Quantitative risk assessment affords an objective approach for assessing ecological risk from crops produced using biotechnology. Ecological risk assessment for plant-incorporated insecticidal proteins necessitates consideration of risks to nontarget insects when species-specific hazard information may be lacking. Screening-level risk assessment methods afford a means by which risks to species of concern may be evaluated conservatively using exposure estimates, host-range information, and a probabilistic estimate of toxicity to sensitive species. This approach was applied to the special case of Bt corn pollen risk to monarch butterfly, Danaus plexippus (L.), populations; the results were compared with more highly refined risk assessment techniques in terms of the risk conclusions which can be developed with more highly certain information. Exposure analysis based on readily available literature showed pollen interception by the host for monarch butterfly larvae (common milkweed, Asclepias syriaca L.) declined exponentially with distance from the pollen source. Intra- and inter-genera sensitivity of lepidopteran species was used to project effect to monarch butterfly larvae. When the 90^th percentile of effect (LC₅₀) was used to estimate monarch butterfly sensitivity to Bt corn pollen expressing Cry1A(b) protein, the risk of lethality to individual larvae was negligible at >1 m from the edge of source corn fields. Subsequent field measurements of pollen distribution, interception by milkweed, and especially effects determinations for monarch butterfly larvae exposed to Cry1A(b) toxin indicate that the screening-level approach was effective in focusing the scope of the problem to exposure from high-expressing Cry1A(b) events occurring within source cornfields or at the near-field edge. Screening level risk assessment conservatively identifies the scope of concern and the uncertainties that need clarification so that subsequent research can be appropriately focused.

Cotesia sesamiae (Cameron) is an indigenous larval endoparasitoid that attacks mid- to late-stage gramineous stem borer larvae in Africa. Two biotypes of C. sesamiae have been reported with differential abilities to suppress the immune system of Busseola fusca Fuller. Eggs of a C. sesamiae population from Mombasa were encapsulated, whereas eggs of a population from Kitale were not. Total and differential hemocytes were counted in larvae of B. fusca at six times (2 h, 14 h, 24 h, 72 h, 120 h, 168 h) after being exposed to parasitoids from Kitale and Mombasa. The total numbers of hemocytes in a larva parasitized by the C. sesamiae population from Mombasa were higher as compared with larvae parasitized by the C. sesamiae population from Kitale. Plasmatocytes, in particular, were reduced in larvae parasitized by C. sesamiae from western Kenya from 72 to 168 h after oviposition. Our results suggest that plasmatocytes probably play an important role in the immune response of B. fusca. Significant proportions of the host larvae were still at the larval stage for those parasitized by C. sesamiae from Mombasa and another species of Cotesia, Cotesia flavipes Cameron at day 12. A reduction of B. fusca larval weight was observed on day 12 after oviposition by C. sesamiae from Kitale.

The impact of a sublethal dose of lambda-cyhalothrin on intraguild predation between three mite predators, Hyaliodes vitripennis (Say), Harmonia axyridis Pallas, and Amblyseius fallacis (Garman) was evaluated in laboratory. The symmetry and level of intraguild predation in selected predator combinations were recorded in the absence and presence of lambda-cyhalothrin. The mobility of the different predatory stages was also recorded in the absence and presence of insecticide. The results showed that lambda-cyhalothrin did not significantly modify intraguild predation but it affected the mobility. A knockdown effect was observed in H. axyridis larvae and in H. vitripennis nymphs, whereas A. fallacis showed an increased mobility. Exposure to a sublethal dose of lambda-cyhalothrin modified predator behavior and must be considered in the implementation of a mite control program in apple orchards.

The behavioral response of the sawtoothed grain beetle, Oryzaephilus surinamensis (L.), to moisture gradients has been studied in some detail, but the effect of carbon dioxide (CO₂), alone and in combination with low humidity, has never been reported. The effect of CO₂ is of some interest because CO₂ levels in stored grain are often elevated well above normal atmospheric levels by the metabolism of insects, fungi, and the grain itself. Also, CO₂ is sometimes applied to bulk grain to control stored-product insects. The response of adult male O. surinamensis to humidity alternatives of 60 or 100% RH was determined in 2-way choice chambers after various treatments. Beetles removed from laboratory cultures and held at 60% RH with food for 4 h showed a strong avoidance of the higher humidity (hygronegative response). Beetles held without food in a dry atmosphere (<5% RH) with an elevated level of CO₂ (39%) for 4 h showed a reversal of the response from hygronegative to hygropositive. The same period of exposure, again without food, to dry air (<5% RH), or to a moist atmosphere (80% RH) with an elevated level of CO₂ did not produce a reversal. The failure of CO₂ to produce a reversal when exposure occurred in a moist atmosphere suggests that the gas acts indirectly on the humidity response by increasing the rate of moisture loss. Elevated levels of CO₂ are known to cause prolonged opening of the spiracular regulatory apparatus that controls moisture loss in insects.

In a 3-yr field experiment, possible effects of Bt transgenic cotton plants expressing cry1A(c) gene from Bacillus thrungiensis Berliner variety kurstaki on diversities of arthropod communities and pest and natural enemy sub-communities were assessed in insecticide treated and untreated cotton fields, as measured by the Shannon-Weaver diversity index. The treatments included: 1) nontransgenic cotton with no insecticide treatment (nontransgenic), 2) nontransgenic cotton with insecticide treatments (nontransgenic insecticide), 3) transgenic Bt-cotton with no insecticide treatment (Bt-cotton), and 4) transgenic Bt-cotton with insecticide treatments (Bt-cotton insecticide). The results indicated that Bt-cotton increased the diversity of arthropod communities and pest sub-communities; however, it decreased the diversities of natural enemy sub-communities. Insecticide treatments increased diversities of communities and sub-communities of arthropods in both transgenic Bt-cotton and nontransgenic cotton agroecosystems, but the increase may be an artifact of increased evenness through mortality of insecticide-targeted species.

The reproductive biology, and larval and adult host range of Diabrotica speciosa (Germar), Diabrotica viridula (F.), Acalymma spp. (Coleoptera: Chrysomelidae: Galerucinae), and other Diabroticina are described. These Diabroticina are pests of several crops in South and Central America. The adult feeding hosts were compared, among species, and within species in different seasons. Laboratory oviposition and larval development tests on several hosts, provided the basis to construct a table of putative hosts, and general reproductive traits related to two species groups of Diabrotica (virgifera and fucata). Eggs of D. speciosa and D. viridula, were exposed to low temperatures to detect the ability to be dormant. Multivoltinism and lack of egg diapause was demonstrated for the three species, and field data suggest other South American species present the same traits. Diabrotica speciosa (fucata group) larvae developed well on maize (Zea mays L.), peanuts (Arachis hypogaea L.), and soybeans (Glycine max (L.) Merrill) roots, and not so well on pumpkin (Cucurbita maxima Duchesne and Cucurbita andreana Naudin), beans (Phaseolus spp.), and potato (Solanum tuberosum L.) roots. Oviposition preferences roughly paralleled larval suitability, but there was a clear preference for cucurbits as adult food, when available; pigweed (Amaranthus quitensis Kunth), sunflower (Helianthus annuus L.), and alfalfa (Medicago sativa L.) were in second place. Diabrotica viridula (virgifera group), preferred maize as adult and larval food, and for oviposition. Acalymma spp., were associated in every respect to cucurbits. Other species showed varying degrees of preference for oviposition and feeding, but in general, cucurbits were the preferred adult feeding hosts, followed by several wild plants, and maize the preferred oviposition host. Whereas cucurbits were consistently visited by the adults of every species, the virgifera group species oviposited and developed exclusively on Monocotyledonae. However, D. speciosa, as expected for a fucata group species, oviposited and developed on a wide range of hosts. This new knowledge on South American Diabroticina is discussed in the context of the current knowledge on North American Diabroticina. Differences and similarities are discussed in connection with their pestiferous status, and their potential for adaptation to new hosts.

Previously, we showed that cabbage loopers (Trichoplusia ni Hübner) can evolve >20X resistance to the single (S) nucleocapsid nucleopolyhedrovirus (NPV) of Trichoplusia ni (TnSNPV). In this study, we investigate one potential cost that resistant cabbage loopers may incur, increased susceptibility to other mortality agents. Contrary to expectation, no such cost was observed with any of the six mortality agents tested. In fact, the LD₅₀ of selected larvae was always greater than that of control caterpillars for each agent tested. However, the differences were never significant for permethrin or Bacillus thuringiensis subsp kurstaki (Berliner). The differences in the LD₅₀ of control and selected T. ni for the wild-type multiple (M) nucleocapsid NPV of Autographa californica Speyer (AcMNPV, clone C6) and the recombinant AcMNPV (AcMNPV-AaIT) were small (≈2X) and significant in only one of three generations. Surprisingly, the highest level of cross-resistance was to the granuloviruses of Pieris rapae L. (4–5X; significant in two of three generations) and T. ni (20–30X; significant in three of three generations). This suggests that the infection pathway of TnSNPV may be more similar to TnGV than to that of AcMNPV.

Overwintering of Trichogramma (Trichogrammanza) funiculatum Carver was studied under seminatural temperate conditions by considering development time within eggs of the light brown apple moth, Epiphyas postvittana, and survival of adult wasps. Maximum and minimum mean development times were 84 and 63.6 d, respectively, for egg masses parasitized in early winter, and 72.6 and 51.5 d, respectively, for eggs parasitized mid-winter. Adults survived a maximum of 20 d in early winter and 22 d mid-winter. Maternal age did not influence either the development time or longevity of progeny. The lower temperature threshold at which T. funiculatum parasitized host eggs was between 8°C and 9°C. The relationship between temperature and development time in the laboratory was successfully used to predict the emergence of T. funiculatum at low temperatures and under the seminatural conditions. This implies that there is no diapause in T. funiculatum. Instead this species overwinters via a combination of slow development, or quiescence, coupled with increased adult longevity. This information should be useful in enhancing populations of this parasitoid in spring when T. funiculatum can suppress light brown apple moth and other pests.

Overwintering mortality of forest tent caterpillar [Malacosoma disstria (Hübner)] eggs was estimated over a 360 km² grid of 83 plots in north-central Alberta over the period 1992–1996 during a local outbreak. Egg mortality in the trembling aspen (Populus tremuloides Michaux) canopy was generally low; however, 20% of the eggs laid in the summer of 1995 failed to hatch in the spring of 1996. In the shrub layer, 70% failed to hatch. In both the canopy and shrub layers, the spatial pattern of mortality was density-independent, with high mortality occurring in low-lying areas. Daily temperature records suggested that the proximal cause of death was freezing during mid-winter. Caterpillar populations peaked in 1995, before perturbation, and collapsed during the summer of 1996, largely as a result of larval parasitism. The timing of this perturbation-assisted population collapse coincided loosely with the penetration of larvae down into the shrub layer. We illustrate how winter temperature, albeit a density-independent factor, probably acts in a partially density-dependent manner through interactions with density-dependent behavioral and physiological processes that influence spatial variation in vulnerability and susceptibility to winter cold. We argue that cold winter temperatures are an important factor influencing the long-term dynamics of forest tent caterpillar populations in northern climates.

The influence of Bacillus thuringiensis Berliner (Bt) cotton on population dynamics of cotton aphid, Aphis gossypii Glover, was investigated during 1999–2000 in northern China. The field experiments were conducted in plots of Bt cotton and conventional cotton that received no insecticide applications, and in plots of conventional cotton in which pyrethroid and organophosphate insecticides were used regularly for control of Helicoverpa armigera. The results indicate that resistance of cotton aphids to majority of insecticides used for control of H. armigera, and lower densities of predators in late June and early July caused by insecticide use, causes population densities of cotton aphids to become significantly higher in plots of insecticide-treated conventional cotton than in Bt cotton plots. These results suggest that Bt cotton planting not only played an important role in the control of H. armigera, but also efficiently prevented cotton aphid resurgence in response to insecticide use.

We studied the spatio-temporal dispersion patterns of Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in a mixed, deciduous, fruit orchard in Thessaloniki (northern Greece), using spatial autocorrelation methods to analyze adult trapping data. Each trapping station consisted of a Jackson trap (baited with trimedlure) and a McPhail trap (baited with ammonium acetate, putrescine, and trimethylamine). More males than females were captured throughout the season. Males and females exhibited different spatial dispersion patterns. Females were first detected during the summer (June–July) in apricot and peach trees bearing ripe fruits and significantly aggregated there toward the end of July. In the autumn, females significantly aggregated in apple orchards bearing mature fruits. Early aggregations of males were first detected in August in cherries and plums. In September, males significantly clustered in pears at the edges of the orchard, and by October, after an increase in population density, their spatial dispersion pattern became random (no significant spatial autocorrelation). At the end of the season (November), the dispersion of both sexes became random. Our results show that spatial autocorrelation statistics can provide an important tool in studying the spatial dynamics of this fly even in small orchards. Results also suggest that the incorporation of knowledge on spatial patterns into area-wide control projects may improve monitoring efforts and reduce program costs.

The life history data of the predator Propylaea japonica Thunberg at 25°C fed on Myzus persicae (Sulzer) were collected in the laboratory. To take both sexes and the variable developmental rate among individuals into consideration, the raw data were analyzed based on the age-stage, two-sex life table. The intrinsic rate of increase for P. japonica is 0.1133 d⁻¹. The net reproductive rate is 67.6 offspring and the mean generation time is 37.7 days. To incorporate the age-stage variability of the predation rate with the two-sex life table, the daily predation rate of individual P. japonica of both sexes was collected for each predatory stage. The net predation rate for P. japonica is 1199.5 aphids.

Oviposition behavior is an important mechanism for establishing spatial distribution and mitigating potential interactions among community members. We studied the oviposition behavior of the European corn borer, Ostrinia nubilalis Hübner, in the presence of conspecific larvae, the aphid Rhopalosiphum maidis (Fitch), and corn pollen to determine whether these potential interacting factors affect the distribution of European corn borer egg masses laid on sweet corn in field cages. We found that ovipositing females in the field differentiate between adjacent corn plants in response to conspecific larvae. We also found that European corn borers laid significantly fewer egg masses on plants with large aphid colonies compared with adjacent plants with few aphids. Furthermore, fewer egg masses were laid on the top one third of the plant where the aphid colonies were located. We also tested for a fitness advantage of European corn borer’s oviposition behavior in response to aphids and found that neonate larvae inoculated on plants with small aphid colonies had higher establishment (survivorship retention) than larvae on plants with large aphid colonies. Pollen, disentangled from any effects of differential plant stage, did not seem to affect oviposition behavior. These results may have important implications for understanding the spatial distribution and interaction of European corn borer, its natural enemies, and potential management strategies.

The grape berry moth, Endopiza viteana (Clemens) feeds on wild and cultivated Vitis spp., causing economic damage in the latter. We studied incidence of pheromone trap catch data, and combined this with previous work on development and diapause to construct a comprehensive model of the temporal dynamics of E. viteana. We explored the behavior of this model in six eastern United States locations along Lakes Erie and Michigan, the Finger Lakes in New York, and in Missouri and Virginia. Voltinism of E. viteana is influenced by the accumulated growing degree-days before the postsummer solstice photoperiod at which eggs develop exclusively into diapausing pupae. Our model generally predicted two full and a partial third generation in Geneva, NY, whereas partial fourth generations existed in vineyards along Lakes Erie and Michigan. In more southern latitudes, such as Missouri and Virginia, the absence of a partial fourth generation would be rare. Also, our model suggested the presence of clinal latitudinal variation in diapause induction, with southern populations of E. viteana responding to shorter daylengths than northern populations. These predictions, based on average 10-yr surface temperatures (1991–2000), are supported by past observations and explain the variability in voltinism from year to year that has been reported in the northeastern United States and Niagara Peninsula of Canada.

Understanding the changes in biodiversity correlated with urbanization is essential for monitoring the complex effects of human activity on native ecosystems. We hypothesized that the Drosophila community native to temperate woodland forests would change along a gradient of urbanization, and could therefore serve as a model system in studies on urbanization. We used an urbanization gradient we had previously characterized in Southwest Ohio. Community composition gradually changed along the gradient, although community diversity did not. Abundance varied significantly among sites, with one species, Drosophila melanogaster, increasing in abundance from the least to the most urbanized sites. We used 28 parameters from three sets of environmental data—land cover, vegetation, and temperature and humidity—to build a model with Canonical Correspondence Analysis and characterize the species-environment relationship. The most predictive variables explaining the distribution of the Drosophila community were maximum temperature, maximum saturation deficit, percent lawn cover, average diameter at breast height (dbh) of shrubs and trees, and number of tree species. We conclude that the presence of individual, easily identifiable Drosophila species may serve as robust indicators of the habitat degradation brought about by urbanization, and as ideal models for exploring animal response to urbanization.

We investigated herbivore suitability, foliar chemistry, and seedling growth of blight-susceptible pure American chestnut, Castanea dentata (Marsh.) Borkh., and a blight-resistant Chinese chestnut, Castanea mollisima Blume × American chestnut hybrid, using supplemental fertilizer and ectomycorrhizal inoculation to affect nutrient availability and nutrient uptake, and the gypsy moth, Lymantria dispar (L.), to measure herbivore suitability. Gypsy moth performance was best on fertilized hybrid seedlings, and was lowest on untreated American chestnut seedlings. Foliar carbohydrates were greatest, and tannin levels were lowest, in mycorrhizae-inoculated American chestnut. Foliar nitrogen was also high in mycorrhizal American chestnut, and was equivalent to that found in fertilized seedlings of both species. American chestnut seedlings had greater height and diameter growth than hybrids, regardless of soil amendments. Our results suggest that blight resistance may exact a cost in plant growth and productivity for this chestnut hybrid, and may enhance plant suitability for a generalist herbivore. Additionally, enhanced gypsy moth performance on blight-resistant chestnut hybrids has implications with respect to the restoration of chestnut to eastern deciduous forests, because intense herbivore pressure could compromise seedling growth and survival, and play a role in sustaining potentially damaging gypsy moth populations. The implications of this work within the context of current theories addressing herbivore–plant relations are discussed.

Four different corn, soybean, and wheat cropping systems were established in small replicated plots and simultaneously in larger (4-hectare) unreplicated fields. Each system was subject to distinct tillage practices, fertility programs, and methods of pest control, based on methods currently in use on farms in the Mid-Atlantic region of the United States. Ground-dwelling arthropods (mostly Carabidae and spiders) were sampled during the fourth and sixth growing season after the establishment of the plots, and foliar insects (pest and beneficial) and pest damage were sampled on corn in the sixth growing season. Overall, beneficial arthropod populations were lowest and corn pest insect populations (especially Western corn rootworms, Diabrotica virgifera virgifera LeConte) were highest in the simplest, most intensively managed continuous corn system, which had annual use of soil insecticides. Generally ground-dwelling species were higher in soybeans than in corn, and in no-till than in deep-tilled crops. Growers wishing to enhance populations of beneficial insects should consider predominantly no-till cropping systems with several different crops in the rotation and minimal insecticide use. For both ground and foliar sampling, patterns of abundance among systems and crops in the small replicated plots generally followed those observed in the large fields, but numbers of spiders and carabids collected per pitfall trap were generally much higher in the large fields.

We compared the performance of three Metaphycus spp. (Hymenoptera: Encyrtidae) as potential biological control agents of black scale, Saissetia oleae (Olivier), on southern California citrus. Metaphycus sp. nr. flavus (Howard), Metaphycus helvolus (Compere), and Metaphycus luteolus (Timberlake) were released into sleeve cages covering black scale infested citrus branches. As indicators of biological control, we assessed scale survival and the percentage of scales parasitized by Metaphycus spp. Three release timings were evaluated (11 November, 24 December, and 28 February). For each release date, terminals were retrieved on three occasions (0.5–1 mo after release, 1.5–2.5 mo after release, and immediately before female scales began reproducing, i.e., mid-May to mid-June). Only M. sp. nr. flavus significantly reduced black scale survival and increased parasitism rates compared with background levels. Metaphycus helvolus showed a tendency to reduce scale survival, although no effect of M. luteolus was evident. To further evaluate M. sp. nr. flavus, an open-field release experiment was performed. An excess of 2,700 female parasitoids per tree, released over a period from January to April, significantly reduced black scale survival and increased parasitism on the trees where the parasitoids were liberated. A tendency of increased scale parasitism on trees adjacent to release trees was observed, but no effect on scale survival was evident. Given our results, and considering that M. sp. nr. flavus can be reared on brown soft scale, Coccus hesperidum L., which is easier to rear than black scale, the required host for M. helvolus, developing M. sp. nr. flavus as an augmentatively released biological control agent against black scale may result in more economic biological control than is the case with the currently released M. helvolus.

Zwittermicin A acts synergistically with the insecticidal activity of Bacillus thuringiensis subsp. kurstaki Berliner against gypsy moth (Lymantria dispar (L.)) larvae. The objective of this study was to assess the influence of insect source and diet on this synergy. Zwittermicin A increased the mortality caused by B. thuringiensis subsp. kurstaki in gypsy moths collected from four population sources feeding on artificial diet, and on larvae feeding on four tree species, in a dose-dependent manner. Zwittermicin A did not cause mortality of L. dispar when applied alone. The ability of zwittermicin A to act synergistically with B. thuringiensis subsp. kurstaki did not differ greatly among these four populations, although mortality was slightly lower in a field-collected population from Michigan. Zwittermicin A increased the activity of B. thuringiensis subsp. kurstaki on L. dispar feeding on white oak, aspen, larch, and willow. Larval mortality was directly proportional to the concentration of zwittermicin A applied to foliage, although the synergistic effect of zwittermicin A differed among host species. These results suggest strategies for employing synergists in the application and resistance management of microbial pesticides.

We evaluated the effect of endophyte infection in the two turfgrasses tall fescue (Festuca arundinacea Schreber) and strong creeping red fescue (F. rubra L. ssp. rubra) on the susceptibility of three white grub species to the entomopathogenic nematode Heterorhabditis bacteriophora Poinar. Endophyte infection in strong creeping red fescue (only tested under greenhouse conditions) had no effect on nematode-susceptibility of third-instar oriental beetle (Exomala (=Anomala) orientalis Waterhouse) and northern masked chafer (Cyclocephala borealis Arrow). In tall fescue under greenhouse conditions, endophyte infection had a weak and variable enhancing effect on nematode-susceptibility of second- and third-instar E. orientalis and no effect on nematode susceptibility of third-instar C. borealis and Popillia japonica. However, under field conditions with natural white grub populations, endophyte infection in tall fescue had no significant effects on nematode efficacy against E. orientalis, P. japonica, and C. borealis. While it is possible that stronger interactions between endophytes and nematodes may occur with different grass species, cultivars, and endophyte strains, nematode-endophyte interactions appear to be too variable to allow predictions on nematode efficacy based on turfgrass endophyte status.

We assess the geographic distribution and rate of spread of Oxyops vitiosa (Pascoe), a classical biological control agent of the invasive Australian tree Melaleuca quinquenervia (Cav.) S.T. Blake. This weevil has been released at 135 locations in south Florida, where it now occurs in 9 of 19 infested counties. When averaging dispersal distances among four representative sites, O. vitiosa spread at a rate of 0.99 (±0.28) km/yr, ranging from 0.10 to 2.78 km/yr. The rate of spread by O. vitiosa across melaleuca-dominated habitats was influenced by both ecological- and human-mediated parameters, including M. quinquenervia stand fragmentation (spatial separation among host plants), the number of weevils released, and time since release. The rate of spread was positively correlated with stand fragmentation level: high = 2.04, medium = 1.07, and low = 0.30 km/yr. By incorporating the dispersal rate from the highest fragmentation level into a simulation model we predicted that 138 months (June 2008) would be required for 50% of the habitat currently invaded by melaleuca to become infested at an economic weevil density (0.5 individuals per branch tip). At medium and low fragmentations, the model predicts 182 (February 2012) and 191 (November 2012) months, respectively. After examining the output from this basic model, we identified 16 possible redistribution sites that may accelerate the spread of the weevil.

Nontarget arthropod populations were monitored in both transgenic and nontransgenic corn and soybean fields in western and central Ohio. A total of 24 fields, 12 corn and 12 soybean, were inspected weekly from late June through mid August. Half of the cornfields were Bacillus thuringiensis (Bt) hybrids and half of the soybean fields were Roundup Ready (RR). Sweep net samples in soybean fields and unbaited Pherocon AM yellow sticky traps in both soybean and cornfields were used to collect nontarget arthropods. Soil samples were also taken from all 24 fields to compare soil mite populations. A select group of 15 readily identifiable arthropods composed mainly of beneficial insects commonly found in field crops, were recorded in weekly sweep net and sticky trap samples for later analysis. Sweep net data from soybean fields revealed no significant differences in nontarget arthropods. Yellow sticky trap data from soybean and corn fields found significantly more green lacewing adults (Chrysopa spp.) in six pooled non-RR soybean fields, significantly more rove beetles in one non-Bt cornfield, and significantly more Orius spp. in one Bt cornfield. There were also significantly more soil inhabiting mites at one non-RR soybean field. Based on the abundance of these arthropod populations in paired transgenic and nontransgenic fields, few negative effects on the 15 nontarget arthropods selected can be directly associated with transgenic soybean and corn crops in Ohio.

Oviposition preferences of a herbivore, the wheat midge Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), on wheat were investigated in relation to two hypotheses: female preferences are adapted to offspring performance; plants may evolve independent defenses that both deter oviposition and reduce offspring performance. Variation in egg density and larval performance were measured for three plant genotypes: a preferred, susceptible wheat; a less preferred, susceptible wheat; a less preferred wheat defended against larval feeding. Oviposition peaked 10–11 d after emergence of the inflorescences and then declined sharply on all three wheat genotypes, although the inflorescences of the genotypes developed at different rates. On the preferred, susceptible wheat, larval performance was high for oviposition that occurred until pollination and low later. On a less preferred wheat, larval performance was high when eggs were laid before or after pollination. On a defended wheat, larval performance was always low. Oviposition preference was associated with larval performance that varied with plant developmental stage, but imperfectly, possibly because females do not detect cues for seed development. Females deposited eggs further from larval feeding sites when ovipositing on less preferred wheats, regardless of whether larval performance on the wheat was high or low. A low preference in combination with a shift in oviposition site supports the hypothesis that some wheats have evolved a defense that deters oviposition. This defense against oviposition is independent of a defense that reduces larval performance, which causes an apparent failure in the expected preference-performance relationship.