Search

Background: Selective tools, including selective insecticides and transgenic cotton, have been crucial in reducing insecticide usage within the integrated pest management (IPM) plan for Arizona cotton. To guide growers effectively, cotton field trials evaluated the effects of the novel insecticides, isocycloseram and afidopyropen against our primary pests, Bemisia argentifolii and Lygus hesperus, and their impacts on nontarget arthropods, including key predators: Collops spp., Orius tristicolor, Geocoris spp., Misumenops celer, Drapetis nr. divergens and Chrysoperla carnea s.l. Assessments involved over 27 arthropod taxa through community analyses, individual predator abundance, and biological control function via predator to prey ratios and a sentinel prey method. Comparisons were made with an untreated check, a proven fully selective insecticide (flonicamid) and acephate-treated positive controls., Results: Overall, relative to the untreated check, afidopyropen showed no significant differences, whereas isocycloseram exhibited some negative impacts, primarily reducing M. celer and Geocoris spp. nymphs, yet it was less detrimental compared with the positive control, acephate, and it did not affect four of the six key predators and most nontarget arthropods., Conclusion: Afidopyropen was classified as a fully selective insecticide and isocycloseram as a partially selective insecticide. Their fit for conservation biological control in Arizona cotton IPM and similar systems is discussed. © 2024 Society of Chemical Industry. Published by John Wiley & Sons Ltd., (© 2024 Society of Chemical Industry. Published by John Wiley & Sons Ltd.)

Plot size is of practical importance in any integrated pest management (IPM) study that has a field component. Such studies need to be conducted at a scale relevant to species dynamics because their abundance and distribution in plots might vary according to plot size. An adequate plot size is especially important for researchers, technology providers and regulatory agencies in understanding effects of various insect control technologies on non-target arthropods. Plots that are too small might fail to detect potential harmful effects of these technologies due to arthropod movement and redistribution among plots, or from untreated areas and outside sources. The Arizona cotton system is heavily dependent on technologies for arthropod control, thus we conducted a 2-year replicated field experiment to estimate the optimal plot size for non-target arthropod studies in our system. Experimental treatments consisted of three square plot sizes and three insecticides in a full factorial. We established three plot sizes that measured 144 m2, 324 m2 and 576 m2. For insecticide treatments, we established an untreated check, a positive control insecticide with known negative effects on the arthropod community and a selective insecticide. We investigated how plot size impacts the estimation of treatment effects relative to community structure (27 taxa), community diversity, individual abundance, effect sizes, biological control function of arthropod taxa with a wide range of mobility, including Collops spp., Orius tristicolor, Geocoris spp., Misumenops celer, Drapetis nr. divergens and Chrysoperla carnea s.l.. Square 144 m2 plots supported similar results for all parameters compared with larger plots, and are thus sufficiently large to measure insecticidal effects on non-target arthropods in cotton. Our results are applicable to cotton systems with related pests, predators or other fauna with similar dispersal characteristics. Moreover, these results also might be generalizable to other crop systems with similar fauna., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

Background: The population dynamics of polyphagous pests such as Bemisia argentifolii (B. tabaci MEAM1) are governed by complex, interacting factors involving its cultivated and wild host plants, seasonality, movement and demography. To understand mechanisms contributing to population development and pest success within the agroecosystem, contiguous multi-host field sites were established in three environmentally distinct areas in Arizona. Life tables quantified and partition models described mortality sources and rates for immature insect stages on each host plant., Results: Predation and dislodgement were the largest sources of marginal mortality, supplied the highest irreplaceable mortality and predation was the key factor. Rates of mortality were best predicted, in order, by source, temperature, host plant and season. Marginal mortality was highest for fourth-stage nymphs followed by eggs. Mortality rates were predicted in descending order by stage, temperature and season. Survivorship patterns varied among host plants, and generational mortality averaged 70% on spring cantaloupes but nearly 95% on all other hosts. Population density varied seasonally, persisting at low levels on winter hosts and expanding beginning in the spring; perennial hosts and weeds bridge populations year-round., Conclusion: Survival on winter hosts such as broccoli, albeit low, enables population continuity, whereas unusually high survivorship on spring crops like cantaloupe is an ecological release propelling population growth and driving regional dynamics in the summer and fall. This detailed understanding of mortality dynamics provides clues to the success of this invasive pest in our agroecosystems and facilitates opportunities for improved pest management at a broader landscape scale. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA., (© 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae) is a key insect pest in soybean fields in Brazil but data are lacking on the relationship between pest abundance and crop yield and quality. Controlled infestation studies were conducted on caged soybean plants in the field over a two year period at two sites in Brazil. Differences in temperature in the two years affected population growth of B. tabaci, reaching 413 nymphs per leaflet in the first year, and 179 the second year even when the average temperature was 3ºC higher. Higher temperatures promoted a shorter lifecycle and nearly one more generation. Yield was affected with losses up to 500 kg/ha in 2017/2018 and 1,147 kg/ha in 2018/2019. A decrease in the weight of a thousand grains of 18 and 33 g was observed in the first and second year, respectively. No significant differences were observed in grain germination, but estimated losses in protein content were up to 440 kg/ha at the highest infestation level. Pest density and yield data were used to estimate economic injury levels (EILs). EILs ranged from 2.5 to 25.67 nymphs per leaflet and 0.17-1.79 adults per leaflet over a range of control costs, soybean production values, and control efficacies. These results should provide data useful toward development of pest management decision making tools., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Hundreds of studies on environmental effects of genetically modified (GM) crops became available over the past 25 years. For maize producing insecticidal proteins from Bacillus thuringiensis (Bt), potential adverse effects on non-target organisms are a major area of concern and addressed in risk assessments. Reviews and meta-analyses have helped various stakeholders to address uncertainties regarding environmental impacts of the technology. Many field studies from Europe and other parts of the world have been published in the last decade, and those data are often not covered by previous meta-analyses. Therefore, we conducted a systematic review to answer the question: "Does the growing of Bt maize change abundance or ecological function of non-target animals compared to the growing of non-GM maize?", Methods: Literature published until August 2019 was searched systematically in 12 bibliographic databases, 17 specialized webpages, and reference sections of 78 review articles. Defined eligibility criteria were applied to screen titles, abstracts, and full texts of the retrieved references. A custom-made database was developed with quantitative data on invertebrate abundance, activity density, or predation/parasitism rates. Eligible data that did not fit the quantitative database were captured in detailed tables and summarized narratively. For the first time, a critical appraisal scheme for field studies on non-targets in GM crops was developed to estimate the risk of bias (internal validity) and the suitability to answer the review question (external validity) of all primary data. Meta-analyses on different taxonomic levels, functional groups, and types of Bt maize were conducted. Untreated Bt maize was either compared with untreated non-Bt maize, or with insecticide-treated non-Bt maize. The influence of contributions by private sector product developers on reported effects was investigated., Review Findings: The database on non-target effects of Bt maize field trials contains more than 7200 records from 233 experiments and 120 articles. Meta-analyses on different taxonomic levels revealed only few and often non-robust significant effect sizes when both Bt maize and non-Bt maize were untreated. Bt maize harboured fewer parasitoids (Braconidae, Tachinidae) of the European corn borer, the main target pest of Lepidoptera-active Bt maize, compared with non-Bt maize. Similarly, sap beetles (Nitidulidae), that are associated with Lepidoptera damage, were recorded less in Bt maize. In some analyses, a negative effect of Bt maize was observed for rove beetles (Staphylinidae) and hoverflies (Syrphidae) and a positive effect for ladybeetles (Coccinellidae), flower bugs (Anthocoridae), and lacewings (Neuroptera). However, those effects were not consistent for different analyses and often related to individual articles. When untreated Bt maize was compared with pyrethroid-treated non-Bt maize, more effect sizes were significant. In particular, populations of predators were reduced after pyrethroid treatment, while few data were available for other insecticides. Funnel plots showed no evidence for publication bias and the analyses of private sector contribution revealed no evidence for influence of vested interests. Conclusions about potential effects of Bt maize on vertebrates or on animals inhabiting off-crop habitats were not possible, because only few such studies fitting the format of direct Bt/non-Bt comparisons on plot or field level were identified., Conclusions: The current work largely confirmed previously published results. The effects of Bt maize on the community of non-target invertebrates inhabiting maize fields were small and mostly neutral, especially when compared with the effects of broad-spectrum pyrethroid insecticide treatments., (© 2022. The Author(s).)

Objectives: To assess potential non-target effects of genetically engineered/modified (GM) maize that produces insecticidal proteins from Bacillus thuringiensis (Bt), numerous field experiments have been conducted worldwide. Field data are often variable and influenced by uncontrolled factors and meta-analyses can recognize general effects with increased statistical power compared to individual studies. This database represents a comprehensive collection of experimental field data on non-target invertebrates in Bt and non-Bt maize. It was created for a systematic review with the question if growing Bt maize changes abundance or ecological function of non-target animals compared to growing of non-GM maize. Systematic literature searches identified relevant data. Authors were contacted for additional information or raw data if needed and a critical appraisal scheme was developed and applied to each data record., Data Description: The database contains 7279 records of non-target invertebrate abundance, activity density, or predation or parasitism extracted from 120 articles. Records for individual species and life stages, but also aggregated data are available. Each record represents a comparison of invertebrates in Bt and non-Bt maize and includes means, standard deviations and sample sizes. Additional variables characterize publication details, experimental setup, cultivars, Bt proteins, geographic location, field management, insecticide treatments, sampling details, and taxonomy., (© 2022. The Author(s).)

Bemisia tabaci (MEAM1) represents a species of economic importance in soybean. One of the obstacles to the management of B. tabaci is the quantification of damage by the pest because damage is indirectly inferred through losses in productivity. The objective of this study was to characterize the influence of B. tabaci feeding on soybean by assessing effects on photosynthetic parameters and the sugar and starch content of soybean leaves. The goal was to identify the optimal parameter to directly quantify pest damage on crop yield. Correlation networks were created among data on sugar content (fructose, glucose, and sucrose), starch and photosynthetic parameters (initial fluorescence, performance index on absorption basis, and turn-over number), and the number of nymphs at each of three infestations level (low, medium, and high) during both the vegetative and reproductive stage of the crop. In general, nymphs were more abundant during the vegetative stage. Starch content was strongly correlated with nymph density. A strong positive correlation was observed between fructose and nymph density during the vegetative stage. Among the photosynthetic parameters, the turn-over number N was positively correlated with nymph density at a low-infestation level and negatively correlated with nymphs when they occurred at a high-infestation level. B. tabaci feeding affected the plant's physiology and its interaction is reflected in part by the relationships among photosynthetic parameters as well as the levels of sugars and starch. This understanding might be useful in developing better monitoring tools for pest management.

Conservation biological control is a fundamental tactic in integrated pest management (IPM). Greater biological control services can be achieved by enhancing agroecosystems to be more favorable to the presence, survival, and growth of natural enemy populations. One approach that has been tested in numerous agricultural systems is the deployment of synthetic chemicals that mimic those produced by the plant when under attack by pests. These signals may attract arthropod natural enemies to crop habitats and thus potentially improve biological control activity locally. A 2-yr field study was conducted in the cotton agroecosystem to evaluate the potential of synthetic methyl salicylate (MeSA) to attract native arthropod natural enemies and to enhance biological control services on two key pests. Slow-release packets of MeSA were deployed in replicated cotton plots season long. The abundance of multiple taxa of natural enemies and two major pests were monitored weekly by several sampling methods. The deployment of MeSA failed to increase natural enemy abundance and pest densities did not decline. Predator to prey ratios, used as a proxy to estimate biological control function, also largely failed to increase with MeSA deployment. One exception was a season-long increase in the ratio of Orius tristicolor (White) (Hemiptera: Anthocoridae) to Bemisia argentifolii Bellows and Perring (= Bemisia tabaci MEAM1) (Hemiptera: Aleyrodidae) adults within the context of biological control informed action thresholds. Overall results suggest that MeSA would not likely enhance conservation biological control by the natural enemy community typical of U.S. western cotton production systems., (Published by Oxford University Press on behalf of Entomological Society of America 2021.)

Invasive organisms pose a global threat and are exceptionally difficult to eradicate after they become abundant in their new habitats. We report a successful multitactic strategy for combating the pink bollworm ( Pectinophora gossypiella ), one of the world's most invasive pests. A coordinated program in the southwestern United States and northern Mexico included releases of billions of sterile pink bollworm moths from airplanes and planting of cotton engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). An analysis of computer simulations and 21 y of field data from Arizona demonstrate that the transgenic Bt cotton and sterile insect releases interacted synergistically to reduce the pest's population size. In Arizona, the program started in 2006 and decreased the pest's estimated statewide population size from over 2 billion in 2005 to zero in 2013. Complementary regional efforts eradicated this pest throughout the cotton-growing areas of the continental United States and northern Mexico a century after it had invaded both countries. The removal of this pest saved farmers in the United States $192 million from 2014 to 2019. It also eliminated the environmental and safety hazards associated with insecticide sprays that had previously targeted the pink bollworm and facilitated an 82% reduction in insecticides used against all cotton pests in Arizona. The economic and social benefits achieved demonstrate the advantages of using agricultural biotechnology in concert with classical pest control tactics., Competing Interests: Competing interest statement: B.E.T. and J.A.F. are coauthors of patents on engineered Bacillus thuringiensis (Bt) toxins (US10704059) and potentiating Bt toxins (US20090175974A1), respectively. T.J.D. is retired and was previously employed by Monsanto, Bayer CropScience, and BASF.

The Green Revolution is credited with alleviating famine, mitigating poverty and driving aggregate economic growth since the 1960s. In Asia, high-input technology packages secured a tripling of rice output, with germplasm improvements providing benefits beyond US$4.3 billion yr -1 . Here, we unveil the magnitude and macro-economic relevance of parallel nature-based contributions to productivity growth in non-rice crops over the period 1918-2018 (across 23 different Asia-Pacific geopolitical entities). We empirically demonstrate how biological control resolved invasive pest threats in multiple agricultural commodities, ensuring annually accruing (on-farm) benefits of US$14.6-19.5 billion yr -1 . Scientifically guided biological control of 43 exotic invertebrate pests permitted 73-100% yield-loss recovery in critical food, feed and fibre crops including banana, breadfruit, cassava and coconut. Biological control thereby promoted rural growth and prosperity even in marginal, poorly endowed, non-rice environments. By placing agro-ecological innovations on equal footing with input-intensive measures, our work provides lessons for future efforts to mitigate invasive species, restore ecological resilience and sustainably raise output of global agrifood systems.

High-dose and refuge are the most important strategies for delaying resistance evolution in Bt crops. Insecticide sprays in refuge areas could be necessary and may limit refuge effectiveness. Here, we evaluated the sublethal effects of two diamide insecticides (chlorantraniliprole and flubendiamide) on Chloridea virescens life history traits and flight performance. Sublethal concentrations of chlorantraniliprole and flubendiamide increased larval and pre-pupal development times and decreased larval weight; flubendiamide increased pupal development times. Chlorantraniliprole increased adult male longevity and reduced female fertility, while flubendiamide reduced fecundity. Overall life table parameters were negatively impacted by both treatments. Males exposed to either insecticide showed significant reductions in flight duration and distance for unsustained flights (<30 min). The duration and distance of the first flights were reduced when exposed to chlorantraniliprole. Sustained flights (>30 min) were generally unaffected by insecticide exposure and both sexes flew >6400 m in a single flight. The sublethal effects of flubendiamide and chlorantraniliprole on C. virescens' population dynamics could lead to generation asynchrony and provide insufficient susceptible moths when sprayed on refuge crops. However, the distance and duration of flight may still be sufficient to ensure mixing of potentially resistant and susceptible populations from refuge plots., Competing Interests: The authors declare no conflict of interest.

Bt cotton was genetically modified to produce insecticidal proteins targeting Lepidopteran pests and is therefore only minimally affected by caterpillar damage. This could lead to reduced levels of inherent, systemically inducible defensive compounds in Bt cotton which might benefit other important cotton herbivores such as plant bugs. We studied the effects of plant defense induction on the performance of the plant bug Lygus hesperus by caging nymphs on different food sources (bolls/squares) of Bt and non-Bt cotton which were either undamaged, damaged by Bt tolerant caterpillars, or treated with jasmonic acid (JA). Terpenoid induction patterns of JA-treated and L. hesperus-damaged plants were characterized for different plant structures and artificial diet assays using purified terpenoids (gossypol/heliocide H1/4) were conducted. Nymphs were negatively affected if kept on plants damaged by caterpillars or sprayed with JA. Performance of nymphs was increased if they fed on squares and by the Bt-trait which had a positive effect on boll quality as food. In general, JA-sprayed plants (but not L. hesperus infested plants) showed increased levels of terpenoids in the plant structures analyzed, which was especially pronounced in Bt cotton. Nymphs were not negatively affected by terpenoids in artificial diet assays indicating that other inducible cotton responses are responsible for the found negative effects on L. hesperus. Overall, genetically engineered plant defenses can benefit plant bugs by releasing them from plant-mediated indirect competition with lepidopterans which might contribute to increasing numbers of hemipterans in Bt cotton.

Eggplant or brinjal (Solanum melongena) is a popular vegetable grown throughout Asia where it is attacked by brinjal fruit and shoot borer (BFSB) (Leucinodes orbonalis). Yield losses in Bangladesh have been reported up to 86% and farmers rely primarily on frequent insecticide applications to reduce injury. Bangladesh has developed and released four brinjal varieties producing Cry1Ac (Bt brinjal) and is the first country to do so. We report on the first replicated field trials comparing four Bt brinjal varieties to their non-Bt isolines, with and without standard insecticide spray regimes. Results of the two-year study (2016-17) indicated Bt varieties had increased fruit production and minimal BFSB fruit infestation compared with their respective non-Bt isolines. Fruit infestation for Bt varieties varied from 0-2.27% in 2016, 0% in 2017, and was not significantly affected by the spray regime in either year. In contrast, fruit infestation in non-Bt lines reached 36.70% in 2016 and 45.51% in 2017, even with weekly spraying. An economic analysis revealed that all Bt lines had higher gross returns than their non-Bt isolines. The non-sprayed non-Bt isolines resulted in negative returns in most cases. Maximum fruit yield was obtained from sprayed plots compared to non-sprayed plots, indicating that other insects such as whiteflies, thrips and mites can reduce plant vigor and subsequent fruit weight. Statistically similar densities of non-target arthropods, including beneficial arthropods, were generally observed in both Bt and non-Bt varieties. An additional trial that focused on a single Bt variety and its isoline provided similar results on infestation levels, with and without sprays, and similarly demonstrated higher gross returns and no significant effects on non-target arthropods. Together, these studies indicate that the four Bt brinjal lines are extremely effective at controlling BFSB in Bangladesh without affecting other arthropods, and provide greater economic returns than their non-Bt isolines., Competing Interests: The authors have declared that no competing interests exist.

Conservation biological control can be an effective tactic for minimizing insect-induced damage to agricultural production. In the Arizona cotton system, a suite of generalist arthropod predators provides critical regulation of Bemisia tabaci Gennadius (MEAM1) (Hemiptera: Aleyrodidae) and other pests. Arthropod predator and B. tabaci populations were manipulated with a range of broad-spectrum and selective insecticide exclusions to vary predator to prey interactions in a 2-yr field study. Predator to prey ratios associated with B. tabaci densities near the existing action threshold were estimated for six predator species found to be negatively associated with either adult and/or large nymphs of B. tabaci [Misumenops celer (Hentz) (Araneae: Thomisidae), Drapetis nr divergens (Diptera: Empididae), Geocoris pallens Stäl (Hemiptera: Geocoridae), Orius tristicolor (White) (Hemiptera: Anthocoridae), Chrysoperla carnea s.l. (Neuroptera: Chrysopidae), and Collops spp. (Coleoptera: Melyridae)] with the first three most consistently associated with declining B. tabaci densities. Ratios ranged from 1 M. celer per 100 sweeps to 1 B. tabaci adult per leaf to 44 D. nr. divergens per 100 sweeps to 1 large nymph per leaf disk. These ratios represent biological control informed thresholds that might serve as simple-to-use decision tool for reducing risk in the current B. tabaci integrated pest management strategy. The identification of key predators within the large, flexible food web of the cotton agro-ecosystem and estimation of predator to B. tabaci ratios clarifies the role of key predators in B. tabaci suppression, yielding potential decision-making advantages that could contribute to further improving economic and environmental sustainability of insect management in the cotton system.

Cabbage looper, Trichoplusia ni (Hübner) is an important lepidopteran pest on many vegetable and greenhouse crops, and some field crops. Although there are no commercial transgenic Bt vegetable or greenhouse crops, T. ni is a target of Bollgard II cotton, which produces Cry1Ac and Cry2Ab. We expand on previous work that examined the effect of Bt crops on parasitoids using Bt-resistant lepidopteran populations as hosts. Cry1Ac/Cry2Ab-resistant T. ni larvae were used to eliminate host quality effects and to evaluate the direct effects of Bt cotton on the parasitoids Copidosoma floridanum (Ashmead) and Cotesia marginiventris (Cresson). These tri-trophic studies confirm that Bt cotton had no significant impact on development, success of parasitism, survival and adult longevity of C. marginiventris when using Bt-resistant T. ni fed on Bt cotton. Similarly, this Bt cotton had no significant impact on the development, mummy weight and the number of progeny produced by C. floridanum. Our studies verified that lyophilized Bt crop tissue maintained its insecticidal bioactivity when incorporated into an artificial diet, demonstrating that hosts and parasitoids were exposed to active Cry proteins. The egg-larval parasitoid C. floridanum, or similar species that consume their entire host, should be considered useful surrogates in risk assessment of Bt crops to non-target arthropods.

Life tables provide a means of measuring the schedules of birth and death from populations over time. They also can be used to quantify the sources and rates of mortality in populations, which has a variety of applications in ecology, including agricultural ecosystems. Horizontal, or cohort-based, life tables provide for the most direct and accurate method of quantifying vital population rates because they follow a group of individuals in a population from birth to death. Here, protocols are presented for conducting and analyzing cohort-based life tables in the field that takes advantage of the sessile nature of the immature life stages of a global insect pest, Bemisia tabaci. Individual insects are located on the underside of cotton leaves and are marked by drawing a small circle around the insect with a non-toxic pen. This insect can then be observed repeatedly over time with the aid of hand lenses to measure development from one stage to the next and to identify stage-specific causes of death associated with natural and introduced mortality forces. Analyses explain how to correctly measure multiple mortality forces that act contemporaneously within each stage and how to use such data to provide meaningful population dynamic metrics. The method does not directly account for adult survival and reproduction, which limits inference to dynamics of immature stages. An example is presented that focused on measuring the impact of bottom-up (plant quality) and top-down (natural enemies) effects on the mortality dynamics of B. tabaci in the cotton system.

In its defense against herbivores, cotton ( Gossypium sp.) relies in part on the production of a set of inducible, non-volatile terpenoids. Under uniform damage levels, in planta allocation of induced cotton terpenoids has been found to be highest in youngest leaves, supporting assumptions of the optimal defense theory (ODT) which predicts that plants allocate defense compounds to tissues depending on their value and the likelihood of herbivore attack. However, our knowledge is limited on how varying, and thus more realistic, damage levels might affect cotton defense organization. We hypothesized that the allocation of terpenoids and densities of terpenoid-storing glands in leaves aligns with assumptions of the ODT, even when plants are subjected to temporally, spatially and quantitatively varying caterpillar ( Heliothis virescens ) damage. As expected, cotton plants allocated most of their defenses to their youngest leaves regardless of damage location. However, defense induction in older leaves varied with damage location. For at least 14 days after damage treatments ended, plants reallocated defense resources from previously young leaves to newly developed leaves. Furthermore, we observed a positive hyperbolic relationship between leaf damage area and both terpenoid concentrations and gland densities, indicating that cotton plants can fine-tune defense allocation. Although it appears that factors like vascular constraints and chemical properties of individual defense compounds can affect defense levels, our results overall demonstrate that induced defense organization of cotton subjected to varying damage treatments is in alignment with key assumptions of the ODT.

Crops producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuringiensis (Bt), are an important tool for managing lepidopteran pests on cotton and maize. However, the effects of these Bt crops on non-target organisms, especially natural enemies that provide biological control services, are required to be addressed in an environmental risk assessment. Amblyseius andersoni (Acari: Phytoseiidae) is a cosmopolitan predator of the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), a significant pest of cotton and maize. Tri-trophic studies were conducted to assess the potential effects of Cry1Ac/Cry2Ab cotton and Cry1F maize on life history parameters (survival rate, development time, fecundity and egg hatching rate) of A. andersoni. We confirmed that these Bt crops have no effects on the biology of T. urticae and, in turn, that there were no differences in any of the life history parameters of A. andersoni when it fed on T. urticae feeding on Cry1Ac/Cry2Ab or non-Bt cotton and Cry1F or non-Bt maize. Use of a susceptible insect assay demonstrated that T. urticae contained biologically active Cry proteins. Cry proteins concentrations declined greatly as they moved from plants to herbivores to predators and protein concentration did not appear to be related to mite density. Free-choice experiments revealed that A. andersoni had no preference for Cry1Ac/Cry2Ab cotton or Cry1F maize-reared T. urticae compared with those reared on non-Bt cotton or maize. Collectively these results provide strong evidence that these crops can complement other integrated pest management tactics including biological control.

Biological control is an underlying pillar of integrated pest management, yet little focus has been placed on assigning economic value to this key ecosystem service. Setting biological control on a firm economic foundation would help to broaden its utility and adoption for sustainable crop protection. Here we discuss approaches and methods available for valuation of biological control of arthropod pests by arthropod natural enemies and summarize economic evaluations in classical, augmentative, and conservation biological control. Emphasis is placed on valuation of conservation biological control, which has received little attention. We identify some of the challenges of and opportunities for applying economics to biological control to advance integrated pest management. Interaction among diverse scientists and stakeholders will be required to measure the direct and indirect costs and benefits of biological control that will allow farmers and others to internalize the benefits that incentivize and accelerate adoption for private and public good.

A concern with Bt-transgenic insect-resistant plants is their potential to harm non-target organisms. Early studies reported that Cry1Ab-producing Bt maize and purified Cry1Ab harmed larvae of the green lacewing, Chrysoperla carnea. Although these effects could not be confirmed in subsequent studies, some authors still refer to them as evidence that Bt maize harms beneficial species. We provide a comprehensive review of the studies evaluating the effects of Bt (Cry1Ab) maize on C. carnea. The evidence indicates that this important predator is not affected by Bt maize or by the produced Cry1Ab protein. We discuss how conceptual models can assist environmental risk assessments, and we emphasize the importance of robust and reproducible studies.

Laboratory studies were conducted to investigate tritrophic transfer of insecticidal Cry proteins from transgenic cotton to an herbivore and its predator, and to examine effects of these proteins on the predator's development, survival, and reproduction. Cry1Ac and Cry2Ab proteins from the bacterium Bacillus thuringiensis (Bt) produced in Bollgard-II (BG-II, Event 15985) cotton plants were acquired by Thrips tabaci Lindeman (Thysanoptera: Thripidae), an important sucking pest of cotton, and its generalist predator, Orius insidiosus (Say) (Hemiptera: Anthocoridae). The average protein titers in BG-II cotton leaves were 1,256 and 43,637 ng Cry1Ac and Cry2Ab per gram fresh leaf tissue, respectively. At the second trophic level, larvae of T. tabaci reared on BG-II cotton for 48-96 h had 22.1 and 2.1% of the Cry1Ac and Cry2Ab levels expressed in leaves, respectively. At the third trophic level, O. insidiosus that fed on T. tabaci larvae had 4.4 and 0.3% of the Cry1Ac and Cry2Ab protein levels, respectively, expressed in BG-II plants. O. insidiosus survivorship, time of nymphal development, adult weight, preoviposition and postoviposition periods, fecundity, and adult longevity were not adversely affected owing to consumption of T. tabaci larvae that had fed on BG-II cotton compared with non-Bt cotton. Our results indicate that O. insidiosus, a common predator of T. tabaci, is not harmed by BG-II cotton when exposed to Bt proteins through its prey. Thus, O. insidiosus can continue to provide important biological control services in the cotton ecosystem when BG-II cotton is used to control primary lepidopteran pests.

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is an important pest of maize in the United States and many tropical areas in the western hemisphere. In 2001, Herculex I(®) (Cry1F) maize was commercially planted in the United States to control Lepidoptera, including S. frugiperda. In 2006, a population of S. frugiperda was discovered in Puerto Rico that had evolved resistance to Cry1F maize in the field, making it the first well-documented case of an insect with field resistance to a plant producing protein from Bacillus thuringiensis (Bt). Using this resistant population, we conducted tri-trophic studies with a natural enemy of S. frugiperda. By using resistant S. frugiperda, we were able to overcome possible prey-mediated effects and avoid concerns about potential differences in laboratory- or field-derived Bt resistance. We used the Cry1F-resistant S. frugiperda to evaluate effects of Cry1F on Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae), a larval endoparasitoid of S. frugiperda, over five generations. Our results clearly demonstrate that Cry1F maize does not affect development, parasitism, survivorship, sex ratio, longevity or fecundity of C. marginiventris when they parasitize Cry1F maize-fed S. frugiperda. Furthermore, the level of Cry1F protein in the leaves was strongly diluted when transferred from Bt maize to S. frugiperda and was not detected in larvae, cocoons or adults of C. marginiventris. Our results refute previous reports of C. marginiventris being harmed by Bt proteins and suggest that such results were caused by prey-mediated effects due to using Bt-susceptible lepidopteran hosts.

Variation in plant quality and natural enemy abundance plays an important role in insect population dynamics. In manipulative field studies, we evaluated the impact of varying irrigation levels and insecticide type on densities of Lygus hesperus Knight and the arthropod predator community in cotton. Three watering levels were established via irrigations timed according to three levels of percent soil water depletion (SWD): 20, 40, or 60, where 40% SWD is considered standard grower practice, 60% represents a deficit condition likely to impose plant productivity losses, and 20% represents surplus conditions with likely consequences on excessive vegetative plant production. The two key L. hesperus insecticides used were the broad-spectrum insecticide acephate and the selective insecticide flonicamid, along with an untreated check. We hypothesized that densities of L. hesperus and its associated predators would be elevated at higher irrigation levels and that insecticides would differentially impact L. hesperus and predator dynamics depending on their selectivity. L. hesperus were more abundant at the higher irrigation level (20% SWD) but the predator densities were unaffected by irrigation levels. Both L. hesperus and its predators were affected by the selectivity of the insecticide with highest L. hesperus densities and lowest predator abundance where the broad spectrum insecticide (acephate) was used. There were no direct interactions between irrigation level and insecticides, indicating that insecticide effects on L. hesperus and its predators were not influenced by the irrigation levels used here. The implications of these findings on the overall ecology of insect-plant dynamics and yield in cotton are discussed.

Geocoris punctipes (Say) and Orius insidiosus (Say) are generalist predators found in a wide range of crops, including cotton (Gossypium hirsutum L.) and maize (Zea mays L.), where they provide important biological control services by feeding on an array of pests, including eggs and small larvae of caterpillars. A high percentage of cotton and maize in the United States and several other countries are transgenic cultivars that produce one or more of the insecticidal Cry proteins of Bacillus thuringiensis Berliner (Bt). Here we quantify effects of three Cry proteins on the life history of these predators over two generations when they are exposed to these Cry proteins indirectly through their prey. To eliminate the confounding prey quality effects that can be introduced by Bt-susceptible prey, we used Cry1Ac/Cry2Ab-resistant Trichoplusia ni (Hübner) and Cry1 F-resistant Spodoptera frugiperda (J.E. Smith) in a series of tri-trophic studies. Survival, development, adult mass, fecundity, and fertility were similar when predators consumed larvae feeding on Cry1Ac/Cry2Ab cotton or Cry1 F maize compared with prey feeding on isogenic or near-isogenic cotton or maize. Repeated exposure of the same initial cohort over a second generation also resulted in no differences in life-history traits when feeding on non-Bt- or Bt-fed prey. Enzyme-linked immunosorbent assay showed that predators were exposed to Bt Cry proteins from their prey and that these proteins became increasingly diluted as they moved up the food chain. Results show a clear lack of effect of three common and widespread Cry proteins on these two important predator species. The use of resistant insects to eliminate prey quality effects provides a robust and meaningful assessment of exposure and hazard.

The abundance and distribution of insect herbivores is determined by, among other things, plant quality and natural enemies. These two factors vary temporally and spatially, subsequently affecting seasonal population dynamics. The relative influence of plant quality and natural enemies on the seasonal dynamics of Bemisia tabaci (Gennadius) was investigated in a 3-yr field study in cotton. Plant quality was manipulated through varying irrigation regimes: irrigations done at 20, 40, and 60% soil water depletions; and natural enemy densities were manipulated using broad spectrum insecticide applications that reduced their densities compared with unsprayed controls. In each year, densities of B. tabaci eggs, large nymphs and adults were consistently higher when natural enemy densities were reduced compared with when they were left unaltered, regardless of irrigation regime. In contrast, effects of plant quality on densities of all whitefly stages were weak and inconsistent. In addition, natural enemy densities and predator:prey ratios also were not generally affected by plant quality. Interactions between natural enemies and plant quality on whitefly dynamics were rare. In general, whitefly densities were elevated two-thirds of the time and increased two- to sixfold when natural enemy densities were reduced compared with plant quality effects which influenced whitefly densities about one-third of the time and were expressed inconsistently over the years. This indicates that natural enemies exert a comparatively greater influence on seasonal dynamics of B. tabaci in cotton than plant quality, as manipulated by differential irrigation.

The biological control function provided by natural enemies is regarded as a protection goal that should not be harmed by the application of any new pest management tool. Plants producing Cry proteins from the bacterium, Bacillus thuringiensis (Bt), have become a major tactic for controlling pest Lepidoptera on cotton and maize and risk assessment studies are needed to ensure they do not harm important natural enemies. However, using Cry protein susceptible hosts as prey often compromises such studies. To avoid this problem we utilized pest Lepidoptera, cabbage looper (Trichoplusia ni) and fall armyworm (Spodoptera frugiperda), that were resistant to Cry1Ac produced in Bt broccoli (T. ni), Cry1Ac/Cry2Ab produced in Bt cotton (T. ni), and Cry1F produced in Bt maize (S. frugiperda). Larvae of these species were fed Bt plants or non-Bt plants and then exposed to predaceous larvae of the green lacewing Chrysoperla rufilabris. Fitness parameters (larval survival, development time, fecundity and egg hatch) of C. rufilabris were assessed over two generations. There were no differences in any of the fitness parameters regardless if C. rufilabris consumed prey (T. ni or S. frugiperda) that had consumed Bt or non-Bt plants. Additional studies confirmed that the prey contained bioactive Cry proteins when they were consumed by the predator. These studies confirm that Cry1Ac, Cry2Ab and Cry1F do not pose a hazard to the important predator C. rufilabris. This study also demonstrates the power of using resistant hosts when assessing the risk of genetically modified plants on non-target organisms.

Spodoptera frugiperda (JE Smith) represents the first documented case of field-evolved resistance to a genetically engineered crop expressing an insecticidal protein from Bacillus thuringiensis (Bt). In this case it was Cry1F-expressing maize (Mycogen 2A517). The ladybird beetle, Coleomegilla maculata, is a common and abundant predator that suppresses pest populations in maize and many other cropping systems. Its larvae and adults are polyphagous, feeding on aphids, thrips, lepidopteran eggs and larvae, as well as plant tissues. Thus, C. maculata may be exposed to Bt proteins expressed in genetically engineered crops by several pathways. Using Cry1F-resistant S. frugiperda larvae as prey, we evaluated the potential impact of Cry1F-expressing maize on several fitness parameters of C. maculata over two generations. Using Cry1F resistant prey removed any potential prey-mediated effects. Duration of larval and pupal stages, adult weight and female fecundity of C. maculata were not different when they were fed resistant S. frugiperda larvae reared on either Bt or control maize leaves during both generations. ELISA and insect-sensitive bioassays showed C. maculata were exposed to bioactive Cry1F protein. The insecticidal protein had no effect on C. maculata larvae, even though larvae contained 20-32 ng of Cry1F/g by fresh weight. Over all, our results demonstrated that the Cry1F protein did not affect important fitness parameters of one of S. frugiperda's major predators and that Cry1F protein did not accumulate but was strongly diluted when transferred during trophic interactions.

The refuge strategy is used worldwide to delay the evolution of pest resistance to insecticides that are either sprayed or produced by transgenic Bacillus thuringiensis (Bt) crops. This strategy is based on the idea that refuges of host plants where pests are not exposed to an insecticide promote survival of susceptible pests. Despite widespread adoption of this approach, large-scale tests of the refuge strategy have been problematic. Here we tested the refuge strategy with 8 y of data on refuges and resistance to the insecticide pyriproxyfen in 84 populations of the sweetpotato whitefly (Bemisia tabaci) from cotton fields in central Arizona. We found that spatial variation in resistance to pyriproxyfen within each year was not affected by refuges of melons or alfalfa near cotton fields. However, resistance was negatively associated with the area of cotton refuges and positively associated with the area of cotton treated with pyriproxyfen. A statistical model based on the first 4 y of data, incorporating the spatial distribution of cotton treated and not treated with pyriproxyfen, adequately predicted the spatial variation in resistance observed in the last 4 y of the study, confirming that cotton refuges delayed resistance and treated cotton fields accelerated resistance. By providing a systematic assessment of the effectiveness of refuges and the scale of their effects, the spatially explicit approach applied here could be useful for testing and improving the refuge strategy in other crop-pest systems.

Background: Many polyphagous pests sequentially use crops and uncultivated habitats in landscapes dominated by annual crops. As these habitats may contribute in increasing or decreasing pest density in fields of a specific crop, understanding the scale and temporal variability of source and sink effects is critical for managing landscapes to enhance pest control., Methodology/principal Findings: We evaluated how local and landscape characteristics affect population density of the western tarnished plant bug, Lygus hesperus (Knight), in cotton fields of the San Joaquin Valley in California. During two periods covering the main window of cotton vulnerability to Lygus attack over three years, we examined the associations between abundance of six common Lygus crops, uncultivated habitats and Lygus population density in these cotton fields. We also investigated impacts of insecticide applications in cotton fields and cotton flowering date. Consistent associations observed across periods and years involved abundances of cotton and uncultivated habitats that were negatively associated with Lygus density, and abundance of seed alfalfa and cotton flowering date that were positively associated with Lygus density. Safflower and forage alfalfa had variable effects, possibly reflecting among-year variation in crop management practices, and tomato, sugar beet and insecticide applications were rarely associated with Lygus density. Using data from the first two years, a multiple regression model including the four consistent factors successfully predicted Lygus density across cotton fields in the last year of the study., Conclusions/significance: Our results show that the approach developed here is appropriate to characterize and test the source and sink effects of various habitats on pest dynamics and improve the design of landscape-level pest management strategies.

Background: Development of pyriproxyfen and neonicotinoid resistance in the B-biotype whitefly and recent introduction of the Q biotype have the potential to threaten current whitefly management programs in Arizona. The possibility of integrating the novel anthranilic diamides chlorantraniliprole and cyantraniliprole into the current program to tackle these threats largely depends on whether these compounds have cross-resistance with pyriproxyfen and neonicotinoids in whiteflies. To address this question, the authors bioassayed a susceptible B-biotype strain, a pyriproxyfen-resistant B-biotype strain, four multiply resistant Q-biotype strains and 16 B-biotype field populations from Arizona with a systemic uptake bioassay developed in the present study., Results: The magnitude of variations in LC(50) and LC(99) among the B-biotype populations or the Q-biotype strains was less than fivefold and tenfold, respectively, for both chlorantraniliprole and cyantraniliprole. The Q-biotype strains were relatively more tolerant than the B-biotype populations. No correlations were observed between the LC(50) (or LC(99)) values of the two diamides against the B- and Q-biotype populations tested and their survival rates at a discriminating dose of pyriproxyfen or imidacloprid., Conclusion: These results indicate the absence of cross-resistance between the two anthranilic diamides and the currently used neonicotinoids and pyriproxyfen. Future variation in susceptibility of field populations to chlorantraniliprole and cyantraniliprole could be documented according to the baseline susceptibility range of the populations tested in this study., (Copyright © 2011 Society of Chemical Industry.)

Lesquerella, Physaria fendleri (A. Gray) S. Watson, is a mustard native to the western United States and is currently being developed as a commercial source of valuable hydroxy fatty acids that can be used in a number of industrial applications, including biolubricants, biofuel additives, motor oils, resins, waxes, nylons, plastics, corrosion inhibitors, cosmetics, and coatings. The plant is cultivated as a winter-spring annual and in the desert southwest it harbors large populations of arthropods, several of which could be significant pests once production expands. Lygus spp. (Hemiptera: Miridae) are common in lesquerella and are known pests of a number of agronomic and horticultural crops where they feed primarily on reproductive tissues. A 4-yr replicated plot study was undertaken to evaluate the probable impact of Lygus spp. on production of this potential new crop. Plant damage and subsequent seed yield and quality were examined relative to variable and representative densities of Lygus spp. (0.3-4.9 insects per sweep net) resulting from variable frequency and timing of insecticide applications. Increasing damage to various fruiting structures (flowers [0.9-13.9%], buds [1.2-7.1%], and seed pods [19.4-42.5%]) was significantly associated with increasing pest abundance, particularly the abundance of nymphs, in all years. This damage, however, did not consistently translate into reductions in seed yield (481-1,336 kg/ha), individual seed weight (0.5-0.7 g per 1,000 seed), or seed oil content (21.8-30.4%), and pest abundance generally explained relatively little of the variation in crop yield and quality. Negative effects on yield were not sensitive to the timing of pest damage (early versus late season) but were more pronounced during years when potential yields were lower due to weed competition and other agronomic factors. Results suggest that if the crop is established and managed in a more optimal fashion, Lygus spp. may not significantly limit yield. Nonetheless, additional work will be needed once more uniform cultivars become available and yield effects can be more precisely measured. Densities of Lygus spp. in unsprayed lesquerella are on par with those in other known agroecosystem level sources of this pest (e.g., forage and seed alfalfa, Medicago sativa L.). Thus, lesquerella production may introduce new challenges to pest management in crops such as cotton.

Transgenic cotton that produced one or more insecticidal proteins of Bacillus thuringiensis (Bt) was planted on over 15 million hectares in 11 countries in 2009 and has contributed to a reduction of over 140 million kilograms of insecticide active ingredient between 1996 and 2008. As a highly selective form of host plant resistance, Bt cotton effectively controls a number of key lepidopteran pests and has become a cornerstone in overall integrated pest management (IPM). Bt cotton has led to large reductions in the abundance of targeted pests and benefited non-Bt cotton adopters and even producers of other crops affected by polyphagous target pests. Reductions in insecticide use have enhanced biological control, which has contributed to significant suppression of other key and sporadic pests in cotton. Although reductions in insecticide use in some regions have elevated the importance of several pest groups, most of these emerging problems can be effectively solved through an IPM approach.

Two systemic neonicotinoids, imidacloprid and thiamethoxam, are widely used for residual control of several insect pests in cotton (Gossypium spp.), vegetables, and citrus (Citrus spp.). We evaluated their impact on six species of beneficial arthropods, including four parasitoid species--Aphytis melinus Debach, Gonatocerus ashmeadi Girault, Eretmocerus eremicus Rose & Zolnerowich, and Encarsia formosa Gahan--and two generalist predators--Geocoris punctipes (Say) and Orius insidiosus (Say)--in the laboratory by using a systemic uptake bioassay. Exposure to systemically treated leaves of both neonicotinoids had negative effects on adult survival in all four parasitoids, with higher potency against A. melinus as indicated by a low LC50. Mortality was also high for G. ashmeadi, E. eremicus, and E. formosa after exposure to both compounds but only after 48 h posttreatment. The two predators G. punctipes and O. insidiosus were variably susceptible to imidacloprid and thiamethoxam after 96-h exposure. However, toxicity to these predators may be related to their feeding on foliage and not just contact with surface residues. Our laboratory results contradict suggestions of little impact of these systemic neonicotinoids on parasitoids or predators but field studies will be needed to better quantify the levels of such impacts under natural conditions.

Fifty years ago, Stern, Smith, van den Bosch and Hagen outlined a simple but sophisticated idea of pest control predicated on the complementary action of chemical and biological control. This integrated control concept has since been a driving force and conceptual foundation for all integrated pest management (IPM) programs. The four basic elements include thresholds for determining the need for control, sampling to determine critical densities, understanding and conserving the biological control capacity in the system and the use of selective insecticides or selective application methods, when needed, to augment biological control. Here we detail the development, evolution, validation and implementation of an integrated control (IC) program for whitefly, Bemisia tabaci (Genn.), in the Arizona cotton system that provides a rare example of the vision of Stern and his colleagues. Economic thresholds derived from research-based economic injury levels were developed and integrated with rapid and accurate sampling plans into validated decision tools widely adopted by consultants and growers. Extensive research that measured the interplay among pest population dynamics, biological control by indigenous natural enemies and selective insecticides using community ordination methods, predator:prey ratios, predator exclusion and demography validated the critical complementary roles played by chemical and biological control. The term 'bioresidual' was coined to describe the extended environmental resistance from biological control and other forces possible when selective insecticides are deployed. The tangible benefits have been a 70% reduction in foliar insecticides, a >$200 million saving in control costs and yield, along with enhanced utilization of ecosystem services over the last 14 years., ((c) 2009 by John Wiley & Sons, Ltd.)

Integrated Pest Management (IPM) is considered the central paradigm of insect pest management and is often characterized as a comprehensive use of multiple control tactics to reduce pest status while minimizing economic and environmental costs. As the principal precursor of IPM, the integrated control concept formulated the economic theory behind pest management decisions and specified an applied methodology for carrying out pest control. Sampling, economic thresholds and selective insecticides were three of the critical elements of that methodology and are now considered indispensable to the goals of IPM. We examine each of these elements in the context of contemporaneous information as well as accumulated experience and knowledge required for their skillful implementation in an IPM program. We conclude that while IPM is principally about integrating control tactics into an effective and sustainable approach to pest control, this overarching goal can only be achieved through well-trained practitioners, knowledgeable of the tenets conceived in the integrated control concept that ultimately yield informed pest management., ((c) 2009 Society of Chemical Industry.)

The cost-reliability of five sampling methods (visual search, drop cloth, beat bucket, shake bucket, and sweep net) was determined for four groups of predatory arthropods on cotton plants in Texas. The beat bucket sample method was the most cost-reliable sampling method for Orius adults, and the beat bucket and drop cloth were the most cost-reliable methods for Orius nymphs. The drop cloth and beat bucket were the most cost-reliable methods for sampling spiders. For sampling adult Coccinellidae, the sweep net and the beat bucket were the most cost-reliable. The visual sample method was the least cost-reliable method for Orius adults and nymphs and spiders. No one sampling method was identified as the optimum method for all four predator groups. However, the relative cost-reliability of the beat bucket method ranked first or second among the five sampling methods and this method was chosen for further evaluation in field studies in Texas and Arizona. The relative cost-reliability of 1-, 3-, 5-, and 10-plants per beat bucket sample varied with predator group, but multiple plant sample units were equal to or more cost-reliable than the one plant sample unit. Fixed sample plans for the beat bucket method were developed for Orius adults, Orius nymphs, spiders, and adult Coccinellidae, and the sum of these groups using the 3-, 5-, and 10-plant sample unit sizes. The greater cost-reliability of the beat bucket sampling method and its ease of use is of particular advantage in assessing predator densities in a commercial cotton field monitoring program.

Background: Uncertainty persists over the environmental effects of genetically-engineered crops that produce the insecticidal Cry proteins of Bacillus thuringiensis (Bt). We performed meta-analyses on a modified public database to synthesize current knowledge about the effects of Bt cotton, maize and potato on the abundance and interactions of arthropod non-target functional guilds., Methodology/principal Findings: We compared the abundance of predators, parasitoids, omnivores, detritivores and herbivores under scenarios in which neither, only the non-Bt crops, or both Bt and non-Bt crops received insecticide treatments. Predators were less abundant in Bt cotton compared to unsprayed non-Bt controls. As expected, fewer specialist parasitoids of the target pest occurred in Bt maize fields compared to unsprayed non-Bt controls, but no significant reduction was detected for other parasitoids. Numbers of predators and herbivores were higher in Bt crops compared to sprayed non-Bt controls, and type of insecticide influenced the magnitude of the difference. Omnivores and detritivores were more abundant in insecticide-treated controls and for the latter guild this was associated with reductions of their predators in sprayed non-Bt maize. No differences in abundance were found when both Bt and non-Bt crops were sprayed. Predator-to-prey ratios were unchanged by either Bt crops or the use of insecticides; ratios were higher in Bt maize relative to the sprayed non-Bt control., Conclusions/significance: Overall, we find no uniform effects of Bt cotton, maize and potato on the functional guilds of non-target arthropods. Use of and type of insecticides influenced the magnitude and direction of effects; insecticde effects were much larger than those of Bt crops. These meta-analyses underscore the importance of using controls not only to isolate the effects of a Bt crop per se but also to reflect the replacement of existing agricultural practices. Results will provide researchers with information to design more robust experiments and will inform the decisions of diverse stakeholders regarding the safety of transgenic insecticidal crops.

Four sampling methods that included A-Vac, D-Vac, pole-bucket, and beat-net devices were evaluated for estimating relative densities of glassy-winged sharpshooter, Homalodisca vitri-pennis (Germar) (Hemiptera: Cicadellidae) nymphs and adults on citrus (Citrus spp.) trees. All four methods produced similar temporal and spatial distribution profiles, although significant differences in quantities of H. vitripennis adults and nymphs caught by each device were observed. The four sampling methods also showed a consistent male bias in adult populations across a range of densities, suggesting that previously reported male-biased sex ratios in H. vitripennis adult populations are real and not a product of sampling bias. A strong relationship (R2 = 0.95) between the monitoring methods we evaluated and yellow sticky trap catches of female H. vitripennis adults suggest that yellow sticky trap catches may provide a good relative index of infestation levels in citrus trees. Based on quantitative analyses examining precision and cost, the pole bucket was the most efficient method for sampling nymphs, and it was as efficient as the beat-net method for sampling adults and both stages combined. In addition to these analyses, consideration of other sampling characteristics such as added flexibility in sampling and higher sensitivity in detecting infestations within individual trees helped to fortify the conclusion that the pole bucket was the best overall sampling method of those tested.

Laboratory studies were carried out to compare the toxicity of seven foliar insecticides to four species of adult beneficial insects representing two families of Hymenoptera: Aphelinidae (Aphytis melinus Debach, Eretmocerus eremicus Rose & Zolnerowich, and Encarsiaformosa Gahan) and Mymaridae (Gonatocerus ashmeadi Girault) that attack California red scale, Aonidiella aurantii (Maskell); sweetpotato whitefly, Bemisia tabaci (Gennadius) (both E. eremicus and E. formosa); and glassy-winged sharpshooter, Homalodisca vitripennis (Germar), respectively. Insecticides from four pesticide classes were evaluated using a petri dish bioassay technique across a range of concentrations to develop dosage-mortality regressions. Insecticides tested included acetamiprid (neonicotinoid); chlorpyrifos (organophosphate); bifenthrin, cyfluthrin, and fenpropathrin (pyrethroids); and buprofezin and pyriproxyfen (insect growth regulators [IGRs]). Chlorpyrifos was consistently the most toxic pesticide to all four species of beneficial insects tested based on LC50 values recorded 24 h posttreatment compared with 48-h LC50 values with the neonicotinoid and pyrethroids or 96 h with the IGRs. Among the three pyrethroids, fenpropathrin was usually less toxic (except similar toxicity to A. melinus) than was cyfluthrin, and it was normally less toxic (except similar toxicity with E. formosa) than was bifenthrin. Acetamiprid was generally less toxic than bifenthrin (except similar toxicity with G. ashmeadi). The IGRs buprofezin and pyriproxyfen were usually less toxic than the contact pesticides, but we did not test for possible impacts on female fecundity. For all seven pesticides tested, A. melinus was the most susceptible parasitoid of the four test species. The data presented here will provide pest managers with specific information on the compatibility of select insecticides with natural enemies attacking citrus and cotton, Gossypium hirsutum L., pests.

Populations of Homalodisca coagulata (Say) were sampled from citrus orchards in southern California, USA to characterize and quantify seasonal occurrences of nymphs and adults with the goal of identifying management opportunities through well-timed treatments and/or natural enemy releases. Higher densities of H. coagulata in 2001 contributed to a complete seasonal profile that began in early spring with the emergence of first instar nymphs and their progression through five nymphal instars lasting until mid-August. Adult emergence began in mid-June with peak adult densities attained from mid to late August followed by a gradual decline through autumn. A persistent and significant male bias was observed in the adult sex ratio from the time of first emergence through mid-October in oranges; the same trend was present in lemons, but with more variability. Adult densities gradually declined through the winter months into the following spring before rapidly increasing again in June as the 2002 spring generation of nymphs began emerging as adults. The seasonal timing of nymphs and adults in 2002 was nearly identical to that observed the previous year. Phenology data from both years were incorporated into a stochastic, temperature-dependent model that predicts the occurrences of H. coagulata stages through time. Applications of imidacloprid early in the spring generation of nymphs proved very effective at reducing nymphs and sustaining lower densities of adults through summer.

Relative flight behavior of methyl-parathion-resistant and -susceptible western corn rootworm, Diabrotica virgifera virgifera LeConte populations, was studied as part of a larger effort to characterize the potential impact of insecticide resistance on adult life history traits and to understand the evolution and spread of resistance. A computer interfaced actograph was used to compare flight of resistant and susceptible individuals, and flight of resistant individuals with and without prior exposure to methyl-parathion. In each case, mean trivial and sustained flight durations were compared among treatments. In general, there were few differences in trivial or sustained flight characteristics as affected by beetle population, insecticide exposure, sex, or age and there were few significant interactions among variables. Tethered flight activity was highly variable and distributions of flight duration were skewed toward flights of short duration. Tethered flight activity was similar among resistant and susceptible beetles with the exception that susceptible beetles initiated more flights per beetle than resistant beetles. After sublethal exposure to methyl-parathion, total flight time, total trivial flight time, and mean number of flights per resistant beetle declined significantly. Because long-range flight was uncommon, short- to medium-duration flights may play an important role in determining gene flow and population spread of resistant D. v. virgifera. These results suggest that organophosphate-resistant beetles can readily move and colonize new areas, but localized selection pressure (e.g., management practices) and exposure to methyl-parathion may contribute to the small-scale differences in resistance intensity often seen in the field.

The integrated control concept emphasizes the importance of both chemical and biological control for pest suppression in agricultural systems. A two-year field study was conducted to evaluate the selectivity of acetamiprid for the control of Bemisia tabaci (Gennadius) in cotton compared with a proven selective regime based on the insect growth regulators (IGRs) pyriproxyfen and buprofezin. Acetamiprid was highly effective in controlling all stages of B tabaci compared with an untreated control, and generally produced lower pest densities than the IGR regime. Univariate analyses indicated that nine of 17 taxa of arthropod predators were significantly depressed with the use of acetamiprid compared with an untreated control, including common species such as Geocoris punctipes (Say), Orius tristicolor (White), Chrysoperla carnea Stephens sensu lato, Collops vittatus (Say), Hippodamia convergens Guérin-Méneville, and Drapetis nr divergens. Compared with results from independent, concurrent studies using mixtures of broad-spectrum insecticides at the same research site, acetamiprid depressed populations of fewer predator taxa; but, for eight predator taxa significantly affected by both regimes, the average population reduction was roughly equal. In contrast, only four taxa were significantly reduced in the IGR regime compared with the untreated control and three of these were omnivores that function primarily as plant pests. Principal response curves analyses (a time-dependent, multivariate ordination method) confirmed these patterns of population change for the entire predator community. Predator:prey ratios generally increased with the use of both IGRs and acetamiprid compared with an untreated control, but ratios were consistently higher with IGRs. Parasitism by aphelinid parasitoids was unaffected or depressed slightly in all insecticide regimes compared with the control. Because of its high efficacy, acetamiprid may play an important role in later stages of B tabaci control where less emphasis is placed on selectivity. However, our results suggest that acetamiprid would be a poor substitute for the currently used IGRs in the initial stage of control where insecticide selectivity is crucial to a functional integrated control program for B tabaci in cotton.

Studies were conducted in 1994 and 1995 to examine the effects of a range of action thresholds for managing Bemisia tabaci (Gennadius) Biotype B (= B. argentifolii Bellows & Perring) with insecticides in cotton on populations of arthropod predators in Imperial Valley, CA, and Maricopa, AZ. Application of insecticides significantly reduced population densities of spiders, Geocoris punctipes (Say), G. pallens (Stål), Orius tristicolor (White), Nabis alternatus Parshley, Zelus renardii Kolenati, Hippodamia convergens Guerin-Méneville, Spanogonicus albofasciatus (Reuter), Drapetis sp., and Chrysoperla carnea Stephens in one or both years and sites compared with untreated controls. Use of higher B. tabaci thresholds conserved some species and groups relative to lower thresholds. Stepwise regression analyses indicated that reductions in predator populations were generally influenced more strongly by the timing of the first insecticide application than by the total number of sprays necessary to maintain suppression of the pest below any given action threshold. A predation index, which weights the importance of each predator species based on their known frequency of predation on B. tabaci and another key pest, Pectinophora gossypiella (Saunders), was developed and analyzed. Patterns were similar to results based on changes in abundance alone, but the index generally revealed less severe effects of insecticides on overall predator function. The current action threshold for conventional insecticidal control of B. tabaci in Arizona and southern California is five adults per leaf. Results here suggest that predator conservation may be enhanced by raising the initial threshold to delay the first application or initially using more selective materials such as insect growth regulators.