Fun with Science Club®


			Why are some beetles cannibals? Beth Tyler 06.01.01 Scientists have observed confused flour beetles, Tribolium confusum, eating each other’s eggs. However, some populations of confused flour beetles are much more likely to be cannibals than other populations. Why would some populations of flour beetles eat a lot of eggs while other populations only eat a small number? Four American scientists in Vermont hypothesized that the confused flour beetles that eat a lot of eggs receive nutritional benefits from the eggs. To test their hypothesis, they took flour beetle larvae (immature flour beetles) from a population with high rates of cannibalism and a population with low rates of cannibalism. In each population, they only gave eggs to half the flour beetles. For each group (high-cannibals with eggs, high-cannibals without eggs, low-cannibals with eggs, and low-cannibals without eggs), they recorded how many larvae survived to adulthood. In the groups with eggs, they recorded the number of eggs the larvae ate. The scientists discovered that in the groups that had eggs, the high-cannibal groups ate more eggs than the low-cannibal groups. Also, in the groups that did not have eggs, more high-cannibal larvae died than low-cannibal larvae. These results support the scientists’ hypothesis that flour beetles eat eggs for nutrition. Populations with high rates of cannibalism need to eat eggs in order to survive.


			Giray, Tugrul, Yvette A. Luyten, Max MacPherson, and Lori Stevens. 2001. Physiological bases of genetic differences in cannibalism behavior of the confused four beetle Tribolium confusum. Evolution 55: 797- 806.