Changes in structural and pigmentary colours in response to cold stress in Polyommatus icarus butterflies

Krisztián Kertész,Zsolt Bálint,Zsolt Endre Horváth,László Péter Biró,Gábor Piszter

doi:10.1038/s41598-017-01273-7

Krisztián Kertész, Zsolt Bálint + Show 3 more

Open Access

https://doi.org/10.1038/s41598-017-01273-7

Copy DOI

Abstract

While numerous papers have investigated the effects of thermal stress on the pigmentary colours of butterfly wings, such studies regarding structural colours are mostly lacking, despite the important role they play in sexual communication. To gain insight into the possible differences between the responses of the two kinds of colouration, we investigated the effects of prolonged cold stress (cooling at 5 °C for up to 62 days) on the pupae of Polyommatus icarus butterflies. The wing surfaces coloured by photonic crystal-type nanoarchitectures (dorsal) and by pigments (ventral) showed markedly different behaviours. The ventral wing surfaces exhibited stress responses proportional in magnitude to the duration of cooling and showed the same trend for all individuals, irrespective of their sex. On the dorsal wing surface of the males, with blue structural colouration, a smaller magnitude response was found with much more pronounced individual variations, possibly revealing hidden genetic variations. Despite the typical, pigmented brown colour of the dorsal wing surface of the females, all cooled females exhibited a certain degree of blue colouration. UV-VIS spectroscopy, optical microscopy, and scanning and transmission electron microscopy were used to evaluate the magnitude and character of the changes induced by the prolonged cold stress.

Highlights

During the past decade, the colour patterns of insects have emerged as model systems for studying the interplay between development and evolution[1]
In an extraordinary field case of a species of lycaenid butterfly, Zizeeria maha, for which plastic phenotypes of wing colour patterns were revealed at the population level during the course of range expansion in Japan, it was confirmed by laboratory experiments that the outbreak of modified phenotypes in the recent range margin population was primed by the revelation of plastic phenotypes in response to temperature stress[13]
The ventral side of the wing surfaces of both the males and females exhibited similar complex pigmentations (Fig. 1c,g,k and o): basal, medial and submarginal patterns comprised of black spots with white rings and orange lunules, typical for the subtribe Polyommatina

Summary

Introduction

The colour patterns of insects have emerged as model systems for studying the interplay between development and evolution[1]. We believe that the structural blue colour of male P. icarus butterflies is more stable against stress-induced variation compared to the pigmentary pattern of the ventral wing surface used for the identification of this species.

Results

Conclusion