Influence of male density on the courtship and mating duration of male rice weevils, Sitophilus oryzae

The rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) is a major pest of stored grains throughout the world. This experiment examined the capacity of male S. oryzae to adjust their mating behaviour in response to male density (i.e. 1, 5 and 10 males) maintained with a single female. Results show that males spent less time in courting females with antennal contact at density 1 when compared to densities 5 and 10. Copulation duration increased in response to the increase in rival densities. The mechanism behind this phenomenon may be (1) a mate guarding strategy to enhance reproductive success by reducing the chance of sperm displacement by competitors and (2) a strategy to avoid damage to the reproductive organs of their mates by multiple mating.