Melatonin and Serotonin: Their Synthesis and Effects in Insects

Melatonin and serotonin are endogenous neurotransmitters and hormones produced by tryptophan metabolism. Melatonin and serotonin are present in the heads, eyes, optic lobes, and brains of various invertebrates. Insects produce serotonin and melatonin via the same pathways that vertebrates do. They are pleiotropic signaling chemicals that regulate a wide range of physiological processes and protect against disease and environmental factors in various species. In insects, they function as neurotransmitters, hormones, and bioregulators, controlling a wide range of endocrines, behavioral, immunological, developmental, and defensive activities, as well as biological cycles.