杀虫真菌对草地贪夜蛾不同虫态的室内活性

Laboratory Efficacy of Insecticidal Fungi for Control of Spodoptera frugiperda

草地贪夜蛾Spodoptera frugiperda(J. E. Smith)是一种联合国粮农组织预警的全球重大害虫。为了评价杀虫真菌对草地贪夜蛾的生防潜力,在室内条件下测定了杀虫真菌金龟子绿僵菌CQMa421、球孢白僵菌ZJU435对草地贪夜蛾不同龄期幼虫、蛹、成虫和卵的杀虫活性以及对卵孵化率、蛹羽化率等影响。结果显示:26℃条件下,菌株CQMa421和ZJU435对草地贪夜蛾低龄幼虫具有杀虫活性,接种10 d后对1龄幼虫的校正死亡率分别为35.6%和50.5%,但随虫龄增大杀虫活性降低,其中菌株CQMa421对4龄幼虫几乎没有杀虫活性;菌株CQMa421和ZJU435都引起草地贪夜蛾蛹黑化,降低其羽化率50%以上;但对成虫没有杀虫活性,也不影响成虫的产卵;卵接种菌株CQMa421和ZJU435后,孵化率分别为82.8%和90.7%,显著低于空白对照的100%,并极大地降低新孵化幼虫的存活率,分别为20.8%和0.0%,而空白对照为79.4%。结果表明,杀虫真菌CQMa421和ZJU435对草地贪夜蛾低龄幼虫、蛹和卵具有杀虫活性,同时降低卵的孵化率、新孵化幼虫存活率和蛹羽化率,对草地贪夜蛾种群控制极具潜力。

Spodoptera frugiperda(J.E.Smith)is a global major pest warned by FAO.To evaluate for potential of insecticidal fungi for control of S.frugiperda,we investigated the activities of entomopathogenic fungi CQMa421 and ZJU435 against the larvae,pupae,adults and eggs of S.frugiperda and its effects on egg hatching and pupal eclosion under laboratory conditions.The results showed that Metarhizium anisoplae strain CQMa421 and Beauveria bassiana strain ZJU435 had larvicidal activity against S.frugiperda young instars.The corrected mortality of the 1st instar larvae was 35.6%and 50.5%10 days post inoculation of CQMa421 and ZJU435,respectively.With the increase of larval instar,the efficacy of the two fungal strains decreased,CQMa421 almost failed to infect the 4th instar larvae.Both CQMa421 and ZJU435 caused pupal melanization of S.frugiperda,and significantly reduced pupal eclosion by about 60%compared with the control group.However,CQMa421 and ZJU435 had no insecticidal activities to adults and did not affect female oviposition.In addition,the hatching rates of eggs inoculated with CQMa421 or ZJU435 were 82.8%and 90.7%,respectively,significantly lower than that of the control(100%).Further investigation revealed that the survival rate of the newly hatched larvae from eggs inoculated with CQMa421 or ZJU435 was reduced to 20.8%and 0.0%,respectively,and were significantly lower than that of the control(79.4%).These results indicated that CQMa421 and ZJU435 had great potential for control of S.frugiperda.