Gut parasites infection increases mate rejection in a species with indirect sperm transfer

In animals where both males and females have high costs associated with reproduction, it is not rare that both sexes evaluate their potential mate conditions to make the most beneficial choice according to their preferences. Parasite-mediated selection theories predict that individuals would evaluate the ability of their potential mates to resist parasites and decide whether to accept or reject mating based on that information. These studies of parasite-mediated sexual selection had been carried out through the traditional sex roles perspectives. Our study species in this article is one with indirect sperm transfer, the pseudoscorpion Lustrochernes argentinus, and we evaluated mating on the health condition (infected or not) of both males and females. Our hypothesis is that the presence of gregarines in potential mates influences mate choice and for that, we analyzed (1) if gregarine-infected individuals suffer a higher proportion of rejection by their uninfected partners and (2) if spermatophore use success is lower when any of the individuals are infected. We tested this in a behavioral laboratory trial, comparing rejection by the male and the female and spermatophore use in four experimental groups. We found that both males and females suffer a higher probability of rejection when infected with gregarines; the maximum probability of sperm uptake success is when both individuals are healthy.