Non-target Arthropods Research Articles

Effects of Insecticide-Treated and Lepidopteran-Active <I>Bt</I> Transgenic Sweet Corn on the Abundance and Diversity of Arthropods

A field study was conducted over 2 yr to determine the effects of transgenic sweet corn containing a gene from the bacterium Bacillus thuringiensis (Bt) on the diversity and abundance of nontarget arthropods. The Bt hybrid (expressing Cry1Ab endotoxin for lepidopteran control) was compared with near-isogenic non-Bt and Bt hybrids treated with a foliar insecticide and with a near-isogenic non-Bt hybrid without insecticides. Plant inspections, sticky cards, and pitfall traps were used to sample a total of 573,672 arthropods, representing 128 taxonomic groups in 95 families and 18 orders. Overall biodiversity and community-level responses were not significantly affected by the transgenic hybrid. The Bt hybrid also had no significant adverse effects on population densities of specific nontarget herbivores, decomposers, and natural enemies enumerated at the family level during the crop cycle. As expected, the insecticide lambda-cyhalothrin had broad negative impacts on the abundance of many nontarget arthropods. One insecticide application in the Bt plots reduced the overall abundance of the natural enemy community by 21-48%. Five applications in the non-Bt plots reduced natural enemy communities by 33-70%. Nontarget communities affected in the insecticide-treated Bt plots exhibited some recovery, but communities exposed to five applications showed no trends toward recovery during the crop cycle. This study clearly showed that the nontarget effects of Bt transgenic sweet corn on natural enemies and other arthropods were minimal and far less than the community-level disruptions caused by lambda-cyhalothrin.

NONTARGET EFFECTS OF THE MOSQUITO ADULTICIDE PYRETHRIN APPLIED AERIALLY DURING A WEST NILE VIRUS OUTBREAK IN AN URBAN CALIFORNIA ENVIRONMENT

In August 2006, a pyrethrin insecticide synergized with piperonyl butoxide (EverGreen Crop Protection EC 60-6, McLaughlin Gormley King Company, Golden Valley, MN) was sprayed in ultralow volumes over the city of Davis, CA, by the Sacramento-Yolo Mosquito and Vector Control District to control mosquitoes transmitting West Nile virus. Concurrently, we evaluated the impact of the insecticide on nontarget arthropods by 1) comparing mortality of treatment and control groups of sentinel arthropods, and 2) measuring the diversity and abundance of dead arthropods found on treatment and control tarps placed on the ground. We found no effect of spraying on nontarget sentinel species including dragonflies (Sympetrum corruptum), spiders (Argiope aurantia), butterflies (Colias eurytheme), and honeybees (Apis mellifera). In contrast, significantly higher diversity and numbers of nontarget arthropods were found on ground tarps placed in sprayed versus unsprayed areas. All of the dead nontarget species were small-bodied arthropods as opposed to the large-bodied sentinels that were not affected. The mortality of sentinel mosquitoes placed at the same sites as the nontarget sentinels and ground tarps ranged from 0% to 100%. Dead mosquitoes were not found on the ground tarps. We conclude that aerial spraying with pyrethrins had no impact on the large-bodied arthropods placed in the spray zone, but did have a measurable impact on a wide range of small-bodied organisms.

High susceptibility of Bt maize to aphids enhances the performance of parasitoids of lepidopteran pests.

Concerns about possible undesired environmental effects of transgenic crops have prompted numerous evaluations of such crops. So-called Bt crops receive particular attention because they carry bacteria-derived genes coding for insecticidal proteins that might negatively affect non-target arthropods. Here we show a remarkable positive effect of Bt maize on the performance of the corn leaf aphid Rhopalosiphum maidis, which in turn enhanced the performance of parasitic wasps that feed on aphid honeydew. Within five out of six pairs that were evaluated, transgenic maize lines were significantly more susceptible to aphids than their near-isogenic equivalents, with the remaining pair being equally susceptible. The aphids feed from the phloem sieve element content and analyses of this sap in selected maize lines revealed marginally, but significantly higher amino acid levels in Bt maize, which might partially explain the observed increased aphid performance. Larger colony densities of aphids on Bt plants resulted in an increased production of honeydew that can be used as food by beneficial insects. Indeed, Cotesia marginiventris, a parasitoid of lepidopteran pests, lived longer and parasitized more pest caterpillars in the presence of aphid-infested Bt maize than in the presence of aphid-infested isogenic maize. Hence, depending on aphid pest thresholds, the observed increased susceptibility of Bt maize to aphids may be either a welcome or an undesirable side effect.

Short-term assessment of bt maize on non-target arthropods in Brazil

Although not yet available for cultivation in Brazil, the effect of Bt maize hybrids on natural enemies and soil dwelling arthropods should be assessed prior to its release to growers. Trials were carried out during one growing season in two different locations with the genetically modified maize hybrids 7590-Bt11 and Avant-ICP4, comparing with their respective non-Bt isogenic hybrids. Arthropods were evaluated through direct observation on plants and pitfall traps. In general, no differences were observed between populations of earwig (Dermaptera: Forficulidae), lady beetles (Coleptera: Coccinellidae), minute pirate bug (Coleoptera: Anthocoridae), ground beetles (Carabidae), tiger beetles (Cicindelidae), and spiders (Araneae). There was no difference in egg parasitism of Helicoverpa zea (Boddie) by Trichogramma sp. (Hymenoptera: Trichogrammatidae). Thus, Bt maize hybrids expressing insecticide proteins Cry1A(b) and VIP 3A do not cause reduction of the main maize dweeling predators and parasitoids.

Comparative toxicity of imidacloprid, of its commercial liquid formulation and of diazinon to a non-target arthropod, the microcrustacean Daphnia magna

Imidacloprid (IMI) is at the moment the insecticide with the world's fastest growing sales and is considered possible replacement for the widely used organophosphorus pesticide, diazinon, which is subject to phased revocation in many countries. In this study, biochemical, reproductive and survival parameters of the water flea (Daphnia magna) after chronic exposure to IMI, its commercial liquid formulation Confidor SL 200 and diazinon are presented and compared. According to the lowest observed effect concentrations, diazinon is more toxic to the reproduction of D. magna than IMI and Confidor SL 200, which exert similar toxicity. The same was observed for the survival, except that Confidor SL 200 is more toxic than IMI. In polluted aquatic environments, the actual levels of diazinon are potentially chronically hazardous to the reproduction of D. magna (risk quotient >1). According to very few measured environmental levels of IMI, the latter is not expected to be chronically hazardous, unless it is accidentally spilled in a small pond. In such case, the predicted concentrations of IMI would present a potential chronic risk to D. magna, and a potential acute risk to other aquatic invertebrates. In the future, higher environmental levels of IMI are expected due to its increasing use and physico-chemical properties. The literature survey summarized in this work suggests that further ecotoxicological studies with a broader spectrum of aquatic organisms are needed before IMI is classified as safer than currently applied pesticides.

Impacts of transgenic cry1Ab rice on non-target planthoppers and their main predator Cyrtorhinus lividipennis (Hemiptera: Miridae)—A case study of the compatibility of Bt rice with biological control

Abstract Transgenic rice containing insecticidal protein(s) from Bt (Bacillus thuringiensis) effectively control lepidopteran pests under laboratory and field conditions. However, Bt rice has not been widely commercialized. A major concern regarding the deployment of Bt rice is its potential impact on non-target arthropods, including herbivorous insect pests and biological control agents (predators and parasitoids) in the rice ecosystem. A 2-year field study was conducted at 3 sites in Zhejiang Province, China to assess the impacts of a homozygous transgenic japonica rice line KMD1 (Bt rice) containing a synthetic cry1Ab gene from Bacillus thuringiensis Berliner. The impacts on three planthoppers (Homoptera: Delphacidae), Sogatella furcifera (Horvath), Nilaparvata lugens (Stal) and Laodelphax striatellus (Fallen), and the natural enemy, Cyrtorhinus lividipennis (Reuter) (Hemiptera: Miridae), were evaluated using two sampling methods: vacuum-suction and Malaise trap. Population densities of planthoppers and C. lividipennis were not significantly affected by rice type (Bt/non-Bt) over the season at any of the 3 sites in each year, regardless of sampling methods. Both in Bt rice and non-Bt rice plots, S. furcifera was the predominant species of planthoppers as determined by either of the two sampling methods, and comprised >50% of the planthoppers at each site. No consistent effects of Bt rice and Bt rice × sampling date interaction on population dynamics of the predominant planthopper species, S. furcifera, and the predator, C. lividipennis, were observed throughout the sampling period. Overall, this 2-year field study indicates that, in comparison with non-Bt rice, Bt rice did not lead to higher planthopper populations and did not negatively affect the predator C. lividipennis. These results suggest that use of Bt rice may provide control of the key lepidopteran pests while promoting the key biological control agent of planthopppers, C. lividipennis.

Ecological effects of imidacloprid on arthropod communities in and around a vegetable crop

To elucidate the ecological impacts of imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] on vegetable crops and their surrounding areas, arthropods on eggplant patches treated with this insecticide were monitored throughout two cultivation seasons, spring and autumn, and the results compared with those of control crops. Residues of imidacloprid in soil accounted for 4-8% of total applied, and concentrations outside the crop were always below 5 μ g/kg. Communities of the crop vegetation experienced significant density reductions, mostly of aphids, and had fewer species diversity during the first month. Those in the surrounding pasture were similarly affected though with less intensity, while non-target ground arthropods both inside and outside the crop only showed significant impacts in the two weeks after planting.

Nontarget Effects of Transgenic Insecticidal Crops: Implications of Source-Sink Population Dynamics

Widespread planting of transgenic insecticidal (TI) crops for pest control has raised concerns about potential harm to nontarget arthropods. Because the first generation of TI crops produce single Bacillus thuringiensis (Bt) toxins causing little or no harm to most nontarget arthropods, they are not likely to cause such negative effects. However, varieties of transgenic crops with multiple Bt toxins or novel toxins might be more harmful to nontarget arthropods. Field studies assessing nontarget effects typically compare the relative abundance of nontarget arthropods in TI crop fields to non-TI crop fields. However, for nontarget arthropods that are killed by TI crops, such analyses may miss important effects. Results from simulations of a spatially explicit population dynamics model show that large-scale planting of TI crops could cause three types of negative effects on nontarget arthropods that suffer mortality caused by TI crops: (1) lower abundance in TI fields than non-TI fields with little or no effect on abundance in non-TI fields, (2) lower abundance in TI fields than non-TI fields and decreased abundance in non-TI fields, and (3) loss of the arthropod from TI and non-TI fields. Simulation results show that factors increasing the potential for negative effects of TI crops on nontarget arthropods in non-TI fields are low reproduction, high emigration, high adoption of TI crops, high mortality in TI fields, insecticide sprays, and rotation of TI and non-TI fields. The results suggest that risk assessment should consider the regional distribution of transgenic crops and the life history traits of nontarget arthropods to identify the most vulnerable regions and nontarget species.

Evaluation of the codling moth granulovirus and spinosad for codling moth control and impact on non-target species in pear orchards

Abstract We compared the efficacy of a commercial preparation of the codling moth, Cydia pomonella L., granulovirus, CpGV (Cyd-X®) and spinosad (Entrust®) at operational rates for codling moth control in 2004 and 2005. Concurrently we monitored the impact of treatments on populations of non-target arthropods. Spinosad was effective at protecting fruit, with ⩽1.6% codling moth injury in experimental plots, compared with up to 37% injury in the untreated plots at harvest. Mid-season outbreaks of the pear psylla, Cacopsylla pyricola Foerster, were also reduced in spinosad plots. Spinosad was safe for several predators, notably the psylla predator Deraeocoris brevis Uhler, but reduced the abundance of hymenopteran parasitoids by 24% and 40% and non-target Diptera by 49% and 35%, respectively in 2004 and 2005. We found no evidence that spinosad disrupted natural control leading to increased densities of secondary pests including aphids and phytophagous mites. CpGV was less effective than spinosad at protecting fruit, with percentage of fruits attacked similar to controls, but killed the majority (67–71%) of neonate coding moth larvae and did not harm non-target species. Additional observations were conducted in commercial orchards (mixed pear and apple) where CpGV and spinosad were used operationally against existing codling moth infestations. In pear, two spray programs applied in replicated 0.4 ha blocks (i.e. CpGV followed by spinosad against the first and second larval generations, respectively and vice versa) reduced fruit injury at harvest and decreased orchard pheromone monitoring trap catches by 74% over two years. In apple, CpGV was less effective at protecting fruit in the first larval generation compared with spinosad, although population suppression was effective early in the season. Spinosad caused no disruptions of beneficial species or secondary pest outbreaks were observed in the commercial orchards. Our results suggest CpGV and spinosad can be effectively used in integrated pest management for codling moth.

Estimating ecotoxicological effects of pesticide drift on nontarget arthropods in field hedgerows

Estimating ecotoxicological effects of pesticide drift on nontarget arthropods in field hedgerows

Six-year monitoring of non-target arthropods in Bt maize (Cry 1Ab) in the European corn borer (Ostrinia nubilalis) infestation area Oderbruch (Germany)

This study was performed in the Oderbruch region, a landscape where Ostrinia nubilalis occurs in high densities. From 2000 to 2005, field pairs (half-fields) planted with Bt maize (Cry 1Ab) and a conventional maize variety, respectively, were investigated using different monitoring methods (visual counts, whole-plant harvesting and pitfall trapping) to determine densities of taxa on plants, activity densities and diversity of ground-dwelling arthropods. A total of 48 taxa were determined in counts and 90 in whole-plant harvests; 75 carabid species and 62 spider species were identified by pitfall trapping. Density comparisons of different taxa, such as aphids, thrips, heteropterans, aphid specific predators, spiders and carabids, revealed a few significant differences for specific taxa but no general tendencies during the six years. Canonical corresponding analyses revealed small but statistically significant differences in community composition between Bt and conventional maize fields. Generally, year-to-year changes in environmental conditions, field characteristics, and population dynamics had much stronger effects on the arthropod community than the use of Bt maize. Three baselines were used for evaluation of findings: (1) mean and variation of a specific variable (e.g. density) in a given conventional maize field, (2) mean and variation of a specific variable in conventional maize fields in the last five years and (3) mean and variation of a specific variable in conventional maize fields within a given year. This methodological approach is tested for suitability for case-specific monitoring.

Impact of insect-resistant transgenic rice on target insect pests and non-target arthropods in China

Progress on the research and development of insect-resistant transgenic rice, especially expressing insecticidal proteins from Bacillus thuringiensis (Bt), in China has been rapid in recent years. A number of insect-resistant transgenic rice lines/varieties have passed restricted and enlarged field testing, and several have been approved for productive testing since 2002 in China, although none was approved for commercial use until 2006. Extensive laboratory and field trials have been conducted for evaluation of the efficiency of transgenic rice on target lepidoteran pests and potential ecological risks on non-target arthropods. The efficacy of a number of transgenic rice lines currently tested in China was excellent for control of the major target insect pests, the rice stem borers (Chilo suppressalis, Scirpophaga incertulas, Sesamia inferens) and leaffolder (Cnaphalocrocis medinalis), and was better than most insecticides extensively used by millions of farmers at present in China. No significantly negative or unintended effects of transgenic rice on non-target arthropods were found compared with non-transgenic rice. In contrast, most of the current insecticides used for the control of rice stem borers and leaffolders proved harmful to natural enemies, and some insecticides may directly induce resurgence of rice planthoppers. Studies for developing a proactive insect resistance management of transgenic rice in the future are discussed to ensure the sustainable use of transgenic rice.

Conference summary

昆虫抵抗的转基因的米饭的研究和发展上的进步，特别从杆菌 thuringiensis (Bt ) 表示杀虫的蛋白质，在中国在最近的年里是快速的。很多昆虫抵抗的转基因的米饭线 / 变化传递了限制并且扩大的现场测试，并且几在中国为生产严峻的 since2002 被同意了，尽管任何一个都没为商业使用被同意直到 2006。广泛的实验室和田间试验在非目标节肢动物上在 targetlepidoteran 害虫和潜在的生态的风险上为转基因的米饭的效率的评估被进行了。当前在中国测试的很多根转基因的米饭线的功效为主要目标害虫的控制是优秀的，米饭茎 borers ( Chilo suppressalis ， Scirpophaga incertulas ， Sesamia 推断 ens )并且叶文件夹( Cnaphalocrocis medinalis )，并且比百万个农民广泛地在中国目前使用的大多数杀虫药剂好。非目标节肢动物上的转基因的米饭的显著地否定或非计划中的效果都没与非转基因的米饭相比被发现。相反，大多数为米饭的控制使用的当前的杀虫药剂起源证明有害到天敌的 borers 和叶文件夹，和一些杀虫药剂可以直接导致 riceplanthoppers 的苏醒。为在未来开发转基因的米饭的一个积极抗虫性管理的研究被讨论保证转基因的米饭的持续使用。

EVALUATION OF SEVERAL REDUCED-RISK INSECTICIDES IN COMBINATION WITH AN ACTION THRESHOLD FOR MANAGING LEPIDOPTERAN PESTS OF COLE CROPS IN ALABAMA

Several reduced-risk insecticides were evaluated for management of three lepidopteran cole crop pests, Plutella xylostella (L.), Pieris rapae (L.), and Trichoplusia ni (Hübner) in central Alabama in 2004 (spring and fall plantings) and 2005 (spring only). The following formulated sprays were evaluated: Dipel® (Bacillus thuringiensis subspecies kursatki), XenTari® (B. thuringiensis subspecies aizawai), Dipel XenTari (a premixed test formulation consisting of both subspecies of B. thuringiensis), Entrust® (a formulation of spinosad for use in organic crop production), and Novaluron (insect growth regulator). Variations in the populations of the three pest species were recorded from season to season with pest pressure being generally higher in both spring seasons than in the fall season. While moderate to high populations of P. xylostella and P. rapae were recorded in all three seasons, T. ni was detected only in spring 2005. An action threshold of 0.5 cabbage looper equivalents (CLE) per plant was used to determine the need for insecticide applications. Insecticide efficacy was determined by comparing densities of larvae and immatures (larvae pupae) of each pest species, crop damage ratings, densities of key non-target arthropods, and number of insecticide applications in plots treated with each material versus untreated control plots. All five reduced-risk insecticide formulations were effective in reducing infestations of the three lepidopteran pests and in providing marketable cabbage and collards in Alabama. Among the treatments, Entrust® consistently produced the lowest mean damage ratings with the minimum number of applications per season. No significant effects of insecticide treatments were recorded in the numbers of spiders and lady beetles found per plant. The results also suggest that the 0.5 CLE action threshold can be used to produce marketable cabbage and collards in Alabama with only minimal applications of reduced-risk insecticides.

Effectiveness and side effects of glue-traps to decrease damages caused by Byturus tomentosus in raspberry

Damages caused by the larvae of Byturus tomentosus (Coleoptera: Byturidae) are a big problem of European raspberry production. Under integrated pest management conditions in Switzerland, B. tomentosus is controlled by chemical-synthetic insecticides. In organic production, no corresponding insecticides are permitted. White sticky traps (type Rebell® bianco) are used for monitoring purposes. Can glue-traps also be used for mass-trapping and damage control? In this study, the attractiveness for adult B. tomentosus of one yellow and several white glue-traps was compared by counting the trapped individuals. Trapped beneficial insects like honey bees, Coccinellidae, Syrphidae and Chrysopidae were also counted. The contamination of the traps caused by other non-target arthropods was measured by a computer-assisted method. The white sticky trap type Rebell bianco was the most attractive for B. tomentosus. The attractiveness for the beneficials was relatively low, except when too much glue was applied on the traps, then the attractiveness for honey bees increased significantly. In this study, traps, which were placed in high densities (17 traps per 100 m2), significantly decreased the damages caused by larvae by around 40%. The trapping method does not cause any residuals of pesticides on the fruits or soil. Therefore, the trapping method could be an alternative to control B. tomentosus, especially in organic production.

Changes in non-target arthropod populations following application of liquid bait formulations of insecticides for control of rangeland grasshoppers

This study was undertaken to determine the non-target impacts of rangeland grasshopper control using liquid bait formulations of insecticides (canola and corn oil as carriers of carbaryl, diflubenzuron, and malathion). The research was conducted on native rangeland in Wyoming under drought conditions. Three collection methods (pitfall traps, yellow sticky cards, and sweep nets) were used to estimate non-target arthropod densities. The formulated insecticides were applied according to the protocol of reduced agent-area treatments, an application method designed to reduce economic and environmental costs by applying insecticides at low rates with incomplete coverage via alternating treated and untreated swaths). Canola and corn oils are vegetable oils high in linolenic and linoleic acids which function as attractants and phagostimulants for many species of grasshoppers. Crop oil is a biologically inert paraffin-based petroleum product that served as a control. Although all treatments markedly reduced grasshopper population densities, non-target populations were nominally affected. There were no consistent, significant differences in the responses of non-target populations to treatments with the liquid baits (canola and corn oil carriers) relative to those observed with the standard carrier (crop oil). Only one taxonomic group (Formicidae) showed a significant negative response to treatment relative to untreated controls. Logistical and ecological factors associated with grasshopper control methods may account for the nominal effects on non-target taxa. Sweep net and sticky trap sampling were more sensitive to treatment effects and time-by-treatment interactions. Temporal changes in population densities may have made treatment effects difficult to distinguish in several taxonomic groups.

The effect of imidacloprid and mixed pirimiphos‐methyl and bifenthrin on non‐target arthropods of cocoa

AbstractImidacloprid was less effective in reducing ant populations than a mixture of pirimiphos‐methyl and bifenthrin, while the mixture also greatly reduced the number of spiders. Imidacloprid caused some reduction in spider numbers for a week after spraying but then numbers rose substantially. Copyright © 2005 John Wiley & Sons, Ltd

Nontarget Arthropod Abundance in Areawide-Managed Corn Habitats Treated with Semiochemical-Based Bait Insecticide for Corn Rootworm (Coleoptera: Chrysomelidae) Control

Impacts of semiochemical-based insecticidal bait applications on beneficial arthropod groups common to field corn, Zea mays L., habitats were assessed in areawide-managed field sites in South Dakota and Iowa during 1997 and 1998. Slam, a commercial bait formulation comprised of 87% cucurbitacin and 13% carbaryl insecticide, was used for management of adult rootworm, Diabrotica spp., and controls consisted of cornfield habitats without bait applications. Effects on beneficial organisms were variable, and negative impacts were infrequent. Coccinellidae, Staphylinidae, and Anthocoridae were usually more abundant in bait-treated plots than in controls that received at-plant soil insecticides, especially by 4 wk postapplication. Carabid beetle activity also had increased in bait-treated corn by proportionally greater rates than in control plots at 4 wk postapplication in two of the four site by year combinations in this study. Impacts of semiochemical-based adulticide applications on Formicidae were not consistently negative or positive. The relative lack of consistent negative impacts on nontarget arthropods suggests that other biotic and abiotic factors leading to natural population fluxes may have more influence on these groups of beneficial organisms than applications of semiochemical-based bait containing carbaryl. Overall, it seems that areawide applications of these baits for managing rootworm populations in corn are not likely to impose deleterious effects on the nontarget faunal groups we surveyed, especially in comparison with the at-plant applications of soil insecticides used as experimental controls in this study.

Nontarget Arthropod Abundance in Areawide-Managed Corn Habitats Treated with Semiochemical-Based Bait Insecticide for Corn Rootworm (Coleoptera: Chrysomelidae) Control

Impacts of semiochemical-based insecticidal bait applications on beneficial arthropod groups common to field corn, Zea mays L., habitats were assessed in areawide-managed field sites in South Dakota and Iowa during 1997 and 1998. Slam, a commercial bait formulation comprised of 87% cucurbitacin and 13% carbaryl insecticide, was used for management of adult rootworm, Diabrotica spp., and controls consisted of cornfield habitats without bait applications. Effects on beneficial organisms were variable, and negative impacts were infrequent. Coccinellidae, Staphylinidae, and Anthocoridae were usually more abundant in bait-treated plots than in controls that received at-plant soil insecticides, especially by 4 wk postapplication. Carabid beetle activity also had increased in bait-treated corn by proportionally greater rates than in control plots at 4 wk postapplication in two of the four site by year combinations in this study. Impacts of semiochemical-based adulticide applications on Formicidae were not consistently negative or positive. The relative lack of consistent negative impacts on nontarget arthropods suggests that other biotic and abiotic factors leading to natural population fluxes may have more influence on these groups of beneficial organisms than applications of semiochemical-based bait containing carbaryl. Overall, it seems that areawide applications of these baits for managing rootworm populations in corn are not likely to impose deleterious effects on the nontarget faunal groups we surveyed, especially in comparison with the at-plant applications of soil insecticides used as experimental controls in this study.

Consequences for Protaphorura armata (Collembola: Onychiuridae) following exposure to genetically modified Bacillus thuringiensis ( Bt) maize and non- Bt maize

Studies on the effect of genetically modified Bacillus thuringiensis ( Bt) crops on true soil dwelling non-target arthropods are scarce. The objective of this study was to assess the influence of a 4-week exposure to two Bt maize varieties (Cry1Ab) Cascade and MEB307 on the collembolan Protaphorura armata. For comparison three non- Bt maize varieties, Rivaldo (isogenic to Cascade), Monumental (isogenic to MEB307) and DK242, and two control diets based on baker's yeast (uncontaminated and contaminated with Bt toxin Cry1Ab) were also tested. Due to a lower C:N ratio, individuals reared on yeast performed significantly better in all of the measured endpoints than those reared on maize. P. armata performed equally well when reared on two Bt and three non- Bt maize varieties. Although there were no negative effects of Bt maize in this experiment, we recommend future studies on Bt crops to focus on species interactions in long-term, multi-species experiments.