Predicting the response of lepidopteran-based food webs to Bt transgene escape

Transgenic rice varieties conferring resistance to Lepidoptera are currently being evaluated for large-scale release in several Asian countries. Because wild rice congeners are commonly found near cultivated rice fields in Asia, the possibility of Bt transgene escape is a concern. To predict the impact of Bt transgene flow on lepidopteran-based food webs, we created Bt hybrids in the lab. We then reared food webs composed of C. medinalis and N. lugens herbivores, as well as several predaceous arthropods, on hybrids and control plants in caged mesocosms. Although Bt hybrids had no impact on the abundance of non-lepidopteran arthropods, biomass may be impacted by Bt transgenes. We discuss the implications of these results for the potential impact of Bt transgene escape on the structure and stability of endemic arthropod food webs in wild rice.