Bt玉米(MG95)对粘虫的抗性和拒食作用

在室内以我国自主培育的转Bt基因玉米 (简称 :Bt玉米 )为材料 ,测定了Bt玉米对不同龄期 ( 1～ 4龄 )粘虫PseudaletiaseparataWalker的影响。测定指标包括 :幼虫体重、幼虫发育历期、幼虫死亡率、化蛹率、蛹重、蛹历期、羽化率、产卵量、成虫历期、卵孵化率。结果显示 :用Bt玉米喂养的 1～ 4龄幼虫在处理 6d及 1～ 3龄幼虫在处理 9d时的体重与对照相比均差异显著 ;除 1龄幼虫外 ,2～ 4龄幼虫处理 6d及 2～ 3龄幼虫处理 9d后的死亡率差异不显著 ;用Bt玉米喂养的各龄幼虫发育历期延长 ,与对照相比差异显著 ;1、2龄幼虫的化蛹率与对照相比有显著差异 ,3、4龄则差异不显著 ;1～ 4龄幼虫的蛹重、蛹历期及羽化率均差异显著 ;成虫历期仅 1龄幼虫差异显著 ;与对照相比 ,各龄粘虫的产卵数、卵孵化率均无显著差异。结果表明 ,1龄幼虫对Bt玉米最为敏感。另外 ,拒食实验结果显示 ,在实验开始后的 8,1 6,2 4,3 2及 48h ,非选择性测定的拒食率为 63 2 0 ,64 60 ,48 99,2 3 3 5和 0 5 4% ,选择性测定的拒食率为98 3 3 ,82 43 ,71 5 4,40 1 6和 0 2 7% ,总体趋势是拒食率随时间延长而降低 ,48h后Bt玉米对粘虫幼虫无拒食活性。

The resistance of Bt corn(MG95) to Pseudaletia separata

Transgenic corn expressing Bacillus thuringiensis cry1Ab and cry1Ac genes developed in China was used for evaluating the effect of Bt corn on different instar(1st to 4th instar)Pseudaletia separata Walker in the laboratory.The indexes include weight of larvae,duration of larvae,mortality rate of larvae,rate of pupation,pupal weight,pupal duration,rate of eclosion,life span of moth,number of eggs and,hatching rate.The results indicated that the weights of larvae(1st to 4th instar)fed with Bt corn had significant difference from those fed with non-Bt corn and the mortality rates of 2nd-3th instar larvae were not significantly different except the 1st instar after 6 and 9 days.Durations of the 1st|4th instar larvae were prolonged than the control group.Significant differences of pupation rates were also observed in the 1st and 2nd instar larvae.The pupal weights, pupal durations and rates of eclosion(1st|4th instar)were different significantly.The durations of moth were significantly different only in the 1st instar larvae.No significant differences were observed on the numbers of eggs and hatching rates at all the 4 instar larvae.The results suggested that the 1st instar larvae were more suscptible to Bt corn than the older larvae.We also investigated the antifeedant activity of Bt corn against P.separata. The antifeedant rates without choice were 63.20,64.60,48.99,23.35 and 0.54% at 8,16,24,36 and 48 h,respectively;and the antifeedant rates with choice were 98.33,82.4,71.54,40.16 and 0.27%.The antifeedant rate declined with the time going by,and antifeedant activity was lost after 48 hours.