Regulation of Tanning and Color Change

Insects exhibit a remarkable diversity in body coloration derived from structural properties and pigments, which is vital for their survival, communication, and reproduction. Coloration is highly adaptable and modulated by biotic and abiotic environmental cues (e.g., temperature, population density), with the endocrine system playing a critical role in regulating these changes. Melanin biosynthesis, the primary pigment system, begins de novo from tyrosine and proceeds via conserved core enzymes, yielding diverse melanin-derived colors. The levels of transcripts encoding these enzymes are highest immediately after molting, tightly linking melanization to cuticle tanning, accompanied by endocrine control. In locusts, neuropeptides such as corazonin (CRZ) induce density-dependent dark coloration. Elevenin signaling regulates melanization in the brown planthoppers by upregulating melanin-biosynthetic enzymes. Melanization and reddish coloration hormone (MRCH) induces larval dark body coloration in some moth larvae via a density-dependent pathway. Although previous reports dealing with the body coloration in insects are limited, we introduce the fact that insect body coloration is an adaptable phenomenon orchestrated by a complex and sophisticated network of hormonal, developmental, environmental, and anthropogenic factors in this chapter.