Seasonal pattern of infestation by pink bollworm Pectinophora gossypiella (Saunders) in field plots of Bt transgenic cotton in the Yangtze River valley of China

Two transgenic cotton lines (BG1560 and GK19) carrying a Cry1A gene from Bacillus thuringiensis subsp. kurstaki (Berliner), developed, respectively, by Monsanto Co. and Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, were evaluated for resistance to pink bollworm Pectinophora gossypiella (Saunders) in field plots in Tianmen County of Hubei Province, located in the Yangtze River valley of China during 2001 and 2002. The results showed that there were no significant differences in egg density among the two Bt cotton lines and a conventional cotton line, but larval densities on both Bt lines were significantly lower than on the conventional line in both years. In comparison with the larval density on a conventional line without chemical control, the control efficacy in different growth stages of cotton in several treatments were 89-100% for BG1560, 73-100% for GK19, and 54-88% for chemically treated conventional cotton, where insecticides were sprayed 9 times in 2001 and 11 times in 2002 for control of pink bollworm. We conclude that Bt cotton planting in the Yangtze River region possesses a high potential for control of pink bollworm. (C) 2003 Elsevier Ltd. All rights reserved.