关键词: 棉铃虫, 转Bt基因, 抗虫棉, 抗性, 模型

Abstract: The commercial use of transgenic cotton expressing an insecticidal protein gene from Bacillus thuringiensis (Bt) began in 1998 in northern China. Resistance management is a major concern for the sustainable use of Bt cotton. With our understanding of the cropping and ecological system in northern China, we developed a simulation model to forecast adaptation of the cotton bollworm, Helicoverpa armigera (Hübner), to Bt cotton. The model incorporated population genetics, biological and operational factors in a multiple cropping system. Variables of reproductive fitness on different host plants, dominance of resistance alleles, expression level of Bt toxin in cotton and use of insecticides in Bt cotton fields were included in the model. In the typical cropping system of northern China, the expected life of Bt cotton are seven years if all cotton is Bt cotton, and ten years if only spring planted cotton (about 70% total cotton area) is Bt cotton in northern China besed on the model. The life expectancy decreases quickly with increases in initial frequency of resistance allele, dominance of the resistance gene, and the percent area of Bt cotton planted. The results also showed that supplemental control is essential on Bt cotton when the expression of Bt toxin declines. Because of the lack of a consistent high dose and the complexity of managing individual fields of Bt cotton by many different growers in the same region, the use of the high-dose/refuge strategy in northern China will be difficult to achieve.

Key words: Helicoverpa armigera, transgenic Bt cotton, resistance, adaptation, simulation model