Production of cardenolides versus sequestration of pyrrolizidine alkaloids in larvae of <i>Oreina</i> species (Coleoptera, Chrysomelidae)

Adult leaf beetles of the genus <i>Oreina</i> are known to be defended either by autogenously produced cardenolides or by pyrrolizidine alkaloids (PAs) sequestered from the food plant, or both. In this paper we analyze larvae of different <i>Oreina</i> species and show that the larvae contain the same defensive toxins as the adults in quantities similar to those released in the adults' secretion. Both classes of toxins are found in the body and hemolymph of the larvae, despite their different origins and later distribution in the adults. Larvae of sequestering species differed in their PA patterns, even though they fed on the same food plants. The concentration in first-instar larvae of a PA-sequestering species was similar to that in fourth-instar larvae. In all stages examined, the amount of PAs per larva did not greatly exceed the estimated uptake of one day. Eggs of two oviparous species contained large concentrations of the adult's toxins, while neonates of a sequestering larviparous species had no PAs.