Assessing the effect of Bt hybridization on lepidopteran-based food webs in wild rice

Transgenic rice varieties conferring resistance to Lepidoptera have recently been released or 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 rice hybridizing with wild rice is a concern. To predict the impact of Bt hybridization on lepidopteran-based food webs, we created Bt hybrids in the lab, and reared lepidopteran food webs on Bt-hybrids and control hybrids in caged mesocosms. As expected, rice-feeding Lepidoptera were negatively affected by Bt hybridization. Impacts on non-lepidopteran arthropods were diffuse. 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.