Infestation with the parasitic nematode Philometra ovata does not impair behavioral sexual competitiveness or odor attractiveness of the male European minnow (Phoxinus phoxinus)

Our understanding on the role of chemical signals in parasite-mediated sexual selection is still limited, and only some existing studies have focused on fish. Furthermore, published studies on the effect of parasite infection on behavioral sexual competition of the male hosts have yielded contradictory results. Here, we examined whether the infection of the body cavity-dwelling parasitic nematode Philometra ovata influences odor-based female choice and behavioral sexual competition (dominance and courtship behavior) between males in the European minnow (Phoxinus phoxinus), the cyprinid fish host. In contrast to our predictions, we found that naive females showed no preference between the odors of infected and non-infected males, thus indicating that P. ovata infection may not affect odor-based female choice. Moreover, P. ovata did not impair sexual competitiveness of their hosts either. Our results indicate that despite its relatively large size, P. ovata may not alter sexual cues and the success of the male hosts in sexual selection.