Color Preference for Pupation Sites of the Butterfly Larvae Inachis io and the Significance of the Pupal Melanization Reducing Factor

摘要

Pupae of rhopaloceran butterfly species which are not covered by cocoons or hidden in the ground show an intense integumental coloration. In some species they adapt their coloration to the background color of the pupation site. In the peacock butterfly Inachis io L. (Nymphalidae) this morphological color adaptation is achieved by a reduction in melanization and at the same time a stimulation of lutein incorporation into the cuticle resulting in yellow, somewhat greenish pupae on yellow background. These pigmentation effects are controlled by a neuropeptide which has been named pupal melanization reducing factor (PMRF) and is located throughout the entire central nervous system (CNS). The hormone is released when wandering larvae are kept on a yellow background. On the other hand, a straight search for a dark background by wandering larvae should make the hormone unnecessary.