Juvenile Hormone

Juvenile hormone (JH) was initially discovered in the 1930s as a factor that is secreted from the corpus allatum (CA) and inhibits insect metamorphosis. The chemical structure of the first JH was solved in 1967, and at least eight JHs have been identified to date. JH regulates development, reproduction, diapause, polyphenism, and behavior throughout insect life. Virtually all tissues are the targets of JH. Numerous JH agonists have been synthesized, and some are practically applied for the control of insect pests. JH biosynthesis is controlled by various neuroendcrine and neuronal factors in complex stage- and species-specific ways. JH exerts its action through both a membrane receptor(s) and a nuclear receptor(s). Recently, two bHLH-PAS transcription factors, Met and SRC, were revealed to form a nuclear receptor for JH. In the presence of JH, the Met/SRC complex interacts with the JH response element in the promoter of early trypsin and Krüppel homolog 1, and activates transcription of these genes.