The social consequences of sexual conflict in bed bugs: social networks and sexual attraction

Sexual conflict is ubiquitous across the animal kingdom and often involves costly sexual harassment of females by males. An overlooked outcome of sexual conflict is its potential impact on social behaviour. Due to their seemingly harmful mode of copulation (traumatic insemination) and tendency to form aggregations, bed bugs are an ideal model for studying the social implications of sexual conflict. Repeated traumatic inseminations are known to reduce some aspects of female fitness, so we expected the benefits to males and the high costs for females of frequent mating to result in divergent social preferences between the sexes. To examine the impact of sexual harassment on social structure, we devised a novel experimental arena with either two shelters or 12 shelters and continuously tracked sexual and social interactions between individually marked bed bugs over 6 days. By constructing aggregation networks, we examined whether female bed bugs occupied more peripheral network positions compared to males as well as whether females preferentially associated with other females as a strategy to reap the benefits of group living while mitigating the costs of unsolicited sexual attention. We found no evidence that females shape their social environment to evade associating with males. However, when tested individually in a follow-up experiment, mated females showed a strong preference for social cues from females over social cues from males. Our results therefore suggest that males and females may be in conflict over the composition of social associations and highlight the importance of both examining behaviour at the individual level and tracking larger groups of freely interacting populations in more complex environments.