Analysing the information content of the multimodal courtship display of a parasitoid wasp

Courtship displays are generally composed of multiple signal components that are transmitted and perceived through different sensory modalities. However, previous studies on multimodal courtship displays have focused mainly on individual signals, thus failing to provide a full explanation of why these displays evolved despite the added costs involved. Therefore, it is essential to identify the purpose of each display component and link them to prevailing hypotheses on multimodal display function. Here, we study the multimodal courtship display of males of the parasitoid wasp Leptopilina heterotoma, which consists of wing fanning and a putative antennal pheromone, by determining the information conveyed about male quality through these two modalities. We found that a high wing-fanning frequency and a large body size led to a higher mating success, whereas we found no correlation of the pheromone composition with mating success. We conclude that the wing-fanning component conveys mate-assessment information, whereas the chemical display component, found to be species specific in a previous study, functions as a species-recognition mechanism but does not reflect the quality of a male. Altogether, our study suggests that the multimodal courtship display of L. heterotoma fits the multiple message hypothesis and might thus be a useful model for further studies.