粘虫高毒力白僵菌菌株筛选及其感菌后虫体内保护酶活性的变化

为获得生物学性状良好且对粘虫具有高毒力的球孢白僵菌菌株,本研究以8株球孢白僵菌(Beauveria bassiana)菌株为材料,根据菌株产孢量、萌发率和生长速率差异筛选优势菌株,然后测定优势菌株孢子悬浮液对粘虫3龄幼虫的致死率,以及3龄幼虫感染高毒力白僵菌后体内抗氧化酶和解毒酶活性的变化。结果表明,8株球孢白僵菌菌株生长特性各项指标均存在显著差异,菌株Bb314、Bb345、Bb412和Bb378的生长速率、产孢量和孢子萌发率高于其他4个菌株。菌株Bb314孢子悬浮液对粘虫3龄幼虫致死率最高,达69%。Bb314侵染粘虫后,感染前期虫体酚氧化酶(PO)和过氧化物酶(POD)活性显著提高,于36 h达峰值;过氧化氢酶(CAT)活性在感染初期(24 h)时低于对照,处理48 h后达到峰值,并显著高于对照;谷胱甘肽-S-转移酶(GSTs)和羧酸酯酶(CarE)活性分别在处理36 h和48 h后达到高峰,并显著高于对照。以上结果表明,菌株Bb314可能通过影响粘虫幼体内抗氧化酶和解毒酶活性的动态平衡,进而影响其生理代谢。本研究为开发粘虫生防菌的潜力菌株提供了参考。

Screening of Beauveria bassiana Strains With High Virulence Against Armyworm and Activities of Protective Enzymes in the Larvae Infected by Fungi

To obtain Beauveria bassiana strains with good biological characteristics and high virulence to armyworm, the dominant strains were selected by examining the spore production, germination rate and growth rate from eight Beauveria bassiana strains, which then were applied to test the lethality to the 3^rd larvae of armyworm. The activities of antioxidant and detoxifying enzymes in the 3^rdlarvae of armyworm infected by the highest virulent isolate were also assayed. The results showed that the eight Beauveria bassiana strains showed significant differences in all the growth characteristics. Growth rate, spore production, and spore germination rate of strains Bb314, Bb345, Bb412 and Bb378 were higher than those of the other four strains. With regard to the lethality to larvae, the strain Bb314 showed the highest lethality (69%) to the 3^rdlarvae of armyworm. After infected by strain Bb314, activities of polyphenol oxidase and peroxidase in the 3^rdlarvae increased significantly at the early stage, and reached to their peaks at 36 h. The activity of catalase enzyme in the 3^rdlarvae infected by Bb314 were lower than that of control at the beginning of infection (24 h), but reached to the highest activities at 48 h after infection. The activities of glutathione-S-transferase and carboxylesterase reached their peak values at 36 h and 48 h respectively after Bb314 treatment, which were dramatically higher than those of the control without infection. These results indicated that the strain Bb314 might influence the activities of antioxidant and detoxifying enzymes in armyworm, which in return affected the physiological metabolism of armyworm. This study provides a reference for the development of potential strains for biological control of armyworm.