马铃薯甲虫虫生真菌分离及强致病菌株筛选

Fungal isolates from Colorado potato beetles and their pathogenicity to silkworm larvae

采用常规组织分离法,从新疆石河子、伊宁和昌吉等地区采集的马铃薯甲虫发病成虫虫体上分离并纯化出36个真菌菌株。经形态学初步观察,这些菌株分属于白僵菌（Beauveria）、轮枝菌（Verticillium）、镰刀菌（Fusarium）、青霉（Penicillium）、木霉（Trichoderma）和曲霉（Aspergillus）等属。用这些菌株的悬浮液喷雾接种家蚕（Bombyx mori）幼虫后显示,有26个菌株（白僵菌19株,轮枝菌4株,镰刀菌2株,木霉1株）对家蚕幼虫表现出不同程度致病力,并在接种后5~9 d始见虫体死亡。白僵菌的19个菌株的致病力都非常强,接菌后11 d幼虫累计死亡率（LR11d）为75.80%~95.76%,致死中时（LT50）为7.5~10.2 d,其中白僵菌MJ01、MJ07、MJ09和MJ19的致病力最强,它们的LR11d和LT50分别达到91.24%~95.76%和7.5~8.0 d。轮枝菌的4个菌株的致病力亦较强,它们的LR11d和LT50分别为56.25%~61.55%和9.1~10.3 d。镰刀菌的2个菌株和木霉的1个菌株的致病力都比较弱,其LR11d和LT50分别为7.25%~11.00%和18.5~28.8 d。

A number of 36 fungal isolates were obtained from diseased adults of Colorado potato beetle（CPB,Leptinotarsa decemlineata）collected from Shihezi,Yining and Changji of Xinjiang Autonomous Region,China.The morphological characteristics of these isolates were observed microscopically and they were preliminarily identified as species of Beauveria,Verticillium,Fusarium,Penicillium,Trichoderma and Aspergillus,respectively.After the 2nd-instar larvae of silkworm（Bombyx mori）were inoculated with the fungal spore suspension,26 isolates infected the insects and induced disease,but the other 10 isolates did not cause visible infection.Amongst these infectious isolates,there were 19 of B.bassiana,4 of Verticillium sp.,2 of Fusarium sp.and 1 of Trichoderma sp.;they resulted in silkworm death starting from 5-9 d following inoculation.The Beauveria isolates were highly pathogenic,they caused more than 75% of accumulated lethal rates of the worms 11 d after inoculation（LR11d）and the time at which 50% of inoculated worms were killed（LT50）were 7.5-10.2 d.The most pathogenic Beauveria isolates were MJ01,MJ07,MJ09 and MJ19：their LR11d and LT50 were 91.24%-95.76% and 7.5-8.0 d,respectively.The 4 Verticillium isolates were also rather pathogenic to silkworm larvae with LR11d and LT50 of 56.25%-61.55% and 9.1-10.3 d,respectively.The pathogenicity of the 2 Fusarium and 1 Trichoderma isolates was relatively weak：silkworm death 8-9 d after inoculation and the LR11d were relatively low（7.25%-11.00%）while the LT50 were rather long（18.5-28.8 d）.