短管赤眼蜂对草地贪夜蛾和斜纹夜蛾不同日龄卵的寄生能力及子代蜂适合度

草地贪夜蛾Spodoptera frugiperda原产于美洲,是新近入侵我国的重大危险性入侵害虫。短管赤眼蜂Trichogramma pretiosum是美洲当地寄生草地贪夜蛾卵的重要自然天敌。该蜂早在1979年就被引入我国。为检测短管赤眼蜂对不同日龄草地贪夜蛾卵的寄生适应性,本研究以发育12 h内、24～36 h和48～60 h的草地贪夜蛾卵为研究对象,以斜纹夜蛾Spodoptera litura卵为对照,探究了短管赤眼蜂对不同日龄草地贪夜蛾卵和斜纹夜蛾卵的寄生效果及子代蜂的适合度。结果表明:短管赤眼蜂对两种寄主不同日龄的卵块寄生率均达到100%,但对草地贪夜蛾卵表现出更高的卵粒寄生率。与斜纹夜蛾卵育出的子代蜂相比,草地贪夜蛾卵育出的子代蜂个体偏小,平均单卵出蜂数较低。研究结果将为今后应用短管赤眼蜂防治草地贪夜蛾提供基础数据。

Parasitic efficacy and offspring fitness of Trichogramma pretiosum against Spodoptera frugiperda and Spodoptera litura at different egg ages

Spodoptera frugiperda, which is native to the Americas, is a new dangerous invasive pest in China. Trichogramma pretiosum has been demonstrated as one of the most important natural enemy against Spodoptera frugiperda in Americas. This Trichogramma specie has been introduced in China since 1979. To test the adaptability of T.pretiosum on S.frugiperda eggs at different ages, the S. frugiperda eggs, which have developed 0-12 h, 24-36 h, or 48-60 h, were examined, and the S. litura eggs were used as the control. We investigated parasitic capacity and offspring fitness parameters of T.pretiosum females as influenced by host species and egg age. The results showed that the parasitic rate of egg masses is 100% regardless of host species and egg age. T. pretiosum females supplied with S. frugiperda eggs performed higher parasitic rate of eggs than those supplied with S. litura eggs. However, offspring wasps emerged from S.frugiperda eggs showed reduced offspring number per host egg and smaller body size when compared with those emerged from S. litura eggs. Our results will supply a primary data for the application of introduced T. pretiosum against S. frugiperda in future.