Red imported fire ant (RIFA), Solenopsis invicta Buren, was one of the most dangerous and devastating invasive pests in the world. The previous studies showed that the biological control agents were the effective ways to control RIFA. In this paper, six strains of entomopathogenic fungi, Paecilomy-ces lilacinus P104 isolated from RIFA, Beauveria bassiana BbOl, BbO2, BbO3 and Bb04 and Metahizium anisopliae Ma01 originally isolated from other different insects were used in bioassays against RIFA workers by spraying serial dilution concentrations (1 × 104 - 1 × 108 mL-1) on RIFA workers. The results showed that the accumulative mortalities of RIFA workers induced by the highest conidia concentration (1 × 108 mL-1) of P104, MaOl, Bb01, Bb02, Bb03 and Bb04 at 15 d were 69.84%, 95.06%, 87.00% , 100% , 92. 16% and 100% , respectively; their median lethal concentrations (LC50) to RIFA workers were 2. 23 × 106, 4. 46 × 105, 4. 07 × 104, 1. 77 × 104, 4. 80 × 104 and 3.71 × 104 mL-1, respectively ; the median lethal times ( LT50 ) were 8. 75 , 3. 04, 4. 73 , 2. 84, 4. 05 and 2. 55 d respectively. The LC50 values of strain BbO4 originally derived from Bactrocera dorsalis were the shortest, while the LC50 values of strain BbO2 originally derived from Ostrinia furnacalis were the lowest. It was considered that the strain Bb04 and Bb02 would be the most suitable candidates against RIFA for further study.%红火蚁Solenopsis invicta是我国的新入侵物种,生物防治是控制红火蚁扩散的有效途径.本文在室内条件下测定6株不同来源的昆虫病原真菌对红火蚁的致病能力.试验采用喷雾法,供试孢子浓度为1×104、1 ×105、1×106、1×107、1×108 mL-1.结果表明,在1×108 mL-1孢子浓度下,淡紫拟青霉Paecilomyces lilacinus菌株P104、绿僵菌Metarhizium anisopliae菌株Ma01、球孢白僵菌Beauveria bassiana菌株Bb01、Bb02、Bb03、Bb04处理后红火蚁工蚁第15天的累计死亡率分别为69.84％、95.06％、87.00％、100％、92.16％和100％,6株菌株对红火蚁工蚁的致死中浓度(LC50)分别为2.23×106、4.46×105、4.07×104、1.77 ×104、4.80×104、3.71 ×104 mL-1,致死中时(LT50)分别为8.75、3.04、4.73、2.84、4.05和2.55 d.综合分析得出,分离自桔小实蝇Bactrocera dorsalis的球孢白僵菌菌株Bb04在处理孢子浓度为1×108 mL-1时对红火蚁工蚁具有最短的致死时间,而分离自玉米螟Ostrinia furnacalis的Bb02菌株具有最低的致死浓度.说明Bb02和Bb04具较强的致病力和致死速度,是红火蚁微生物防治的优良菌株.
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