【目的】 弄清分离自云南省师宗县玉米田罹病草地贪夜蛾幼虫的莱氏绿僵菌SZCY200812菌株的生物防治潜力。【方法】 以菌落生长速率及单位面积产孢量作为评价指标，研究该菌株在不同培养基、温度、光周期条件下的生长情况；以分生孢子萌发率为评价指标，评价菌株在不同培养条件下所产分生孢子的抗逆性。【结果】 莱氏绿僵菌SZCY200812菌株对草地贪夜蛾具有较强的侵染致病作用，在1×10⁸ 孢子/mL孢子悬浮液分别处理3龄及5龄幼虫后，分别在第6 天和第8 天时累积死亡率达到100%，LT₅₀分别为3.89和4.66 d；在SMAY培养基上于25 ℃、L∶D=24∶0条件下，该菌落直径日增长量达（1.68±0.01） mm/d，产孢量为（8.05±0.37）×10⁷孢子/mm²；在适宜培养条件下所产分生孢子对胁迫温度及紫外线胁迫时间的最大耐受值分别为70 ℃及12 min，在此条件下将所产分生孢子配制为1×10⁸ 孢子/mL孢子悬浮液处理3龄草地贪夜蛾幼虫的LT₅₀为3.26 d。【结论】 莱氏绿僵菌SZCY200812适宜在SMAY培养基上于25 ℃、L∶D=24∶0条件下生长，所产分生孢子温度耐受能力、紫外线耐受能力及致病力均为最强，在莱氏绿僵菌生防制剂开发中具有良好潜力。

[Objectives]  To investigate the potential of using the fungal strain Metarhizium rileyi SZCY200812, isolated from infected Spodoptera frugiperda larvae in corn fields in Shizong county, Yunnan province, as a biological control for S. frugiperda. [Methods]  The growth rate and spore yield per unit area of the SZCY200812 strain were measured to evaluate its growth under different conditions. Its tolerance for different environmental factors was assessed based on the conidial germination rate. [Results]  M. rileyi SZCY200812 was highly virulent to S. frugiperda larvae; cumulative mortality of 3rd and 5th larval instars reached 100 % after 6 d and 8 d, respectively, with respective LT₅₀ values of 3.89 d and 4.66 d, respectively. The mycelial growth rate of M. rileyi SZCY200812 cultured on SMAY medium at 25 °C and L︰D=24︰0 was (1.68±0.01) mm/d on the 15th day, and the spore yield per unit area was (8.05±0.37) × 10⁷ conidia/mm². The maximum thermal and UV tolerances of SZCY200812 were 70 ℃ and 12 min, respectively. The temperature and UV tolerance of conidia produced under these conditions were the best. Under these conditions, the LT₅₀ of 3rd instar larvae treated with a conidial suspension of 1×10⁸ spores/mL was 3.26 d. [Conclusion]  The SZCY200812 strain is more tolerant to short-term exposure to high temperature and ultraviolet radiation than other M. rileyi strains, and could therefore be used to develop an additional biological control agents for this pest.