球孢白僵菌不同菌株生物学特性及对小菜蛾的毒力研究*

 室内测定了从鳞翅目小菜蛾、斜纹夜蛾和块茎蛾罹病虫体上分离纯化的球孢白僵菌菌株DBM001,XWYE001和PTM001的菌落生长速率、产孢量、孢子萌发速度，及对小菜蛾幼虫的致病力，并用时间－剂量－死亡率模型进行了分析。结果表明，各菌株在菌落生长速率上无显著差异，但各菌株的孢子萌发速率有显著差异。供试DBM001,PTM001 XWYE001三菌株对小菜蛾二龄幼虫的毒力测定结果表明：供试3菌株对于小菜蛾均具有一定的毒力，剂量效应参数分别为0.424，0.304，0.297。在10⁸孢子/mL,10⁷ 孢子/mL,10⁶孢子/mL,10⁵孢子/mL,10⁴孢子/mL的孢子悬浮液下，3菌株孢子液处理后小菜蛾的累积死亡率分别为94.0%～48.0%，76.0%～28.0%和62.0%～28.0%。3菌株处理后第3d时的LC₅₀分别为6.5×10⁷孢子/mL； 4.07×10⁷孢子/mL和2.88×10⁷孢子/mL。在10⁶孢子/mL下,3菌株对小菜蛾幼虫的致死亡中时LT₅₀依次为3.0, 4.1,3.5d。由此表明，斜纹夜蛾和马铃薯块茎蛾菌株的对小菜蛾幼虫的致死时间效应较长，均在3d以上，即球孢白僵菌不同菌株对小菜蛾种群增长的抑制作用时效差异较大，尤其是斜纹夜蛾和马铃薯块茎蛾分离株对小菜蛾的毒力发挥较慢。

Study on the Biological Characters of Isolates of Beauveria bassiana and their Virulence Against the Plutella xylostella

The biolgical characters of three isolates of Beauveria bassiana was tested, isolates were marked as DBM001,XWYE001 and PTM001. More over, the virulence against the diamondback moth, Plutella xylostella was evaluated．Among the tested isolates, no significant difference was found in spore yield，germination rate, as well as the mycelium growth rates on SDAY medium. But the virulence against diamondback moth was similar. A time-dose-mortality model was used for analyzing the mortality as affected by both time and dosage. The results showed that all tested isolates were virulent to the larvae of diamondback moth, accumulative mortality was 94.0%～48.0%,76.0%～28.0%,62.0%～28.0%.The value of LC₅₀ for the these three isolate was 6.5×10⁷conidia/mL；4.07×10⁷conidia/mL；2.88×10⁷conidia/mL,on the 3rd day after inoculation, the LT₅₀ for the 3 isolates ranged from 3.0, 3.5, 4.1 days under the inoculation of 10⁶ conidia/mL.