六斑月瓢虫幼虫和草地贪夜蛾幼虫之间的双向捕食功能评价

Evaluation of Two-way Predatory Function between Menochilus sexmaculatus Larvae and Spodoptera frugiperda Larvae

草地贪夜蛾自2019年4月首次在海口市发现,逐渐在各市县扩散,成为海南省多种作物上的重要害虫。六斑月瓢虫是海南地区农田生态系统中重要的捕食性天敌。为评价六斑月瓢虫对草地贪夜蛾的控制能力,室内测定了六斑月瓢虫3龄幼虫对草地贪夜蛾卵和2龄幼虫,以及草地贪夜蛾3、4龄幼虫对六斑月瓢虫卵和1龄幼虫的双向捕食作用。结果显示,草地贪夜蛾与六斑月瓢虫的双向捕食功能反应均符合Holling II功能反应模型。六斑月瓢虫3龄幼虫对草地贪夜蛾卵和2龄幼虫日最大捕食量分别为82.40粒、54.63头。草地贪夜蛾幼虫也可捕食六斑月瓢虫幼虫,其捕食量随草地贪夜蛾龄期增加而增大。草地贪夜蛾3龄幼虫对六斑月瓢虫卵和1龄幼虫日最大捕食量分别为133.68粒、9.89头,草地贪夜蛾4龄幼虫对六斑月瓢虫卵和1龄幼虫日最大捕食量分别为266.04粒、219.08头。而且,不论是六斑月瓢虫捕食草地贪夜蛾,还是草地贪夜蛾捕食六斑月瓢虫,捕食者的搜寻效应均随猎物密度的增加而降低。结果表明,用六斑月瓢虫来防治草地贪夜蛾时,应在草地贪夜蛾出现暴食期前进行,这时防治会有较好的控害效果。

Spodoptera frugiperda was first discovered in Haikou City in April 2019,and has gradually spread to all the cities and counties,becoming an important pest on multiple crops in Hainan Province.The ladybeetle Menochilus sexmaculatus is an important predatory natural enemy in the agricultural ecosystem of Hainan.To evaluate the control ability of M.sexmaculatus on S.frugiperda,the predatory function responses of the 3rd instar larvae of M.sexmaculatus to the eggs and 2nd instar larvae of S.frugiperda,as well as the responses of the 3rd and 4th instar larvae of S.frugiperda to the eggs and 1st instar larvae of M.sexmaculatus were studied in laboratory.The results showed that the two-way predatory function responses of S.frugiperda and M.sexmaculatus fitted well with the Holling II model.The maximum daily predation of the 3rd instars of M. sexmaculatus on the eggs and 2nd instars of S. frugiperda were 82.40 and 54.63, respectively. The larvae of S. frugiperda also preyed on the M. sexmaculatus larvae, which correlated with the growth stages of the S. frugiperda larvae. The maximum daily predation of the 3rd instars of S. frugiperda on the eggs and 1st instars of M. sexmaculatus were 133.68 and 9.89, respectively. The data of the 4th instars S. frugiperda were 266.04 and 219.08, respectively. Moreover, the prey search efficiency of predators decreased with the increase of prey density in the predatory interaction between M. sexmaculatus and S. frugiperda. The results show that, in order to achieve control S. frugiperda effectively, M. sexmaculatus has to be released before the feeding period outbreak of S. frugiperda larvae.