筛胸梳爪叩甲(Melanotus cribricollis)幼虫共生细菌对绿僵菌的抑菌活性

Antimicrobial activity of endosymbiotic bacteria isolated from Melanotus cribricollis larva against Metarhizium pingshaense

绿僵菌是重要的害虫生防资源,其防治效果常受到环境中其他微生物的影响,而其内在机制尚不明晰。本研究测定了筛胸梳爪叩甲(Melanotus cribricollis)幼虫体内次生内共生菌——吉伯伦不动杆菌(Acinetobacter gyllenbergii)对平沙绿僵菌(Metarhizium pingshaense)活性的抑制作用。结果表明,不动杆菌发酵液与挥发物对平沙绿僵菌孢子萌发及产孢量均有极显著的抑制效果;发酵液对菌丝生长存在抑制作用,但作用时间较短,至处理后第7天,这种抑制效果即不明显,挥发物则对菌丝生长无影响;利用气相色谱质谱联用仪(GC-MS)分析筛选不动杆菌9种挥发性物质,其中α-蒎烯、苯胺、壬醛、2,4二叔丁基苯酚、柠檬烯、1-十二烯和二甲基三硫对绿僵菌活性具有显著的抑制作用。金针虫内共生菌吉伯伦不动杆菌对绿僵菌活性具有强烈的抑制作用。

Metarhiziumspp. is an important biocontrol resource for the management of underground pests. While it is known that the control efficiency as entomopathogenic fungi is often affected by other microorganisms, the underlying mechanism is unclear. In this study, we examined the inhibitory effect ofAcinetobacter gyllenbergii, a secondary endosymbiont isolated from Melanotus cribricollislarva, on the activity ofMetarhizium pingshaensethat effectively infects wireworm. The results showed that both the fermentation broth and volatiles ofA. gyllenbergii showed significant inhibitory effects on spore germination and production ofM. pingshaense.The fermentation broth ofA. gyllenbergiisignificantly inhibited mycelium growth ofM. pingshaensein seven days, while the volatiles ofA. gyllenbergiidid not affect mycelium growth ofM. pingshaense. Nine effective volatile compounds ofA. gyllenbergiiwere identified by GC-MS analysis.Seven compounds, inclduing α-pinene, aniline, nonanal, 2,4-di-tert-butylphenol, limonene, 1-dodecene and dimethyl trisulfide, had significant inhibitory effects on the activity ofM. pingshaense. Therefore, the endosymbiotic bacteria ofM. cribricollislarva showed a strong inhibitory effect on the growth ofM. pingshaense.