一株淡紫拟青霉GDIZM-2的分离鉴定及其对柑橘木虱的毒力评价

昆虫病原真菌是一类能够侵染昆虫并造成其死亡的病原微生物，在自然界中广泛存在，是农业害虫绿色防控的无公害优质资源。本研究从田间采集到的柑橘木虱Diaphorina citri成虫僵虫上分离出一株对柑橘木虱具有强致病性的病原真菌菌株。利用形态学和rDNA-ITS序列分析相结合的方法鉴定其为淡紫拟青霉Purpureocillium lilacinum，命名为GDIZM-2，并在室内测定了该菌株对柑橘木虱若虫和成虫的毒力以及在温室条件下对柑橘木虱成虫的致病力。室内毒力试验结果表明，菌株GDIZM-2可侵染柑橘木虱若虫和成虫，且随着孢子浓度和处理时间的增加，柑橘木虱若虫和成虫的校正死亡率逐渐上升，LC50和LT50值逐渐递减。当浓度为1×108孢子/mL处理第7天时，各龄期柑橘木虱的死亡率均高于75%，具有较高的致病力。温室致病力试验结果表明，淡紫拟青霉GDIZM-2在1×108孢子/mL处理第14天时，柑橘木虱成虫的存活率为1.67%，显著低于金龟子绿僵菌Metarhizium anisopliae GDIZMMa-3和无菌水。本研究结果表明，淡紫拟青霉GDIZM-2对柑橘木虱有良好的生物防治效果，具有开发成为一种新型微生物真菌制剂的应用潜力。

Isolation and identification of a Purpureocillium lilacinum GDIZM-2 isolate and its toxicity evaluation against Diaphorina citri

Entomopathogenic fungi are a class of pathogenic microorganisms capable of infesting insects and causing their death. They are harmless high-quality resources for the green prevention and control of agricultural pests, which are widely existed in nature. In this study, a highly pathogenic fungus strain was isolated from adult Diaphorina citri cadavers, which were collected from the field. The species was identified using morphological characterization and ITS-rDNA sequence analysis indicated that the isolated strain belonged to Purpureocillium lilacinum, and named GDIZM-2. The virulence of the strain was determined in the laboratory against nymphs and adults of the D. citri, as well as the pathogenicity of the strain against D. citri adults under greenhouse conditions. The results of laboratory bioassay showed that nymphs from 1st to 5th instar and adults of D. citri were infected by P. lilacinum strain GDIZM-2. The corrected mortality of nymphs and adults of D. citri caused by infection of P. lilacinum increased with the concentration of conidial suspension and the time after treatment gradually increased, and the LC50 and LT50 values gradually decreased. The mortality of D. citri at all instar were higher than 75% with high pathogenicity at a concentration of 1×108 conidia/mL. The results of greenhouse pathogenicity test showed that the survival of D. citri adults were 1.67% on the 14th day after treatment with 1×108 conidia/mL of P. lilacinum GDIZM-2, which were significantly lower than that of Metarhizium anisopliae GDIZMMa-3 and sterile water. The results of this study showed that P. lilacinum GDIZM-2 had a good biocontrol effect on D. citri, and had the potential to develop into a new microbial fungal agent.