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.

Resistance to Bacillus thuringiensis toxin Cry2Ab and survival on single‐toxin and pyramided cotton in cotton bollworm from China

“…Nevertheless, the frequency of resistance to Cry1Ac has regularly and significantly increased in populations of two target pests, Helicoverpa armigera and Pectinophora gossypiella, indicating that replacement of Cry1Ac cotton with pyramided Bt cotton is needed to counter the threat of resistance (Jin et al., ; Tabashnik, Wu, & Wu, ; Wan et al., ; Wu, ; Zhang et al., ). Because Cry1Ac+Cry2Ab cotton may provide appropriate control of both pests when the frequency of resistance to at least one of the toxins is low (Downes & Mahon, ; Fabrick et al., ; Mahon & Olsen, ; Tabashnik et al., ), this pyramid has been evaluated for replacement of Cry1Ac cotton in China (Gao, Liu, Wu, & Wu, ; Tabashnik et al., ). Here, we used laboratory experiments to better understand the risk of H. armigera resistance to Cry1Ac+Cry2Ab cotton in China, by assessing several of the conditions underlying success of the refuge strategy for delaying resistance to this pyramided Bt crops.…”