Monitoring of key non-target arthropods in insect-resistant transgenic maize linesduring 2010 and 2011 in field studies in central Germany

Abstract: In Europe, sustainable land use management is a primary environmental protection goal. Compared to conventional crop production aided by chemical insecticides, insect-resistant transgenic crop production can enhance animal and plant biodiversity and thus ecological services such as biological control of pests and diseases, as well as reducing the need for chemical inputs. The objective of this study was to evaluate the impact of insect-resistant transgenic maize hybrids on the abundance of key non-target arthropods. During the 2010 and 2011 seasons, three treatments were compared, one Bt-transgenic maize hybrid targeting Ostrinia nubilalis, the corresponding non-Bt control (negative control), and the non-Bt control treated with insecticide (positive control), each with four replications. Two monitoring methods, pitfall and sticky traps, were used to collect non-target arthropods.Arthropods caught in pitfall traps differed significantly between years. Carabids and collembolans were more abundant in 2010 than in 2011. In contrast, staphylinids and millipedes were more abundant in 2011 than in 2010. Arthropod abundance based on captures on sticky traps also differed significantly between the 2010 and 2011 seasons. Aphids and parasitoid wasps (chalcidids, ichneumonids, and braconids) as well as predators (lacewings, dance flies and spiders) were more abundant in 2011 than in 2010. In contrast, thrips, leafhoppers, mirids, and the beneficial insects Aeolothrips intermedius, syrphids, and Propylea spp. were more abundant in 2010 than in 2011. Most arthropods were recorded at the VT growth stage (fully visible tassel). Overall, we observed stronger variability between study years than among treatments. Furthermore, our study results indicate that biodiversity is greater in untreated Bt-transgenic maize compared to non-Bt maize treated with conventional insecticides. Thus, transgenic maize should be considered for sustainable land use management.