Hemolymph loss during nuptial feeding constrains male mating success in sagebrush crickets

Abstract

Although costs of mating have been widely documented in females, intrinsic costs of copulation have been poorly documented in males, and there is little evidence that such costs constrain male mating success under natural conditions. Male sagebrush crickets, Cyphoderris strepitans, offer females an unusual somatic food gift at copulation that may constitute a significant cost of copulation: females chew on the ends of the males’ fleshy hind wings and ingest hemolymph seeping from the wounds they inflict. Previous studies have shown that once a male has mated, his probability of obtaining an additional copulation is reduced relative to that of a virgin male seeking to secure his first mating. If the future mating prospects of nonvirgin males are diminished because of the costs of copulation, this could stem either from the resources required to manufacture a new spermatophore or through the energy needed to replenish hemolymph lost through female wing-feeding. To distinguish between these two alternatives, we experimentally depleted virgin males of varying amounts hemolymph in a way that mimicked hemolymph loss of nonvirgin males, without the attendant costs of spermatophore production. After they had been treated, males were released in the field and recaptured over the course of the breeding season to monitor their mating success. Control males mated significantly sooner than did males depleted of hemolymph. We conclude, therefore, that the depletion of hemolymph that occurs through female wing feeding is sufficient by itself to diminish a nonvirgin male’s ability to secure another mating. Key words: costs of mating, Cyphoderris strepitans, mating success, nuptial food gift, sagebrush crickets, sexual selection. [Behav Ecol 15:845–849 (2004)]