樟巢螟致病菌的分离鉴定及其杀虫活性测定

Isolation and Identification of a Bacteria Pathogen from Orthaga achatina and its Bioactivity Assay

从樟巢螟自然死亡的虫尸体内分离得到1株具有较高毒力的致病菌LS-1,对其生防潜能进行评估。经过形态学特征、16S r DNA序列分析,确定该菌株LS-1为粘质沙雷氏菌(Serratia marcescens);以浓度为3.38×10~8cfu/m L的该菌对樟巢螟幼虫进行室内生物测定:感染第3天和第5天,樟巢螟的死亡率分别为50%和71.67%,校正死亡率分别为47.36%和69.1%;以浓度为3.38×10~8cfu/m L、3.38×10~7cfu/m L、3.38×10~6cfu/m L、3.38×10~5cfu/m L 4个浓度梯度对二化螟幼虫进行室内生物测定,感染第4天,水稻二化螟幼虫的死亡率分别为90.67%、86.67%、84%、82.67%,校正死亡率分别为87.51%、82.17%、78.57%、76.79%。结果说明该菌株对控制螟蛾类害虫具有较好的效果,研究为下一步开发螟蛾类绿色生物杀虫剂提供了研究基础。

A bacteria isolated LS-1 was isolated from natural dead insect larvae of Orthaga achatina moth and its insecticidal bioactivities. Through morphological and 16 S r DNA sequences analysis,it was identified as Serratia marcescen. Bioactivity of S marcescens LS-1（3. 38 ×10^8 cfu/m L） agains the3 rd-instar larvae of Orthaga olivacea Warre and Chilo suppressalis（ Walker） were assayed in laboratory. The mortality of Orthaga olivacea Warre was 50% after 3 d infection andr infection and above71. 67 % for 5 d after infection,the corrected mortality rates were 47. 36% and 69. 1%. The 3 rd-instar larvae of Chilo suppressalis（ Walker） were treated with four different concentrations（3. 38 ×10^8 cfu/ml,3. 38 ×10^7 cfu/ml,3. 38 ×10^6 cfu/ml,3. 38 ×10^5 cfu/ml） of S. marcescens LS-1,the re-sults showed that the mortality of Chilo suppressalis（ Walker） respectively were 90. 67%,86. 67%,84%,82. 67%,after 4 d infection,respectively. The corrected mortality rates were 87. 51%,82. 17%,78. 57%,76. 79%,respectively. This stuty demonstrate LS-1 can effectively control epipaschiid moth and may be used in biocontrol.