Sexual conflict over nuptial gifts in insects.

Edible and seminal gifts that male arthropods transfer to their mates range from important material donations to items that provide little direct benefit. Recent reviews and research have emphasized the negative effect of gifts on female fitness, suggesting that male donations reduce the female's remating rate below her optimum or even that nuptial feeding is a net detriment to her fitness. However, comparative, experimental, and natural history evidence reveal that most edible gifts of prey or glandular products provide direct benefits to females. Gifts clearly supply nutrients when females compete for them or increase mating rates when food from other sources is limited. I point out the difficulties in determining that female remating rates are suboptimal and suggest several alternative hypotheses for the apparently low female mating rates in some gift-giving species. With regard to seminal contributions (absorbed from the ejaculate), I discuss how to separate hormonal (potentially manipulative) and material-benefit effects of male secretions on females.