寄生不同龄期草地贪夜蛾的斑痣悬茧蜂生长发育表现

Development performance of Meteorus pulchricornis in different instar larvae of Spodoptera frugiperda

草地贪夜蛾Spodoptera frugiperda(J. E. Smith),又称秋黏虫,是新入侵我国的外来物种。为探究本土天敌斑痣悬茧蜂寄生不同龄期草地贪夜蛾幼虫后的生长发育表现,本研究检测了斑痣悬茧蜂寄生2龄、3龄和4龄草地贪夜蛾幼虫后子代蜂幼虫发育历期、茧历期、羽化率、茧重、成蜂个体大小和成蜂寿命。结果表明,寄主龄期对子代蜂的幼虫发育历期、茧历期和成蜂寿命存在显著影响。与寄生4龄幼虫的子代蜂相比,寄生2龄和3龄幼虫的子代蜂幼虫发育历期分别平均延长了2.08 d(z=5.42,P<0.05)和1.64 d(z=4.23,P<0.05);寄生2龄幼虫的子代蜂茧历期平均延长了0.46 d(z=3.51,P<0.05),但寄生4龄幼虫的子代蜂茧历期与寄生3龄幼虫的子代蜂茧历期无显著差异。4龄幼虫体内羽化的子代蜂成蜂寿命比在2龄和3龄幼虫体内羽化的子代蜂成蜂寿命分别平均延长了1.46 d(z=-2.60,P<0.05)和1.68 d(z=-2.98,P<0.05)。寄主龄期对子代蜂羽化率、茧重和成蜂个体大小无显著影响。随寄主龄期增大,子代蜂的发育速度加快,但寿命缩短。研究结果将为揭示斑痣悬茧蜂与寄主草地贪夜蛾的互作关系提供参考。

The Spodoptera frugiperda(J. E. Smith), also known as fall armyworm, is a new invasive species in China. To investigate the developmental performance of Meteorus pulchricornis in different instar larvae of S. frugiperda, we examined the development duration of larvae and cocoon, emergence rate, cocoon weight, adult body size and adults’ lifespan of M. pulchricornis when they developed in 2nd, 3rd, and 4th instar larvae of S. frugiperda, respectively. The results showed the developmental duration of larvae and cocoon, as well as the adults’ lifespan of offspring were significantly influenced by host instar. Compared with M. pulchricornis offspring developed in 4th instar larvae of S. frugiperda, the larval durations of M. pulchricornis developed in 2nd and 3rd instar larvae of S. frugiperda were prolonged by 2.08 d(z=5.42, P<0.05) and 1.64 d(z=4.23, P<0.05), respectively. The cocoon duration of M. pulchricornis developed in 4th instar larvae of S. frugiperda was significantly shortened by 0.46 d(z=3.51, P<0.05) than those developed in 2nd instar larvae of S. frugiperda, but not different from those developed in 3rd instar larvae of S. frugiperda. Compared with that of M. pulchricornis emerged from 4th instar larvae of S. frugiperda, the adults’ lifespan of M. pulchricornis emerged from 2nd and 3rd instar larvae was significantly shortened by 1.46 d(z=-2.60, P<0.05) and 1.68 d(z=-2.98, P<0.05), respectively. The emergence rate, cocoon weight, and adults’ body size were not influenced by host instar. Our research revealed that both the development rate and adults’ lifespan of M. pulchricornis increased with host instars. The results will be helpful to make an illustration of the interaction of M. pulchricornis and its host S. frugiperda.