一株感染杨尺蠖蛹的病原真菌的分离及鉴定

Isolation and identification of an entomopathogenic fungus isolated from the pupae of Apocheima cinerarius

【目的】从山西省洪洞县的杨树丰产林中采集到几头自然染菌的杨尺蠖Apocheima cinerarius越冬蛹虫尸,经分离纯化得到一株病原真菌,定名为YHT01,确定该菌株的分类地位。【方法】用该菌株孢子悬浮液(1.0×108 conidia/m L)感染杨尺蠖蛹进行回接杀虫实验,扫描电镜观察菌株形态学特征,ITS序列测定并构建系统发育树对YHT01菌株进行分子鉴定。【结果】经YHT01菌株感染之后,杨尺蠖蛹节间处长出白色菌丝。该菌株在PDA培养基上的菌落呈椭圆形,白色,绒毛状,菌落背面呈橙黄色;扫描电镜观察结果显示,该菌株孢梗束呈扫帚状,分生孢子小,卵形至椭圆形,壁光滑,大小为(2.1-3.4)μm×(1.1-1.8)μm。该菌株的r DNA-ITS序列与Gen Bank中粉棒束孢Isaria farinosa(Holm:Fr.)Fr.(AB233337)的序列相似性达99%,在系统发育树的同一分支上。【结论】YHT01是杨尺蠖蛹的一株病原真菌,粉棒束孢Isaria farinosa。

[Objective] Some naturally diseased Apocheima cinerarius pupae were collected in poplar forests in Hongtong, Shanxi province, China. The strain of YHT01 was isolated and purified from these naturally diseased pupae, and its classification status was determined. [Methods] A. cinerarius inoculation was conducted with conidial suspension（1.0×10^8 conidia/m L） of strain YHT01. The morphological characteristic was observed using scanning electron microscopy and the molecular identification was conducted by ITS sequence determination and phylogenetic analysis. [Results] White mycelia emerged between body segments after inoculated by strain YHT01. The colonies of the strain in PDA culture medium showed oval shape, white and fluffy, while the back of the colonies showed orange yellow. The coremium of the strain were like brooms, and the conidium was small（2.1–3.4） μm×（1.1–1.8） μm, oval to ellipsoid, smooth observed by scanning electron microscope. The comparability between the r DNA-ITS sequence of strain YHT01 and Isaria farinosa（Holm： Fr.） Fr.（AB233337） in Gen Bank is 99%, and these two strains are gathered in one branch in the phylogenetic tree. [Conclusion] Strain YHT01 is a pathogenic fungus of A. cinerarius, and identified as I. farinosa.