美国白蛾高毒Bt菌株复配增效试验

苏云金芽孢杆菌是一种重要的生物杀虫剂，有着低毒、无公害、环境友好等优点，在防治美国白蛾中取得了较好成效。但单一使用时也存在着对美国白蛾幼虫致死效率不高及致死速率较慢的问题。首先利用前期筛选的美国白蛾高毒苏云金芽孢杆菌CF1262菌株与常用生物制剂（灭幼脲III号、阿维菌素、苦参碱）进行相容性测定试验，筛选出与苏云金芽孢杆菌相容性好的生物杀虫剂灭幼脲III号和阿维菌素；再用筛选出的生物杀虫剂进行不同浓度的复配增效试验，测试室内联合毒力，并通过共毒系数的计算优选出表现增效作用的组合。综合复配剂对美国白蛾4龄幼虫的联合毒力及共毒系数的整体情况来看，1.8%阿维菌素乳油、25%灭幼脲III号悬浮剂与苏云金芽孢杆菌CF1262复配剂均对美国白蛾的生物防治显示出了很好的增效作用。其中，苏云金芽孢杆菌CF1262与1.8%阿维菌素乳油体积比1∶1混合后增效作用尤为明显，共毒系数达到179.88。试验结果为美国白蛾的生物防治提供更多值得参考的方法和选择。

Synergistic test of Bt strain with high virulence of Hyphantria cunea

Bacillus thuringiensis is an important biological insecticide. It has the advantages of low toxicity, no pollution and environment friendliness. It has exhibited high efficiency in control of Hyphantria cunea. However, it also has the shortage of relatively low lethal efficiency and rate against the larvae of H. cunea. Firstly, the compatibility test between CF1262 strain of B. thuringiensis that have selected for H. cunea control and commonly used biological control agents (chlorbenzuron III, avermectin and matrine) was carried out. The chlorbenzuron III and avermectin exhibited good compatibility with B. thuringiensis. Secondlly, the screened two biological pesticides were used to carry out the synergistic test under different concentrations, and the combined virulence was tested in laboratory. the best synergistic combination was deduced by calculating the co-toxicity coefficient. The results showed that the combination of 1.8% avermectin EC, or 25% chlorbenzuron III suspension with B. thuringiensis CF1262 had good synergistic effect on the biological control of H. cunea. Among them, the synergistic effect of B. thuringiensis CF1262 and 1.8% avermectin emulsifiable concentrate with volume ratio of 1:1 was particularly obvious, the co-toxicity coefficient reached 179.88. These results will provide more valuable methods and choices for the biological control of H. cunea.