Benefits of insect colours: a review from social insect studies

Abstract

Insect colours assist in body protection, signalling, and physiological adaptations. Colours also convey multiple channels of information. These channels are valuable for species identification, distinguishing individual quality, and revealing ecological or evolutionary aspects of animals' life. During recent years, the emerging interest in colour research has been raised in social hymenopterans such as ants, wasps, and bees. These insects provide important ecosystem services and many of those are model research organisms. Here we review benefits that various colour types give to social insects, summarize practical applications, and highlight further directions. Ants might use colours principally for camouflage, however the evolutionary function of colour in ants needs more attention; in case of melanin colouration there is evidence for its interrelation with thermoregulation and pathogen resistance. Colours in wasps and bees have confirmed linkages to thermoregulation, which is increasingly important in face of global climate change. Besides wasps use colours for various types of signalling. Colour variations of well chemically defended social insects are the mimetic model for unprotected organisms. Despite recent progress in molecular identification of species, colour variations are still widely in use for species identification. Therefore, further studies on variability is encouraged. Being closely interconnected with physiological and biochemical processes, insect colouration is a great source for finding new ecological indicators and biomarkers. Due to novel digital imaging techniques, software, and artificial intelligence there are emerging possibilities for new advances in this topic. Further colour research in social insects should consider specific features of sociality.

Keywords: Aposematism; Camouflage; Colouration; Hymenoptera; Thermal melanism.

Fig. 1

Main classes of pigment- and structure-based colours in insects. Photo © ProtasovAN

Fig. 2

Interconnections between colour functions in social insects (ants, wasps, and bees)

Fig. 3

Main groups of hymenopteran social insects (ants, bees, wasps), demonstrating different levels of sociality, and diverse aspects: (1) positive (marked with green) and (2) negative (marked with red) of their ecological role

Fig. 4

Examples of various colouration types in different species of hymenopteran insects with different levels of eusociality. a melanin-based pigmental black-and-red colouration of the red wood ant Formica rufa (highly eusocial species); photo © Andrey Pavlov. b Melanin and pterin black- and-yellow pigment cuticular colouration of the European paper wasp Polistes dominula (primitively eusocial species); photo © Andrey Pavlov. c Melanin-, purine-, pteridine-based pigment colouration the Oriental hornet Vespa orientalis (highly eusocial species); photo © Tennesssee Witney d Melanin- and pterine-based hair colours in the White-tailed bumblebee Bombus lucorum; photo © Sergey. e Structural green colouration in Orchid bee Euglossa dilemma (species, exhibiting eusocial plasticity); photo © Laurel A Egan. f Blue pigment and structural cuticular colouration of Carpenter bee Xylocopa sp. (species with signs of week sociality); photo © YuRi Photolife