苏云金杆菌与粘虫颗粒体病毒联合作用对甜菜夜蛾的影响

Impact on toxicity of Bacillus thuringiensis to Spodoptera exigua with Pseudaletia unipuncta Granulovirus-Ps

以甜菜夜蛾为试虫,研究粘虫颗粒体病毒(PuGV-Ps)对苏云金杆菌(Bt)毒力的增效作用。结果表明:PuGV-Ps对甜菜夜蛾无致毒作用,但Bt中加入PuGV-Ps后可提高Bt对甜菜夜蛾的毒力,甜菜夜蛾致死中量LC50由Bt单剂的1.094 mg.mL-1下降到0.862 mg.mL-1,共毒系数达127。亚致死剂量Bt处理甜菜夜蛾能影响昆虫的生长发育,表现为幼虫生长量相对减少、蛹重下降、化蛹率降低和化蛹历期延长,添加PuGV-Ps后可进一步增强Bt对甜菜夜蛾生长发育的抑制作用。甜菜夜蛾中肠蛋白酶活性测定结果表明,PuGV-Ps对甜菜夜蛾中肠酶活性具有抑制作用;昆虫同时取食PuGV-Ps和Bt后,中肠酶液总蛋白酶活力均有所下降,在中肠酶液最适pH范围内蛋白酶活力抑制作用最明显。

Enhancement of toxicity of Bacillus thuringiensis（Bt） with Pseudaletia unipuncta Granulovirus-Ps（PuGV-Ps） was demonstrated by bio-assays employing larvae of S.exigua.Combinations of Bt and PuGV-Ps were-synergistic-and enhanced toxicity of Bt while PuGV-Ps presented no effect to the larvae.The co-toxicity coefficients（CTC） of Bt combined with PuGV-Ps was 127.Sub-deadly dosage of Bt influenced the larval growth of S.exigua,with less weight of larvae and pupae,delay of pupating and lower ratio of pupation.PuGV-Ps also enhanced the effect of Bt on the development of larvae.The proteolytic activity of midgut juice from Spodotera exigua was influenced by PuGV-Ps.When larvae of S.exigua swallowed the food contain some Bt and PuGV-Ps,the total proteolysis was reduced for some degree by PuGV-Ps under the suited pH value of midgut juice.