The regulation of juvenile hormone production in arthropods. Functional and evolutionary perspectives.

Although sesquiterpenoids are probably the ancestral regulators of reproduction and secondarily of metamorphosis in arthropods, our discussion suggests that the neuropeptides that regulate the biosynthesis of these compounds have arisen on several distinct occasions. These peptides probably occurred originally as regulators of other physiological processes and were subsequently co-opted for the regulation of sesquiterpenoid biosynthesis, perhaps first in adult forms and thereafter in larval forms. The evolution of peptides to assume additional physiological functions probably occurred as a result of gene duplication, both at the peptide level and at the receptor level. There are likely to be numerous regulators of sesquiterpenoid biosynthesis in both Insecta and Crustacea, and investigations to date have only begun to reveal the host of peptide families involved in the regulation of juvenile hormone-related biosynthesis across the arthropods.