EVALUATION OF LYCOSID, MICRYPHANTID AND LINYPHIID SPIDERS AS PREDATORS OF RHOPALOSIPHUM-PADI (HOM, APHIDIDAE) AND THEIR FUNCTIONAL-RESPONSETO PREY DENSITY - LABORATORY EXPERIMENTS

Laboratory experiments were performed to determine the potential of do minant spider species in winter wheat in Germany, Erigone atra (Blackw all), Lepthyphantes tenuis (Blackwall) and Pardosa agrestis (Westring) adults and youngs, in suppressing the population of Rhopalosiphum pad i (L.) on wheat plants and their functional response to different aphi d densities. The presence of spiders significantly caused between 34 a nd 58 % reduction in aphid population development on wheat plants comp ared to the aphid population in the absence of spiders. The functional response curves for these spiders as predators of R. padi seem to des cribe a typical type II functional response with the prey consumed inc reasing to a plateau as aphid densities increased. Prey killed without eating was linear on prey density.