Abstract: 【Objective】Cotton planting region in southern Xinjiang has become one of the most important regions for China′s cotton production. As a major negative factor in cotton industry, cotton bollworm, Helicoverpa armigera, possesses a biological potential to outbreak in this region. 【Method】 The current research results on trend of occurrence of H. armigera and control efficacy of Bt cotton in southern Xinjiang are reported. 【Result】The monitoring on population density of the pests in wheat field from 1993 to 2004 indicated that as the regulation of cotton-corn planting system in southern Xinjiang, the occurrence and damage of H. armigera increased year by year after 1997, and it has become a main pest in agriculture in comparison with old system containing a small proportion of cotton. The field trials on population dynamics of cotton bollworm on GM cotton varieties expressing Cry1A toxin and Cry1A/CpTI, and their parental varieties during 2002-2004 showed that the second generation bollworm mainly injure cotton, and the control efficacies from both GM cotton varieties were more than 75%. It is suggested that the Bt cotton could effectively control damages caused by cotton bollworm in the moderate outbreak year. 【Conclusion】In view of the severe damage of cotton bollworm, it is necessary to develop a cotton IPM system based on the application of GM cotton varieties in southern Xinjiang.

Key words: cotton bollworm, population dynamics, Bt cotton, Xinjiang