两种甜菜夜蛾致病菌的分离、鉴定及杀虫成分初步分析

Isolation,identification and active ingredient analysis of two pathogenic bacterial strains isolated from Spodoptera exigua

从室内饲养的甜菜夜蛾患病死亡虫体中分离、纯化出5个细菌菌株,进行毒力测试,筛选出对甜菜夜蛾具有较高致病力的菌株B30和B32。通过革兰氏染色、常规形态学观察及16S rDNA序列分析,将B30和B32分别鉴定为黏质沙雷氏菌Serratia marcescens和类芽孢杆菌Paenibacillus cookii。杀虫活性成分分析显示,2个菌株培养液的菌体沉淀破碎液对甜菜夜蛾的致病力高于上清液;上清液和菌体破碎液经蛋白酶K处理后致病力均显著降低。由此推断,两种致病菌的杀虫活性成分主要是胞内蛋白质。

Five bacterial strains were isolated from diseased larvae of Spodoptera exigua.Bioassay analysis demonstrated that two strains（B30 and B32） had higher toxicities to S.exigua than the other three.Based on the Gram stain result,morphological characteristics and 16S rDNA sequences analysis,strains B30 and B32 were identified as Serratia marcescnes and Paenibacillus cookii,respectively.The analysis of active ingredients showed that the pathogenicities of the two strains to S.exigua were much higher in sonicated cell pellet than those in supernatant of bacterial cultures.Pathogenicity of both supernatant and sonicated cell pellet declined after proteinase K treatment,which suggested that the insecticidal active ingredients in strains B30 and B32 were mostly intracellular proteins.