一株对桃蚜有高致病性球孢白僵菌的分离、筛选与鉴定

为筛选出对桃蚜Myzus persicae具有高致病性的生防真菌,以从陕西省秦岭原始森林采集到的鳞翅目僵虫虫体中分离获得的5株真菌为研究对象,测定其对桃蚜的致病性并筛选出高致病性菌株表现最佳杀蚜活性时的孢子悬浮液浓度,同时结合形态学及18S rDNA和ITS-rDNA序列分析对致病性最高的病原菌进行鉴定。结果显示,从5株菌株中初步筛选出1株高致病性菌株BQ-63,处理7 d后桃蚜的死亡率为80.33%,校正死亡率为81.58%,僵虫率也达到最高,为80.78%;当菌株BQ-63的孢子浓度为108个/mL时,对桃蚜的致病性达到最高,处理7 d后死亡率为89.53%,校正死亡率为90.10%,僵虫率为89.84%;通过形态学和分子生物学鉴定,确定菌株BQ-63为球孢白僵菌Beauveria bassiana。表明菌株BQ-63对桃蚜具有高致病性,可作为生防真菌进行进一步的研究。

Separation, screening and identification of one isolate of Beauveria bassiana with high pathogenicity to Myzus persicae

In order to select highly pathogenic biocontrol strains for Myzus persicae (Sulzer), five fungal isolates were isolated from Lepidoptera muscardine cadavers in the primeval forests of Qinling in Shaanxi Province. Based on pathogenicity test, the most highly pathogenic biocontrol strain and its optimal concentration of spore were screened out. Morphological characteristics and molecular identification of the partial sequences of 18S rDNA and ITS-rDNA were used. The results showed that the best strain, BQ-63, was obtained from the five isolates. After seven-day-treatment, the mortality rate of M. persicae was 80.33%; the corrected mortality was 81.58% and the rate of corpse was 80.78%. Under different spore concentrations of BQ-63, the pathogenicity against M. persicae was measured, and the results showed that the best spore concentration was 10⁸/mL, with a mortality rate, corrected mortality and the rate of corpse of 89.53%, 90.10% and 89.84%, respectively. The strain BQ-63 was identified as Beauveria bassiana by using morphological and molecular methods. The results indicated that strain BQ-63 was highly virulent to M. persicae and could be used as a biocontrol fungus for further research.