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.

Classical biological control can be an important tool for managing invasive species such as emerald ash borer (EAB), Agrilus planipennis Fairmaire. Emerald ash borer was first detected in Maryland in 2003, and the biological control program to manage this beetle in Maryland was initiated in 2009. Here we examine the establishment and abundance of two introduced parasitoids of EAB larvae (Spathius agrili Yang and Tetrastichus planipennisi Yang). Overall, 56,677 S. agrili and 191,506 T. planipennisi were released at 26 and 32 sites, respectively, from 2009-2014. Monitoring parasitoids involved debarking trees, and harvesting trees to place in rearing barrels, and was conducted at 47 sites (23 of which received parasitoids, and 24 of which served as controls) from 2010-2015. We recovered 77 S. agrili from 16 EAB larvae at six sites, and 1,856 T. planipennisi from 110 EAB larvae at 19 sites. Percentage parasitism by T. planipennisi, and the mean percentage of trees containing T. planipennisi broods, were positively associated with the number of years post-release of the parasitoids (reaching 11.6 % and 41.7% four years post-release, respectively). The relationship between T. planipennisi parasitism and tree size was best described by an exponential decrease model, with over 95% of parasitism occurring in trees with a diameter at breast height of <16 cm. In conclusion, T. planipennisi has established populations and dispersed in Maryland, while S. agrili releases have been largely unsuccessful. These findings are a step towards optimizing EAB biological control release and recovery strategies, and are particularly pertinent for other states in the Mid-Atlantic region.

Emerald ash borer (EAB) Agrilus planipennis Fairmaire is an invasive non‐native woodboring beetle that has killed hundreds of millions of ash trees (Fraxinus spp.) in North America. Identifying the arthropod community associated with ash trees has been highlighted as an important research requirement in understanding the wider effects of EAB. We harvested live ash trees infested with EAB at 37 sites in Maryland from 2011 to 2014 and collected a total of 2031 arthropods. All arthropods were identified to order and 94.6% were identified to family or below. The community comprised 13 orders, 60 families and 41 genera, with 28 arthropod species identified. Coleoptera, Diptera, Hymenoptera and Lepidoptera accounted for 98.3% of arthropods collected. Data on changes in richness and diversity over time were fitted to second‐order polynomial models, corresponding with a transition in the dominant taxa from woodboring beetles (Cerambycidae) to parasitoids (Braconidae and Eulophidae). This resulted in changes to community composition as the EAB infestation intensified. The findings of the present study provide further evidence of the diversity of arthropods at risk from EAB. Given the number of invasive non‐native insects threatening North American forests, establishing what taxa are present is important for predicting the likely broader impacts of these invasions.

Field-cage methods were developed to evaluate the abilities of Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) and Spathius agrili Yang (Hymenoptera: Braconidae), biocontrol agents of Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), to parasitize, develop and overwinter following three late-season releases at both a northern (Michigan) and a southern (Maryland) location within the current North American range of A. planipennis. In August, September and October of 2009, five young green ash trees were selected at each location. Tetrastichus planipennisi and S. agrili were each randomly assigned to one of two cages attached to each tree, surrounding separate sections of trunk in which late-instar A. planipennis had been inserted. The following April, the caged trunk sections were dissected to determine the fate of each A. planipennis larva and the developmental stages of all recovered parasitoid progeny. At both locations, T. planipennisi and S. agrili were able to parasitize hosts and successfully overwinter (i.e., reach adulthood the following spring). For T. planipennisi, successful parasitism (i.e., parasitoid progeny reached adulthood) occurred for all caged releases in Maryland, but only for the August and September releases in Michigan. At both locations, percent parasitism by T. planipennisi was higher in August and September than in October. For S. agrili, successful parasitism occurred for all caged releases in Maryland, but only for the August release in Michigan. In Maryland, percent parasitism by S. agrili in August and September was higher than in October. The caging method described here should be useful in determining the climatic suitability of other regions before proceeding with large-scale releases of either species and may have utility in other wood-borer parasitoid systems as well.

Emerald ash borer (EAB) (Agrilus planipennis) is one of the most destructive insect pests of urban trees in the United States. The objective of the current study was to determine the rate of spread of EAB in a quarantine zone where aggressive intervention tactics such as tree destruction occurred. Historical records were examined from the Maryland Department of Agriculture for the years 2003, 2006, 2007, and 2008, to determine the rate of spread of EAB in Maryland, U.S., within the quarantine zone. Despite attempts at eradication and public education, EAB persisted, and the leading edge of beetles moved away from the central infestation point at an average annual rate of 1 km per year and a maximum annual rate of 1.37 km per year between 2003 and 2008. This paper discusses the relative merits and limitations of this quarantine and eradication program and makes suggestions for future management of EAB.