Risk Assessment Of Transgenic Bt Corn On Non-target Arthropods And Resistance Management On Target Pest

The ecological safety of Bt-transgenic corn has been concerned worldwide.The goal of the research was to assess effect of crylF gene corn in laboratory condition and under field conditions on arthropod community.1.The security of Bt-transgenic corn on the ground non-target arthropod communityNo significant differences were observed for the Bt-transgenic corn on the ground part to the non-target arthropod community.There were no significant differences in the species richness(S),Shannon-Winner diversity index(H'),evenness index(J),Simpson dominant concentration index(C)between Bt fields and control fields by means of systematic investigation,suction-implement method and traps survey.Systematic investigation results showed that transgenic corn and non-transgenic corn have the same types of arthropods community,mainly ladybug,aphid,Orius,lacewing,spider and plant hopper.There were no significant differences on number of arthropods.Suction-implement method results showed that about 20 species of arthropods were found,and no significant differences in the dominance of arthropods between transgenic corn and non-transgenic corn.Trap survey method results showed that no significant differences in the number and species of arthropods between different fields.The species of anthropods were cricket,carabid,ant,spider,centipede,millipede,locust,house centipede,snout bettle,scarabs and tiger bettle.Transgenic corn hadn't significant effects on the migration activities of arthropods in the fields.2.Bt-transgenic corn on the underground non-target arthropod communityThe results showed that no significant effect of Bt-transgenic corn on soil arthropods community was observed.There were no significant difference in the number of arthropods.The occur time and the distribution under soil were different between Bt-transgenic corn and non-transgenic corn,but the difference was not significant regularity.Bt-transgenic com had no significant impact on the community structure of soil arthropod.No significant difference in the number of individuals,species richness(S),Shannon-Winner diversity index(H"),evenness index(J),Simpson dominant concentration index(C)were found between Bt-transgenic corn and non-transgenic corn.3.Bt-transgenic corn on parasitoid of corn borerThe effects of Bt-transgenic corn on Trichogramma and Lydella grisescens were conducted by field survey and indoor experiment.The results showed no significant direct effects of Bt-transgenic corn on this two species of parasitic enemies of corn borer.No obvious differences of transgenic corn on activity of corn borer parasitic enemies be found by field survey.There were no significant difference in the parasitic rate of Trichogramma and Lydella grisescens between transgenic corn and non-transgenic corn in the field,and the dynamic fluctuation of time and space were similar.However the sticky board method results indicated that the number of captured Trichogramma wasp in Bt-transgenic corn fields was significantly less than the number of non-transgenic fields.Feeding trials of Bt-transgenic corn pollen for Trichogramma was conducted in laboratory.The results showed that no significant adverse effects to parasitic rate and reproductive capability of the wasp were found.The offspring total numbers and sex ratio of Trichogramma had improved to some degree after adding Bt-transgenic corn pollen into food for the wasps.The Bt toxin in the body of Lydella grisescens could be detected by ELISA after feeding on Bt toxin-containing foods,but there were no significant effects on its biological characteristics.The glutathione-S-transferase enzyme,a-naphthyl acetate esterase,acetylcholinesterase,acid phosphatase and alkaline phosphatase enzyme's activity of Lydella grisescens were fluctuated after feeding on Bt toxin-containing foods.The results indicated that the activity of a-naphthyl acetate esterase increased suddenly from third day after feeding on foods containing 125?g/ml and 250?g/ml Bt toxin.The activity of a-naphthyl acetate esterase increased suddenly from second day after feeding on foods containing 500Lg/ml Bt toxin.The activity of acetylcholinesterase increased suddenly from third day after feeding on foods containing 125?g/ml Bt toxin.The activity of acetylcholinesterase increased suddenly from fourth day after feeding on foods containing 250?g/ml and 500?g/ml Bt toxin.The activity of acid phosphatase and alkaline phosphatase increased suddenly from third day after feeding on foods containing 125?g/ml and 250pg/ml Bt toxin,then decreased to normal activity levels.The results showed that the detoxifying enzyme system of Lydella grisescens was strong enough to decompose the Bt toxin in vivo in time.4.The resistance management of Bt-transgenic corn-shelter strategyThe results showed that sorghum could attract more corn borer to damage and sorghum could better maintain the sensitive corn borer populations of Bt-transgenic corn and delay the production process of corn borer resistance in field than corn.In addition,the areas of sorghum refuge about 20%could attract and maintain more sensitive populations of corn borer than that of other areas.The results of simulated by shelter model showed that the area of shelter should be different for different refuge crops and different kind of pest.The optimum shelter area of corn or sorghum were 16%and 15%for the first generation of corn borer,and were 6%and 5.7%for second generation of corn borer.