A three-dimensional fluorescence analysis of the wings of male Morpho sulkowskyi and Papilio xuthus butterflies

Abstract

Fluorescence properties from the wings of male M. sulkowskyi and Papilio xuthus butterflies were investigated for the first time over a wide range of excitation and emission wavelengths using a three-dimensional (3-D) fluorescence method. From the 3-D plots of the pale blue region of the wings of M. sulkowskyi, four contour peaks were observed. On the other hand, from the yellow region of the wings of Papilio xuthus, one peak was observed. The origins of these contour peaks are discussed based on a comparison with standard pigments. Of the four contour peaks seen for M. sulkowskyi, a specific peak (A), located at an excitation wavelength of about 325 nm and an emission wavelength of about 410 nm, was thought to be mainly due to a mixture or compound of three pteridine pigments (i.e., biopterin, pterin and isoxanthopterin). The single specific peak observed for Papilio xuthus, located at an excitation wavelength of about 400 nm and an emission wavelength of about 470 nm, was thought to be due to the Papiliochrom II pigment. Based on these results, the possibility of using 3-D fluorescence analysis as a tool for classifying butterflies is briefly described.