Potential non-target impacts on lepidopteran-based food webs from Bt transgene flow into wild rice

Transgenic rice varieties with Bt endotoxins are currently being evaluated for release in several Asian countries. A major environmental biosafety concern is the consequence of transgene escape into wild rice. We surveyed species richness, and the abundance and diversity of of non-target Lepidoptera and natural enemies in wild rice ecosystems found in the Mekong Delta of Vietnam. We found that wild rice (Oryza rufipogon) supported a more diverse and structurally complex arthropod community than cultivated rice. Three lepidopteran species abundant in wild rice were examined for their susceptibility to the Bt cry1Ac toxin. While there was variation in the level of susceptibility, the bioassays found that all three lepidoteran species were susceptible to the cry1Ac toxin. Therefore, Bt transgene flow has the potential to significantly impact the abundance of Lepidoptera in wild rice and the stability of lepidopteran-based food webs.