Evolutionary ecology of insect egg coloration: a review

Abstract

Body coloration in animals is often adaptive and used for defense against biotic (e.g., predators, competitors) and abiotic (e.g., solar radiation, desiccation) threats. The study of adaptive coloration in insects usually favors obvious model species such as yellowjacket wasps (Vespula spp.) and longwing butterflies (Heliconius spp.), partly because they actively interact with their environment. Yet, one life stage has received less attention because of its immobility: the egg. So far, vertebrate eggs, especially avian eggs, have held the ‘‘big end of the stick’’ when it comes to research effort on adaptive egg coloration. In species where eggs are not provided with parental care and left to survive on their own until hatching, studying the defensive roles played by their colors is imperative to understand their evolutionary ecology. Adaptive functions provided by egg coloration such as crypsis, aposematism and photoprotection against ultraviolet radiation potentially have huge fitness impacts and deserve more attention. Here, the current literature on insect egg coloration is reviewed, reporting its known adaptive significance. Clear distinctions are made between functions tested empirically and functions that remain hypothetical despite often being treated as facts. Avenues for future work in the field are also provided.