Morphological and physiological comparisons of two types of allatostatin in the brain and retrocerebral complex of the tomato moth, Lacanobia oleracea (Lepidoptera : Noctuidae)

The cellular localisation of two types of allatostatin in the brain and ret rocerebral complex has been studied in larvae of Lacanobia oleracea (Noctui dae) using antisera against Manduca sexta allatostatin (Mas-AS) and two mem bers of the Y/FXFGL-NH2 allatostatin family. The axons of two groups of Mas -AS-immunoreactive neurosecretory cells in the pars lateralis form part of the nervi corporis cardiaci (NCC 1). They exit the brain as the combined NC C 1 and NCC 2 and pass through the corpora cardiaca (CC), where they divide to innervate the corpora allata (CA) and the mandibular (salivary) gland. The presence of Mas-AS immunoreactivity in the CA is consistent with the in hibitory action of this peptide on juvenile hormone (JH) biosynthesis in L. oleracea. Immunoreactivity in the mandibular gland nerve suggests an addit ional, as yet unidentified role for this peptide. Cells of the pars interme dialis, the main contributors to NCC 2, do not show Mas-AS immunoreactivity . The distribution of Y/FXFGL-NH2 immunoreactivity is different from that o f Mas-AS. Although there are fewer cells in the pars lateralis, immunoreact ivity is observed in certain neurones of the pars intermedialis and the tri tocerebrum. Axons of these latter neurones contribute to NCC 2 and NCC 3, r espectively, and, combined with those from NCC 1, result in the prominent o ccurrence of Y/FXFGL-NH2 immunoreactivity in the CC, particularly in the st orage lobe. The CA has far less Y/FXFGL-NH2 immunoreactivity compared with Mas-AS. In bioassays, the Y/FXFGL-NH2 allatostatins did not inhibit JH synt hesis by CA of L. oleracea. J. Comp. Neurol. 424:37-46, 2000. (C) 2000 Wile y-Liss, Inc.