Abstract:Cybocephalus nipponicus Endrdy-Younga is an important predatory natural enemy of diaspidids, such as Yanon scale, Unaspis yanonensis (Kuwana). In order to better grasp and use their predatory performance, the authors studied the predatory functional response and searching efficiency of C.nipponicus to 1st instar of male U.yanonensis at different temperature, relative humidity, light intensity and illumination time in the lab. Different models were simulated respectively with Holling-Ⅱ type equation and new equations of Holling-Ⅲ type. The results indicated that there were significant differences of predacious number under different conditions. The most favorable preying conditions for the adult C.nipponicus was temperature 25℃, relative humidity 70%-90%, and 12000lx light intensity, L∶ D=14∶ 10. Under these conditions, parameters of predatory functional response reached maximum including rate of successful attack (α‘), maximal predacious number (a), α‘/Th and optimal seeking density (b). However, the average handling time (Th) was minimum. At the same time Holling-Ⅱ equation of functional response was Na=1.002N/(1+0.0001N). The searching efficiency decreased with the increase of Yanon scale density under different conditions, the mathematical model was E=1.002/(1+1.002×0.0001N). Holling-Ⅲ new equation was Na=308.86e-95.18/N. The theoretical maximum predacious numbers and the optimal searching efficiency was 308.86 and 95.18 Yanon scales respectively. So it could be released to against Yanon scale in field, according to the ratio of 1∶ 95 (natural enemy∶ insect).