不同Bt蛋白对棉铃虫存活率和生长发育的影响

在我国Bt棉主要以Cry1Ab或Cry1Ac为主，其他新型Bt基因未被转入棉花中用来控制害虫，然而大面积种植单价Bt基因的棉花，将可能会大大增加靶标害虫对该类型Bt棉花抗性频率，因此研究其他新型Bt蛋白对靶标害虫的控制作用显得十分必要。采用蛋白混入人工饲料的生物测定方法，在室内测定了6种Bt蛋白对棉铃虫初孵幼虫的毒力，比较了浓度为1．0μg· g-1时不同Bt蛋白对棉铃虫幼虫生长发育的影响。毒力测定结果表明，不同Bt蛋白对棉铃虫初孵幼虫的毒力不同，LC50值由低到高依次为Cry1Ab 0．065μg· g-1、Cry1Ac 0．074μg· g-1、Cry2Ab 0．133μg· g-1、Cry2Aa 11．670μg· g-1、Cry1Ah 13．010μg· g-1和Cry1Ca＞20μg· g-1。生长发育测定结果表明，Cry1Ab和Cry1Ac对棉铃虫幼虫的生长发育影响最大，Cry2Ab次之；Cry1Ah和Cry2Aa对1龄幼虫的校正死亡率和体重抑制率差别不大，但对2龄幼虫的差异较大，Cry1Ah处理2龄幼虫后体重和生长发育参数与Cry2Ab接近，而Cry1Ca对棉铃虫幼虫生长发育几乎没影响。Cry1Ah、Cry2Aa和Cry2Ab的毒力不如Cry1Ac和Cry1Ab，但仍可以作为控制棉铃虫幼虫的替代策略。

The effect of different Bt proteins on the survival rate, growth and development of cotton bollworm larvae

Background In China, genes of Bt cotton mainly express Cry1Ab or Cry1Ac proteins.Until now, few new Bt genes have not be studied as potential used topest control pests .However , large-scale cultivation of Bt cotton will most likely increase the possibility of pests to become resistant against these types of Bt cotton .It is necessary to examine the responses of cotton bollworm to other Bt proteins.[Method]Using a diet incorporation method, we evaluated the toxicity of six types of Bt proteins （1.0μg· g-1） against cotton bollworm′s larval growth and development .[Result]The results showed that the LC50 of Bt proteins to neonate larvae of cotton bollworm were Cry1Ab （0.065μg· g-1）, Cry1Ac （0.074μg· g-1）, Cry2Ab （0.133μg· g-1）, Cry2Aa （11.67μg· g-1）, Cry1Ah （13.010 μg· g-1 ） and Cry1Ca （ 〉20 μg· g-1 ）.When a concentration of 1.0 μg· g-1 was applied, Cry1Ab and Cry1Ac had the strongest effects among the six Bt proteins followed by Cry 2Ab.There were no difference between Cry 1Ah and Cry2Aa effects on first-instar larval mortality and weight reduction .However, there were significant differences between these two proteins at the second-instar larvae.There were no significant differences between Cry 1Ah and Cry2Ab in terms of body weight and growth rate of cotton bollworm second-instar larvae.Cry1Ca has almost no effect on the survival rate , growth and development of cot-ton bollworm when compared with the control .[Conclusion and significance]The LC50 of Cry1Ah, Cry2Aa and Cry2Ab are compara-ble to Cry1Ac and Cry1Ab.They could be used as an alternative strategy to control cotton bollworm larvae .