脐腹小蠹高致病力虫生真菌菌株的筛选

Screening of highly virulent strains of fungi entomopathogenic to Scolytus schevyrewi Semenov

【目的】脐腹小蠹ScolytusschevyrewiSemenov是白榆的钻蛀性害虫之一，为找到对脐腹小蠹的高致病力虫生真菌菌株。【方法】通过室内喷雾法研究了5株虫生真菌菌株对脐腹小蠹幼虫的致病力，结合各菌株菌落直径、孢子萌发率、产孢量和菌落生长速率4个培养特征，筛选到Bb773和Pc5462株优良的菌株，在此基础上，进～步对这2株菌株的几丁质酶、蛋白质酶和荧光素二乙酸酯（FDA）水解酶活性进行了测定。【结果】菌株Bb773和菌株Pc546在浓度为1×10^7孢子／mL悬浮液处理后，10d的后脐腹小蠹幼虫的校正死亡率分别达96．67％和90．00％，致死中时分别为3．61d和4．18d。菌株Bb773的几丁质酶、FDA水解酶和蛋白质酶活性在接种后第2-10天均高于菌株Pc546，2株菌株蛋白质酶活性差异均达到了显著水平（P〈0．05）。【结论】确定了菌株Bb773在脐腹小蠹害虫生物防治中具有潜在的应用价值。

[Objectives] To identify highly virulent strains of fungi entomopathogenic to Scolyms schevyrewi Semenov, one of the boring pests of Ulmus pumila. [Methods] The pathogenicity of two superior strains, Bb773 and Pc546, to S. schevyrewi larvae was examined and the culture characteristics of these strains, including the final colony size, spore generation, sporulation and average growth rate, determined. A preliminary screening examined chitinase, proteinase and FDA hydrolase activities of the two selected strains. [Results] Adjusted death rates and median lethal time （LT50） of S. schevyrewi larvae ten days after infection with strains Bb773 and Pc546 at a concentration of 1×107 conidia/mL were 96.67%, 90,00% and 3.61 d, 4.18 d, respectively, Chitinase, proteinase and FDA hydrolase activity of strain Bb773 was higher than that of strain Pe546 after about 2-10 days culture and proteinase activity was also significantly higher （P〈0.05）. [Conclusion] Strain Bb773 has greater potential as a biological control agent for the sustainable control ofS. schevyrewi.