ROLES OF JUVENILE-HORMONE, A BRAIN FACTOR AND ADIPOKINETIC HORMONE INREGULATION OF VITELLOGENIN BIOSYNTHESIS IN LOCUSTA-MIGRATORIA

In maturing adult female migratory locusts, the rises in JH and Vg in the hemolymph are greatly accelerated by enriched feeding; hereafter t he JH titer fluctuates with vitellogenic cycles, falling to a low leve l at the oviposition stage. In fat bodies incubated in vitro, the JH a nalog, methoprene, and brain extract from well-fed locusts(but not sta rved locusts) stimulated Vg synthesis synergistically. Repeated washin g of fat bodies from oviposition stage locusts led to a rise in Vg syn thesis after 4 h, which was prevented by addition of locust adipokinet ic hormone (AKH). We conclude that at least three hormonal factors int eract in the control of Vg synthesis in locust fat body: JH and a brai n factor stimulate, reflecting development and nutrition, while AKH in hibits at the oviposition stage.