转cry1Ac和CpTI双基因抗虫水稻对二化螟和大螟的致死效应及田间螟虫构成的影响

 就转cry1Ac＋CpTI双基因抗虫水稻不同生育期对二化螟Chilo suppressalis和大螟Sesamia inferens的室内致死特性及田间螟虫的构成进行了研究。室内测定结果表明，不同生育期转基因水稻对二化螟、大螟都表现明显的致死效应，但水稻生长后期的致死效果降低。转基因水稻对大螟的致死效应显著弱于对二化螟的，其中，二化螟除在齐穗期和成熟期有少量幼虫（0.5%~6.4%）存活到第4天外，其余均在第4天死亡；大螟在两种转基因水稻上的存活率高于二化螟，且少量个体（<1.6%）还能化蛹、羽化，但化蛹率和羽化率均明显低于在非转基因对照上的。早、晚两季水稻的田间调查结果表明，转基因水稻上两种螟虫虫口数量均显著低于相应的非转基因对照品种，转基因水稻上二化螟虫口减退率>99％；大螟虫口减退率相对较低，早、晚稻上有所不同，其中早稻 >93％，晚稻仅44％～64％。转基因水稻上残存螟虫中，大螟所占比例明显上升，推测转基因水稻对两种螟虫致死效应差异可能是其主要原因。

Effects of Transgenic Rice Harboring crylAc and CpTI Genes on Survival of Chilo suppressalis and Sesamia inferens and Field Composition of Rice Stemborers

The effects of transgenic rice containing both cry1Ac and CpTI genes on survival of the stripped stem borer (SSB), Chilo suppressalis, and the pink stem borer (PSB), Sesamia inferens, and the field composition of stem borers were studied in both laboratory and field tests. The laboratory bioassay results showed that the survival of SSB and PSB on transgenic rice was significantly lower than that on non-transgenic control. The toxicity of transgenic rice to SSB and PSB declined at the late growing stage of rice. The lethal effect of the transgenic rice to SSB was stronger than that to PSB. As for SSB, only a few larvae (0.5%-6.4%) could survive at the 4th day after infestation at the heading and maturity stage in transgenic rice, and the survival rate of PSB on transgenic rice was higher than that of SSB. Furthermore, there were a few larvae (<1.6%) could pupate and emerge although the pupation and emergence rates were substantially lower than those on non- transgenic control. The results of field tests in both early and late rice indicated that the number of SSB and PSB larvae on transgenic rice were significantly reduced compared with the control. Compared with non-transgenic check, the number of SSB in transgenic rice was reduced by over 99%, and the effect of transgenic rice on PSB was relatively low and varied with different cropping seasons. The number of PSB was decreased by over 93% in early rice and by 44%-64% in late rice. Among the surviving stem borers in transgenic rice field, the percentage of PSB increased significantly. It is inferred that the change is possibly caused by the different susceptibilities for the two stemborers to transgenic rice expressing Cry1Ac and CpTI toxins.