Natural variation in long-term memory formation among Nasonia parasitic wasp species

• Parasitic wasp species of the genus Nasonia differ in long-term memory formation.
• Nasonia vitripennis forms long-term memory after a single conditioning trial.
• Nasonia giraulti requires at least two trials to form this memory.
• The rewarding stimulus, i.e. host feeding vs. oviposition, does not affect memory.
• Nasonia offers unique opportunities for multidisciplinary studies on long-term memory formation.

Closely related species of parasitic wasps can differ substantially in memory dynamics. In this study we demonstrate differences in the number of conditioning trials required to form long-term memory between the closely related parasitic wasp species Nasonia vitripennis and Nasonia giraulti (Hymenoptera: Pteromalidae). A single conditioning trial, in which a female wasp associates an odour with the reward of finding a host, results in the formation of transcription-dependent long-term memory in N. vitripennis, whereas N. giraulti requires spaced training to do so. Memory formation does not depend on the type of reward: oviposition, which was hypothesized to be a ‘larger’ reward results in similar memory retention as host feeding in both Nasonia species. There are several genetic and genomic tools available for Nasonia species to identify genetic mechanisms that underlie the observed variation in the number of trials required to form long-term memory.