A field experiment was conducted in the spring of 2001 to determine the influence of transgenic insect resistant cotton, expressing either a Bt toxin gene or a Bt toxin gene plus a cowpea trypsin inhibitor gene, on the seasonal abundance of the cotton aphid and its major predator and parasite species. Laboratory experiments showed a 22. 0% higher predation bv the ladybeetle Harmonia axyridis and a 23.5% lower parasitization by the parasitoid Lysiphlebia japonica when Bt cotton fed aphids were offered, in comparison to conventional cotton-fed aphids. In the field, differences in aphid population dynamics between cotton genotypes were small and largely insignificant.Aphid populations increased 5 days earlier and to a 1.6 times higher maximum level in monoculture cotton than in intercropped cotton,confirming the use of wheat cotton intercropPing to enhance biological aphid control.%2001年田间小区试验研究了转Bt基因棉和转双价基因(Bt+CpTI)棉对棉苗蚜及其天敌种群动态的影响;室内研究了转基因抗虫棉对两种棉蚜天敌的生物学影响.结果表明,转基因抗虫棉对棉蚜种群数量的影响不明显,未达显著水平.单作转基因棉田棉蚜发生期比麦套棉田提前5天左右,发生数量是麦套棉田的1.6倍,表明麦棉套作可有效的控制苗蚜的为害.室内研究表明,异色瓢虫对用Bt棉处理的的棉蚜的捕食量比对照增加22.0%,棉蚜茧蜂对用Bt棉处理的棉蚜的寄主率降低23.5%.
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