Regulation of juvenile hormone biosynthesis in Heliothis virescens by Manduca sexta allatotropin

In Heliothis virescens , reproduction is strictly dependent on juvenile hormone (JH). In females, mating induces a sharp increase in JH titers, which stimulates increased vitellogenin biosynthesis and higher rates of egg production. JH biosynthesis is presumably stimulated by production and/or release of stimulatory neuropeptides such as allatotropins. There is evidence that allatotropin of H. virescens may be structurally related to Manduca sexta allatotropin (Manse‐AT). In a radiochemical in vitro assay, synthetic Manse‐AT stimulated JH biosynthesis by corpora allata (CA) of virgin H. virescens females in a dose‐dependent manner, but had no effect on CA activity in H. virescens males. In females, the CA showed a transient increase in sensitivity to Manse‐AT shortly after mating. Several structurally related peptides stimulated CA activity to a similar extent as Manse‐AT. Corpora allata activity was stimulated by a Ca 2+ ionophore, A23187. A membrane‐permeable Ca 2+ chelator, BAPTA/AM, antagonized the stimulatory effects of Manse‐AT, suggesting that Manse‐AT may enhance CA activity by increasing intracellular Ca 2+ concentration. Arch. Insect Biochem. Physiol. 54:121–133, 2003. © 2003 Wiley‐Liss, Inc.