四株虫生真菌的鉴定及其对小菜蛾的室内毒力

为了明确4株虫生真菌在小菜蛾防治中的应用潜力,采用生物测定法测定其室内毒力,并通过多相分类法研究其分类地位。结果表明:菌株GZU-BCECWC113对小菜蛾的毒力最强,在1.6×108孢子/mL浓度下对小菜蛾的校正死亡率最高,达到89.47%;半致死时间LT50值最小,为3.33天;感染8天时的LC50值最小,为0.45×105孢子/mL。根据形态特征、培养性状及ITS序列分析结果明确4株菌的分类地位,即GZU-BCECWC113为环链拟青霉Paecilomyces catenianulatus,GZU-BCECWQ16为玫烟色拟青霉P.fumosorosenus,GZU-BCECW122为蝉拟青霉P.cicadae,GZU-BCEC-WKKS2为细脚拟青霉P.tenuipes。

Identification of four entomogenous fungi and preliminary evaluation on their insecticidal activities to Plutella xylostellaL.

In order to confirm the potential application of four isolates of entomogenous fungi for biocontrol of Plutella xylostella, the insecticidal activities of the four isolates to P.xylostella was determined by bioassay method. The taxonomic identification of the isolates was also carried out with multiphase taxonomy. The virulent bioassay against P.xylostella showed that the best isolate was GZU-BCECWC113, with the lowest value of LT₅₀ and LC₅₀. The LT₅₀ was 3.33 days when the concentration of conidia was 1.6×10⁸ conidia/mL,and the value of LC₅₀ was 0.45×10⁵ conidia/mL when the tested insects were infested 8 days. The corrected mortality rate of GZU-BCECWC113 was 89.47%, which was the highest one among the four isolates. By using the traditional taxonomic methods and phylogenetic analysis based on ITS1-5.8S-ITS2 rRNA sequences, the four isolates were identified. The results showed that GZU-BCECWC113, GZU-BCECWQ16, GZU-BCECW122 and GZU-BCECWKKS2 belonging to Paecilomyces catenianulatus, P.fumosorosenus, P.cicadae and P.tenuipes, respectively.