Male body size does not affect the refractory period of females in the West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) and the seed bug Togo hemipterus (Scott) (Heteroptera: Lygaeidae)

Abstract

Multiple mating by females increases both the risk and intensity of sperm competition for males. The ability to temporarily or permanently inhibit female receptivity to further mating represents a highly adaptive strategy to reduce the risk of sperm competition. Males of the West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) and the seed bug Togo hemipterus (Scott) (Heteroptera: Lygaeidae) use accessory gland substances to inhibit remating in females. It is known that there is variance in the length of the female refractory period (i.e., the effectiveness of male ejaculate substances that inhibit female remating) within a species. However, it is unclear what types of male traits affect the length of the female refractory period. The mechanism of the female refractory period is not sufficiently revealed. We focused on male body size, which is often a target of sexual selection, and investigated the relationship between male body size and both the refractory period of females and mating duration. Contrary to our thought, male body size did not significantly influence the refractory period of females or mating duration in either species. Smaller male body size was not particularly favored by post-copulatory sexual selection in either species.