Biased social transmission in Drosophila oviposition choice

Within a group, animals adjust individual decisions to environmental conditions both through their own experience and by interacting with other animals. How individuals balance social vs. personal information may have a deep impact on their fitness, and this might be particularly relevant when individuals interact with conspecifics that carry different, or even conflicting, information. In animals, conformist strategy of social learning, defined by the tendency of individuals to disproportionately adopt the most commonly encountered social information, appears to be more widespread than previously thought. Here, we investigated whether females of the fruit fly, Drosophila melanogaster, conform their oviposition site choice to social cues coming from conspecifics. Groups of na < ve observer flies were exposed to two oviposition media (banana or strawberry flavored) and to other demonstrator flies that were previously trained to prefer one of the two media. All flies were then tested for their oviposition preference. The preference of observer flies was highly sensitive to the social composition of the demonstrator group, and even the presence of a small proportion of individuals trained to oviposit on banana was enough to induce a biased preference for the banana medium. Our results suggest that D. melanogaster females combine their personal preference with social information to choose oviposition sites rather than showing social conformity.