Sources of Host-Location Cues for the Parasitic Wasp Orgilus-Lepidus (Braconidae)

Abstract

The responses of the parasitic wasp Orgilus lepidus to potato plants infested by its host Phthorimae, operculella were investigated. Wasps flew to both undamaged and mechanically damaged potatoes when they were presented alone in a flight tunnel, indicating that the odour of potato alone is attractive to them. When given a choice, females flew preferentially to either mechanically damaged plants or to plants infested by P. operculella rather than to intact plants. Thus, when O. lepidus is searching for hosts, it first flies toward the odour of plants, especially those that are damaged. There was no difference in the behaviour of wasps on either undamaged or mechanically damaged potato leaves, but they spent considerably more time probing with their ovipositor on leaves infested by their host. Wasps responded similarly to leaves infested with hosts and leaves from which hosts were removed, indicating that plant damage caused by their host or host products are the primary cues used to discriminate different kinds of damage.