栎旋木柄天牛高毒力球孢白僵菌菌株的筛选

Screening of high virulent strains of Beauveria bassiana against a dangerous forest cerambycid beetle,Aphrodisium sauteri(Coleoptera:Cerambycidae)

栎旋木柄天牛Aphrodisium sauteri是近年来在安徽黄山风景区大面积暴发的危险性林业有害生物之一,其发生危害已经严重影响了风景区自然与生态景观。本研究选择分离自不同天牛成虫的8个球孢白僵菌Beauveria bassiana菌株,依据菌落形态、菌株生长速度、产孢量、萌发率、抗旱力和产胞外蛋白酶水平等生物学性状进行初步筛选。在此基础上,筛选出生物学性状优良菌株Bb202、Bb646和Bb1898,并进一步对栎旋木柄天牛幼虫进行生物测定。基于此种筛选模式的菌株筛选方法筛选出了具有菌落生长速度快、萌发率高、产孢和抗旱能力强、胞外蛋白酶产酶水平高及毒力强的球孢白僵菌Bb202菌株。该菌株对栎旋木柄天牛的校正死亡率达92.8%,侵染率达93.3%,在浓度为1×107/mL时的半致死中时仅为5.86天,显示出对目标天牛的极强毒力,在栎旋木柄天牛的生物防治中将有重要的应用价值。

Aphrodisium sauteri is one of the most dangerous forest pests in China and has caused extensive mortality of oak trees in Huangshan mountains. In this study we surveyed the possibility of using the entomopathogenic fungus, Beauveria bassiana as a biological control agent against the notorious longhorn beetle. Here eight strains of B. bassiana, isolated from different longhorn beetles, were employed as the candidate strains against the pest insect. As the preliminary screening, the biological characteristics of these eight strains, including colony morphology, growth rate, sporulation, germination rate, drought tolerance, and extracellular protease production, were examined. Based on the comparison of the biological characteristics, three strains Bb202, Bb646 and Bb1898 among the tested strains were adopted for further bioassay against A. sauteri larvae. The bioassay results showed that Bb202 showed the highest virulence on the target beetle with a mortality of 93.3%, and the median lethal time （LTso） was 5.86 d at a concentration of 1 ×10^7 conidia/mL. Thus Bb202 exhibits the great potential as one of the biological control agents for the sustainable control of A. sauteri in the future.