Meeting Abstract

12.3  Jan. 4  UV reflectance in female sulphur butterflies: DIversity and Mechanisms RUTOWSKI, R. L.*; MACEDONIA, J. ; KEMP, D. ; TAYLOR-TAFT, L.; Arizona State University r.rutowski@asu.edu

In some species of sulphur butterflies (Pieridae: Coliadinae) females as well as males display bright structural reflectance on their dorsal wing surfaces, although comparatively little attention has been paid to this coloration in females. We examined the spectral properties of female dorsal coloration and scale structure in three species of sulphurs for which published images show bright UV reflectance in females: Anteos clorinde and two species of Eurema, E. hecabe and E. candida. In A. clorinde and E. hecabe, female UV reflectance is iridescent and produced by thin film interference in a system of ridges and lamellae, as it is in conspecific males. Female A. clorinde exhibit the same spatial distribution and chromaticity of UV reflectance as seen in males, but the UV reflectance in female E. hecabe is much smaller in area compared to that of conspecific males and is both less bright and less chromatic than observed in males. In contrast, UV reflectance in E. candida females is diffuse, and arises from a lack of pterin pigments in the wings, which permits a broad-band scattered reflection to be seen. This latter mechanism also is known to produce bright UV reflectance in females of some confamilial whites. While the functional significance of female UV reflectance in these species is unclear, our results highlight the diversity of UV reflectances and underlying mechanisms in sulphurs and suggest multiple evolutionary pathways leading to this diversity in female sulphur butterflies.