马尼拉陡胸茧蜂对甜菜夜蛾的控害潜能

为评价幼虫寄生蜂马尼拉陡胸茧蜂对甜菜夜蛾的控害潜能,编制了寄主和寄生蜂的实验种群生命表,测定了马尼拉陡胸茧蜂对甜菜夜蛾幼虫的寄生功能反应。结果表明:甜菜夜蛾年龄特征生命表参数为:净生殖力(种群趋势指数)R0(I)=122.0172,内禀增长率rm=0.1522,世代平均历期T=40.8556(d),周限增长率λ=1.1644;马尼拉陡胸茧蜂寄生甜菜夜蛾幼虫的生殖力表参数为:R0(I)=20.2479,rm=0.3045,T=9.8788,λ=1.3559。马尼拉陡胸茧蜂对甜菜夜蛾幼虫的捕食功能反应符合HollingⅡ型模型,a=0.8952,Th=0.0205,Namax=48.78(头)。通过生命表参数比较和功能反应模型分析,可见马尼拉陡胸茧蜂对甜菜夜蛾幼虫的寄生能力强,繁殖速率高,对甜菜夜蛾种群有较强的控制能力;从世代平均历期T的比较可知,在甜菜夜蛾繁殖1代的时间内,马尼拉陡胸茧蜂可以繁殖4个世代,在时间上天敌对害虫的发生是"超前的"而不是"跟随的"。因此在放蜂技术上应采取相应的对策,才能充分发挥天敌的控害潜能。

Evaluation of potential control ability of Snellenius manilae(Ashmead)against Spodoptera exigua(Hübner)

The experimental population life tables of Snellenius manilae (Ashmead) and Spodoptera exigua (HUbner) were established respectively to evaluate the control potential of this parasitoid on this pest.The results showed that the parameters of S.exigua were as follows:Net reproduction (Population trend index) R_0 (I) =122.0172,Intrinsic rate of increase rm=0.1522,Average generation time T=40.8556d,Finite Rate of Increase λ=1.1644.The parameters of S.manilae,were as follows:R_0 (I) =20.2479,r_m=0.3045,T=9.8788d,λ=1.3559.The functional response of S,manilae rearing on S.exigua larvae coincided with the Holling model type-Ⅱ,with the index of a=0.8952,Th=0.0205,Na_ (max) =48.78.The above results indicated that S.manilae had high reproductive speed and strong parasitizing ability on S.exigua.In addition,shorter generation time of S.manilae hinted that it could control S.exigua effectively.