The distribution of PBAN (pheromone biosynthesis activating neuropeptide)‐like immunoreactivity in the nervous system of the gypsy moth, Lymantria dispar

Abstract

The production of sex pheromone in many moths is regulated by the neuropeptide PBAN (pheromone biosynthesis-activating neuropeptide). Studies in a number of species have shown that pheromone production can be linked to a hemolymph factor and that continuity in the ventral chain of ganglia is not required. However, it has recently been shown that production of pheromone in the gypsy moth, Lymantria dispar, is largely prevented in females with a transected ventral nerve cord (VNC). To begin to understand the cellular basis for this dependence on the VNC, we sought to determine the distribution of PBAN in the central nervous system and its neurohemal sites, including those associated with the VNC. 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 subesophageal ganglion (SEG), in three clusters of midline cells in each segmental ganglion, and in bilateral pairs of cells located posterolaterally in each abdominal ganglion. The SEG cells comprise both interneurons, 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 SEG. The latter structure, which we have named the corpus ventralis, receives axons from the two anterior clusters of cells in the SEG. In the abdominal ganglia, the posterolateral clusters of cells have immunoreactive axons exiting the ganglia via the ventral nerves. Endings of these 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 findings raise the possibility that the requirement for an intact VNC in pheromone production reflects a role for descending regulation of neurosecretory cells in the segmental ganglia. Arch.

Activity patterns of neurosecretory cells releasing pheromonotropic neuropeptides in the moth Bombyx mori

“…However, hormonal regulation of the sex-pheromone gland of B. mori does not preclude neural regulation of pheromone production. The latter mechanism is inferred from the presence of PBAN-immunoreactive interneurons that descend the ventral nerve cord and terminate in the terminal abdominal ganglion of several species of moths (21)(22)(23)(24)(25). Several lines of evidence suggest efferent neural regulation of the pheromone gland in Lymantria disper (26), and Christensen et al (27,28) proposed a neural mechanism mediated by octopaminergic neurons innervating the pheromone gland in Helicoverpa zea and Helicoverpa virescens.…”

“…Numerous neurosecretory cells are anatomically mapped in the brain, but little success has been achieved in analyzing long-term activity of any particular unit because they send an axon to a common pathway (42). The SOG contains a few groups of neurosecretory cells having a unique axonal pathway beneath the cuticle, including PBAN-immunoreactive cells (11,(21)(22)(23)(24)(25). This situation facilitates identification of cells and long-term recordings without serious damage due to massive dissection of the head (43).…”

Identification of PBAN-like immunoreactivity in the neuroendocrine system and midgut of Dysdercus cingulatus (Heteroptera: Pyrrhocoridae)

“…In the gypsy moth, the prothoracic ganglion and pterothoracic ganglion each contain a pair of ir-somata (Golubeva et al, 1997). A pair of ventral midline cells in each of the abdominal ganglion including the terminal one (TAG) are immunopositive in the Euro pean corn borer (Ma & Roelofs, 1995).…”

“…Two clusters of immunoreactive somata were detected in the SOG of Dysdercus cingulatus. This also differs from that reported for several lepidopteran insects like Helicoverpa zea Kingan et al, 1992), Bombyx mori (Ichikawa et al, 1995), Manduca sexta (Davis et al, 1996), Lymantria dispar (Golubeva et al, 1997) and recently for Agrotis ipsilon (Duportets et al, 1998) where there are three clusters of cells -the mandibular, maxillary and labial. The insect SOG is formed by the fusion of the neuromeres of the mandibular, maxillary and labial segments.…”

“…In this study maxillary and labial neuroendocrine cells showed PBANlike immunoreactivity. Golubeva et al (1997) have shown that many of the SOG cells in L. dispar are neu rosecretory, in that they have varicose endings in identi fied neurohaemal organs. In D. cingulatus the immuno reactivity found in the CC may indicate its functions as a neurohaemal structure for the peptide.…”