球孢白僵菌的分离鉴定及其对蒙古拟地甲的毒力分析

Isolation and identification of Beauveria bassiana strains and test of their virulence to Gonocephalum mongolicum

摘要:

【背景】昆虫病原真菌是自然界昆虫种群消长的重要调节因子，但目前对蒙古拟地甲(Gonocephalum mongolicum)高毒力菌株的研究非常缺乏。【目的】分离鉴定昆虫病原真菌，探究昆虫病原真菌对蒙古拟地甲成虫的毒力，为蒙古拟地甲的绿色防控提供新思路。【方法】从自然染菌的蒙古拟地甲僵虫上分离昆虫病原真菌，使用形态学特征和分子生物学技术鉴定真菌种属，采用浸虫法测定蒙古拟地甲成虫的校正死亡率和致死中时间(LT₅₀)。【结果】3株真菌均为球孢白僵菌(Beauveria bassiana)，编号为Bb23、Bb24和Bb25。室内试验发现3株球孢白僵菌对蒙古拟地甲成虫的毒力存在差异，在1.0×10⁸ CFU/mL剂量下接种后20 d，菌株Bb24处理组试虫校正死亡率为87.88%，LT₅₀为6.74 d；而菌株Bb23和Bb25处理组试虫校正死亡率分别为42.42%和33.34%。【结论】本研究获得了3株球孢白僵菌，其中菌株Bb24对蒙古拟地甲成虫具有高毒力，具有进一步开发利用的潜力。

Abstract:

[Background] Entomopathogenic fungi are important regulators of insect population dynamics in nature. However, the research of entomopathogenic fungi with high virulence to Gonocephalum mongolicum are scarce. [Objective] To isolate and identify entomopathogenic fungi and test the virulence of these fungi to G. mongolicum, providing ideas for the green prevention and control of G. mongolicum. [Methods] Entomopathogenic fungi were isolated from naturally infected G. mongolicum and identified by morphological and molecular biological methods. The corrected mortality rate of G. mongolicum adults and the median lethal time (LT₅₀) of the isolates were determined by an immersion method. [Results] The three fungal isolates were identified as Beauveria bassiana and designated Bb23, Bb24, and Bb25. The laboratory test results showed variations in the virulence among the three B. bassiana strains against G. mongolicum adults. Inoculation with the conidial suspension of Bb24 at a concentration of 1.0×10⁸ CFU/mL resulted in a corrected mortality rate of 87.88% on day 20 and the LT₅₀ of 6.74 days, while the corrected mortality rates of Bb23- and Bb25-treated G. mongolicum adults were 42.42% and 33.34%, respectively. [Conclusion] This study identifies three strains of B. bassiana, among which Bb24 displays the highest virulence to the adults of G. mongolica and has the potential for further development and utilization.