草地贪夜蛾莱氏绿僵菌的分离鉴定

草地贪夜蛾Spodoptera frugiperda(J.E.Smith)是2019年入侵我国的一种迁飞性害虫,已成为严重影响我国玉米生产的重要害虫。目前国内关于草地贪夜蛾昆虫病原真菌的研究报道很少。2019年6月,在云南省曲靖市沾益县安东村玉米田调查发现了被虫生真菌感染的草地贪夜蛾幼虫。经室内分离培养,结合形态和ITS序列相似性分析鉴定确认,感染草地贪夜蛾幼虫病原性真菌为莱氏绿僵菌Metarhizium rileyi,编号为ZYSP190701菌株。调查表明,2019年7月17日田间草地贪夜蛾的莱氏绿僵菌感染率为15.46%±2.52%,8月2日感染率达29.83%±13.71%。用莱氏绿僵菌ZYSP190701菌株1×10~8个/mL孢子浓度接种草地贪夜蛾3龄幼虫后第7天时草地贪夜蛾的感染死亡率高达100%。上述结果表明,莱氏绿僵菌ZYSP190701对草地贪夜蛾有良好的生防潜力,具有草地贪夜蛾生防菌剂开发应用的前景。

Isolation and identification of entomopathogenic fungi Metarhizium rileyiisolated from Spodoptera frugiperda (J.E.Smith)

Spodoptera frugiperda (J.E.Smith) is an outbreak invasive pest, especially for maize. To date, little information about entomopathogenic fungi of Spodoptera frugiperda is available in China. In this study, fungi infected S.frugiperda larvae were found in Andong village, Zhanyi county, Qujing city, Yunnan province. The fungi were isolated from the infected cadaver of S.frugiperda, and then the species was identified based on the morphological and molecular biology, the virulence of the fungi against the larvae of S.frugiperda was tested. Results showed that this strain was identified as Metarhizium rileyi (No. ZYSP190701). The infection rate of S.frugiperda was 15.46%±2.52% on 17th, July and 29.83%±13.71% on 2nd, August, respectively. The cumulative mortality of the 3rd instar larvae of S.frugiperda 7 d after immersion inoculation at 1 ×108 conidia/mL was 100%. Our results demonstrated that M.rileyi ZYSP190701 is a promising candidate for S.frugiperda biocontrol in field.