Genetic control of a seasonal morph in Precis coenia (Lepidoptera: Nymphalidae)

Abstract

The seasonal color polyphenism of the buckeye butterfly, Precis coenia, is controlled by environmental and genetic factors. Environmental stimuli, such as photoperiod and tempertaure, alter the pattern of ecdysteroid secretion. If ecdysteroids are present during a critical period early in the pupal stage the pale beige linea form develops, while in the absence of ecdysteroids the dark reddish-brown sa form develops. In this paper we report on the isolation of a genetic strain that constitutively expresses the rosa phenotype. Breeding experiments show that this effect is due to a single recessive gene. The ecdysteroid titer profile of the rosa strain is identical to that of the environmentally induced linea form, and not to that of the environmentally-induced rosa form. Ecdysteroid injections and reciprocal wing imaginai disk transplant studies between genetic rosa and wild-type strains, show that the rosa gene does not affect the endocrine system, but alters the physiological response mechanism that follows the ecdysteroid-sensitive period for linea induction and culminates in the wing-specific synthesis of ommochrome pigments.