大草蛉对桃蚜和夹竹桃蚜的捕食作用研究

大草蛉在我国分布广泛,能捕食多种农作物害虫。本试验首先研究了大草蛉一龄幼虫对桃蚜、大草蛉二龄幼虫对桃蚜和夹竹桃蚜的捕食功能反应。三个反应的最大捕食量Namax分别为144.93、303.03和151.51(头),瞬时攻击率a分别为0.7428、0.8654和0.6644。大草蛉一龄幼虫有较强的种内干扰反应,随着捕食者密度的增加,捕食作用率(E)依次为0.2025、0.1185、0.0866、0.0694和0.0584;对桃蚜的捕食作用率(E)与自身密度(P)的函数关系式为E=0.2025P-0.7727。在桃蚜和夹竹桃蚜的混合种群中,大草蛉二龄幼虫对桃蚜的选择效应大于夹竹桃蚜。

Predation of Chrysopa pallens on Myzus persicae and Aphis nerii

Chrysopa pallens distributes widely in China,and is the predator of many species of field pests.The present studies investigated the functional response of the 1st instar larvae of C.pallens to M.persicae,2nd instar larvae of C.pallens to M.persicae and A.nerii.The largest amounts of caught per day(Namax) were 144.93,303.03 and 151.51,respectively.And the moment attack parameters(a) were 0.7428,0.8654 and 0.6644,respectively.Intraspecific interference of the 1st instar larvae of C.pallens was found in the experiment.The predation rate of the 1st instar larvae of C.pallens decreased along with the increase of its density.The values were 0.2025,0.1185,0.0866,0.0694 and 0.0584,respectively.The relationship between predation ratio(E) and the spider density(P) was described by equation of E=0.2025P-0.7727.When the 2nd instar larvae of C.pallens was placed in the mixed populations of M.persicae and A.nerii,it had higher selecting efficiency to M.persicae than A.nerii.