WEIL, K. A.*; SPARKES, T.C.: Parasite and sexual conflict in a stream isopod

Sexual conflict is common in aquatic isopods and occurs prior to pair formation in the form of conspicuous mating contests. Females control the outcome of these contests and previous work has shown that female resistance during contests results in discrimination against males with low energy reserves. Here, we examined whether female resistance in the stream isopod (Caecidotea itermedius) also results in discrimination against males with parasites (acanthocephalans). First, we quantified the relationship between parasite infection and male success in nature by comparing parasite load of paired and unpaired males. We found no relationship between parasite infection and male mating success. Second we examined dynamics of mating contests between males and females where males varied in parasite load. Preliminary data suggests that there was no effect of parasite infection on mating dynamics. Third, we quantified costs to females of mating with parasitized males. We found that parasite infection of males increased the frequency of abnormal egg development of females. Thus, females pay a cost of mating with parastized males but this costs does not appear to translate into discrimination against males with parasites.