Sexual Conflict Over Spermatophore Attachment in a Nuptially Feeding Cricket

摘要

Sexual conflict is implicated in the evolution of nuptial feeding. One function of nuptial gifts lies in mating effort, where the female's eating of the gift reduces her likelihood of prematurely terminating sperm transfer. We test several ideas regarding sexual conflict in the nuptially feeding wood cricket Nemobius sylvestris. In this cricket, males pass two kinds of spermatophores to females: spermless microspermatophores and larger sperm-filled macrospermatophores. Females may palpate the males' forewing secretions as a possible additional form of nuptial feeding. We manipulated male mobility and female feeding regime to examine the effects on spermatophore transfer, macrospermatophore attachment duration, and palpations of the males' forewings. Neither male confinement nor female feeding regime affected the occurrence of macrospermatophore transfer. Males transferred the macrospermatophore sooner to low-food females than to high-food females. Males that were freely mobile (unconfined and sham treatments) had longer macrospermatophore attachment durations than confined males, while female feeding regime did not affect attachment duration. The overall occurrence of female palpation was not significantly affected by female feeding regime. However, high-food females were more likely to perform short palpations before microspermatophore transfer, while low-food females were more likely to palpate after macrospermatophore transfer. Sexual conflict is evident in that males appear to guard against premature removal of the sperm-filled macrospermatophore. Low-food females appear to facilitate the early transfer of the macrospermatophore, while being more likely to perform relatively long post-insemination palpations than better-fed females.