Fun with Science Club®


			Are those cute little “ladybugs” cannibals? Carrie Straight 05.18.01 There are cannibals in all areas of the animal kingdom. Many species that are generalists (a species that doesn’t have to eat one specific type of food) are cannibals. Cannibalism usually occurs when food is scarce, but not for the multicolored Asian lady beetle, Harmonia axyridis. This beetle will eat one of its own even when there is lots of food around (one of the common foods for these ladybug larvae are aphids, Aphis spp. This led scientists to predict that these beetles must benefit in some way from being cannibals, especially if the food around is not good in quality. These scientists set up an experiment to test this prediction. They got some larvae of the ladybeetle and collected some aphids. The larvae that would later be “the food” were fed one of three different types of aphids. The experimental larvae ate aphids only, larvae only, or aphids and larvae. The scientists measured the growth of the larvae and kept track of each larva to see if it survived to adulthood. The scientists discovered that the larvae that ate other larvae had a better chance of surviving, but if they ate other larvae and aphids they had an even better chance of surviving. Now the scientists know that the benefit to cannibalism for lady beetles is longer life. a benefit to cannibalism for lady beetles.


			Snyder, William E., Sarah B. Joseph, R. F. Preziosi, and Allen J. Moore. 2000. Nutritional benefits of cannibalism for the lady beetle Harmonia axyridis (Coleoptera: Coccinellidae) when prey quality is poor. Environmental Entomology 29(6): 1173-1179.