How does juvenile hormone control insect metamorphosis and reproduction?

In insects juvenile hormone (JH) regulates both metamorphosis and reproduction. This lecture focuses on our current understanding of JH action at the molecular level in both of these processes based primarily on studies in the tobacco hornworm Manduca sexta, the flour beetle Tribolium castaneum, the mosquito Aedes aegypti, and the fruit fly Drosophila melanogaster. The roles of the JH receptor complex and the transcription factors that it regulates during larval molting and metamorphosis are summarized. Also highlighted are the intriguing interactions of the JH and insulin signaling pathways in both imaginal disc development and vitellogenesis. Critical actions of JH and its receptor in the timing of maturation of the adult optic lobe and of female receptivity in Drosophila are also discussed.

► The JH–Methoprene-tolerant (Met)–cofactor complex regulates specific genes.
► JH regulates larval molting through Krüppel homolog.
► JH regulates metamorphosis by controlling ecdysone-induced Broad (Br) expression.
► JH stimulates Tribolium vitellogenesis indirectly via production of specific ILPs.
► Timing of Drosophila optic lobe development and female receptivity requires JH-Met.