Effect of Pupation Site on Pupal Cannibalism and Parasitism in the Ladybird Beetle Harmonia axyridis PALLAS (Coleoptera, Coccinellidae)

Pupal cannibalism and parasitism of the ladybird beetle, Harmonia axyridis PALLAS, were studied in relation to the pupation sites and the direct distance from the pupation site to the nearest aphid colony. Cannibalism and parasitism occurred more intensely on host plants of prey aphids than in the other pupation sites. Cannibalism was more intense in a pupation site which was closer to an aphid colony, but it was not the case with the parasitism by Phalacrotophora sp. The higher rate of cannibalism near an aphid colony seemed to be due to the intensive searching of a cannibal near an aphid colony, whereas the frequent occurrence of parasitism on prey's host plants seemed to be due to the host searching of the parasitoid concentrating on host plants.