Status of resistance to Bt cotton in China: cotton bollworm and pink bollworm.

Abstract Transgenic cotton that expresses a gene derived from the bacterium Bacillus thuringiensis (Bt) has been deployed for combating the cotton pests Helicoverpa armigera and Pectinophora gossypiella since 1997 in China. The pest management tactics associated with Bt cotton have resulted in a drastic reduction in insecticide use. However, the evolution of resistance by the pests threatens the continued success of Bt cotton. The development of resistance to Bt is of great concern, and there is a vast body of research in this area aimed at ensuring the continued success of Bt cotton. Here, we review studies on the evolution of Bt resistance in these two bollworms, focusing on the commercial release of Bt cotton varieties in China, and the biochemical and molecular basis of Bt resistance. We also discuss resistance management strategies, and monitoring programmes implemented in China and other countries.