Non-random mating in the beetle Cryptocephalus hypochaeridis

Non-random mating has been observed in many species of beetle, where larger or heavier males have a greater mating success. This difference in male mating success could be through direct competition between males, or female choice. We examined non-random mating in the leaf beetle Cryptocephalus hypochaeridis (L.) (Coleoptera Chrysomelidae). In the field, we found that successfully mating males were significantly heavier than unsuccessful males. We also found that the flowers in which we found beetles were significantly taller and wider than unoccupied flowers. However, we found no relationship between flower morphology and the mass of male occupants, suggesting that females are actively choosing the larger males. In the laboratory, females were found to show no preference for male size, and mated randomly. This suggests that mate choice in C. hypochaeridis is dependent upon cues other than flower size and height or male mass. We discuss what these cues might be, and how our results relate to the mating strategies of chrysomelid beetles. We also describe the mating behaviour of C. hypochaeridis.