Submitted to: Peptides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 26, 2001
Publication Date: N/A
Interpretive Summary: Insects use chemicals called hormones to regulate development. One such hormone is juvenile hormone. In adult female moths this hormone is required for sexual maturity. The production of juvenile hormone is, itself, controlled by two other hormones produced in the brain. These neuropeptide hormones, called allatotropin and allatostatin are responsible for stimulation and inhibition of juvenile hormone production respectively. A scientist at the Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville Florida has been studying how these neuropeptides regulate juvenile hormone biosynthesis. The results of his work have identified the key steps, early in juvenile hormone biosynthesis, that are regulated by allatotropin and allatostatin in the tobacco hornworm and tobacco budworm moths, serious pests of agricultural crops. This discovery paves the way for design of agonists and antagonists of these neurohormones that could be used for development of novel, selective and environmentally friendly ways to control these and other pest Lepidoptera.
Technical Abstract: Capillary gas chromatography-chemical ionization (isobutane)-mass spectroscopy was used to analyze amounts of different homologs of juvenile hormone (JH) produced by isolated retrocerebral complexes (RCs) of adult females of the moths Heliothis virescens and Manduca sexta. Only JH 8, II and III were identified. Incubation of RCs from both species in media containing acetate but no propionate induced production of approximatlely equal amounts of JH II and JH III but the amounts of JH I present was very low in all samples. Incubation of RCs with synthetic Manduca sexta allatotropin stimulated significant increases in production of all three homologs but increases in JH I and JH II were greater than those for JH III. The effect of allatotrpoin was mimicked by addition of propionate to medium indicating that allatropin increased supply of acetyl- and propionyl-CoA precursors. Incubation of tissue from H. virescens females during the first 24h after eclosion with synthetic Manduca sexta allatosta in failed to reduce production of JH. However, incubation of tissue from 3-day-old females with allatostatin significantly reduced production of JH. Similarly, incubation of tissue from H. virescens females during the first 24h after eclosion with both allatotropin and allatostatin resulted in production of no more JH than was present in extracts from tissue incubated without the neruopepties, indicating that allatostat inhibited the action of allatotropin. Incubation of tissue from H. virescens females with allatostatin plus farnesol or JH III acid resulted in significant production of JH III but neither JH I nor JH II could be detected in extracts indicating that allatostatin acts prior to formation of the sesquiterpene alcohol precursors of JH.