ATTRACTIVENESS OF MALE ODORS TO FEMALES VARIES DIRECTLY WITH PLASMA TESTOSTERONE CONCENTRATION IN MEADOW VOLES

We examined the hypothesis that differences in androgen concentrations may cause differences in the attractiveness of male odors to female m eadow voles, Microtus pennsylvanicus. Males that were to be used as od or donors were castrated and implanted with Silastic capsules filled w ith no hormone or one of four different amounts of testosterone. Four different odors from males were assessed for each comparison; the odor s were from the anogenital area, feces, urine, and posterolateral regi on. Treatment of scent donor males with the lowest dosage of testoster one was not sufficient to increase the attractiveness of their odors a bove that of males receiving no hormone. The three higher dosages incr eased attractiveness in a dose-dependent manner. The shape of the dose -response curve differed across scents: two scents reached maximum att ractiveness in the middle of the dose range and remained there at high er doses, whereas the other two scents continued to increase in attrac tiveness as testosterone titers increased. The results suggest that sc ent glands produce graded signals that reflect circulating testosteron e titers.