Die rolle der Carotinoide und des Gallenfarbstoffs bei der Farbmodifikation der Puppen von Pieris brassicae

Abstract

The carotenoids and the bile pigment in larvae and pupae of Pieris brassicae were analysed. Their rôle in the morphological colour adaptation of the pupae was studied by quantitative measurements. The carotenoids are β-carotene, lutein mono-ester, free lutein, and zeaxanthin. Metabolized carotenoids were not found. There are no differences between pupae showing different grades of melanization in the quality of the carotenoids, or in the total amounts, or in the relative portions of each carotenoid fraction. However, the carotenoid content of the integument alone is twofold in the light pupae as compared to dark ones. The integumental carotenoids are deposited mainly in the epidermis. β-Carotene, lutein, and zeaxanthin are selectively absorbed by the larvae from the diet. β-Carotene and lutein ester are localized mainly in the fat body, whereas lutein is predominant in the haemolymph and in the integument. The pupal bile pigment is protobiliverdin-IXγ (pterobilin), which is also known to be the larval pigment. The bile pigment is synthesized mainly during the last larval instar up to the pharate pupal stage. In the pupae the bile pigment content is related to the melanization: pupae exposed to the same light conditions contain less bile pigment the more melanized they are (negative correlation). On the whole there is a strong enhancement by blue light of the bile pigment content besides the known stimulation of melanization (positive correlation). But within such a sample the negative correlation between the amounts of bile pigment and melanin is maintained.