Cannibalism studies on eggs and newly hatched caterpillars in a wild population of Ascia monuste (Godart) (Lepidoptera, Pieridae)

Ascia monuste (Godart), also known as cabbage caterpillar, is considered herbivorous and specialist in Brassicaceae; however, it performs cannibalism. Experiments carried out in this work aimed to quantify the cannibalism occurrence in A. monuste, to verify whether cannibalism interferes in the species performance and to check whether cannibalism is influenced by the population size. The parameters used in order to evaluate the performance were time of development, adults weight and size, fecundity, oviposition and survival rate. Cannibalism occurred in all larval instars. There was a tendency to increase the cannibalism practice as the number of co-specific increased (potential preys). Cannibalism was more intense in larvae at the end of larval development. Generally, cannibalism did not interfere in the population performance. The most probable hypothesis for the occurrence of cannibalism in the conditions here studied would be the hypothesis of cannibalism as having the function of population control.