Effects And Mechanisms Of The Transgenic Cry1Ac Plus CpTI (Cowpea Trypsin Inhibitor) Cotton On Insect Communities

Effects and mechanisms of transgenic Cryl Ac plus CpTI (Cowpea Trypsin Inhibitor) cotton on insect communities were studied by laboratory feeding, chemistry analyzing, field plots investigating from the view of bionomics, population ecology, community ecology and integrated pest management. The experimental cotton varieties were CCRI 41 (transgenic Cry1Ac plus CpTI cotton), CCRI 32 (transgenic Cryl Ac cotton) and CCRI23 (common cotton, the mother variety of CCRI41). The purpose of this study is to accumulating scientific basis for the evaluating of bio-safety of transgenic cotton, utilizing the transgenic cotton reasonably and providing scientific basis for building IPM system for transgenic cotton. The results were as follows:The structures, species richness, the dynamic of species in spatiao-temporal of insect community of transgenic Cryl Ac plus CpTI cotton (double gene cotton) all were not obvious different comparing with transgenic Cryl Ac cotton (Bt cotton) and traditional cotton with no pest control cotton (traditional cotton), but there were clear different from traditional cotton with pest control cotton (control cotton). The diversity index and evenness index of insect community in double gene cotton and Bt cotton were higher than traditional cotton, obvious higher than control cotton, but there was not clear difference between double gene cotton and Bt cotton. So the insect community of double gene cotton and Bt cotton were more stable, they had better buffering action to the changing from population inside or the changing of environment.The reason why the dominant pests species and dominant parasitoids species had changed much were determined by the experiments of feeding and biology. Double gene cotton and Bt cotton all had obvious resistance to Cotton Bollworm and the effects covered the pest's survival, development, reproduction and behavior; the parasitic rate and molting rate, the weight of cocoon and adult of parasitoids of Cotton Bollworm decreased clearly, but the effects of double gene cotton and Bt cotton to Lysiphlebia japonica Ashmead were not clear. The effects of double gene cotton and Bt cotton on the duration of larvae, weight of adult, number of eggs, mortality of larvae of predator enemies were not obvious.Double gene cotton was highly resistant to Cotton Bollworm (Helicoverp armigera), but the degree of its resistance fluctuated both in time and space. The results showed thatthe resistance of double gene cotton and Bt cotton decreased in the period of third and forth generation of Cotton Bollworm occurring, the pest should be monitored and controlled. The difference of resistance between double gene cotton and Bt cotton was determined by monitored the amount of Bt toxin using the way of ELISA. There was not clear different between double gene cotton and Bt cotton in the amount of Bt toxin, so the difference of the resistance of double gene cotton to lower instar larvae of Cotton Bollworm was not clear, but the resistance of double gene cotton to the higher instar larvae was higher than Bt cotton, because of the co-operating action of Bt gene and CpTI gene. The flower of double gene cotton contains more Bt toxin than that of Bt cotton, so it had higher resistance to Cotton Bollworm. The amount of gossypol in double gene cotton were higher than traditional cotton in May, June and July, and higher than that of Bt cotton after June, because gossypol could enhanced the action of Bt toxin, so the double gene cotton had higher resistance to Cotton Bollworm than Bt cotton, and the resistance of double gene cotton was more stable.It was determined why the number of sucking pests in double gene cotton increased than traditional cotton from the view of chemistry analyzing, the reasons were that the contain of tannin was lower than that of traditional cotton, the amount of protein was higher than that of traditional cotton, the amount of carbohydrate was evident higher than that of traditional cotton after June. There were more numbers of sucking pests in Bt cotton comparing...