Nearly bitten, twice shy: effects of prior and current parasite exposure on host mating behaviour

Parasite exposure without infection can lead to risk-induced trait responses with potential costs to host fitness or non-consumptive effects (NCEs). The various ways in which NCEs can manifest has gained considerable research attention, but the NCEs of parasite exposure on host mating behaviour remain unknown. Using a host-parasite system involving cactophilic flies (Drosophila nigrospiracula) and ectoparasitic mites (Macrocheles subbadius), we investigated the effects of current and prior parasite exposure (sans infection) on host mating behaviour. Current exposure did not influence host mating behaviour. However, female flies previously exposed to mites exhibited increased copulation latency, and were less likely to mate or be courted by males, suggesting that prior exposure makes females less receptive to mating, or that previously exposed females are less attractive to males. On average, previously exposed males invested less time per mating. Our results demonstrate that prior exposure potentially leads to a trade-off between reproduction and parasite defense even after exposure has ended, likely in favour of increased vigilance and parasite avoidance. While other studies have examined the impact of infection on host behaviour, this study represents the first investigation of NCEs on host mating behaviour. Additionally, our findings suggest that the NCEs of parasite exposure without infection could play an important role in parasite-mediated sexual selection.