球孢白僵菌对烟粉虱和小菜蛾的致病力及其侵染差异分析

为研究球孢白僵菌对不同昆虫的致病力及其在昆虫体表侵染的差异，探讨球孢白僵菌对不同寄主昆虫侵染的毒力差异，本研究选择了不同分离来源的9株球孢白僵菌，以半翅目的烟粉虱和鳞翅目的小菜蛾为试验材料，详细比较了球孢白僵菌对烟粉虱2龄若虫和小菜蛾2龄幼虫的毒力差异，以及在侵染过程中孢子吸附、孢子萌发及芽管伸长速度差异。结果表明，9株球孢白僵菌有6株对2种昆虫毒力差异显著，3个菌株差异不显著。对2种昆虫毒力差异不显著的菌株Bb271在2种昆虫体表单位面积的孢子吸附数量、孢子萌发率和芽管伸长速度均无显著差异；对2种昆虫毒力差异显著的2个菌株Bb104和Bb120在2种昆虫体表单位面积的孢子吸附数量和孢子萌发率无显著差异，但在2种昆虫体表的芽管伸长速度差异显著（P<0.05）。因此，从本研究结果来看，球孢白僵菌对不同昆虫的致病力强弱与昆虫体表单位面积的孢子吸附数量和孢子萌发率无关，与球孢白僵菌在昆虫体表的芽管伸长速度有关。芽管伸长速度可以作为球孢白僵菌菌株对寄主昆虫致病力强弱的形态学依据。

Pathogenecity and Infectation Differentiations of Beauveria bassiana against Bemisia tabaci and Plutella xylostella

To study the pathogenecity and morphological differentiations of Beauveria bassiana on cuticles of different insects, and to investigate the virulence-related characteristics of morphological differentiation, nine B. bassiana strains isolated from various insects were selected. The Hemiptera whitefly (Bemisia tabaci Gennadius) and Lepidoptera diamond back moth (Plutella xylostella Linnaeus) were used as hosts, a detailed comparison of pathogenecity, spores attachment, spores germination and growth rate of germ tubes of B. bassiana strains were conducted. The results suggested that virulence of six B. bassiana strains differed significantly between the two host insects, and three strains showed no significant difference. The Bb271 strain showed significant difference in pathogenecity to B. tabaci and P. xylostella, however the number of spores attached on per unit area, the germination rate, and the growth rate of germ tubes showed no significant difference between the two insects. The Bb104 and Bb120 strains also showed significant difference in pathogenecity to B. tabaci and P. xylostella, but the number of spores attached on per unit area and the germination rate showed no significant difference between the two insects, while the growth rates of germ tubes were significantly different. Therefore, it can be concluded that the virulence differentiation of B. bassiana to B. tabaci and P. xylostella was not related to spores attachment and spores germination, but to the growth rate of germ tubes on insect cuticles. The growth rate of germ tubes on insect cuticles may serve as the typical morphological characteristics in identifying pathogenecity of B. bassiana strains to different insects.