THE DISTRIBUTION OF PBAN (PHEROMONE BIOSYNTHESIS ACTIVATING NEUROPEPTIDE)-LIKE IMMUNOREACTIVITY IN THE NERVOUS-SYSTEM OF THE GYPSY-MOTH, LYMANTRIA-DISPAR

The production of sex pheromone in many moths is regulated by the neur opeptide PBAN (pheromone biosynthesis-activating neuropeptide). Studie s in a number of species have shown that pheromone production can be l inked to a hemolymph factor and that continuity in the ventral chain o f ganglia is not required. However, it has recently been shown that pr oduction of pheromone in the gypsy moth, Lymantria dispar, is largely prevented in females with a transected ventral nerve cord (VNC). To be gin to understand the cellular basis for this dependence on the VNC, w e sought to determine the distribution of PBAN in the central nervous system and its neurohemal sites, including those associated with the V NC. Using an antiserum to L. dispar-PBAN in immunocytochemical methods , we have mapped the distribution of PBAN-like immunoreactivity (PLI). PLI is found in three clusters of ventral midline somata in the subes ophageal ganglion (SEC), in three clusters of midline cells in each se gmental ganglion, and in bilateral pairs of cells located posterolater ally in each abdominal ganglion. The SEG cells comprise both interneur ons, with endings in the neuropil of each segmental ganglion, as well as neurosecretory cells, with endings in the retrocerebral complex and in an unusual neurohemal structure near the anterior aspect of the SE G. The latter structure, which we have named the corpus ventralis, rec eives axons from the two anterior clusters of cells in the SEG. In the abdominal ganglia, the posterolateral clusters of cells have immunore active axons exiting the ganglia via the ventral nerves. Endings of th ese axons reach the perivisceral organ in the next posterior ganglion and pass anteriorly into the median nerve, forming additional varicose endings. We did not detect PLI in the terminal nerve. Thus, our findi ngs raise the possibility that the requirement for an intact VNC in ph eromone production reflects a role for descending regulation of neuros ecretory cells in the segmental ganglia. (C) 1997 Wiley-Liss, Inc.