Larval Development of Non-Insect Arthropods: Metamorphosis and Sexual Differentiation

Abstract

In insects, metamorphosis is one of the most important research topics. Their drastic morphological and physiological changes from larvae to pupae, and then to adults, have fascinated many people. These changing life history patterns are tightly regulated by two endocrine systems, the ecdysteroids (molting hormones) and the juvenile hormones. Metamorphosis is also the most universal phenomenon in non-insect arthropods (especially crustaceans). Additionally, as dwarf males (e.g., barnacle crustaceans) show distinct sexual dimorphism during the larval developmental stage, larval development and sexual differentiation are also intimately associated. Our knowledge of endocrinology and gene cascades underlying metamorphosis and sexual differentiation in non-insect arthropods is rudimentary at best and relies heavily on well-studied insect models. Advances in newly developed applications, omics technologies and gene-targeting, are expected to lead to explorative molecular studies that reveal components and pathways unique to non-insect arthropods. This chapter reconciles known components of metamorphosis and sexual differentiation in non-insect arthropods and reflects on our findings in insects to outline future research.