|Bogner, FX; Eisner, T: Chemical Basis of Pupal Cannibalism in a Caterpillar (Utetheisa ornatrix)., Experientia, 48, 97-102 (1992)|
The moth Utetheisa ornatrix derives protection against predation from systemic pyrrolizidine alkaloids (Pas) that it sequesters as a larva from its foodplants (Leguminosae, Crotalaria spp.). We here show, in laboratory tests, that Utetheisa deficient in body PA can make up for the chemical shortfall by cannibalizing pupae. We present evidence indicating that cannibalism in larvae is elicited not by hunger, but possibly by PA deficiency itself, and that in making cannibalistic larvae prefer PA-containing or PA-free pupae. Pas themselves, either in crystalline form or as additives to food items, proved phagostimulatory to larvae. In nature Utetheisa tend to pupate away from their food-plant, essentially out of reach of larval attack. The threat of cannibalism may have contributed to the evolution of this pupation behavior. Key words Lepidoptera; Arctiidae; pyrrolizidine alkaloids; cannibalism; acquired defence; phagostimulation; specific hunger.