| Transgenic technology will be quite the key technology of biotechnical industry in a long period in the future including at present. Transgenic crops have been spread and commercial plantings in large range, which have brought huge economic benefits, but at the same time, it has many unknown and potential risks of ecological environment. So far, the impact on populations of natural enemies is one of the important matter of its ecological risks in the resistant to insect crops of transgenic Bt gene. The single gene Bt-cotton farm system and a single gene Bt-poplar played a very important role on the control of lepidopteran pests, however, the ecological risk has been the focus of the international research and attention. In recent years, as Bt-cotton, Bt-poplar have been created and uesd in China, its composite ecological community consisting of both more comprehensive and natural of agroforestry ecosystem on ecological risk, in particular for natural enemies of insect species, individual number and dynamic change in the number of groups influence, which is a production and science major issues and needs to be faced and answered. Based on the methods of ecological community and system investigation, the composition of natural enemies, population dynamics and community characteristics in the four transgenic poplar-cotton ecosystem which including non-transgenic Bt gene poplar and non-Bt-transgenic cotton system (NN), non-transgenic Bt gene poplar and transgenic Bt transgenic cotton system (NT), Bt-gene poplar and non-Bt-transgenic cotton systems (TN), Bt-gene Bt transgenic cotton and transgenic poplar system (TT) were evaluated during 2009-2010. The main results were as follows:1. Their number of species and individuals of natural enemies in the 4 composite systems which were composed transgenic poplar-cotton were basically the same, but the number of dynamic fluctiation were had some differences.We found that NN, NT, TN, TT system in the number of species and individuals of natural enemies and were followed during 2009: the 973 individuals belonging to 57 species, 34 families, the 958 individuals belonging to 58 species, 37 families, the 971 individuals belonging to 54 species, 36 families, the 1009 individuals belonging to 61 species, 36 families. In 2009, the insects number of the various community is 722 belonging to 52 species, 32 families, 674 belonging to 50 species, 32 families, 757 belonging to 56 species, 35 families, 846 belonging to 58 species, 36 families. This results showed that the number of species and their individuals of natural enemies in the TT were more than the other three system, but the difference was not significant.From the dynamic fluctiation of time, each system's species abundance change basic consistent in 2009, before the adult stage of cotton, there were a big gap between each system, basically the same after the change, which explained that the species abundance the change tendency has a difference in 4 systems in 2010; the dynamic change trend of natural enemies populations in 2009-2010 was basically the same and the natural enemy class group's individual number's change is bigger than 2009 in 2010. The result showed that the ecosystem of transgenic Bt poplar-cotton had some influence to the natural enemy community and predatism natural enemy's species quantity and individual number in each multiplexed system relative stabilization, parasitic natural enemies in the great differences of each system, and it changed greater in 2010 than 2009.2. Compared with index of community characteristic of natural enemies of the 4 ecosystems of transgenic Bt poplar-cotton, and makes the cluster analysis by 4 system's community similar coefficient, finally demonstrates between each multiplexed system the existence difference, but difference is not patency.The multiple indices of the NN, NT, TN, TT were respectively 3.5279, 3.4731, 3.4336, 3.4895 in 2009, the respectively number in turn was 3.4003, 3.3302, 3.4533, 3.3594 in 2010, which indicated that 4 systems no significant differences between the diversity index.The cluster analysis result was in 2009 four systems divided into two groups, the similarity between the NN and the TN was high, the similarity between the NT and the TT was high, the similarity between the NN and the TN in 2010 was high, but the NT and TT had not presented the result of 2009, which explained that every system of transgenic Bt poplar-cotton to natural enemy class group there were certain difference, finally the multiple index's tendencies were quite basic consistently.The innovation of this research is take object of North China agroforestry cultivation mode, which is the most common poplar-cotton agroforestry ecosystem. At the same time, we have conducted on study with transgenic crops' ecological risks, which has been being dispute. From the systematic investigation and comparison among the the species, individual and dynamic fluctiation of natural enemies of agroforestry ecosystem, we have initially evaluated their ecological risks in the agroforestry ecosystem and it has little effect to natural enemy. It not only provides important reference of ecological effects which are caused by Chinese large area, continuous cultivation of single transgenic plants, but also provides a theoretical basis for popularize and scientificlly use their agroforestry ecosystem's cultivated mode. It has a unique perspective and broad application prospects and it, has very important significance application and in theory.
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