一株侵染豌豆蚜的昆虫病原真菌的分离及鉴定

【目的】从采集到的自然染菌的豌豆蚜Acyrthosiphon pisum虫尸分离纯化得到一株病原真菌,定名为TF-2。本研究旨在确定该菌株的分类地位,为豌豆蚜生物防治提供真菌资源。【方法】对自然染菌的豌豆蚜虫尸上寄生真菌TF-2进行回接试验,分离纯化出致病菌株TF-2;在显微镜下配制TF-2菌株不同浓度孢子悬浮液,采用浸渍法和离体叶片饲养法测定其对豌豆蚜成虫的毒力;利用光学显微镜观察菌株形态学特征。PCR扩增TF-2的rDNA-ITS序列并测序,构建系统发育树对TF-2菌株进行分子鉴定。【结果】毒力测定结果表明,TF-2菌株对豌豆蚜成虫表现出很强的致病力,1×10^7孢子/mL处理6 d后豌豆蚜成虫校正死亡率达到100%。TF-2在PDA培养基上菌落呈圆形,白色或淡黄色毡状,菌落背面呈奶油色;菌株孢梗呈瓶状,在菌丝上单生或侧生2~3个,大小为(19-42)μm×(1.1-2.5)μm,基部较粗至尖端逐渐变细,分生孢子长椭圆形,大小为(4.2-11.8)μm×(1.6-2.6)μm。菌丝体产生晶体呈八面体。该菌株的rDNA-ITS序列与长孢蜡蚧菌Lecanicillium longisporum(GenBank登录号:KX426564)的rDNA-ITS核苷酸序列一致性达99%,位于系统发育树的同一分支。【结论】菌株TF-2被鉴定为豌豆蚜的病原真菌长孢蜡蚧菌L.longisporum,对豌豆蚜的生物防治具有潜在的应用价值。

Isolation and identification of an entomopathogenic fungus infectingAcyrthosiphon pisum(Hemiptera: Aphididae)

【Aim】 One pathogenic fungus named TF-2 was isolated and purified fromnaturally entomopathogen-infected Acyrthosiphon pisum. This study aims to determine theclassification status of the strain and to provide fungal resources for biological controlof A. pisum. 【Methods】 The pathogenetic strain TF-2 was isolated and purified by backinfestation test. Spore suspensions of TF-2 strain at different concentrations wereprepared under microscope, and its virulence to adult pea aphid was measured by dippingmethod and in vitro leaf feeding method. The morphological characteristics of TF-2 strainwere observed by optical microscope. The rDNA-ITS sequence of TF-2 strain was amplifiedby PCR and sequenced, and the phylogenetic tree was constructed for molecularidentification of TF-2 strain. 【Results】 The results of virulence test showed that TF-2strain showed strong pathogenicity to A. pisum adults, causing 100% corrected mortality at6 d after treatment at a concentration of 1×10⁷ conidia/mL spore suspension. The colony ofTF-2 is round on PDA medium, white or light yellow felt-like, and the bottom of thecolony is creamy. The results of optical microscope observation showed that the sporephialides of the strain are bottle-shaped, and there are 2-3 spore phialides singly orlaterally grown on the hypha, (19-42) μm×(1.1-2.5) μm in size. The base is relativelythick and gradually taper to the tip, and the conidia are oval, (4.2-11.8) μm×(1.6-2.6)μm in size. Mycelium produces crystals as octahedra. The rDNA-ITS sequence of the strainTF-2 has 99% nucleotide identity with that of Lecanicillium longisporum (GenBank accessionno.: KX426564) and shares the same branch of phylogenetic tree. 【Conclusion】 The strainTF-2 is determined as the pathogenic fungus L. longisporum with potential applicationvalue in biological control of A. pisum.