转Bt基因棉花对棉铃虫不同龄期幼虫的杀虫活性和抑制生长作用

以我国培育的转Bt基因棉花(简称Bt棉)为材料，系统测定了Bt棉叶片对棉铃虫 Helicoverpa armigera(Hubner)不同龄期幼虫的杀虫活性和抑制生长的作用。结果表明，Bt棉的杀虫活性随着龄期的增大而趋于降低，其中处理3d只对1龄幼虫有较高效果；从1～4龄开始连续取食Bt棉后均不能化蛹，5龄幼虫则能正常化蛹。3龄幼虫取食Bt棉叶3d后的体重与初始体重之比为0.94，而取食常规棉叶的相应比值为5.48，对幼虫生长的抑制作用明显。在28℃条件下用Bt棉饲养棉铃虫1～3龄幼虫3d，对幼虫的致死率显著高于25℃处理，对3龄幼虫抑制生长的作用也显著提高。研究结果可为确定棉铃虫对Bt棉的抗性监测与治理技术以及Bt棉的田间应用技术提供依据。

SURVIVAL AND GROWTH OF DIFFERENT INSTAR LARVAE OF HELICOVERPA ARMIGERA (HUBNER) ON TRANSGENIC BT COTTON

Transgenic cotton line R93-4 expressing Bacillus thuringiensis CrylA genewas used for evaluating the effects of Bt cotton on the survival and growth of different instar larvae of the cotton bollworm, Helicoverpa arrnigera (Htibner). Significant insecticidal activity of Bt cotton leaves was observed only on the first instar larvae successively feeding for 3 days. No larva could survive to pupation when fed on Bt cotton leaves continuously starting at 1st, 2nd, 3rd or 4th instar. But started feeding on Bt cotton leaves at fifth instar, larvae could normally survive to pupae. The inhibition effect of Btcotton on the growth of larvae was more obvious than the lethal effect. The mortality and growth inhibition of larvae by Bt cotton were higher at 28℃ as compared with 25℃. The results are valuable for further research on the monitoring and management techniques of the pest resistance to Bt cotton.