The Influence of Aphid-Induced Plant Volatiles on Ladybird Beetle Searching Behavior

Field-collected individuals of the seven-spotted ladybird, Coccinella septempunctata L. (Coleoptera, Coccinellidae), were tested for response to volatiles from aphids (Rhopalosiphum padi (L.)), from aphid-infested barley plants (Hordeum vulgare), and from previously aphid-infested and uninfested plants. The volatiles were collected by conventional polymer entrainment techniques, and diethyl ether eluates of the entrainments were used as odor sources in olfactometer bioassays. C. septempunctata responded positively to volatiles from aphid-infested plants and from previously aphid-infested plants but not to volatiles from uninfested plants or from undisturbed aphids. The ecological implications of the findings are discussed.