| Transgenic cotton has been developed and used to control cotton bollworm in several countries. As a new genetic modified crop and a new method for pest control, its efficiency, stability and possible influence on ecology has been extensively studied in different area. Our work with 3 transgenic and one common cotton varieties concentrated on the temporal and spatial express of the resistance and the influence on the diversity of arthropod community in east China. The results were summarized as fellows:1) Resistance bioassay and Bt toxin ELISA test demonstrated that both Bt toxin content and resistance to cotton bollworm varied with cotton developing stages and the plant organs. Transgenic cotton had highest resistance at the seedling stage. As the plants developed, the resistance went down step by step, and almost diminished in the boiling stage. Among the plant organs, leaves and buds showed higher resistance than bolls. The flowers were found with the lowest resistance. The Bt toxin content tested by ELISA was in the similar pattern, but not exactly. Because a lot of factors could affect the test results, Bt toxin ELISA test should be used as a supplementary method for the resistance evaluation.2) In door experiment and field caged experiment also revealed that beside the mortality effect, transgenic cotton can depress the feeding and development of the survive larvae, and decrease the damage. When cotton bollworms feed on transgenic cotton, they eat less and develop more slowly. Anyway, the transgenic cotton showed no effect on adult for egg laying.3) Field survey found that there were 69 species of arthropods in the cotton field in Nanjing area. Of which, 32 species were pests, 33 natural enemies and 4 neutral insects. The component species in transgenic and common cotton fields were similar. But there was a little difference in the individual numbers of some special species. The dominant pests in transgenic cotton fields were aphids (Aphis gossypii Glover), cotton whitefly (Bemisia (abaci Gennadius) and leafhopper (Empoasca biguttula Ishida), whereas aphids, cottonleafroller (Sylepta derogata Fabricius) were the dominant pests in conventional cotton fields. Ladybugs (Propylaea japonica Thunberg), green lacewings (Chrysopa septempunctata Wesmael), and spiders (Misumeenops tricuspidatus Fabticius) were the dominant species of natural enemy in both kinds of cotton fields. This results indicated that transgenic cotton could depress the population of caterpillar, but had little effect on the natural enemies.4) Bases on their trophic relationships and taxonomy, the field arthropods including pest groups, natural enemy groups and neutral arthropods were divided into 4 nutrient classes, 6 guilds and 26 groups. The dynamics of the major pests groups and natural enemy groups were displayed by following the sampling times order, which were changed with the growth of cotton plants. The relationships between two trophic levels of pests and natural enemies were analyzed by temporal niche. The temporal niche breadth value B (I) and the time niche overlapping values were acquired. In general, temporal niche overlapping value of pests and natural enemies were very high in all cotton fields. This means that natural enemies have good control of the pests in different cotton fields.5) Species richness, community diversity indexes, and DG index were used to analyze and compare the seasonal trends of different groups in different cotton fields. The results showed that the species richness and the DG index of the pest sub-community and the arthropod community were a little higher in transgenic cotton field. But no obvious difference was found in different cotton fields. In the whole, the similarity coefficients of community among all cotton fields were kept very high. The similarity coefficient of the natural enemy sub-community between conventional cotton fields and transgenic cotton field was higher than that of the arthropod community. The similarity coefficients for the pest sub-community were the sma...
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