2株感染蠼螋的球孢白僵菌的分离鉴定及对草地贪夜蛾的毒力

Isolation and identification of two Beauveria bassiana strains from the infected earwig and their virulence to Spodoptera frugiperda larvae

对采自玉米田自然罹病蠼螋成虫上的病原菌进行分离培养,结合形态学和rDNA-ITS序列分析,对分离纯化获得的2株病原菌进行生物学特性测定及种类鉴定,并采用浸渍法测定了2株病原菌对草地贪夜蛾3龄幼虫的毒力。结果表明,从自然罹病的2头蠼螋分离获得的病原菌均为球孢白僵菌Beauveria bassiana,编号为YY-1和HNC-1。在25℃下,YY-1和HNC-1菌株在SDAY培养基上菌落直径日增长速率分别为(3.06±0.20)mm/d和(4.57±0.23)mm/d,培养第15天时产孢量分别为(5.20±1.06)×10^(7)个/cm^(2)和(1.83±0.47)×10^(8)个/cm^(2)。球孢白僵菌YY-1和HNC-1对草地贪夜蛾3龄幼虫均具有致病力,其中在1.0×10^(8)个/mL浓度下第8天草地贪夜蛾3龄幼虫累计校正死亡率分别达到83.3%和63.3%,对草地贪夜蛾3龄幼虫的LC_(50)为1.56×10^(5)个/mL和2.11×10^(5)个/mL,LT_(50)分别为4.23 d和6.12 d。综合以上结果,2株球孢白僵菌对草地贪夜蛾幼虫具有较强的毒力,其中YY-1菌株对草地贪夜蛾幼虫的毒力强于HNC-1菌株,因此球孢白僵菌YY-1菌株在草地贪夜蛾生物防治中具有良好的开发潜力。

Two strains of entomopathogen were isolated from the infected earwig which collected from corn fields.They were identified according to the morphological characteristics and rDNA-ITS sequence analysis,and the virulence of two strains to the 3rd instar larvae of Spodoptera frugiperda were tested by impregnating method.The results showed that two strains,named YY-1 and HNC-1,belonged to Beauveria bassiana.At 25℃,the daily growth rates of colony diameter of YY-1 and HNC-1 were(3.06±0.20)mm/d and(4.57±0.23)mm/d on SDAY medium,respectively,and the conidia yield on the 15th day were(5.20±1.06)×10^(7) and(1.83±0.47)×10^(8) conidia/cm^(2),respectively.The accumulated adjusted mortality of the third instar larvae of S.frugiperda in eight days reached 83.3%and 63.3%at the concentration of 1.0×10^(8) conidia/mL,respectively,and the LC_(50) and LT_(50) values were 1.56×10^(5) spore/mL and 2.11×10^(5) spore/mL,4.23 d and 6.12 d,respectively.Based on the above results,the two strains of B.bassiana have high virulence to the larvae of S.frugiperda,and the YY-1 has more advantage potential in biological control of S.frugiperda.