Abstract: The functional reaction of old Harmonia axyridis nymphs preying on wheat aphides shows the Holling Ⅱ type, i. e., preferring to feed on young aphid nymphs. The predation ratio is the lowest at 40C and the second at 10℃, being the highest at 25℃. At the range of 10～ 25℃, the relationship between predation ratio (y) and temperature (x) is y= 28.1303+ 2.6665x, and at 25～40℃,y=199. 9275 - 3. 642x. Under intraspecific interference, the relationship between predation ratio (E) and natural enemies density (P) is E=0.6897P^-0.7930, searching constant Q is 0.6897, disturbing coefficient M is 0.7930.The relationship between intensity of scrambling competition (I) and density of H.axyridis(P) is I= 0.0400+1.0383 logp.

Key words: Harmonia axyridis, Predation, Intraspecific interference, Competition, Platycladus orientalis forest, instantaneous water use efficiency, canopy height, short-term water use efficiency