Mating and Oviposition Experience Influence Odor Learning inLeptopilina boulardi(Hymenoptera: Eucoilidae), a Parasitoid ofDrosophila

In many parasitoid species, behaviors leading to host selection are triggered by the perception of mostly chemical cues, which often depends on learning processes. Among the latter, associative learning, where a neutral stimulus (e.g., an odor) is perceived as associated with a reward (e.g., oviposition or contact with host products), ensures a higher probability of locating a host. In this work we investigated the effect of two physiological factors, mating and oviposition experience, on odor learning involved in the ovipositor search in the parasitoidLeptopilina boulardi(Barbotinet al.). We developed a bioassay to quantify individual learning performances based on the observation of an odor-conditioned probing response, characterized by several parameters such as the latency (i.e., the time elapsed between the onset of the conditioned odor and the start of the conditioned probing behavior), the duration of the first probing, and the total probing duration. The percentage of females that learned a fruit odor (banana) associated to an oviposition reward did not depend on mating or prior oviposition experience. However, both factors influenced the parameters of the learned response: oviposition experience could induce a higher latency and a shorter probing duration, whereas the opposite changes could result from mating. These results were discussed with regard to physiological changes known to influence host-searching activity. We concluded on the possible consequences of these variabilities at the individual level. The evaluation of how such physiological events affect traits correlated to parasitization efficiency is important for improving biocontrol strategies.