美国白蛾高毒力球孢白僵菌菌株筛选

Evaluation of Beauveria bassiana isolates as potential agents for control of Hyphantria cunea(Lepidoptera: Arctiidae)

【目的】美国白蛾Hyphantria cunea（Drury）是世界性检疫害虫,目前已经入侵到我国长江下游地区（从辽宁丹东至安徽芜湖）。作者在前期研究中,在芜湖地区成功获得了被球孢白僵菌Beauveria bassiana侵染的美国白蛾僵虫。本研究拟在前期已获取菌株的基础上,筛选生物学性状良好且对美国白蛾幼虫具有高致病力的球孢白僵菌菌株,以期为我国长江下游地区利用昆虫病原真菌防治美国白蛾奠定基础。【方法】对采集自美国白蛾僵虫的7株球孢白僵菌菌株（Bb01-1,Bb08-5,Bb08-6,Bb08-11,Bb22-2,Bb22-3和Bb22-5）进行生物学特性研究,以候选菌株菌落形态、生长速率、产孢量、萌发率和抗紫外能力等参数确定优良菌株;并将生物学性状良好的球孢白僵菌菌株配制成5个浓度（5×10^6,1×10^7,5×10^7,1×10^8和5×10^8孢子/m L）的孢悬液,采用浸渍法处理美国白蛾4龄幼虫,以幼虫死亡率、侵染率等指标评价菌株的致病力。【结果】供试菌株Bb22-2,Bb22-3和Bb22-5为粉状菌落,其菌落直径大,产孢早且孢子层厚;同时,这3个菌株在菌落生长速率和产孢量以及孢子萌发率、紫外照射处理后的萌发率也均显著优于其他4个菌株。毒力测定结果表明,这3个菌株对美国白蛾4龄幼虫表现出很强的致病力,各菌株处理11 d后美国白蛾幼虫校正死亡率为80%^90%。这3个菌株对美国白蛾幼虫的侵染率均高（侵染率53%^87%）,并且呈现随浓度升高侵染率上升的趋势。其中,菌株Bb22-2侵染率均要高于其他2个菌株。【结论】本研究成功筛选获得了生物学性状良好且对美国白蛾高毒力的球孢白僵菌菌株。鉴于中国长江下游地区气候特点与美国白蛾生物学习性,可以预期采用昆虫病原真菌防治美国白蛾在该地区将具有很好的应用前景,但其实际应用价值尚需进一步的田间试验进行确认。

[ Aim ] The fall webworm, Hyphantria cunea （Dmry） （Lepidoptera： Arctiidae）, a destructiveinvasive pest and native to North America, has spread from Dandong city, Liaoning province of northeastern China to Wuhu city, Anhui province of southeastern China. Effective control measures are urgently needed. In this study, Beauveria bassiana isolates from 11. cunea were examined for biological characteristics and virulence, to assess their potential as a bio-control agent for H. cunea. [ Methods ] The biological characteristics of seven isolates （ Bb01-1, Bb08-5, Bb08-6, Bb08-11, Bb22-2, Bb22-3 and Bb22-5 ）, including colony morphology, growth rate, conidial yield, conidial germination and tolerance to UV light, were examined. Then, three isolates with better performance were selected for bioassays against the 4th instar larvae of H. cunea. [ Results ] There were significant differences in colony growth rate, conidial yield, conidial germination and tolerance to UV light among the tested B. bassiana isolates. The isolates Bb22-2, Bb22-3 and Bb22-5 exhibited better characteristics with faster hyphal growth rate, higher spore production, faster spore germination and higher UV tolerance. The results of pathogenicity test of B. bassiana to the H. cunea larvae showed that the three isolates of B. bassiana demonstrated a higher efficacy. The three isolates caused the corrected mortality rates of 80% -90% in H. cunea at 11 d post inoculation. And the infection rates of B. bassiana against H. cunea were between 53% and 87% at 11 d post inoculation. The isolate Bb22-2 caused higher infection rates of B. bassiana against H. cunea than the other two isolates. [ Conclusion ] This study demonstrated that B. bassiana is a highly effective entomopathogen against H. cunea. The isolate Bb22-2 has a great potential for sustainable control of H. cunea in forests. Further field experiments are needed to investigate its efficacy under natural conditions.