Molecular basis and ecological relevance of aphid body colors.

Aphids are small phloem sap-feeding insects, and show color polymorphism even within the same species. Crossing experiments have revealed the inheritance pattern of the body color. Coloration of aphids is determined by mainly three pigments, melanin, carotenoid, and aphin, and is influenced by both abiotic and biotic environmental factors. Aphid body colors also seem to correspond with specific biological functions under various environments. Partly due to the presence of natural enemies in the environment, a variety of physiological and behavioral responses have evolved in each color form. Thus, predation is one of the most significant external factors for maintaining body color polymorphisms. In addition, endosymbiont infections also influence aphid body color and prey-predator interactions. However, many unsolved questions remain regarding the molecular basis for and biological functions of aphid body colors. Further work, including the development of molecular techniques for comprehensive functional analysis, is needed in these areas.