6 - Cuticular Sclerotization and Tanning

Abstract

This chapter discusses the cuticular sclerotization and tanning. The cuticle covers the insect body as an effective barrier between the animal and its surroundings; it provides protection against desiccation, microorganisms, and predators, and as an exoskeleton it provides attachment sites for muscles. Cuticle can occur as relatively hard and stiff regions, the sclerites, separated by more flexible and pliable cuticular regions, the arthrodial membranes, which make the various forms of locomotion possible. Cuticular sclerotization is a chemical process by which certain regions of the insect cuticle are transformed irreversibly from a pliant material into a stiffer and harder structure, characterized by decreased deformability, decreased extractability of the matrix proteins, and increased resistance to enzymatic degradation. During sclerotization the color of the cuticle may change; some cuticles remain nearly colorless, and some become lighter or darker shades of brown or black. The term “tanning” is often used synonymously with sclerotization, but sometimes it is specifically used for the processes whereby brownish (tan) cuticles are formed.