The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is one of the most destructive cosmopolitan insect pests of brassicaceous crops. It is the first crop insect reported to be resistant to DDT and now, in many crucifer producing regions, it shows significant resistance to almost every synthetic insecticide applied in the field. The present study examined the difference of growth rate, sporulation, germination rate, and extracellular protease production among eight Isaria fumosorosea strains isolated from Lepidoptera in China. Three strains RCEF218(K RCEF3423 and RCEF3496 with good biological characters were selected for further bioassay against the larvae of P. xylostellais. The strain RCEF3423 showed high virulence to P. xylostellais with a corrected mortality of 96.16%, a infection ratio of 91.67%, and a lethal time for 50% mortality (LT50) of 4.58 d at a concentration of 1 ×107 conidia/mL. The strain showed great potential for sustainable for use in microbial control of P. xylostella.%小菜蛾(Plutella xylostella)是全球十字花科蔬菜上的重要害虫,并且对常用的化学杀虫剂产生了严重的抗性,每年给农业蔬菜带来了巨大损失.本研究选择分离自不同鳞翅目的8个玫烟色棒束孢(Isaria fumosorosea)菌株,依据菌株生长速度、产孢量、萌发率和产胞外蛋白酶水平等生物学性状进行初步筛选.在此基础上,筛选出生物学性状优良菌株RCEF2180、RCEF3423、RCEF3496对小菜蛾幼虫进行生物测定.最后筛选出了生长速度快、产孢能力强、萌发率高、胞外蛋白酶产酶水平高及杀虫效果好的玫烟色棒束孢RCEF3423菌株.该菌株对小菜蛾的校正死亡率达96.16％,感染率达91.67％,在浓度为1×107孢子/mL时的半致死中时仅为4.58 d,显示出对小菜蛾的极强毒力,因此该菌株在小菜蛾的生物防治中具潜在的应用价值.
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