Cry2Ab蛋白对甜菜夜蛾和斜纹夜蛾低龄幼虫的抗性

【背景】在我国，由于Bt棉的种植，棉铃虫和红铃虫等靶标害虫得到了控制，但棉田其他鳞翅目害虫如甜菜夜蛾和斜纹夜蛾的危害仍较严重。美国商业化种植的双价棉BollgardⅡ所表达的Cry2Ab蛋白不仅对棉铃虫有较好的控制效果，而且对甜菜夜蛾和草地贪夜蛾有较好的控制作用。因此，该双价棉在我国被环境释放前，有必要研究其对棉田其他鳞翅目害虫的影响。【方法】在人工饲料中分别添加质量浓度为1．25、2．5、5．0、10．0和20．0μg·g^-1的Cry2Ab蛋白，采用生物测定的方法，在室内研究了其对甜菜夜蛾和斜纹夜蛾低龄幼虫存活率和体质量抑制率的影响。【结果】随着Cry2Ab蛋白浓度的增大，甜菜夜蛾初孵幼虫和1龄幼虫的存活率逐渐降低，2龄幼虫和3龄幼虫以及斜纹夜蛾各龄期幼虫的存活率在不同浓度处理下与对照差异均不显著。但与对照相比，高浓度处理对这2种害虫各龄期幼虫的体质量均有显著影响。【结论与意义】高浓度Cry2Ab蛋白（10．0和20．0μg·g^-1）对甜菜夜蛾低龄幼虫有较好的控制作用，但对斜纹夜蛾低龄幼虫的控制效果不太理想。这为该双价基因棉花在我国的推广提供了依据。

The effectiveness of Cry2Ab protein against early-instar larvae of Spodoptera exigua and S. fitura

Background ] After the widespread planting of Bt cotton in China, the target pests cotton bollworm, Helicoverpa armigera and the pink bollworm H. zea were no longer major pests. However, two other herbivores, Spodoptera exigua and S. litura remained important. The Cry2Ab protein, expressed in Bollgard 11 cotton seems to have higher effects against these two pests. In this paper, the effect of Cry2Ab protein on these lepidopteran pests was investigated. Method] The effects of different Cry2Ab protein concen- trations （ 1.25, 2.5, 5.0, 10.0 and 20.0 μg·g^-1 ） mixed into artificial diet on the survival rate and growth rate inhibition in S. exigua and S. litura were described under laboratory conditions. Result] With the increase of Cry2Ab protein concentration, first- instar and neonate larvae of S. exigua displayed a lower survival rate, but second and third-instar larvae of either species showed no significant differences compared with the control. However, body mass of these two insects was obviously negatively affected by feeding on Cry2Ab protein containing diets. Conclusion and significance] High concentrations of Cry2Ab protein （10.0 and 20.0 μg·g^-1 ） had stronger effects against neonates and first-instar S. exigua larvae but had little effect against S. litura.