Abstract: Parental investment theory and sexual selection theory suggests that investment by males through courtship feeding of their mates may represent an important source of nutrition and ultimately influences patterns of sexual selection. In certain insects males provide nutritional products from reproductive accessory glands during mating; these are either eaten by the female or are absorbed in her genital tract. Male bushcrickets (Orthoptera: Tettigoniidae) feed their mates with an elaborate spermatophore consisting of a spermatophylax, which is eaten by the female after mating, and a sperm ampulla, eaten after the ejaculate has emptied. Studies of the species with very large spermatophores have revealed a rolereversal in reproductive behaviour, with females aggressively competing for males capable of producing spermatophores. Population density, nutritional condition and operational sex ratio are the three main affecting factors.

Key words: parental investment, sexrole reversal, nuptial gift, katydid