Effects Of Transgenic Bt Corn Expressing Cry1Ab Toxin On Diversity Of Arthropod Community

Effects on arthropod communities' diversity, non-target pest sub-community, natural enemy sub-community and resistance to major target pest of transgenic Bt corn expressing Cry1Ab toxin were carried out in field conditions from 2003 to 2004, to assess the environment risk of the transgenic Bt corn . In addition, effects of Bt corn kernels on storage pest insect, rice moth, Corcyra cephalonica Stainton, were conducted. The results are as follows:1. The group compositions and the dominant group of arthropod guilds of Bt corn all were not different comparing with non-Bt isolines .The abundance of guilds in Bt corn were almost significantly different but the abundance of parasitoids by the way of directly observing and the abundance of Lepidoptera insect by the way of vacuum-suction machine. The arthropod community structure parameters, such as the total numbers of arthropods, species richness, Shannon-Winner diversity index, evenness index, dominant index and their dynamics, were almost the same between Bt corn and non-Bt corn field. The arthropod community structure, predator sub-community, parasitoid sub-community and neuter insect sub-community in Bt corn field were very similar to the control. In genenal, the arthropod community structure in Bt corn field were stable, and the Bt corn was no negative effect on arthropod community.2. Bt corn had good resistance to the major target pests, such as the Asian corn borer, (Ostrinia furnacalis(Guenee)), cotton bollworm (Helicoverpa armigera (Hubner)) and Dichocrocis punctiferalis (Guenee). The damage on Bt corn by the insects was significantly lower than the control. Bt corn had no negative effect on the oviposition of the Asian corn borer.3. The species composition of non-target sub-community, the abundance of species and species richness in Bt corn field were similar to the control. The population dynamics of dominant species was no different in Bt corn field comparing with the control.4. The total numbers and the dynamics of predator population, the species composition and abundance of species in Bt corn field were not significantly different comparing with the control. No significant difference were observed, in dominant species and the population dynamics between Bt corn field and the control.5. Spider sub-community structure was observed by the method of pitfall trap. In Bt corn field, the species composition and the dominant species of the spiders, structure parameters, such as the species richness, Shannon-Winner diversity index, evenness index, dominant index, and the dynamics of spiders population, were similar to the control. The result indicated that the structure of spiders sub-community in Bt corn field is stable according to that the Shannon-Winner diversity index and evenness index are bigger, the dominant index is lower.6. The movement of arthropods in ground between Bt corn field and the control was monitored by mean of pitfall trap. Some arthropods, such as some of predators and non-target pest, always move between Bt corn field and the control during the corn growing seasons. There were no significant differences in species, the total numbers that moved between the Bt corn field and the control during the corn growing seasons. In general, the arthropods in ground did not show the obvious preference neither Bt corn habitat nor the control.