Trichinella spiralis infection in voles alters female odor preference but not partner preference

Females may choose mates based on secondary sex traits that reflect disease resistance. Accordingly, females should be able to distinguish between unp arasitized and parasitized males, and should prefer to mate with unparasiti zed individuals. Mate and odor preferences for uninfected males or males in fected with the nematode, Trichinella spiralis, were examined among prairie voles (Microtus ochrogaster) and meadow voles (M. pennsylvanicus). In a 15 -min odor preference test, only female meadow voles distinguished between b edding from parasitized and unparasitized conspecific males, and preferred to spend time with bedding from unparasitized males, Although T. spiralis i nfection influenced odor preference in female meadow voles, there was no ef fect of infection status on mate preference among either species. Testoster one and corticosterone concentrations were not different between parasitize d and unparasitized males. However, among prairie voles, males that spent a n increased amount of time with females during the mate preference test had elevated testosterone concentrations. Taken together, these data suggest t hat (1) female meadow voles can discriminate between unparasitized and para sitized males, (2) the effects of infection on steroid hormone concentratio ns may be masked by the effects of social interactions, and (3) parasites m ay represent a selective constraint on partner preference in voles; however , the life cycle of parasites may influence female preference and should be considered in studies of female preference.