龟纹瓢虫对棉蚜的捕食行为

为探讨天敌对害虫的捕食作用机制，充分发挥生物防治的作用，本文从捕食能学角度，系统地观测了龟纹瓢虫Propylea japonica (Thunberg)对棉蚜Aphis gossypii Glover的捕食行为及影响的因素。结果表明：龟纹瓢虫对棉蚜的捕食行为依棉蚜的密度变化而逐渐转变；它在棉蚜密度高时，搜索活动下降；而在棉蚜密度低时，则搜索活动增加。产生这种行为是由于肠胃量与棉蚜遭遇率变化的综合作用结果。因此，将瓢蚜比调控在一定水平上，可以更有效地发挥以瓢治蚜的生物防治作用。

THE FORAGING BEHAVIOR OF LADY BEETLE PROPYLAEA JAPONICA TOWARDS COTTON APHIDS APHIS COSSYPII

The foraging behavior of the lady beetle Propylea japonica to wards the cotton aphid Aphis gossypii was systematically examined. The results indicated that the foraging behavior of the lady beetle changed gradully at different aphid densities. When the aphid density changed from low to high, the lady beetle switched from active search to ambush search, and when the aphid density changed from high to low, the lady beetle switched from ambush to active search. Such behavioral change resulted from the integrated effect of the amount of food alreadly present in the gut and the encounter rate with aphids. We suggest that better control effect of foe lady beetles on cotton aphids might be gaind by regulating their density ratio.