Infochemicals mediating the foraging behaviour of Aleochara bilineata Gyllenhal adults: sources of attractants

Aleochara bilineata Gyll. (Coleoptera: Staphylinidae) adults feed on eggs a nd larvae of cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae), an d might be used to control this pest. We undertook tests in a Y-tube olfact ometer to determine if infochemicals are involved in the food foraging beha viour of A. bilineata adults and to precisely determine the potential sourc es of stimuli. A. bilineata adults oriented toward the stimuli from both th e food-plant of the prey (rutabaga: Brassica napus var. napobrassica (L.) R eichb.) and the prey-plant complex (rutabaga infested by cabbage maggot lar vae), but adults significantly preferred the effluvia of infested to uninfe sted rutabaga in a choice test. The sources of infochemicals in the infeste d rutabaga were the cabbage maggot larvae themselves and their frass. Howev er, in a choice test adults preferred the effluvia of the larvae to that of the damaged rutabaga from which those larvae were obtained. It is not expe cted that a generalist predator uses precise herbivore-derived signals in f ood foraging activity, but the preference of A. bilineata adults for the la rval volatiles over frass volatiles may reflect the dependence of this spec ies on dipteran pupae for reproduction.