Male mating costs in two insect species ( Protohermes, Megaloptera) that produce large spermatophores

Abstract

Abstract. Male Protohermes attach a large, gelatinous spermatophore externally to the female's genitalia at copulation. Following separation, the female bends and eats it. Males have a large internal reproductive organ consisting of testes, accessory glands and spermatophore sacs in which the spermatophore is prepared before mating. In this study, recovery patterns from the depletion of the internal reproductive organ and remating intervals of males of P. grandis and the closely related P. immaculatus were compared. The reproductive organ of P. immaculatus was smaller and recovered more rapidly after copulation than that of P. grandis. Male P. immaculatus were able to remate daily, while P. grandis required about 2 days before remating. Thus, P. grandis, which invest more heavily in each spermatophore (7·-20% body weight), require longer periods between matings than P. immaculatus (spermatophore 2·3-10% body weight). There was, however, no tendency for longevity to decrease in multiply mated males of either species.