some effects of insecticides on predatory beetles. Ann. Appl. Biol. 80: 132-135.
Edwards, C. A. 1990. The importance of integration in lower input agricultural systems. Agriculture, Ecosystems and Environment 27: 25-35.
Harris, C. R. 1972. Factors influencing the effectiveness of soil insecticides. Ann. Rev. Entomol. 17: 177-98.
Hills, T. M. And D. C. Peters. 1971. A method of evaluating postplanting insecticide treatment for control of western com rootworm larvae. J. Econ. Entomol. 64: 764-765.
Hsin, C. Y., L. G. Sellers, and P. A. Dahm. 1979. Seasonal activity of Carabid beetles and the toxicity of carbofuran and terbufos to Pterostichus. Environ. Entomol. 8:154-159.
Kirk, V. M. 1971. Ground beetles in cropland in South Dakota. Ann. Entomol. Soc. Am. 64:238-241.
150 1973. Biology of a ground beetle, Harpalus pensylvanicus. Ann. Entomol. Soc. Am. 66: 513-517.
1975. Biology o f/’ferosftc/ius c/ia/cite5, a ground beetle of cropland. Ann. Entomol. Soc. Am. 68: 855-858.
Lindroth, C. H. 1961-199. The ground-beetles (Coleoptera: Carabidae) of Canada and Alaska, Pt 1-6. Opusc. Entomol. Suppl. 20,24,29,33,24,25, Lund. 1192pp.
Luff, M. L. 1986. Aggregation of some Carabidae in pitfall traps, pp. 385-397. 7nP. L. den Boer, M. L. Luff, D. Mossakowski, and F. Weber [eds.], Carabid beetles, their adaptions and dynamics. XVn International Congress of Entomology, Hamburg, 1984.
McPherson, R. M., J. C. Smith, and W. A. Allen. 1982. Incidence of arthropod predators in different soybean cropping systems. Environ. Entomol. 11:685-689.
Miller T. A. and M. E. Adams. 1982. Mode of action of pyrethroids, pp 3-27. Ini.K. Coats [ed]. Insecticide Mode of Action. Academic Press. New York.
Norris, R-F. 1982. Interactions between weeds and other pests in the agro-ecosystem, pp. 343-406. InJ. L. Hatfield and I. J. Thomason [eds.]. Biometeorology in Integrated Pest Management. Academic Press, New York.
Reed, J. P., F. R. Hall, and H. R. Krueger. 1992. Contact and volatile toxicity of insecticides to black cutworm larvae (Lepeoptera: Noctuidae) and carabid beetles (Coleoptera: Carabidae) in soil. J. Econ. Entomol. 85:256-261.
Rivard, I. 1966. Ground beetles (Coleoptera: Carabidae) in relation to agricultural crops. Can. Entomol. 98: 189-195.
Speight, M. and J. H. Lawton. 1976. The influence of weed cover on mortality imposed on artificial prey by predatory ground beetles in cereal fields. Oecologia, 23:211-223.
Thiele, H-U. 1977. Carabid beetles in their environments, a study on habitat selection. Spring-Verlag, Berlin, New York.
Willson, H. R. and J. B. Eisley. 1992. Effects of tillage and prior crop on the incidence of five key pests on Ohio com. J. Econ. Entomol. 85: 853-858.
Wright, D. W., T. D. Hughes, and J. Worral. 1960. The efiect of certain predators on the numbers of cabbage root fly {Erioischia brassica Bouche) and on the subsequent damage caused by the pest. Ann. Appl. Biol. 48: 756-763.
151 CHAPTER 6
TEMPORAL AND SPATIAL DISTRIBUTION OF CARABIDS
IN RESPONSE TO THE HETEROGENEITY OF FIELD HABITATS
IN CORN AGROECOSYSTEMS
Abstract A three-year study of carabid species dynamics in com fields was conducted at the Western Branch of Ohio Agricultural Research and Development Center, in South
Charleston, Clark county, Ohio. A total of 18,605 carabids representing 32 species were collected in pitfall trapping in a total of 11,392 trap-days from 1994 to 1996 in two field plots. Five species found dominating the carabid fauna are: Harpalus pensylvanicus Say
(38% of the total catch), Pterostichus chalcites Say (22.67%), Scarites substriatus
Haldeman (13.48%), P. stygicus (Say) (6.69%), and Anisodactylus sanctaecrucis F.
(4.39%). Data analysis by computing the Bray-Curtis index of percentage similarity,
Spearman’s coefficient of rank correlation, and index of dispersion, and with Principal
Component Analysis found carabid species composition and abundance varied between field plots and among years. Factors that affect the spatial distribution and species composition of carabids were likely related to primarily the heterogeneity of field habitats and secondly the variation of weather conditions between years. Seasonal abundance of
152 carabids exhibited the species characteristic. H. pensylvanicus and P. stygicus appeared to be the later season species while P. chalcites, S. substriatus, andA sanctaecrucis are the early season species. Typical seasonal abundance of these species suggests their role in the fluctuation of soil plant pests in the com field.
6.1 Introduction
Carabids are mainly generalist predators that dominate the epigaeic fauna in temperate agroecosystems and there is increasing interest in their importance as natural control agents (Luff 1986). Several workers have shown that polyphagous predators may have a role to play in reducing the numbers of soil insect pests in com fields (Edwards and Thompson 1975, Best and Beegle 1977, Chiverton 1984). Although carabids alone may not depress pest populations below economic thresholds (Floate et al. 1990), this group of insects is one of the important components of the predator complex known to prevent pest outbreaks in some systems (Winter 1990). The distribution of carabids in arable fields has been the subject of many investigations. Some studies have confirmed the existence of an important duality between the distribution of carabids in arable fields and the distribution in the surrounding habitats, such as field borders and grassy border strips (Best etal. 1981, Coombes and Sotherton 1986). The dual dependence includes seasonal migration between habitats, with hibernation of carabids in areas adjacent to the fields. Habitats closely adjacent to arable fields play an important role during the life cycle of many field-inhabiting carabids (Coombes and Sotherton 1986). This applies
153 especially to those carabid species that belong to the reproductive group of spring-
breeders, which hibernate in the adult stage.
Based on the adult reproduction activity, carabids are commonly divided into two
groups, spring-breeders and autunm-breeders (Thiele 1977). Spring-breeders hibernate as
adults only, whereas autumn-breeders mainly hibernate as larvae. Their period of
reproduction is often, but not always, simultaneous with respective peak of occurrence of
adult carabids within a certain habitat (Wallin 1985). From the pitfall trapping studies,
Thiele (1977) concluded that the seasonal activity period of spring-breeders is generally
characterized by one peak in the spring (May - June) and one in the autumn (August -
September), while autumn-breeders mainly exhibit a single peak in the middle of the
summer (July - August).
As a rule, carabids show non-random spatial distribution both within and between
habitats due to the environmental heterogeneity (Thiele 1977, Luff 1986). Dispersion
patterns of carabids are mostly aggregated. However, Best etal. (1981) commented that
aggregated dispersion pattern of carabids may be in response to the environment
conditions rather than true contagion between individuals, because that the aggregations
observed were never very dense, and they covered fairly large and relatively consistent areas of the grid.
This paper presents the differences of the spatial and temporal distribution of carabids observed in two com field plots in three years, and the variations of species composition of carabids in the two com fields.
154 6.2 Materials and Methods
This study was conducted at the Western Branch of OARDC firom 1994 to 1996.
The study sites were reduced tillage continuous com fields used to evaluate efficacy of soil insecticides on com soil insect pests. Two field plots were used in this study. Field plots A (hereafter field A) was initiated in 1994 with application of soil insecticides and was kept untreated in 1995. Field plots B (hereafter field B) was initiated with applications of soil insecticides in 1995 and was untreated in 1996. In 1994, field A, 40 m X 200 m in size, was divided into 4 blocks with a 1.5 m alley between every two blocks. A block (40 m x 48.8 m) was then divided into 4 plots enabled planting of 4 x 16 rows of 0.76 m (30 in.) in width. Com (Zeat mays L. variety Pioneer 3293) were planted on 18 May with the application of tefluthrin (Force 1.5G, Zeneca) and chiorpyrifos
(Lorsban 15G, DowElanco). Permethrin (Pounce 3.2EC, FMC) was applied on 2 June when com was in the growth stage of 2-3 leaves. In 1995, field B was a field of 95 m x
100 m, which was cross a drive way next to the field used in 1994, was divided into four blocks of 42.6 m x 48.8 m. Com {Zea mays L., variety Country Mark 693) were planted with 16 rows of 0.76 m (30 in.) in width with the soil insecticides. Permethrin was sprayed on 9 June when com was in 2-3 leaves stage.
Pitfall trap technique was used to sample carabid beetles. Pitfall traps were set up by burying a plastic cup with a volume of 280 cm^ (top radius = 3.5 cm, bottom radius =
2.5 cm, depth = 10 cm) in soil with the rim even with soil surface. Diluted (about 1:1) formulations of commercial antifireeze (ethylene glycol) in water were used in each trap to preserve the caught beetles and to prevent escape of trapped specimens from the
155 container. Four pitfall traps were set up in the middle two rows of each plot at about 10
m interval between traps. Pitfall trapping was conducted at one week interval from early
May and to mid October (about 22 to 24 trappings). The number of species and
specimens were recorded for individual traps. For each trapping period, traps were
allowed to remain in the field for two days (48 h). Carabid beetles collected in the pitfall
traps were taken to lab and washed under tap water through a No. 18 standard sieve.
Specimens were kept in alcohol and reference specimens were pinned for taxonomic
referencing.
Data analysis
Indices of Shannon Weaver species diversity and species evenness were
calculated. Index of dispersion (Ludwig and Reynolds 1988) and Chi-square test was
used to determine the aggregation of carabids. Spearman’s coefiBcient of rank correlation, and Bray-Curtis’s index (1957) of percentage similarity were used to compare the difference of carabid species assemblage among the two fields in different years. The heterogeneity of field habitats for the two field plots in different years were further studied by ordination of the carabid species with trapping stations, using Principal
Component Analysis (PCA) with varimax rotation (Statistica 1995). The cumulative catches per trap station (rows) were ordinated with the individual carabid species
(column) for separation of the difference in field conditions between years. Only the species that had a total of more than 20 specimens were used in PCA. For the PCA and coefficient correlation analysis, data was transformed (/ogX+1) before analysis.
156 63 Results and Discussion
6.3.1 Carabid Abundance and Assemblage in Com Agroecosystems
A total of 18,605 carabid specimens representing 32 species were collected in a total of 11,392 trap-days during the three year study. The cumulative catches in field A was 11,996, which was about twice as much as that in field B (6,609) in two years respectively (Table 6.1). Harpalus pensylvanicus Say was the most dominant species in this study, representing 38% of the total catch, while Pterostichus chalcites Say (22.67%),
Scarites substriatus Haldeman (13.48%), P. stygicus (Say) (6.69%), mà Anisodactylus sanctaecrucis F. (4.39%) were the other dominant species that comprised > 85% of the total catch (Table 6.1). H. pensylvanicus was the most dominant species in field A, representing 54% of total catch in field A in 1994 and 1995 (Table 6.1), whereas P. chalcites was the most dominant species in field B, representing 49% of the total catches in field B in 1995 and 1996 (Table 6.1). Although H. pensylvanicus was the most dominant species in the field A in 1995 (56.05%), the activity of this species was very low comparing with other dominant species in field B in 1996 when it represented only
2.17% of the total catch (Table 6.2). The four dominant species were the same in field A in 1994 and 1995 and field B in 1995. However, in field B in 1996, H pensylvanicus and
P. stygicus were not included in the most abundant species that represented > 85% of the total catch (Table 6.2). Species diversity (H’) and evenness (J’) were similar for field A in 1994 and field B in 1995 and 1996 (Table 6.2). In contrast, H’ and J’ in field A in
1995 were 0.535 and 0.165 respectively, which were lower than that in the other fields in different years. Since the total species presented in each field in different years did not
157 Table 6.1 Total catch of carabids, species presented, their percentages in pitfall traps, and indices of species diversity and evenness in each field and year. Western Branch of OARDC, 1994-1996.
158 sp. Field A 1994 Field A 1995 Field B 1995 Field B 1996 Species et al.* code n % n % n % n %
Total catch 5446 6550 3611 2998 Species presented 23 25 22 27 H’ 1.588 0.535 1.705 1.606 J’ 0.507 0.165 0.552 0.482 Individual species
Harpalus pensylvanicus Say HP 2828 51.91 3672 56.05 679 18.81 65 2.17 Pterostichus chalcites Say PC 406 7.45 627 9.57 1643 45.51 1622 54.12 Scarites substriatus Haldeman SSH 766 14.06 686 10.47 461 12.77 643 21.45 Pterostichus stygicus (Say) PS 681 12.50 301 4.59 271 7.51 15 0.50 Anisodactylus sanctaecrucis F. AS 246 4.52 252 3.85 174 4.82 161 5.37 Abacidus atratus Newman AA 165 3.03 271 4.14 29 0.80 5 0.17 Amara familiaris Duitschmidt AF 31 0.57 218 3.33 41 1.14 155 5.17 Chtaenius tricolor Dejean CT 31 0.57 143 2.18 81 2.24 84 2.80 Harpalus herbivagus Say HH 68 1.25 94 1.43 19 0.53 13 0.43 Cyclotrachelus sodalis (LeConte) CS 33 0.61 96 1.47 38 1.05 4 0.13 Clivinia impressifrons Leconte Cl 15 0.28 36 0.55 21 0.58 98 3.27 Pterostichus lucublandus Say PL 65 1.19 48 0.73 45 125 2 0.07 Stenolophus common F. SC 50 0.92 10 0.15 22 0.61 27 0.90 Pterostichus femoralis Kirby PF 14 026 19 029 52 1.44 8 027 Stenolophus ochropezus (Say) SO 7 0.13 4 0.06 6 0.17 38 127 Harpalus qffinis Schrank HA 7 0.13 26 0.40 11 0.30 5 0.17 Scarites substerraneus F. SSF 18 0.33 7 0.11 10 0.28 2 0.07 Anisodactylus ovalaris Casey AO 5 0.09 17 0.26 2 0.06 2 0.07 Amara cupreolata Puteys AC 0 0.00 0 0.00 2 0.06 24 0.80 Harpalus caliginosus F. HC 3 0.06 15 023 2 0.06 0 0.03 Amara impucticollis (Say) 1 2 0 6 Agnonum octepuctatum (F.) 2 1 0 5 Clivinia bipustulata (F.) 0 0 0 7 Anisodactylus rusticus (Say) 1 2 0 2 Agnonum puctiforme (Say) 3 1 0 1 Acupalpus partiarius (Say) 0 1 0 0 HarpcUus affinis Schrank 0 1 0 0 Colliurs pensylvanicus (L.) 0 0 0 1 Hapalus julgens Csiki 0 0 1 0 Abaciduspennundus (Say) 0 0 0 1 Stenolophus conjunctus (Say) 0 0 1 0 Harpalus bicolor (F.) 0 0 0 1 * The airangement of the order was based on the total catch of three years in the two field plots.
Table 6.1 159 Table 6.2 Total catch of carabids, species presented, and their percentages in pitfall traps in each field. Western Branch of OARDC, 1994-1996
160 Sp. Field A Field B Total catches Species code n % n % n %
Hccrpalus pensylvanicus Say HP 6500 54.17 744 11.26 7244 38.20 Pterostichus chalcites Say PC 1033 8.61 3265 49.42 4298 22.67 Scarites substriatus Haldeman SSH 1452 12.10 1104 16.71 2556 13.48 Pterostichus stygicus (Say) PS 982 8.18 286 4.33 1268 6.69 Anisodactylus sanctaecrucis F. AS 498 4.15 335 5.07 833 4.39 Abacidus atratus Newman AA 436 3.63 34 0.51 470 2.48 Amara familiaris Duftschmidt AF 249 2.08 196 2.97 445 2.35 Chlaenius tricolor De jean CT 174 1.45 165 2.50 339 1.79 Harpalus herbivagus Say HH 162 1.35 32 0.48 194 1.02 Cyclotrachelus sodalis (LeConte) CS 129 1.08 42 0.64 171 0.90 Clivinia impressifrons LeConte Cl 51 0.43 119 1.80 170 0.90 Pterostichus lucublandus Say PL 113 0.94 47 0.71 160 0.84 Stenolophus common F. SC 60 0.50 49 0.74 109 0.57 Pterostichus femoralis Kirby PF 33 0.28 60 0.91 93 0.49 Stenolophus ochropezus (Say) SO 11 0.09 44 0.67 55 0.29 Harpalus affinis Schrank HA 33 0.28 16 0.24 49 0.26 Scarites substerraneus F. SSF 25 0.21 12 0.18 37 0.20 Anisodactylus ovalaris Casey AO 22 0.18 4 0.06 26 0.14 Amara cupreolata Puteys AC 0 26 0.39 26 0.14 Harpalus caliginosus F. HC 18 0.15 2 0.03 20 0.10 Amara impucticollis (Say) 3 6 9 Agnonum octepuctatum (F.) 3 5 8 Clivinia bipustulata (F.) 0 7 7 Anisodactylus rusticus (Say) 3 3 6 Agnonum puctiforme (Say) 4 1 5 Acupalpus partiarius (Say) 1 0 1 Harpalus affinis Schrank 1 0 1 Colliurs pensylvanicus (L.) 0 1 1 Hapalus fulgens Csiki 0 1 1 Abacidus permundus (Say) 0 1 1 Stenolophus conjunctus (Say) 0 1 1 Harpalus bicolor (F.) 0 1 1 Total catch 11996 6609 18605
Table 6.2
161 vary too much, the low H’ and J’ value in field A in 1995 indicate that the carabids
population (presenting in the pitfall traps) was dominated by very few species.
The number and species of carabids collected in pitfall traps varied between years
and were relatively constant with the fields (Table 6.3). The Bray-Curtis index of
percentage similarity between years were relatively high for both fields over the years, in
which 77.17% for the field A between 1994 and 1995 and 74.66% for the field B between
1995 and 1996. The Spearman’s coefficient of rank correlation for the two fields in
different years also indicated that carabid catches were significantly correlated {P <
0.0001) between years for each field (Table 6.3). Furthermore, a significant coefficient of
rank correlation was found between the two fields in 1995 ( R = 0.454, P < 0.0001),
indicating that the total carabid catches in both fields were correlated in 1995 (Table 6.3).
This may be due to the fact that carabid catches in both fields in 1995 were dominated by
a single species {H. pensylvanicus in field A and P. chalcites in field B). The result of
Spearman’s correlation analysis for individual dominant species in the two fields in
different years was presented in Table 6.4. Although no significant correlation
relationship (P < 0.05) between the two field in different years were found for most of
dominant species, a significant coefficient correlation was found on P. chalcites between
the two years in field A, between the two years in field B, between field A and field B in
1995, and between field A in 1995 and field B in 1996.
6.3.2 Spatial Distribution o f Carabids
Analysis of the Indices of Dispersion of the dominant carabid species found that the carabids collected in pitfall traps for the five dominant species and the total carabid
162 Field A B
Year 1994 1995 1995 1996
1994 77.172 47.978 36.190 1995 0.352* 41.153 34.071 1995 0.151 0.454* 74.656 B 1996 0.184 0.011 0.430* * P value < 0.0001.
Table 6.3 Percentage of Similarity {PS, upper right) and Spearman’s coeficient of rank correlation (R, lower left) of total carabid catches in the two field plots in three years.
163 Field A 1994 Field A 1995 Field B 1995 Field/year^ R f(n-2) P R /(n-2) P R f(n-2) P
P. chalcites Field A 1995 0.601 5.920 <0.0001 Field B 1995 0.112 0.887 0.278 0.367 0.310 0.003 Field B 1996 0.294 2.410 0.018 0.400 3.463 0.001 0.603 5.955 <0.0001
A. sanctaecrucis Field A 1995 0.305 2.526 0.014 Field B 1995 0.210 1.688 0.096 0.171 1.365 0.177 Field B 1996 0.282 2.311 0.024 0.297 2.446 0.017 0.339 3.427 <0.0001
S. substriatus Field A 1995 -0.089 -0.704 0.484 Field B 1995 -0.119-0.943 0.349 0.177 1.417 0.116 Field B 1996 0.229 1.850 0.069 -0.116 1.116 0.269 -0.114-0.901 0.371
P. stygicus Field A 1995 0.402 3.454 0.001 Field B 1995 0.503 4.583 <0.0001 0.198 1.593 0.116 Field B 1996 0.138 l.IOl 0.275 0.140 1.116 0.269 0.006 0.046 0.963
H. pensylvanicus Field A 1995 0.096 0.762 0.449 Field B 1995 0.152 1.215 0.229 0.026 0.203 0.840 Field B 1996 0.046 0.366 0.715 -0.037 -0.289 0.774 0.052 0.407 0.685
* n = 64.
Table 6.4 The value of Spearman’s coefBcient of rank correlation (R) of the cumulative catches of dominant carabid species among the two field plots in different years
164 catches were significantly higher from 1.0, which indicates that these dominant species
exhibited significantly aggregated pattern in every year and each field (Table 6.5). The
difference of the measured variables between field A and B and among the years may
reflect possible factors that cause the e^gregation (Table 6.6). Vegetation is an important
factor that causes the aggregation of carabids (Luff 1986). Variation of vegetation in a
field may relate to the difference of soil type, soil moisture, organic matter contents, and
this will in turn influence the soil biota and the growth and development of com and
weeds; to a varying degree, the abundance and distribution of arthropods thus will be
impacted (Wilson 1994). As canopy is partially opened, weeds invade and shift the plant
community to a polyculture. The presence of weeds in crops affects both plant density
and spacing patterns which significantly influences insect populations (Mayse 1983).
Certain species, such as H. pensylvanicus and P. stygicus, were found to be weed feeders
(Best and Beegle 1977, Kirk 1973). Thus the abundance of weeds could alter the spatial distribution of these herbivorous carabids. However, further studies are needed to identify the cause of the aggregation.
The PGA analysis for the carabid activities in the two fields in three years found that
35% of the total variation among catches in plots was explained by factor 1 and 18% by factor 2. For the factor loadings of species (Fig. 6. la), H. pensylvanicus and P. stygicus had a high score for factor 1 and were caught mostly in field A. P. chalcites had the lowest score for the factor 1 and was collected steadily in the two fields and between years; and had modest score for factor 2 and was trapped relatively higher in 1996.
Chlaeniids tricolor Dejean exhibited the highest catch in field A in 1995 compared with
165 Field A Field B Species 1994 1995 1995 1996 ID ID ID ID //. pensylvanicus 9.31 586.36* 2.38 149.66* 3.58 225.88* 1.05 66.07* P. chalcites 4.49 282.58* 7.08 446.06* 5.06 318.96* 7.16 450.94* S. scarites 2.17 136.91* 2.48 156.32* 2.85 179.59* 2.36 148.67* P. stygicus 5.26 331.64* 2.59 162.95* 1.55 97.77* 1.96 123.72* A. sanctaecrucis 2.74 172.57* 5.18 326.43* 10.02 631.00* 7.04 443.29* Total catch 7.08 446.06* 4.41 277.79* 1.82 114.44* 1.08 67.92* C3so\ * indicates that the P < 0.0001 for value of the ID significantly higher than 1.0.
Table 6.5 The Indices of Dispersion (ID) of the dominant carabid species and the Chi-square test for significant departures of ID from 1.0 field B in both years and field A in 1994, and has the highest score of factor 2. Total
catch of Abacidus atratus Newman in field A for both years and in field B in 1995 were
high, but in field B in 1996 was very low; this species has high score of factor 2 and
relatively high score of factor 1. Amara familiaris Duftschmidt exhibited the highest
catch in 1995 for field A and in 1996 for field B, and has a high score of factor 2. In the
factor score plot (Fig. lb), the factor score basically separated the total carabid catch in
field B fi’om field A on the factor 1 axis, while the separation between years appears to be
in an diagonal pattern but not clearly separated.
A factor score for a site in a (species x sites) PCA ordination is the correlation
coefBcient between the species-abundance vector for that site and the species-abundance
vector for the factor (Holliday 1992). Traps with the similar variables could exhibit
similar species assemblage, and will appear relatively close together in a factor score plot.
If variations among carabid assemblages in the different fields exceed those among
assemblages within individual traps in a field, the grouping patterns for each field will be
become distinct in a factor score plots. In another word, the clear separation of the factor
score indicates the habitat heterogeneity between the fields. The separation between
years also applies to the variation of catch of carabids among years.
The factor loadings (Fig. 6.1a) basically exhibited relationship with pitfall trap
catch patterns, which suggests that factor 1 is associated with high catch of H. pensylvanicus in the field A. The factor score between fields in the PCA ordination
exhibited a clear separation between the total catches of the two fields and among years
167 0.8
CT 0.6 AF 0.4 CS HC :0 0.2 -^SSH. PS PC Oi PF HA ■Pt-
- 0.2
30 SSF -0.4 J-AS.
- 0.6 JSC.
-0.8 -0.8 - 0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 Factor 1
3.5
ZS
O: 1.5
0.5 o o**' o o I -0.5 ### -1.5 O FieM A. 1994 • FieM A. 1995 -2 5 A R(SM 8. 1995 A Reid 8.1996 -3.5 -2 5 -1.5 -0.5 0.5 1.5 2 5 3.5 Factor 1
Figure 6.1. Plot of Principal Component Analysis using Variraax normalized ordination, a. Factor loadings of species (plot of factor 1 vs. factor 2); The letters beside the data points are the species code referred to Table 1 and 2; b. Factor scores of respondents (plot of factor 1 vs factor 2).
168 (Fig. 6.1b) indicating that carabid assemblage differed between field A and field B, and
the species assemblage varied between years. Pterostichus stygicus and H. pensylvanicus
has high score of the factor 1 indicating that the factor 1 was associated with the variation
of the field habitats. Moreover, P. chalcites had a lowest score of factor 1 in this
ordination, indicating that the number of catches were very sensitive to factor 1.
Although C. tricolor, A. atratus, exA A. familiaris exhibited high score for factor 2, and
their catches are different among years, these species presented only small portion of the
total catch and only exhibited slightly separation among years. However, the diagonal
separation pattern in the plot of factor scores for 1994 and 1995 in field A, and for 1995
and 1996 in field B was likely associated with factor 2, which indicates the variation of
the carabid species assemblages between years. The variation of carabid species
assemblages is more likely the result of the interaction of the fields and year variable.
The year variation may be due to the variation of weather conditions and consequently the change of field habitats. However, the difference between field habitats is more important than the change from year to year.
Based on the Table 6.2, the variations of the carabid species assemblages between the two fields among years may be due to the dominant species of H. pensylvanicus and
P. stygicus. The other dominant species, such as P. chalcites and 5. substriatus, were relatively consistent between the fields and among the years, which may indicate that these species are relatively tolerant to variation of field habitats or a higher recovery capability. Cumulative catch of P. stygicus was significantly reduced in the second year, which may indicate that this species was sensitive to the year variable. The total catch of
169 Amara familiaris showed an increase in the second year in both field sets, while the total
catches of A. atratus and C. tricolor exhibited an increase in the second year in field A
but appeared to be consistent in field B. Because the field A and B were treated with the
insecticides in the first year, the variation of carabid activities may be in response to the
carry-over effect of insecticide treatments on carabids.
6.3.3 Temporal distribution o f carabids
In field A, the highest total catch was in the late season, especially during early
September (Fig. 2&4), whereas in field B the total catches appeared to be the highest in
the early season during late May to mid June (Fig. 3&5). Pterostichus chalcites, A.
sanctaecrucis and S. substriatus were the spring breeders, of which the beetles were
abundant in the early season, while P. stygicus and H. pensylvanicus were the autumn
breeders, of which the adults were most abundant in the late season. In field A, the most dominant species was H. pensylvanicus, which exhibited the most abundant in the late season in field A in both years (Fig. 2&4). In field B, the most dominant species was P. chalcites, which was consistent to be the most abundant species in this field, especially in the early season (Fig. 3&5).
Harpalus pensylvanicus is among the most widely distributed carabid species in
North America. This species appeared to be the most abundant species in field A and only in the late season, while it comprised 11.26% of the total catch in field B in the two sampling years and was only 2.17% of the total catch in field B in 1996. In a previous study of an adjacent soybean field, this species comprised only 2.94% of the total catch
(Chen and Willson 1996). Com field is a preferred habitat for both adults and larvae of
170 Figure 6.2 Total catches of dominant carabid species and the total carabid catch in field plot A. Western Branch of OARDC, 1994.
171 2.5
A. sancteacmsis P. chalcites 1.5
0.5
0 TT T Q. 4
2.5 P. stygicus 3
1.5 2 io 1 S 0.5 ia o El. = H ea 0
16 Total catch H. pensylvanicus
Sampling Date
Figure 6.2 Figure 6.3 Total catches of dominant carabid species and the total carabid catch in field plot A. Western Branch of OARDC, 1995.
173 2.5 1.2
2 iA. sancteacrusis p. chalcites 0.8 1.5 0.6 1 III 0.4 0.5 0.2
0 ÏW- "I" ‘r 'I r -T' "P" T I T 1 'I* I— r 1.2
& substriatus P. stygicus Q. 2.5 0.8 0.6 I 1.5 I 0.4 C 13 0 5 0.2 s ° (0 10
H. pensyivanicus Total catcti
Sampling Date
Figure 6.3 Figure 6.4 Total catches of dominant carabid species and the total carabid catch in field plot B. Western Branch of OARDC, 1995.
175 10 0.6
8 0.5 I chalcites A. sancteacmsis P. 0.4 6 0.3 4 0.2
2 0.1 a ELep. 0 II' f T i‘ 'r I T I I I r 1.2 r2 14 P. stygicus Q. 12 0.8 © ^ J3 0.8 0.6 0 0.6 0.4 C 0.4 0.2 o\ 5 ®2 2 0 n O 5 14 12 Total catch H. pensylvanicus 10 I 8 6 4 I 2
0 r mT mT 'r 'r -r 'r r-' T ‘r l‘r i T lt ‘r a i ' li s ' ‘r ‘r M T ‘rn i m '
Sampling Date Figure 6.4 Figure 6.5 Total catches of dominant carabid species and the total carabid catch in field plot B. Western Branch of OARDC, 1996.
177 1.2
1 P. chatciies A. sancteacrusis 0.8 I I ... I 0.6 0.4 0.2
T ‘r n- n'-i 1 I r I I I I T I I I I I I I ' I I r Û. 3.5 0.07 2 0.06 S. substriatus P. sfy^g/cus I 2.5 0.05 0.04 0.03 a Pi 0.02 IC oo 2 0.5 0.01 x>s 0 T—I—I—T I I I I I I I I “ I” p I I r r-^ ^ 0.2 12 H. pensylvanicus 10 0.15 Total catch 8 0.1 6 4 0.05 2 0
Sampling Date
Figure 6.5 this species (Kirk 1973). H. pensylvanicus is a grass seed feeder and has been often found abundant in fields with high population of foxtail grass (Kirk 1973, Best and
Beegle 1977). The decrease in the activity of H. pensylvanicus in field B could be related to the change of vegetation, such as foxtail populations. The population of foxtail,
Setaria spp. was high in field A in both years which could attract more beetles, while the foxtails were rare in field B for both years. Although this species feeds on dead black cutworm (Best and Beegle 1977), the beetles were rarely observed to capture prey in fields (Kirk 1973). Harpalus pensylvanicus is basically an autumn breeder. The above ground activity increased greatly after late June or early July, which included the overwintering adults and the emerged adults fi:om overwintering larvae. Peak activity of this species was in early September. In 1994, few adults were caught in pitfall trap during
October trapping, while in 1995, the population continued to be abundant throughout the last trapping on 10 October.
Pterostichus chalcites was consistently abundant in the two fields throughout the study period. This species has been reported to be in many crop habitats of America
(Lindroth 1961-69). It may be more abundant in certain fields than other fields regardless the crop being grown (Kirk, 1975). During a previous study in an adjacent field grown with soybeans, this species was a dominant species, comprising of 19.14% of the total catch (Chen and Willson 1996). However, Esau and Peters (1975), Best et al. (1981) reported that P. chalcites preferred cornfield.
Pterostichus chalcites is a spring breeder, and overwinters as an adult (Kirk
1975). Overwintered adults were increasingly active in early May and peaked in late May
179 or early June. This species prefers low, poorly drained fields where soil is moist but not waterlogged (Kirks 1975). When the soil surface was dry and the relative humidity was low, the beetle remained beneath the surface rather than risk death from desiccation (Kirk
1973). Furthermore, this species was most numerous in fields where continuous com was grown.
The activity of S. substriatus was consistent in both fields during the study period.
This species preferred a habitat of high moisture, organic content, and less sandy soil
(Best et al. 1981). It avoided the portion of the field which is characterized by less clay soil, open ground cover, and low moisture (Chen and Willson 1996). In a previous study, this species was a dominant species in an adjacent soybean field (Chen and Willson
1996). However, Esau and Peters (1975) reported that this species has been reported to prefer com field habitats, whereas, Lesiewicz et al. (1983) commented that this species had irregular activity in different years.
S. substriatus is a spring breeder. Data from the pitfall trap showed two peaks of the above ground activity. The overwintered adults were increasingly active from early
May, reached the first peak in early to late June, and started to decline after early July until mid August when there was another period of increasing activity through
September. The abundance of the 2nd activity peak was relatively low comparing with the 1st peak.
The average catch of P. stygicus in both fields were similar, but abundance of this species was low in field B in 1996. This species was the most dominant species in a previous study in soybean field where it represented 31.76% of the total catch (Chen and
180 Willson 1996). F. stygicus has been reported as a forest species (Bousquet 1986); they
live beneath logs etc. in open woods in Indiana (Blatchley 1910) and in hardwood forests
or on a joining meadow with high vegetation in Northern America (Lindroth 1961-1969).
This species has been reported in com fields (Esau and Peters 1975, Purrington et al.
1989). The activity of P. stygicus exhibited two peaks. The overwintered adults become
active in the late May, reached the peak in early to mid June, and declined after early July
until the early August when there was another increasing period of activity through late
September. The 2nd activity is due to the emerge of the new adults from the
overwintered larvae. However, Bousquet (1986) noted that this species was an autumn
breeder.
The activity of A. sanctaecrucis was the least abundant species of the five
dominant species. The abundance of this species was consistent in the two fields among
the three years. In a previous study in a soybean field, this species was the least abundant
one of the five dominant species, which comprised of 5.64% of the total catch (Chen and
Willson 1996). The activity pattern of this species was similar to an investigation in
South Dakota (Kirk 1971). Kirk (1977) reported that this species was a spring breeder and the average developmental period is about 40 days at 20 - 30°C. This species is basically a spring breeder. The activity of this species were already high when the 1st pitfall traps were set up, indicating that the overwintered adults become active in the time earlier than early May. However, the activity reached the peak in late May, and declined after mid June.
181 High adult catches usually coincide with reproduction in carabids and the activity
cycles of carabids also follow fluctuations in their prey. The dominant species in this
study, such as P. chalcites, S. substriatus, coincided with the early com pests, such as
cutworms and com rootworms (Best and Beegles 1977). While H. pensylvanicus may
have relatively little potential as a natural enemy agent on insect pests, it could be an
effective natural enemy in the control of weed population. However, the aggregation of
carabids is likely to be in response to the environmental conditions. Soil characteristics such as temperature, pH, moisture, organic matter content are important factors that directly alter the abundance and distribution of carabids in the agroecosystem. The variation of field vegetation and microbial populations, that are influenced by agricultural practices, could also influence the distribution of carabids (Felsot 1987). Therefore, the variation of carabid distribution, carabid species assemblage that are in response to the environmental factors should be taken into consideration in implementation of biological control by using predatory carabids.
References
Best, R. L. and C. C. Beegle. 1977. Food preferences of five species of carabid beetles commonly found in Iowa cornfields. Environ. Entomol. 6: 9-12.
Best, R. L., C. C. Beegle, J. C. Owens, and M. Ortiz. 1981. Population density, dispersion, and dispersal estimates for Scarites substriatus, Pterostichus chalcites, and Harpalus pensylvanicus (Carabidae) in an Iowa cornfield. Environ. Entomol. 10: 847-856.
Blatchley, W. S. 1910. An illustrated descriptive catalogue of the Coleoptera beetles know to occur in Indiana. The Nature Publishing Co., Indianapolis.
182 Bousquet, Y. 1986. Observation on the life cycle of some species of Pterostichus (Coleoptera: Carabidae) occurring in Northeastern America. Naturaliste Canada. 113: 295-307.
Bray, J. R. and J. T. Curtis . 1957. An ordination of the upland forest communities of southern Wisconsin. Ecological Monographs, 27:325-349.
Brust, G. E., B. R. Stinner, and D. A. McCartney. 1986. Predation by soil inhabiting arthropods in intercropped and monoculture agroecosystems. Agriculture, Ecosystems and Environment. 18: 145-154. Elsevier Science Publishers, B. V. Amsterdam.
Chen, Z. Z. and H. R. Willson. 1996. Species composition and seasonal distribution of carabids (Coleoptera: Carabidae) in an Ohio soybean field. J. Kans. Entomol. Soc. 69: 310-316.
Chiverton, P. A. 1984. Pitfall trap catches of the carabid beetle Pterostichus melanarius in relation to gut contents and associated organs in the locust. Entomologia Experimentalis et Applicata 36: 23-30.
Coombes, D. S. and N. W, Sotherton. 1986. The dispersal and distribution of polyphagous predatory Coleoptera in cereals. Ann. Appl. Biol. 108:461-474.
Edwards, C. A. and A. R. Thompson. 1975. Some effects of insecticides on predatory beetles. Annals of Applied Biology. 80: 132-135.
Esau, K. L. and D. C. Peters. 1975. Carabidae collected in pitfall trap in Iowa cornfields, fencerows, and prairies. Environ. Entomol. 4: 509-513.
Felsot, A. 1987. Fate and interactions of pesticides in conservation tillage systems. pp.35-43, In G. J. Stinner [ed.], Arthropods in Conservation Tillage Systems. College Park, MD: Misc. Pab. 65. Entomol. Soc. Am.
Felsot, A., L. K. Mitchell, and A. L. Kenimer. 1990. Assessment of management practices for reducing pesticide runoff from cropland in Illinois. J. Environ. Qual. 19: 539-95.
Holliday, N.J. 1992. The carabid fauna (Coleoptera: Carabidae) during postfire regeneration of boreal forest: properties and dynamics of species assemblages. Can. J. Zool. 70: 440-52.
Kirk, V. M. 1971. Ground beetles in cropland in South Dakota. Ann. Entomol. Soc. Am. 64: 238-241.
183 1973. Biology of a ground beetle, Harpalus pensylvanicus. Ann. Entomol. Soc. Am. 66: 513-517.
1975. Biology of c/ttz/c/rej, a groimd beetle of cropland. Ann. Entomol. Soc. Am. 68: 855-858.
1977. Notes on the biology o f Anisodactylus sanctaecrucis, a ground beetle of cropland. Ann. Entomol. Soc. Am. 70: 596-598
Lesiewicz, D. S., J. W. Van Duyn, and J. R. Bradley, Jr. 1983. Determination on cornfield carabid populations in Northeastern North Carolina. Environ. Entomol. 12: 1636-1640.
Lindroth, C. H. 1961-1969. The ground-beeties (Coleoptera: Carabidae) of Canada and Alaska, Pt 1-6. Opusc. Entomol. Suppl. 20. 24. 29.33. 34. 35, Lund, 1192pp.
Ludwig, J. A. and J. F. Reynolds. 1988. Statistical Ecology: a primer on methods and computing. Wiley-Interscience Publication, 337pp.
Luff, M. L. 1986. Aggregation of some Carabidae in pitfall traps, pp. 385-397. In?.L. den Boer, M. L. Luff, D. Mossakowski, and F. Weber [eds.], Carabid Beetles, Their Adaptions and Dynamics. XVIIIntematonal Congress of Entomology, Hamburg, 1984.
Mayse, M.A. 1983. Cultural control in crop fields: a habitat management technique. Environ. Entomol. 7:15-22.
Purrington, F. F., J. E. Bater, M. G. Paoletti, and B. R. Stinner. 1989. Ground beetles from remnant oak-maple-beech forest and its surroundings in northeastern Ohio (Coleoptera: Carabidae). The Great Lakes Entomologist. 22:105-110.
Statistica 1995. Statistica for Windows, Computer Program Manual. Tulsa. OK. StatSoft, Inc., 2325 East 13th St, Tulsa, OK 74104.
Thiele, H.U. 1977. Carabid Beetles in Their Environments, a study on habitat selection. Spring-Verlag, Berlin, New York.
Wallin, H. 1985. Spatial and temporal distribution of some abundant carabids beetles (Coleoptera: Carabidae) in cereal fields and adjacent habitats. Pedobiologia. 28: 19-34.
Wilson, L. T. 1994. Estimating abundance impact, and interactions among arthropods in cotton agroecosystems, pp.475-514. In L. P. Pedigo and G. D. Buntin [eds], Handbook of Sampling Methods for Arthropods in Agriculture.
184 Winter, L. 1990. Predation of the cereal aphid Sitobion aveme by polyphagous predators on the ground. Ecological Entomology 15: 105-110.
185 CHAPTER?
SUMMARY
Insecticide treatment strategies resulted in different com yields. When the activity
of black cutworm (BCW) is high enough to warrant rescue treatments, the rescue
treatments provided limited stand protection and marginal reduction of yield losses. On
the other hand, preventive treatments at planting achieved excellent protection for com
stands and yield. From this study, it is recommended that preventive treatments at
planting should be preferred when potential BCW outbreaks are predicted. Although the
preventive strategies seem to be the most consistent in preventing yield loss, IPM
principles, adopted by many com producers and agricultural consultants, suggest that
rescue treatments should be preferred over preventive treatments. Therefore, the
influence of both preventive and rescue treatments insecticides on predatory carabids was
deemed necessary for further study.
Numerous species of Carabidae have been considered as beneficial predatory
insects in the com fields. Five carabid species, Harpaliis pensylvanicus Say, Pterostichiis
chalcites Say, Scarites substriatus Haldeman, P. stygicus (Say), and Anisodactylus sanctaecrucis F. were found to be the dominant species, which comprised > 85% of the
186 total catch of 18,605 carabid beetles that representing 32 species collected in a total of
11,392 trap-days in three years of pitfall trapping in two com plots. Laboratory bioassay
using standard topical application and insecticide-soil medium exposure techniques
showed that tefluthrin, chlorpyrifos and permethrin were toxic to H. pensylvanicus, P.
chalcites and S. substriatus. In the microplot studies using enclosed technique, the
mortality of the introduced adult carabid, S. substriatus, was as high as 80%, and the total
number of soil inhabiting arthropods alive in the untreated controls were significantly
higher than that in the insecticide treated plots. Laboratory and microplot studies
demonstrated that insecticides commonly used in field com can greatly reduce the local
populations of nontarget insects. In the field plot studies, although the significant
differences of total carabid catches were found between the insecticide treatments and the
untreated controls, the differences were not considered absolutely due to the direct effect
of insecticide treatments, but partly due to the change of field habitats indirectly
influenced by different insecticide applications in the com agroecosystem. In addition,
significant differences of carabid catches between treatments for individual pitfall
trapping have been rarely observed during the two field plot studies, even in the first trapping immediately following the broadcasting rescue treatment. The aggregated distribution and active walking behavior of carabids are considered two important factors that masked the effect of the insecticide treatments.
Movement patterns of carabids in response to the insecticide applications in com plots were observed by a barrier-pitfall trap technique. Carabids in the plots with post emergence (PE) treatment tended to move out of the treated plots in the first 3 d
187 following the PE treatment. This response is believed to be motivated by contact with chemical residues causing hyperactivity. For the plots with PE treatments, the mortality of carabids caught on the way moving out was significantly higher than that moving into the treated plots. The mortality data suggest that insecticide treatments caused a great reduction in local carabid populations though large acre plots would probably be needed to confirm this result.
S. substriatus and H. pensylvanicus, which represented of more than 90% of the total catch, dominated the early and late season respectively in the barrier-pitfall trap study. S. substriatus suffered high mortality in the plots with PE treatments, while H. pensylvanicus exhibited a trend of dispersing from the grassy alley into the com plots.
These studies suggest that the effect of insecticide treatments on carabids in field plots is difficult to measure using pitfall trapping because of the hyperactivity of carabid caused by contact with the chemical residues. Additionally, this study demonstrated that the barrier-pitfall trap technique is an effective technique for detection of movement pattern of the active carabids after exposure to sublethal levels of insecticide residues.
The influence of insecticide treatments on the soil dwelling arthropods also appeared to be the result of the interactions of carabid population, soil insect pests, com plant and weed populations, and the insecticide application strategies. When the pest variables for the field plots in the treatment year and in the year without insecticide treatments were compared, interactions between the key pest variables, between soil insect pests and carabids were observed. Insecticides applied at planting effectively controlled BCW and CRW activities and protect com stands. CRW adults were found to
188 prefer well grown com field plots that have been effectively protected by soil insecticide
treatments. On the other hand, weed populations greatly increased in the untreated
controls with poor grown com and these weed populations were carried over into the
following growing season. This change of vegetation among the field plots appeared to
attract different carabid species. The field plots with good com stands and low weed
population actually formed relative open areas on the ground surface for the walking
activities of certain species of carabids (e.g., S. substriatus and P. chalcites), while the
weedy field plots became the favored habitats for some herbivorous species such as H pensylvanicus. This indirect carry-over effect of insecticide treatments on the field
habitats was carried over to the following growing season where the activities of carabids
appeared to response to the heterogeneity of field habitats. The correlation coefficient
analysis showed that the total carabid catch in the 1st year significantly correlated with the com population in the 1st year and the weed cover in the 2nd year. Relationships of carabid activities and other key pest variables indicate the direct and indirect effects of the insecticide treatments on the interactions of carabid species, soil insect pests, and field vegetation in com field.
Dominant carabid species responded differently to the application of insecticides and the field habitats. The activities of dominant species, P. chalcites and S. substriatus, in the 2nd year had a significantly negative correlation with the root rating in the 1st year for both fields. The possible explanation for this correlation may be that: 1) carabids may have had to search further for prey that were reduced by the insecticides; 2) carabids were excited by the chemical residues carried over fi-om the previous year's treatments.
189 Besides the influence of insecticides on soil dwelling arthropods, variations of
field habitats and weather conditions among years were considered important factors that
influence the population and activity of carabids. Data analysis of pitfall catches found
carabids were strongly aggregated and the carabid species composition and abundance
varied between field plots among years. The factors that affect the spatial distribution of
carabids species were likely related primarily to the heterogeneity of field habitats and
secondly to the year variable. The heterogeneity of field habitats may be related to prey
populations, soil type, soil moisture, as well as their surroundings that may have different
carabid activities. The year variable may be associated with the weather conditions that
varied between years.
Seasonal abundance of carabid adults exhibited the specific species
characteristics. H. pensylvanicus and P. stygicus appeared to be the later season species
while P. chalcites, S. substriatus, and A. sanctaecrucis were the early season species.
Though seasonal abundance of these species suggests their roles in influencing soil insect pests in com field, their activities varied greatly in response to the variation of environmental conditions.
In conclusion, insecticide treatment strategies are critical for soil insect pest control in field com. It was demonstrated that both preventive and rescue insecticide treatments caused high mortality on nontarget insects, especially predatory carabids.
Under field conditions, the response of the activities of nontarget insects to the insecticide treatments differed due to the seasonal behavior and specific habits of each individual species, the heterogeneity of field habitats, and weather conditions. Spatial distribution of
190 carabids responded to field habitats and were strongly aggregated. The early season
carabid species were likely motivated by insecticide residues causing hyperactivity and
subsequently died, while late seasonal species dispersed from the field borders into the
fields for favored habitats. The movement ability of carabids, whether in response to insecticide exposure or not, appeared to obfuscate the evaluation of the full impact of insecticide treatments on carabid populations. Much larger field plots and more replications are needed for a better evaluation of the effects. In addition, impact of insecticide treatments on the target and the nontarget insect populations is the result of direct toxic effects and the indirect effects from the changes of field habitats. These efîècts may be carried over into the following growing seasons.
191 BIBLIOGRAPHY
Althoff, G. -H., P. Hockmann, M. Klenner, F. -J. Nieheus, and F. Weber. 1994. Dependence of running activity and net reproduction in Cccrabus auronitens on temperature, pp. 95-100. In K. Desender, M. Dufrene, M. Loreau, M. L. Luff, and J-P. Maelfait [eds], Carabid Beetles: Ecology and Evolution. Kluwer Academic Publishers, Dordrecht.
Abbott, W. S. 1925. A method for computing the effectiveness of an insecticide. J. Econ. Entomol. 18: 265-267.
Ahmad, N., D. D. Waigenbach, and G. R. Sutter. 1979. Degradation rates of technical carbofhran and a granular formulation in four soils with known insecticide use history. Bull. Environ. Contam. Toxicol. 23: 572-74.
Alderweireldt, M. and K. Densender. 1990 Variation of carabid diel activity patterns in pastures and cultivated fields, pp 335-38. In N. E. Stork [ed]. The Role of Ground Beetles in Ecological and Environmental Studies. Intercept, Andover.
Altieri, M. A. 1994. Biodiversity and Pest Management in a Agroecosystems. Food Product Press. New York. 185pp.
Altieri, M. A. and D. K. Letoumeau. 1982. Vegetation management and biological control in agroecosystems. Crop Prot. 1:4 05-430.
Archer, T. L. and G. J. Musick. 1977. Gutting potential of the black cutworm on field com. J. Econ. Entomol. 70: 745-747.
Baars, M. A. 1979a. Catches in pitfall traps in relation to mean densities of carabid beetles. Oecologia (Berl.) 41:25-46.
1979b. Patterns of movement of radioactive carabid beetles. Oecologia (Bel.) 44:125-140.
192 Ball, G. E. 1960. Carabidae, pp. 55-127. In R. H. Amett, Jr. [éd.], The Beetles of the United states. The Catholic University of America Press, Washington, D. C.
Bell, R. T. 1970. Insecta: Coleoptera: Carabidae, adtilts and larvae, pp. 1053-1092. In D. L. Dindal [ed.]. Soil Biology Guide. John Wiley and Sons, New York.
Bergman, M. 1987. Com rootwonn control: do we have any new solutions? Proc. 111. Agric. Pestic. Conf. 87, pp. 41-49. Urbana-Champaign.
Best, R. L. and C. C. Beegle. 1977. Food preferences of five species of carabids commonly found in Iowa cornfields. Environ. Entomol. 6: 9-12
Best, R. L., C. C. Beegle, J. C. Owens, and M. Ortiz. 1981. Population density, dispersion, and dispersal estimates for Scarites substriatus, Pterostichus chalcites, and Harpaluspensylvanicus (Carabidae) in an Iowa cornfield. Environ. Entomol. 10: 847-856.
Blatchley, W. S. 1910. An illustrated descriptive catalogue of the Coleoptera beetles know to occur in Indiana. The Nature Publishing Co., Indianapolis.
Bledsoe, L. W., P. J. Boeve, and C. R. Edwards. 1997. History of com rootworm larval damage to com following soybean in Indiana. Submitted Papers at The North Central ESA Meeting, Columbus, U.S.A., March 23-25, 1997.
Boetel, M. A., D. D. Waigenbach, G. L. Hein, B. W. Fuller, and M. E. Gray. 1972. Oviposition site selection of the northern com rootworm (Coleoptera: Chrysmelidae). J. Econ. Entomol. 85: 246-49.
Booij, C. J. H. and L. J. F. M. den Hijs. 1992. Agroecological infirastructure and dynamics of carabid beetles. Proc. Sect. Exp. Appl. Entomol., Neth. Entomol. Soc. 3: 72-78.
Borror, D. J., C. A. Triplehom, and N. F. Johnson. 1989. An Introduction to the Study of Insects. 6th ed. Saunders College Publishing. 875pp.
Bousquet, Y. 1986. Observation on the life cycle of some species of f (Coleoptera: Carabidae) occurring in Northeastem America. Naturaliste Canada. 113: 295-307.
Bray, J. R. and J. T. Curtis. 1957. An ordination of the upland forest communities of southern Wisconsin. Ecological Monographs, 27: 325-349.
193 Briggs, J. B. 1961. A comparison of pitfall trapping and soil sampling in assessing population of two species of ground beetles (Col: Carabidae). E. Mailing Res. Sta. Annu. Rep. 1960: 108-112.
Brown, R. W. A. 1978. Ecology of Pesticide. Jone and Wiley, 525pp.
Brown, R. A., J. A. White, and C. J. Everett 1988. How does an autumn pyrethroid affect the terrestrial arthropod community? pp. 137-146. In M. P. Greaves, B. D. Smith, and P. W. Grieg-Smith [eds.]. Field methods for the study of environmental effects of pesticides. BCPC Monograph 40, BCPC Famham, Surrey.
Brust, G. B., B. R. Stinner, and D. A. McCartney. 1985. Tillage and soil insecticide effects on predator-black cutworm (Lepidoptera: Noctuidae) interactions in com agroecosystems. J. Econ. Entomol. 78: 1389-1392.
1986. Predation by soil inhabiting arthropods in intercropped and monoculture agroecosystems. Agriculture, Ecosystems and Environment. 18: 145-154. Elsevier Science Publishers, B. V. Amsterdam.
1986. Predator activity and predation in com agroecosystems. Environ. Entomol. 15: 1017-21.
Chapman, R. A. and C. R. Harris. 1980. Insecticidal activity and persistence of terbufos, terbufo sulfoxide and terbufos sulfone in soil. J. Econ. Entomol. 73: 536-543.
Chen, Z. Z.and H. R. Willson. 1996. Species composition and seasonal distribution of carabids (Coleoptera: Carabidae) in an Ohio soybean field. J. Kans. Entomol. Soc. 69: 310-316.
Chiang, H. C. 1973. Bionomics of the westem com rootworais. Annu. Rev. Entomol. 18: 47-73.
1978. Pest management in com. Ann. Rev. Entomol. 23: 101-23.
Chiang, H. C. and R. S. Raros. 1968. Effects on populations of com rootworms of aldrin residues in soil four years after application. J. Econ. Entomol. 61: 1204-8.
Chiverton, P. A. 1984. Pitfall trap catches of the carabid beetle Pterostichus melanarius in relation to gut contents and associated organs in the locust. Entomologia Experimentalis et Applicata 36:23-30.
194 Clement, S. L. and D. A. McCartney. 1982. Black cutworm (Lepidoptera: Noctuidae): measurement of larval feeding parameters on field com in the greenhouse. J. Econ. Entomol. 75: 1005-1008.
Coombes, D. S. and N. W. Sotherton. 1986. The dispersal and distribution of polyphagous predatory Coleoptera in cereals. Ann. Appl. Biol. 108:461-474.
Craighead, F. C. 1950. Insect enemies of eastern forests. USDA. Misc. Publ. 657, 679pp.
Critchely, B. R. 1972a. A laboratory study of the effects of some soil applied organophosphorus pesticide on Carabidae (Coleoptera). Bull. Ent Res. 62: 229-242.
1972b. Field investigations on the effects of an organophosphorus pesticide, thionazin, on predacious Carabidae (Col.). Bull. Ent Res. 62: 326-342.
De Ruiter, P. C., M. R. van Stralen, F. A. van Euwijik, W. Slob, J. J. M. Bedaux, and G. Emsting. 1989. Effects of hunger and prey traces on the search activity of the predatory hçQÛcNotiophilus biguttatus. Entomol. Exp. Appl. 51:87-95.
Dempster, J. P. 1968. The sub-lethal effect of DDT on the rate of feeding by the ground beetle Harpalus rufipes. Ent. Exp. Appl. 11: 51-54.
den Boer, P. J. 1969. On the significance of dispersal power for populations of carabid-beetles (Coleoptera, Carabidae). Oecologia (Berl.). 4: 29-73.
1977. Dispersal Power and Survival — Carabids in a cultivated countryside (with a mathematical appendix by J. Reddingius). Misc. Pap. Landbouwhogesch. Wageningen 14:1-190.
1979. Populations of carabid beetles and individual behaviour, pp 145-9. In P. J. den Den Boer, H-U Thiele, and F. Weber, [eds], On the Evolution of Behaviour in Carabid Beetles. Misc. Pap. Agric. Univ. Wageningen 18.
Desender, K. and J. Maelfait. 1986. Pitfall trapping within enclosures: a method for estimating the relationship between the abundances of coexisting carabid species (Coleoptera: Carabidae). Holarctic Ecology. 9: 245-250.
Edwards, C. A. 1990. The importance of integration in lower input agricultural systems. Agriculture, Ecosystems and Environment. 27: 25-35.
195 Edwards, C. A., A. R. Thompson, and J. R. Lofty. 1967. Changes in soil invertebrate populations caused by some OP insecticides. Proc. 4th. Br. Insectic. Fungic. Conf. 1 : 48-55.
Edwards, C. A. and A. R. Thompson. 1973. Pesticides and the soil fauna. Residue Reviews. 45: 1-79.
1975. Some effects of insecticides on predatory beetles. Ann. Appl. Biol. 80: 132-135.
Epstein, M. E. and H. M. Kulman. 1990. Habitat distribution and seasonal occurrence of carabid beetles in East-central Minnesota. Midi. Nat. 13:09-225.
Erwin, T. L. 1985. The taxon pulse: a general pattern of lineage radiation and extinction among carabid beetles, pp. 437-72. In G. E. Ball [ed.]. Taxonomy, Phylogeny and Zoogeography of Beetles and Ants. Dordrecht: Junk.
Esau, K. L. and D. C. Peters. 1975. Carabidae collected in pitfall trap in Iowa cornfields, fencerows, and prairies. Environ. Entomol. 4:509-513.
Everly, R.T. 1927. A check list of the Carabidae of Columbus, Ohio and vicinity. Ohio J. Sci. 27: 155-156.
Felsot, A. 1985. Factors affecting the bioactivity of soil insecticides. Proc. 37th 111. Custom Spray Oper. Train. Sch., pp. 134-38. Urbana-Champaign, IL: Univ. 111.
1987. Fate and interactions of pesticides in conservation tillage systems, pp.35- 43. 7n G. J. Stinner [ed.]. Arthropods in Conservation Tillage Systems. College Park, MD; Misc. Pab. 65. Entomol. Soc. Am.
1990. An assessment of insecticide rotations for long-term management of com rootworm feeding damage. Proc. 111. Agric. Pestic. Conf. 90, pp. 71- 80. Urbana- Champaign, IL: Univ. 111.
Felsot, A., L. K. Mitchell, and A. L. Kenimer. 1990. Assessment of management practices for reducing pesticide runoff from siopland in Illinois. J. Environ. Qual. 19: 539-95.
Felsot, A. S., J. G. Wilson, D. E. Kuhlman, and K. L. Steffey. 1982. Rapid dissipation of carbofiiran as a limiting factor in com rootworm (Coleoptera: Chrysomelidae) control in fields with histories of continuous carbofiiran use. J. Econ. Entomol. 75: 1098-103.
196 Floate, K. D., R. H. Elliott, J. F. Doane, and C. Gillott. 1989. Field bioassay to evaluate contact and residual toxicities of insecticides to carabid beetles (Coleoptera: Carabidae). J. Econ. Entomol. 82:1543-1547.
Forsythe, T. G. 1987. Common ground beetles. Naturalists'Handbook 8. Richmond Publishing. 74pp.
Frank,!. H. 1971. Carabidae (Coleoptera) as predator of the red-backed cutworm (Lepidoptera: Noctuidae) in central Alberta. Can. Ent. 103: 1039-1044.
Gholson, L. E., C. C. Beegle, R. L. Best, and J. C. Owen. 1978. Effects of several commonly used insecticides on cornfield carabids in Iowa. J. Econ. Entomol. 71: 416- 418.
Gist, C. S. and D. A. Crossley, Jr. 1973. A method for quantifying pitfall trapping. Environ. Entomol. 2: 951-952.
Goulet, H. 1974. Biology and relationships of Pterostichus adstrictus Eschscholtz and Pterostichus pensylvanicus LeConte (Coleoptera: Carabidae). Questiones Entomologicae 10: 3-33.
Greenslade, P. J. M. 1963b. Further notes on aggregation in Carabidae (Coleoptera) with especial reference to Nebria brevicollis (F.). Ent. Mon. Mag. 99: 109-114.
1963a. Daily rhythms of locomotor activity in some Carabidae (Coleoptera). Ent. Exp. Appl. 6:171-180.
1964. Pitfall trapping as a method for studying populations of Carabidae (Coleoptera). J. Anim. Ecol. 2: 301-310.
Hagley, E. A. C. D. J. Pree, and N. J. Holiday. 1980. Toxicity of insecticides to some orchard carabids (Coleoptera: Carabidae). Can. Ent. 112:457-462.
Halsall, N. B. and S. D. Wratten. 1988. The efficiency of pitfall trapping for polyphagous predatory Carabidae. Ecological Entomology 13:293-299.
Harris, C.R. 1964a. Influence of soil type on the activity of insecticides in soil. J. Econ. Entomol. 59:1221-25.
1964b. Influence of soil type and soil moisture on the toxicity of insecticides in soils to insects. Nature (London) 202: 724-7.
197 1972. Factors influencing the effectiveness of soil insecticides. Annu. Rev. Entomol. 17: 177-98.
Harris, C. R. and H. J. Sveg. 1968a. Toxicologicai studies on cutworms. I. Laboratory studies on the toxicity of insecticides to the dark-sided cutworm. J. Econ. Entomol. 61: 788-793.
1968b. Toxicologicai studies on cutworms. H. Field studies on the control of the dark-sided cutworm with soil insecticides. J. Econ. Entomol. 61:961-965.
Hassell, M. P. and R. M. May. 1974. Aggregation of predators and insect parasites and its effect on stability. J. Anim. Ecol. 43: 567-594.
Hendrix, W. H. and W. S. Showers. 1992. Tracing black cutworm and armyworm (Lepidoptera; Noctuidae) northward migration using Pithecellobium calliandra pollen. Environ. Entomol. 21: 1029-1096.
Heneghan, P. A. 1992. Assessing the effects on an insecticide on the activity of predatory ground beetles, pp. 113-120. Interpretation of Pesticide Effects on Beneficial Arthropods. Association of Applied Biologists.
Heme, D. H. 1963. Carabids collected in a DDT-sprayed peach orchard in Ontario. Can. Entomol. 95: 357-362.
House, G. J. and J. N. All. 1981. Carabid beetles in soybean agroecosystems. Environ. Entomol. 10: 194-196.
Hills, T. M. and D. C. Peters. 1971. A method of evaluating postplanting insecticide treatment for control of westem com rootworm larvae. J. Econ. Entomol. 64: 764-765.
Holliday, N. J. 1992. The carabid fauna (Coleoptera; Carabidae) during postfire regeneration of boreal forest; properties and dynamics of species assemblages. Can. J. Zool. 70:440-52.
Hsin, C-Y., L. G. Sellers, and P. A. Dahm. 1979. Carabids and the toxicity of carbofiiran and terbufos to Pferojftc/iwy c/ia/cires. Environ. Entomol. 8:154-159.
Humphrey, B. J. and P. A. Dahm. 1976. Chlorinated hydrocarbon insecticide residues in Carabidae and the toxicity of dieldrin to Pterostichus chalcites. Environ. Entomol. 5 : 729-734.
198 Jepson, P. C., S. J. DufBeld, J. R. M. Thacker, C. F. G. Thamas, and J. A. Eiles. 1990. Predicting the side-effect of pesticides on beneficial invertebrates. Brighton Crop Protection Conference - Pests and Diseases 1990, pp 957-962.
Jenson, S. G. 1985. Laboratory transmission of maize chlorotic mottle virus by three species of com rootworms. Plant Dis. 69: 864-68.
Johnson, T. B., F. T. Turpin, M. M. Schreiber, and D. R. GrifSth. 1984. Effects of crop rotation, tillage, and weed management systems on black cutworm (Lepidoptera: Noctuidae) infestations in com. J. Econ. Entomol. 77: 919-921.
Kirk, V. M. 1971. Ground beetles in cropland in South Dakota. Ann. Entomol. Soc. Am. 64:238-241.
1973. Biology of a ground beetle, Harpaltis pensylvanicus. Ann. Entomol. Soc. Am. 66:513-517.
1975. Biology of Pterostichus chalcites, a ground beetle of cropland. Ann. Entomol. Soc. Am. 68; 855-858.
1977. Notes on the biology o f Anisodactylus sanctaecrucis, a ground beetle of cropland. Ann. Entomol. Soc. Am. 70: 596-598
1982. Carabid beetles; minimal role in pest management of com rootworms. Environ. Entomol. 11:5-8.
Krysan, J. L., J. J. Jackson, and A. C. Lew. 1984. Field termination of egg diapause in Diabrotica with new evidence of extended diapause in Diabrotica (Coleoptera: Chrysomelidae). Environ. Entomol. 13: 1237-40.
Krysan, J. L. and T. A. Miller [eds.]. 1986. Methods for the Study of Pest Diabrotica. New York: Spninger-Verlag. 260pp.
Lesiewicz, D. S., J. W. Van Duyn, and J. R. Bradley, Jr. 1983. Determination on cornfield carabid populations in Northeastem North Carolina. Environ. Entomol. 12: 1636-1640.
Lester, D. G. and W. L. Morrill. 1989. Activity density of ground beetles (Coleoptera: Carabidae) in alfalfa and sainfoin. J. Agric. Entomol. 6: 71-76.
Levine, E., D. Kuhlman, K. Steffey, and H. Oloumi-Sadeghi. 1988. New developments regarding extended diapause in northem com rootworms: research and survey results. Proc. ni. Agric. Pestic. Conf. 88, pp. 145-53. Urbana-Champaign, IL: Univ. 111.
199 Levine, E. and H. Oloumi-Sadeghi. 1988. Larval dam%e to com following soybeans by the westem com rootworm, Diabrotica virgifera virgifera, in east central Illinois. Abstr. 43rd. Annu. Meet. North Cen. Branch Entomol. Soc. Am. Denver Colo. Abstr. 98.
1991. Management of Diabroticite rootworms. Annu. Rev. Entomol. 36: 229- 255.
Levine, E., S. L. Clement, W. L. Rubink, and D. A. McCartney. 1983. Regrowth of com seedlings after injury at different growth stages by black cutworm, Agrotis ipsilon (Lepidoptera: Noctuidae) larvae. J. Econ. Entomol. 76:389-391.
Lilly, J. H. 1956. Soil insects and their control. Annu. Rev. Entomol. 1:203-22.
Lindroth, C. H. 1961-1969. The ground-beetles (Coleoptera: Carabidae) of Canada and Alaska, Pt.1-6. Opusc. Entomol. Suppl. 20.24.29. 33. 34. 35, Lund. 1192pp.
Los, L. M. and W. A. Allen. 1983. Abundance and diversity of adult Carabidae in insecticide-treated and untreated alfalfa fields. Environ. Entomol. 12:1068-1072.
Lovei, G. L. and K. D. Sunderland. 1996. Ecology and behavior of ground beetles (Coleoptera: Carabidae). Annu. Rev. Entomol. 41: 231-56.
Ludwig, J. A. and J. F. Reynolds. 1988. Statistical Ecology: a primer on methods and computing. Wiley-lnterscience Publication, 337pp.
Luff, M. L. 1986. Aggregation of some Carabidae in pitfall traps, pp. 385-397. In P. L. den Boer, M. L. Luff, D. Mossakowski, and F. Weber [eds.], Carabid Beetles, Their Adaptions and Dynamics. XVn Intematonal Congress of Entomology, Hamburg, 1984.
Maclean, D. B. and J. D. Usis. 1992. Ground beetles (Coleoptera: Carabidae) of eastem Ohio forests threatened by the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae). Ohio J. Sci. 92:46-50.
Mayse, M. A. 1983. Cultural control in crop fields: a habitat management technique. Environ. Entomol. 7:15-22.
McPherson, R. M., J. C. Smith, and W. A. Allen. 1982. Incidence of arthropod predators in different soybean cropping systems. Environ. Entomol. 11: 685-689.
Metcalf, R.L. and W.H. Luckmaim 1982. Introduction to Pest Management. 2nd Edition, John Wiley and Sons, New York, 587pp.
200 Miller, T. A. and M. E. Adams. 1982. Mode of Action of Pyrethroids, pp 3-27. In J. R. Coats [éd.], Insecticide Mode of Action. Academic Press. New York.
Mitchell, B. 1963. Ecology of two carabid beetles, /amproj (Herbst) and Trechus quadristriatus (Schrank). H. Studies on populations of adults in the field, with special reference to the technique of pitfall trapping. J. Anim. Ecol. 32: 377-92.
Mois, P. J. M. 1979. Motivation and walking behaviour of the carabid beetle Pterostichus coerulescens L. at different densities and distributions of the prey, pp. 185- 98. In den Boer P. J., Thiele H-U. and Weber F. [Eds], On the Evolution of Behaviour in Carabid Beetles. Misc. Pap. Agric. Univ. Wageningen. 18.
Monke, B. J. and Z. B. Mayo. 1990. Influence of edaphological factors on residual activity of selected insecticide in laboratory studies with emphasis on soil moisture and temperature. J. Econ. Entomol. 83: 226-233.
Morril, W. L., D. G. Lester, and A. E. Wrona. 1990. Factors affecting efiBcacy of pitfall traps for beetles (Coleoptera: Carabidae and Tenebrionidae). J. Entomol. Sci. 25: 284- 293.
Mowat, D. J. and T. H. Coaker. 1967. The toxicity of some soil insecticides to carabid predators of the cabbage root fly. Ann. Appl. Biol. 59: 349-354.
Muma, M. H. 1975. Comparison of ground-surface species in four central Florida ecosystems. Flo. Entomol. 56: 173-196.
Norris, R. F. 1982. Interactions between weeds and other pests in the agro-ecosystem, pp. 343-405. In J. L. Hatfield and G. J. Thomason [eds.], Biometocology in Integrated Pest Management Academic Press, New York.
O'Neil, M., M. Gray, E. Levine, and K. Steffey. 1996. Westem com rootworm damage to first-year com in east-central Illinois. Poster Display at ESA meeting, Louisville, U.S.A., December, 1996.
Oloumi-Sadeghi, H., E. Levine, K. L. Steffey, and M. E. Gray. 1992. Black cutworm damage and recovery of com plants: influence of pyrethroid and organophosphate soil insecticide treatments. Crop Protection. Vol 11, August. 323-328.
Pakarine, E. 1994. The importance of mucus as a defence against carabid beetles by the slugs Arion fasciatus and Deroceras reticulatum. J. Mollusc. Stud. 60:149-55.
Pimentel, D. 1961. The influence of plant spatial patterns on insect population. Ann. Entomol. Soc. Am. 54: 61-69.
201 Powell, W., G. J. Dean, and R. Bardner. 1985. Effects of pirimicarb, dimethoate and benomul on natural enemies of cereal aphids in winter wheat. Ann. Appl. biol. 106: 235-42.
Price, J. F. and M. Shepard. 1978. Calosoma sayi: seasonal history and response to insecticides in soybeans. Environ. Entomol. 7:359-363.
Purrington, F. F., J. E. Bater, M. G. Paoletti, and B. R. Stinner. 1989. Ground beetles &om remnant oak-maple-beech forest and its surroundings in northeastem Ohio (Coleoptera: Carabidae). The Great Lakes Entomologist. 22: 105-110.
Reed, J. P., F. R. Hall, and H. R. Krueger. 1992. Contact and volatile toxicity of insecticides to black cutworm larvae (Lepeoptera: Noctuidae) and carabid beetles (Coleoptera: Carabidae) in soil. J. Econ. Entomol. 85: 256-261.
Riddick, E. W. and N.J. Mills. 1995. Seasonal activity of carabids (Coleoptera: Carabidae) affected by microbial and oil insecticides in an apple orchard in California. Environ. Entomol. 24: 361-366.
Riley, T. J. 1988. Plant stress from arthropods: insecticide and acaricide effects on insect, mite, and host plant biology, pp. 168-187. In E. A. Heinrichs [ed.], Plant Stress- insect Interactions. John Wiley and Sons. New York.
Rings, R. W., F. J. Arnold, A. J. Keaster, and G. J. Musick. 1976. A worldwide, annonated bibliography of the black cutworm. Ohio Agric. Res. Dev. Ctr. Res. Circ. 198. 106pp.
Rivard, I. 1964. Carabid beetles (Coleoptera: Carabidae) from agricultural lands near Belleville, Ontario, Can. Entomol. 96: 517-520.
1966. Ground beetles (Coleoptera; Carabidae) in relation to agricultural crops. Can. Entomol. 98:189-195.
Shepherd, M. and D. L. Dahlman. 1988. Plant-induced stress as factors in natural enemy efBcacy, pp 363-379. In E. A. Heinrichs [ed.]. Plant Stress-insect Interactions. John Wiley & Sons, New York.
Sherrod, D. W., J. T. Show, and W. H. Luckmann. 1979. Concepts of black cutworm field biology in Illinois. Environ. Entomol. 8: 191-195.
Showers, W. B., L. V. Raster, and P. G. Mulder. 1983. Com seedling growth stage and black cutworm (Lepidoptera: Noctuidae) damage. Environ. Entomol. 12: 241-244.
202 Showers, W. B., R. E. Sechriest, F. T. Turpin, Z. B. Mayo, and G. Szatmari-Goodinan. 1979. Stimulated black cutworm damage to seedling com. J. Econ. Entomol. 72: 432- 436.
Southwood, T. R. E. 1978. Ecological Methods with Particular Reference to the Study of Insect Populations, 2nd ed. Chapman and Hall. London.
Speight, M. and J. H. Lawton. 1976. The influence of weed cover on the mortality imposed on artificial prey by predatory ground beetles in cereal fields. Oecologia. 23: 211-223.
Spencer, J. L. and E, Levine. 1997. “It’s not easy being green”: Westem com rootworms in soybeans. Submitted Papers at North Central ESA Meeting, Columbus, U.S.A., March 23-25, 1997.
Spemkel, R. K., W. M. Brooks, J. W. Van Duyn, and L. L. Deitz. 1979. The effects of three cultural variables on the incidence of Nomuraearileyi, phytophagous Lepidoptera, and their predators on soybeans. Environ. Entomol. 8: 334-339.
Stark, J. D. and U. Wetmergren. 1995. Can population effects of pesticides be predicted from demographic toxicologicai studies? J. Econ. Entomol. 88: 1089-1096.
Statistica 1995. STATISTICA for Windows, Computer Program Manual. Tulsa. OK. StatSoft, Inc., 2325 East 13th St, Tulsa, OK 74104.
Story, R. N. and A. J. Keaster. 1982. Development and evaluation of a larval sampling technique foe the black cutworm (Lepidoptera: Noctuidae). J. Econ. Entomol. 75: 604- 610.
Story, R. N., A. J. Keaster, W. B. Showers, J. T. Shaw and B. L. Wright. 1983. Economic-Threshold dynamics of black and ciaybacked cutworms (Lepidoptera: Noctuidae) in field com. Environ. Entomol. 12: 1718-1732.
Sutter, G. and R. Gustin. 1989. Environmental factors influencing com rootworm biology and control. Proc. Ill Agric, Pestic. Conf. 89, pp. 43-48. Urbana-Champaign, IL: Univ. m.
Thiele, H-U. 1977. Carabid beetles in their environments, a study on habitat selection. Spring-Verlag, Berlin, New York.
Tomlin, A. D. 1975. The toxicity of insecticides by contact and soil treatment to two species of ground beetles (Coleoptera: Carabidae). Can. Ent. 107: 529-532.
203 Tonhasca, A. Jr. and B. R. Stinner. 1991. Effects of strip intercroping and no-tillage on some pests and beneficial invertebrates of com in Ohio. Environ. Entomol. 20: 1251-1258.
Trevors, J. T. 1986. A BASIC program for estimation LDjo values using the IBM-PC. Bull. Environ. Contam. Toxicity. 37:18-26
Troester, S. J. 1982. Damage and yield reduction in field com due to black cutworm (Lepidaptera: Noctuidae) feeding: Results of a computer simulation study. J. Econ. Entomol. 75:1125-1131.
Tumer, F. B. and C. S. Gist. 1965. Influences of a thermonuclear cratering device on close-in populations of lizards. Ecology. 46:645-652.
Tyler, B. M. J. and C. R. Ellis. 1979. Ground beetles in three tillage plots in Ontario and observations on their importance as predators of the northem com rootworm, Diabrotica longicomis (Coleoptera: Chrysomelidae). Proc. Entomol. Soc. Ont. 110: 65-73.
van Huizen, H. H. P. 1979. Individual and environmental factors determining flight in carabid beetles, pp 199-21. In P. J. den Boer, H-U Thiele, and P. Weber, [eds], 1979. On the evolution of behaviour in carabid beetles. Misc. Pap. Agric. Univ. Wageningen.
Wallin, H. 1985. Spatial and temporal distribution of some abundant carabids beetles (Coleoptera: Carabidae) in cereal fields and adjacent habitats. Pedobiologia. 28: 19-34.
Willim, H. and B. S. Ekbow. 1988. Movements of carabid beetles (Coleoptera: Carabidae) inhabiting cereal fields: a field tracing study. Oecologia 77: 34-43.
Willson, H. R. and B. Eisley. 1987. Insect pests of field crops. Ohio Cooperative Extension Service Bull. 545. 2Ip.
1992a. Effects of tillage and prior crop on the incidence of five key pests on Ohio com. J. Econ. Entomol. 85: 853-858.
1992b. Evaluation of soil insecticides on first year and continuous com in OH, 1991. Insecticide & Acaricide Tests. 17:219.
1993. Evaluation of soil insecticides on first year and continuous com in Ohio, 1992. Insecticide and Acaricide tests. 18: 213.
1994. Evaluation of soil insecticides in Ohio, 1993. Insecticide and Acaricide tests. 19:213-214.
204 1995. Evaluation of soil insecticides for stand protection of no-till first year com in Ohio, 1994. Insecticide and Acaricide tests. 20:184.
1996. Evaluation of soil insecticides on com in Ohio, 1995. Insecticide & Acaricide Tests. 21:233.
Wilson, L. T. 1994. Estimating abundance impact, and interactions among arthropods in cotton agroecosystems, pp.475-514. In L. P. Pedigo and G. D. Bimtin [eds], Handbook of Sampling Methods for Arthropods in Agriculture.
Winter, L. 1990. Predation of the cereal aphid Sitobion avenae by polyphagous predators on the ground. Ecological Entomology 15: 105-110.
Wratten, S. D. 1988. The role offieid boundaries as reservoirs of beneficial insects, pp. 144-50. In J. R. Pard [ed.]. Environmental Management in Agriculture: European Perspectives, EEC/Pinter Publishers Ltd. London.
Wright, D. W., R. D. Hughes, and J. Worrall. 1960. The effect of certain predators on the numbers of cabbage root fly (Erioischia brassica Bouche) and on the subsequent damage caused by the pest. Ann. Appl. Biol. 48: 756-763.
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