OLFACTORY ASSOCIATIVE LEARNING OF THE PUPAL PARASITOID PIMPLA-LUCTUOSA SMITH (HYMENOPTERA, ICHNEUMONIDAE)

Laboratory experiments were conducted to determine the role of learnin g in olfactory host searching by the ichneumonid pupal parasitoid, Pim pla luctuosa Smith. Females learned to associate novel odors such as v anilla and strawberry with hosts when they oviposited in at least seve ral hosts with the odors. Repeated experiences of hosts with an odor i ncreased the response of the experienced odor, and females that had ex perienced host odor seven rimes responded to the experienced odors 90% of the time. Although the response by females to a learned odor gradu ally decreased with increasing host-deprivation time, 60% of the femal es that had experienced host odor 7 days earlier still responded to th e experienced odor. Females also learned two separate odors associated with hosts at a time and responded to both odors without a preference for one odor over the other, When trained two separate odors with hos ts, females learned the second odor more quickly than the first odor. After females experienced several stings in ''simulated hosts'' with t he previously learned odor, they ceased to respond to the learned odor , suggesting that repeated unrewarding experiences cause females to ce ase to respond to the learned odors.