Effects Of Transgenic Insect-Resistant Rice On The Major Non-Target Insect Pests And Natural Enemies

The effects of transgenic insect-resistant rice on the paddy field population dynamics of majornon-target pests（rice planthoppers and leafhoppers）, as well as their natural enemies（parasitoids andspiders）, were investigated from June to September2011at the Wufeng Experimental Station andShoushan Experimental Station, Fujian Province, China. Transgenic insect-resistant rice B4b68wastransfected with the cry1Ab gene, and the non-transgenic rice isoline MH86was used as a control; asecond transgenic insect-resistant rice strain ⅡYKF8was transfected with both the cry1Ac and CpTIgenes, and the non-transgenic rice isoline IIYM86was used as a control. The results showed that therewere no significant differences between the population dynamics of planthoppers and leafhoppers onthe two transgenic insect-resistant rice lines and their parental controls over the course of the entire ricegrowing season. The two transgenic insect-resistant rice lines also had no significant effect on speciesrichness, diversity, evenness or dominance indices of the spider communities in the paddy fields.However, the species diversity of parasitoids in the two transgenic insect-resistant rice lines weresignificantly lower than in the controls.In the same year, the bottom-up effects of transgenic insect-resistant rice on Nilaparvata lugensand its predatory enemy Lycosa pseudoannulata in the context of the tritrophic system were studied inthe laboratory. The results showed that the feeding preference of N. lugens was different between thetwo transgenic insect-resistant rice strains and their controls at the structural level of the leaf sheath.Under the selection condition of host plants by N. lugens, the oviposition preference and egg-layingnumber of N. lugens, as well as the growth and development of N. lugens on transgenic crylAb riceB4b68, were not significantly different from the control MH86. However, the survival rate of N. lugensnymphs on transgenic cry1Ac/CpTI rice ⅡYKF8was significant higher than on its control ⅡYM86. Thepredatory behavior, growth development, and olfactory responses of female adult L. pseudoannulatawith respect to rice-N. lugens were studied under laboratory conditions; no marked adverseness of thetwo transgenic insect-resistant rice strains on L. pseudoannulata was found.In conclusion, field trials showed that the two transgenic insect-resistant rice lines tested generallydisplayed neither direct adverse effects on main non-target pests（rice planthoppers and leafhoppers）norindirect adverse effects on spider communities. However, the species diversity of the parasitoids in thetwo transgenic insect-resistant rice lines was significantly lower than in the control. Laboratory testsshowed that the two transgenic insect-resistant rice lines tested generally had no adverse effects on N.lugens or its predatory enemy L. pseudoannulata, even indirectly through the food chain.