PERSISTENCE OF EXPERIENCE EFFECTS IN THE PARASITOID TRICHOGRAMMA NR. BRASSICAE

1. The importance of learning in parasitoids is likely to depend on ho w long learning effects persist, the number of learned stimuli that ca n be retained, and whether learning effects are confined to low ranked hosts. 2. The duration of learning of host-specific stimuli was teste d in four strains of Trichogramma nr. brassicae (Hymenoptera: Trichogr ammatidae). Both the persistence of learning of the rearing host and o viposition experience were tested in separate experiments. 3. The resp onse to a non-preferred host, Sitotroga cerealella, was measured at di fferent times following experience on that host or an alternative host , Heliothis punctigera. Both types of experience persisted for at leas t 5 days in all four strains. 4. The effect of oviposition in a highly preferred host, H. punctigera, following oviposition in S. cerealella was also tested. The increased acceptance of S. cerealella following oviposition on this host persisted despite a subsequent oviposition on H. punctigera. 5. The implications for host range at both individual and population levels are discussed.