7 - Metamorphosis of the Cuticle, Its Proteins, and Their Genes

Abstract

This chapter focuses on the metamorphosis of the cuticle, and describes the morphological and molecular changes it undergoes during metamorphosis. The morphological changes in body shape, surface morphology, and texture that accompany insect metamorphosis have been subjected to serious scientific analysis for decades. For many hemimetabolous insects, the appearance of new body parts such as wings and genitalia is the most conspicuous external change that signifies that a metamorphic molt has taken place. The surface cuticle has a similar morphology, superficially and histologically, in both larva and adult, but in some hemimetabolous insects, conspicuous differences in cuticle morphology accompany metamorphosis. In the holometabolous insects, changes in cuticle morphology can be as dramatic as the changes in body shape that accompany metamorphosis. Instant recognition of the metamorphic stage is generally provided by a brief glimpse of the cuticle. After the first metamorphic molt, the pupa is shrouded in brown cuticle, rigid in sclerites, flexible in intersegmental membranes. The adult, which emerges after the second metamorphic molt, is covered with red, black, and white scales, embedded in a thin, amber-colored, flexible surface cuticle. Specialized regions of the adult cuticle are rigid, such as the wing hinges and genitalia.