The Effect Of Adverse Circumstances On Predation And Survival Of Delphastus Cataline (Horn)

Delphastus cataline (Horn), originating from North America, is an important predator as biological control agent for the whitefly pests. In this paper, the effect of adverse circumstances on predation and survival of Delphastus cataline was studied.Functional response models of Delphastus cataline to eggs of Bemisia tabaci belonged to Holling â…¡. The functional response types of adult Delphastus cataline on various ranges of starvation had no difference. Results revealed that the functional response models of ladybird preying on whitefly were still conformed to Holling II in spite of pretreated with sublethal doses of insecticides, just only the parameters of models had some changes. The searching efficiency decreased with increasing of predator density.Susceptibility measurement indicated that the susceptibility order of LC₅₀ of adult Delphastus cataline were cypermethrin, imidacloprid, methomyl, fenvalerate, dimethoae, dichlorvos, fipronil, Methamidophos. The susceptibility order of LC₅₀ of the 3^rd instar larva of ladybird were cypermethrin, imidacloprid, methomyl, fipronil, Methamidophos. The susceptibility order of LC₅₀ of the 2nd instar larva of ladybird were cypermethrin, imidacloprid, fipronil.The results of starvation endurance ability of Delphastus cataline showed that different temperatures had obvious effectiveness on survival time. At 15℃ and 35℃, survival time of adult female is longer than adult male. Illumination had no obvious effectiveness on survival time. Survival time of Delphastus cataline feeding on water was longer than starvation. Feeding on water, survival time of the fed Delphastus cataline survived longer than the just emergenced Delphastus cataline.