The Effects Of Insecticides To The Brown Planthopper Nilaparvata Lugens (Stal) (Hemiptera:Delphacidae) On Transgenic Cry1C And Cry2A Rice Lines And Their Non-Bt Parental Rice

Rice is one of the most important staple food crops in China with about 452 million acres of production area, and was one of the main foods for about 65% of the population in China. Nevertheless, rice yield and quality always was influenced by pests. With the development of transgenic technology, cry gene derived from Bacillus thuringiensis was embedded into rice plant to prevent the damages from rice Lepidiopterans. Biosaefty of Bt rice was concerned by publics. The control of nontarget pests of Bt rice was manily relied on chemicals. Due to the misuse and overuse of insecticides, there were many reports on the resurgence of brown planthopper (BPH), Nilaparvata lugens (Stal) (Hemiptera:Delphacidae). There were no reports on the resurgence of BPH on Bt rice. In the present study, the ability of BPH resurgence on Bt rice, TIC-19 with cry1C gene and T2A-1 with cry2A gene, and their parental rice MH63, were evaluated induced by triazophos and deltamethrin. The results are showed as follows:1. Response to insecticides of BPH fed on Bt rice under tillering periodIn the present study, the non-target pest BPH, cultured on Bt rice, TIC-19 with crylC gene and T2A-1 with cry2A gene, and their parental rice MH63 under tillering periods, were treated with a series of concentrations of triazophos and deltamethrin when BPH nymphs reached third instar for evaluating the effects of Bt rice on BPH resurgence induced by pesticides. Nymphal duration decreased with the increasing concentration of deltamethrin. while no significant differences of BPH nymphal duration were observed on same rice variety treated with the different concentration of triazophos. The results indicated that the survival rate significantly declined and fecundity significantly increased with the increasing concentration of insecticides. However, ecological fitness parameters including nymphal duration, survival rate, female adult weight, fecundity and egg hatchability were not significant different among Bt and non-Bt rice varieties when they treated with the same concentration of insecticide. It implied that no significant difference on the BPH resurgence induced by pesticides was detected among the two tested Bt rice varieties and their non-Bt parental rice variety.2. Ecological responses to insecticeds of BPH on Bt rice under different nitrogen regimes.After different nitrogen treatments (Okg N/ha,100kg N/ha and 250kg N/ha), till rice grew up to 60d, response of BPH to insecticides were evaluated on Bt and non-Bt rice. The results indicated that the ecological fitness of the BPH increased with the increase nitrogen concertration. The BPH fecundity and egg hatchability did not significant differed reared on Bt and non-Bt rice varieties treated with insecticides under Okg N/ha. At the 100kg N/ha and 250kg N/ha, the BPH fecundity significantly increased with the increased insecticides concentration. Fitness prameters of BPH were not significant different on Bt and non-Bt rice varieties treated with the same concentration of insecticide under same nitrogen regime.3. Enzymatic activity of BPH treated with insecticides on Bt rice lines and their non-Bt parental nee.Esterase (EST), glutathione S-transferase (GST) and acetylcholinesterase (AChE) activities of BPH treat with insecticides were determined on transgenic cry1C and cry2A rice lines and their non-Bt parental rice MH63. Results showed that the EST and GST activity increased with the increase of insecticides concerntration, AChE activities declined with the increase of triazophos concerntration, while increased with the increase of deltamethrin concerntration. There were no significant differences on the enzymes activities among the two tested Bt rice varieties and their non-Bt parental rice variety.