斜纹夜蛾高致病力菌株的筛选及四种杀虫剂的毒力测定

Screening of Highly Virulent Strains of Spodoptera litura and Virulence Determination of Four Insecticides

为筛选出相容性好且具有增效作用的菌药复配剂,本研究通过饲喂法,选用永州地区土壤中分离纯化的66株菌株以及保藏于华南农业大学生物防治中心的13株菌株,对斜纹夜蛾二龄幼虫进行高毒力菌株筛选试验,筛选出的高毒力菌株以不同浓度梯度进行毒力测定。同时测定了不同浓度梯度甲维盐、阿维菌素、多杀霉素和氯虫苯甲酰胺对斜纹夜蛾二龄幼虫的致死率。结果表明:孢子悬浮液浓度为1×10^(8) conidia·mL^(-1)时,79株菌株处理斜纹夜蛾二龄幼虫7 d后,球孢白僵菌SCAUYZ16和SCAUJH19的致病力最高,其校正死亡率分别为70.71%和57.84%,LT_(50)分别为5.01和5.98 d。球孢白僵菌SCAUYZ16、SCAUJH19以1×10^(4),1×10^(5),1×10^(6),1×10^(7)和1×10^(8) conidia·mL^(-1)的浓度梯度进行毒力分析试验,LC_(50)分别为3.29×10^(7)和8.09×10^(7) conidia·mL^(-1)。甲维盐、阿维菌素、多杀霉素和氯虫苯甲酰胺分别对斜纹夜蛾二龄幼虫处理3 d后,LC_(50)分别为3.56,59.14,18.82和2.76 mg·L^(-1)。SCAUYZ16和SCAUJH19对斜纹夜蛾有较高的毒力,可作为斜纹夜蛾生物防治的潜力菌株。在后续试验中,可选取杀虫剂较低的LC_(50)剂量为基础,设置不同浓度梯度进行菌药复配试验。

In order to screen out the bacterial-drug blends with good compatibility and synergistic effect,through the feeding method,66 strains isolated and purified from the soil in the Yongzhou area,as well as 13 strains preserved at the Biological Control Center of South China Agricultural University,were used to screen the highly virulent strains for the second instar larvae of Spodoptera litura,the highly virulent strains were assessed using different concentration gradients.At the same time,the mortality of emamectin benzoate,abamectin,spinosad,and chlorantraniliprole against the second instar larvae of insects was studied using different concentration gradients.When the spore suspension concentration of 79 strains was 1×10^(8) conidia·mL^(-1) and the second instar larvae of Spodoptera litura were treated for 7 days,the results showed that Beauveria bassiana SCAUYZ16 and SCAUJH19 had the highest virulence,with corrected mortality rates of 70.71%and 57.84%,LT_(50) of 5.01 days and 5.98 days,respectively.The virulence of Beauveria bassiana SCAUYZ16 and SCAUJH19 were tested at concentration gradients of 1×10^(4),1×10^(5),1×10^(6),1×10^(7),and 1×10^(8) conidia·mL^(-1),with LC_(50) values of 3.29×10^(7) and 8.09×10^(7) conidia·mL^(-1),respectively.After treatment with emamectin benzoate,abamectin,spinosad and chlorantraniliprole on the second instar larvae of Spodoptera litura for 3 days,and the LC_(50) were 3.56,59.14,18.82 and 2.76 mg·L^(-1).SCAUYZ16 and SCAUJH19 showed a high level of virulence against Spodoptera litura and could be exploited as prospective Spodoptera litura biological control strains.The lower LC_(50) dose of the pesticide can be used as the basis for the follow-up test,and different concentration gradients for the compound test of bacteria and pharmaceuticals can be adjusted.