Transgenic crops containing the bacterium (Bt) genes reduce pests and insecticide usage, promote biocontrol services, and economically benefit growers. Area-wide Bt adoption suppresses pests regionally, with declines expanding beyond the planted Bt crops into other non-Bt crop fields. However, the offsite benefits to growers of other crops from such regional suppression remain uncertain. With data spanning 1976-2016, we demonstrate that vegetable growers benefit via decreased crop damage and insecticide applications in relation to pest suppression in the Mid-Atlantic United States. We provide evidence for the regional suppression of (Hübner), European corn borer, and (Boddie), corn earworm, populations in association with widespread Bt maize adoption (1996-2016) and decreased economic levels for injury in vegetable crops [peppers ( L.), green beans ( L.), and sweet corn ( L., convar. )] compared with the pre-Bt period (1976-1995). Moth populations of both species significantly declined in association with widespread Bt maize (field corn) adoption, even as increased temperatures buffered the population reduction. We show marked decreases in the number of recommended insecticidal applications, insecticides applied, and damage in vegetable crops in association with widespread Bt maize adoption. These offsite benefits to vegetable growers in the agricultural landscape have not been previously documented, and the positive impacts identified here expand on the reported ecological effects of Bt adoption. Our results also underscore the need to account for offsite economic benefits of pest suppression, in addition to the direct economic benefits of Bt crops.

Sweet corn, Zea mays L., transformed to express a novel vegetative insecticidal protein, Vip3A (event MIR162, Syngenta Seeds, Inc..), produced by the bacterium, Bacillus thuringiensis (Bt), was evaluated over four field seasons in Maryland and two field seasons in Minnesota for efficacy against the corn earworm, Helicoverpa zea (Boddie). Hybrids expressing the Vip3A protein and pyramided in hybrids also expressing the Cry1Ab Bt protein (event Bt11, ATTRIBUTE(®), Syngenta Seeds, Inc.) were compared to hybrids expressing only Cry1Ab or to genetically similar non-Bt hybrids each year. In addition to H. zea efficacy, results for Ostrinia nubilalis (Hübner) and Spodoptera frugiperda (J.E. Smith) are presented. Over all years and locations, the non-Bt hybrids, without insecticide protection, averaged between 43 and 100% ears infested with a range of 0.24 to 1.74 H. zea larvae per ear. By comparison, in the pyramided Vip3A x Cry1Ab hybrids, no larvae were found and only minimal kernel damage (likely due to other insect pests) was recorded. Hybrids expressing only Cry1Ab incurred a moderate level of H. zea feeding damage, with surviving larvae mostly limited to the first or second instar as a result of previously documented growth inhibition from Cry1Ab. These results suggest that the Vip3A protein, pyramided with Cry1Ab, appears to provide the first "high-dose" under field conditions and will be valuable for ongoing resistance management.

Eggplant Solanum melongena L., is often colonized by two early season insect defoliators. The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), and flea beetles Epitrix spp., emerge from their overwintering sites in early spring and seek out emerging host plants such as eggplant. During the 2009 and 2010 growing season, field studies were conducted to investigate the impact of inter‐planting eggplant into a crimson clover (CC), Trifolium incarnatum L., winter cover crop on populations of flea beetles, CPB and their associated arthropod predators. The experiment consisted also of two levels of insecticide usage such as an application of azadirachtins plus pyrethrins followed by several applications of spinosad or no insecticide sprays as subplot treatments. During both study years, significantly fewer (adults, larvae and egg masses) were found on eggplant inter‐planted into CC than in bare‐ground (BG) eggplant plots. Although flea beetle abundance was greater in BG eggplant during 2010, they appeared to be less influenced by the presence of CC than were CPB. Additionally, there was no apparent impact of insecticide treatment on CPB populations on eggplant inter‐planted into CC. However, there was a decline in CPB following treatments with insecticides in BG eggplant plots. This suggests that a winter cover crop such as CC can be used to help manage CPB in eggplant, however, using this tactic in tandem with insecticide sprays may not result in greater CPB management.

The effect of using crimson clover (CC) (Trifolium incarnatum L.) as a companion plant on crop growth, marketable yield and insect feeding injury was examined using Eggplant, Solanum melongena L. as the neighbouring cash crop. There were two subplot treatments, which included applications of organic insecticides and no insecticides. Planting eggplant directly into CC did not improve most eggplant growth variables and resulted in a yield reduction during year 1. During year 2, when the CC was strip-tilled prior to transplanting the eggplant, several eggplant growth variables were more strongly enhanced in CC than bare-ground (BG) habitats. Eggplant in CC plots suffered less damage by insect folivores but yields were similar among treatments. There were no benefits of using organic insecticides with respect to increased marketable yields in CC treatment plots, but there was an increase in marketable yield in sprayed compared with unsprayed BG subplots. If properly managed, CC may help protect eggplant from insect feeding injury; however, this may not cause an increase in marketable yield.

European corn borer (ECB, Ostrinia nubilalis Hübner) and corn earworm (CEW, Helicoverpa zea Boddie) are important yield-reducing insect pests of fi eld corn (Zea mays L. var. indentata) in the northeastern United States. Transgenic hybrids bioengineered to express insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have revolutionized methods to control these caterpillars and other insect pests in corn. However, corn producers are faced with two decisionmaking challenges every year: selection of the most appropriate Bt hybrids for the targeted pest complex from a large list of commercially available hybrids, and fi nding competitively yielding conventional hybrids for the required refuge hectare. Th is study was conducted at fi ve sites across Maryland for 3 yr to evaluate more than 100 hybrids representing six Bt trait groups (three single-protein and three multi-protein genes) and a conventional non-Bt group for their relative susceptibility to lepidopteran feeding injury and yield performance. Conventional hybrid tolerance to ECB injury or CEW ear damage and their yield varied each year except Dekalb DKC61-22, which consistently produced greater yield than other non-Bt hybrids. Injury caused by ECB was not found among any of the Bt hybrid groups. Hybrids with multi-protein Bt traits showed greater ear protection than those with single-protein Bt traits, but this improvement was small. Genuity VT3 Pro and Agrisure Viptera 3111 hybrids had the best ear protection and yield performance among the six tested Bt traits.

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