Demonstration of long‐term memory in the parasitic wasp Nasonia vitripennis

We studied the formation of protein synthesis‐dependent long‐term memory (LTM) in the parasitic wasp Nasonia vitripennis Walker (Hymenoptera: Pteromalidae), a parasitoid of fly pupae. Female wasps were trained in one of five different training procedures in the presence of hosts and the odour cinnamon. Six days later the reaction of the wasps towards the odour was tested in a static four‐chamber olfactometer. When wasps were trained by a single drilling experience we could not find any reaction to cinnamon after 6 days. In contrast, when wasps were trained either via drilling plus host feeding, three drilling events (spaced training), 1 h training, or 24 h training including oviposition, they significantly preferred cinnamon 6 days later. Wasps which were injected the transcription inhibitor actinomycin D after a 1‐h training to block protein synthesis showed normal memory retention up to 3 days, but did not react to cinnamon after 4 and 6 days. Control experiments showed no influence of actinomycin D on the natural behaviour and the general odour discrimination ability of N. vitripennis . This demonstrates that protein synthesis‐dependent LTM has been formed. To our knowledge this is the first time that LTM formation after drilling plus host feeding but without oviposition is demonstrated in a parasitic wasp. These results were combined with additional findings about anaesthesia‐sensitive memory, anaesthesia‐resistant memory, and intermediate memory to develop a multiphase model of memory dynamics in N. vitripennis and to discuss ecological adaptations of memory formation in N. vitripennis and other parasitic wasp species.