Sexual differences in spectral sensitivity and wing colouration of 13 species of Japanese Thecline butterflies (Lepidoptera: Lycaenidae)

Michio Imafuku

doi:10.14411/eje.2013.058

Abstract

The correlation between dorsal wing colours and spectral sensitivity of the compound eyes of 13 species of thecline butterflies, consisting of 8 sexually monomorphic and 5 dimorphic species, was investigated. Spectral reflectance of the dorsal surfaces of the wings was measured using a spectrophotometer and spectral sensitivities using electroretinography. All 13 species examined showed a common basic pattern of spectral sensitivity with a primary peak at a wavelength of 440-460 nm. Detailed analyses of the deviations in sensitivity from the basic pattern revealed a correlation in monomorphic species with conspicuous wing hues, especially in males.

Highlights

Butterflies have the most conspicuous and varied wing colours of all insects
The results reveal significant correlations in monomorphic species but not in dimorphic species
The spectral sensitivity of the compound eyes of thirteen species of butterflies belonging to the tribe Theclini, Theclinae, Lycaenidae were determined (Table 1)

Summary

Introduction

Butterflies have the most conspicuous and varied wing colours of all insects. This colouration plays a role in interspecific communication, such as aposematism (Benson, 1972), mimicry (Uésugi, 1996) and as an isolating mechanism (Meyer-Rochow, 1991).As for intra-specific communication, males are known to respond to wing colours of potential mates in the Nymphalidae (Crane, 1955; Stride, 1956; Magnus, 1958; Silberglied, 1984), Pieridae (Obara, 1970; Rutowski, 1977, 1981; Silberglied & Taylor, 1978) and Papilionidae (Hidaka & Yamashita, 1975), with the exception that males of Hipparchia semele (Linnaeus, 1758) show a higher response to darker coloured butterfly models independent of their hues (Tinbergen et al, 1942).Males of Lycaeides idas (Linnaeus, 1761) distinguish between conspecific and heterospecific females by the size of the black spots scattered over the ventral surface of their wings (Fordyce et al, 2002). Butterflies have the most conspicuous and varied wing colours of all insects. This colouration plays a role in interspecific communication, such as aposematism (Benson, 1972), mimicry (Uésugi, 1996) and as an isolating mechanism (Meyer-Rochow, 1991). As for intra-specific communication, males are known to respond to wing colours of potential mates in the Nymphalidae (Crane, 1955; Stride, 1956; Magnus, 1958; Silberglied, 1984), Pieridae (Obara, 1970; Rutowski, 1977, 1981; Silberglied & Taylor, 1978) and Papilionidae (Hidaka & Yamashita, 1975), with the exception that males of Hipparchia semele (Linnaeus, 1758) show a higher response to darker coloured butterfly models independent of their hues (Tinbergen et al, 1942). Males of Lycaeides idas (Linnaeus, 1761) distinguish between conspecific and heterospecific females by the size of the black spots scattered over the ventral surface of their wings (Fordyce et al, 2002). In H. cydno Doubleday, 1874, mates are recognized by the polarized UV-light reflected from the dorsal surface of the wings (Sweeney et al, 2003)

Methods

Results

Conclusion