The Significance of Manduca sexta Allatostatin in the Tomato Moth Lacanobia oleracea

Abstract

The nature and regulation of juvenile hormone (JH) biosynthesis have been investigated in isolated corpora allata (CA) of adult males and females, and larvae of the tomato moth Lacanobia oleracea (Noctuidae). Larval CA (Vth day 1 to VIth day 1) appear to synthesize JH at very low rates (< 0.5 fmol/pr/h). This synthesis was not affected by Manduca sexta allatostatin (Mas-AS) nor Manduca sexta allatotropin. In contrast, adult female CA synthesize relatively high levels of JHI and JHII (> 10 pmol/pr/h), each of which can be inhibited (approx. 60%) by Mas-AS. CA from adult male L. oleracea do not produce detectable levels of JH but would appear to synthesize JH-acids instead, which can also be inhibited (approx. 50%) by Mas-AS. When assayed on adult female L. oleracea CA, brain extracts separated by liquid chromatography show inhibitory activity. The major biologically active fraction also has the greatest Mas-AS-like immunoreactivity and co-elutes with synthetic Mas-AS, indicating that most of the allatostatic activity in brain extracts is due to a Mas-AS-like peptide. In adult male brains, even though relatively high levels of immunoreactivity co-elute with synthetic Mas-As, the majority of the Mas-AS-like immunoreactivity is more hydrophobic.