Attractive and repellent social cues are used during mosquito oviposition-site seeking

Description of social behavior in adult mosquitoes have been restricted to swarming during mating and interactions between immature stages and adults. Acoustic and chemical cues play major signaling roles during mating, while some semiochemicals emanated by eggs or larvae have been identified as attractants modulating female oviposition. However, social interactions among mosquito adult females have been poorly explored. Performing choice oviposition assays, we found an aggregation behavior during the selection of equivalent oviposition sites by Aedes aegypti females. We have quantified this aggregation in different conditions and showed that visual and acoustics cues do not play a significant role in this behavior. Female aggregation during oviposition also occurs regardless of the presence of eggs and is regulated by the number of females present in the choice assay. We observed that gravid females significantly avoid chambers containing an oviposition site when it is occupied by confined females. Interestingly, Gr3 mutants are significantly less likely to avoid chambers with confined females. In contrast, orco mutants show a significantly increased avoidance of chambers with confined females. Our results suggest that the decision-making process on breeding site selection is dependent upon olfactory interactions of females and relies on competing attractive and repulsive behavioral drives mediated by the OR pathway and CO₂ detection, respectively. We describe a chemosensory-dependent social communication among female mosquitoes that orient their choices when selecting an oviposition site.