麦套夏播转Bt基因棉R93-6对昆虫群落的影响

以转Bt(Bacillusthuringiensis)基因棉品系R93-6为试验材料，以中棉所16号为对照，研究了在麦套夏播条件下转基因棉对昆虫群落的影响。结果表明，转基因棉田昆虫群落、害虫和天敌亚群落的多样性指数和均匀度指数均低于常规棉田，而优势集中性则高于常规棉田，所以转基因棉田昆虫群落、害虫和天敌亚群落的稳定性不如常规棉田，某种害虫大发生的可能性较大。对季节性变化格局的研究表明，转基因棉田昆虫群落可以划分为前期(6月初至7月下旬)、中期(7月底至8月底)和后期(9月份以后)三个发展阶段，根据不同阶段害虫和天敌发生的特点， 提出了害虫综合治理的策略。即前期害虫的防治应以生物生态调控为主；中期以化学防治为主，以生物生态调控为辅，协调好生物防治和化学防治的矛盾；后期应以生物生态调控为主，并加强农业防治。

Effects of transgenic Bt cotton R93-6 on the insect community

Characteristics and dynamics of arthropod communities were investigated in three experimental plots of cotton,the plot where the transgenic Bt cotton R93 6 was planted and integrated pest management was carried out (IPM),the plot of the Bt cotton in which pests were controlled only by their natural enemies(NEC),and the control plot of routine cotton CCRI No.16 with no insecticide application throughout whole growing seasons(CK).The results showed that the diversity indexes and evennesses of insect community,pest and natural enemy sub communities were lower in NEC than in CK,while their dominant concentrations were higher than that in CK.So the insect community,pest and natural enemy sub communities had poorer stability in NEC than in CK,suggesting some species of pests might go into outbreak.The insect community and pest sub community in IPM were more stable as compared with those in NEC and CK. The analyses on seasonal change in the insect community in NEC showed it could be divided into three stages.The first stage was from early June to late July,the second one from the end of July to the end of August,and the third one after September.The corresponding management strategies against the insect pests were put forward according to occurring characteristics of insect pests and their natural enemies during these three stages.