Virgin-male mating advantage in sagebrush crickets: Differential male competitiveness or non-independent female mate choice?

Female sagebrush crickets (Cyphoderris strepitans) feed on males' fleshy hi nd wings during copulation and ingest haemolymph oozing from the wounds the y inflict. The wounds are not fatal and usually only a portion of the hind wings are eaten at any one mating, so that mated males are not precluded fr om mating again. However, based on their relative abundance in the populati on, virgin males have a higher mating success than non-virgin males. One ex planation for this virgin-male mating advantage is that non-virgin males, h aving been depleted of their energy reserves through the wing-feeding behav iour of their mates, are unable to sustain the same level of acoustic signa lling they produce prior to copulation. Previous assays of male signalling behaviour have provided some support to this hypothesis. However, an altern ative explanation is that females actively seek out virgin males as mates b ecause of the greater material resources they offer. If the acoustic struct ure of males signals were systematically altered by the loss of hind-wing m aterial underlying the sound-producing tegmina, females could potentially d iscriminate against mated males through reduced phonotaxis to their calls. We tested this hypothesis by experimentally removing one hind wing from vir gin males, thereby simulating the non-virgin condition without the attendan t costs of copulation. We compared the mating success of these 'asymmetrica l' males with that of sham-operated virgin males when competing under natur al conditions. In a companion laboratory study, we used time-lapse video re cording to examine the possibility that female preferences are exerted only after pair formation has occurred. There was no significant difference in male mating success across treatments in either study. We conclude, therefo re, that the virgin-male mating advantage does not stem from an acousticall y mediated, non-independent female mating preference, but rather, from the differential competitiveness of males.