A large number of transgenic crop varieties expressing the Bt (Bacillus thuringiensis) insecticidal proteins have been commercialized in 13 countries since 1996. Although the use of these insect-resistant Bt crops can increase crop quality and yields, concerns remain about the potential negative effects of such crops on ecosystems. Transgenic soybean containing cry1Ac gene have been developed to control Lepidopteran pests of soybean and we aimed to investigate whether this soybean could affect non-target arthropods, which play a major role in ecological functions in agricultural ecosystems. In the present study, we first measured the levels of Cry1Ac protein in Bt soybean at different growth stages of soybean and then we compared the community structure of arthropods occurred in fields of transgenic and wild-type soybean. The levels of Cry1Ac protein in transgenic soybean leaves ranged from 252.9 to 604.5 μg g-1 DW. Multivariate analyses (PerMANOVA and NMDS) showed that the composition of the non-target arthropod community was affected by sampling date but not by soybean genotype. These results suggest that transgenic soybean expressing Cry1Ac protein may not adversely affect such non-target arthropod communities.

Under field conditions, we investigated how transgenic Bt cabbage expressing the insecticidal Cry1Ac1 protein affects two target Lepidoptera species — Plutella xylostella (Plutellidae) and Pieris rapae (Pieridae) — as well as the structure of the local non-target arthropod community. When exposed to Bt cabbage line C30, Plutella xylostella and Pieris rapae were significantly less abundant than when in the presence of the non-transgenic control. Multivariate analyses (PerMANOVA and NMDS) showed that composition of the non-target arthropod community was affected by sampling date but not by cabbage genotype. These results suggest that transgenic cabbage expressing Cry1Ac1 protein can be effective in controlling Plutella xylostella and Pieris rapae in the field and that cultivation of this cabbage may not adversely affect such non-target arthropod communities.

Transgenic lines of insect resistant cabbage (Brassica oleracea var. capitata) expressing Cry1Ac1 protein has been developed to control diamondback moth (Plutella xylostella). The potential adverse effects of Bt crops on non-target arthropod herbivores and predators are major concerns. We conducted a tritrophic bioassay to study the ecological impacts of insecticidal transgenic cabbage on the wolf spider (Pardosa astrigera), a non-target generalist predator. First, we measured the levels of Cry1Ac1 proteins in fruit flies that were fed with the transgenic cabbage as well as those levels in the wolf spiders preying on the Bt cabbage-fed fruit flies using enzyme linked immunosorbent assay (ELISA). Cry1Ac1 proteins were detected in the Bt cabbage fed fruit flies and also in the wolf spiders after preying on Bt cabbage-fed fruit flies. Second, we compared the life history characteristics of the wolf spiders preying on the Bt or non-Bt cabbage. Growth, development time and survival of the wolf spiders were not significantly different between Bt and non-Bt cabbage. Although the wolf spiders were exposed to Cry1Ac1 protein via feeding on the preys containing Cry1Ac1 proteins, their growth and survival was not significantly affected.