REGULATION OF PHEROMONE PRODUCTION IN THE GYPSY-MOTH, LYMANTRIA-DISPAR, AND DEVELOPMENT OF AN IN-VIVO BIOASSAY

Production of sex pheromone in females of the gypsy moth, Lymantria di spar, is regulated primarily by a pheromonotropic factor originating i n the head. Decapitation of a female caused depletion of pheromone in the pheromone gland; however, in contrast with several other species o f moths, biosynthesis could not be reinitiated by injection of brain-s uboesophageal ganglion homogenates or synthetic pheromone biosynthesis activating neuropeptide (PBAN). Severing the ventral nerve cord (VNC) in the abdominal region of females caused termination of pheromone pr oduction, While PBAN was inactive in decapitated females, if the VNC w as also transected, PBAN injection resulted in significant pheromone p roduction. Moreover, delivery of PBAN directly to tie posterior cut-en d of VNC, injection of PBAN into the terminal abdominal ganglion (TAG) , or electrical stimulation of TAG, resulted in significant pheromone production. Together, these results suggest that in this species, the pheromonotropic factor travelling via the VNC is an important regulato r of pheromone production. However, the pheromonotropic response was v ery high only if VNC posterior to the thoracic ganglia was severed bef ore injection of PBAN into the TAG or electrical stimulation of TAG. T he latter result indicates that an inhibitory factor may be present in the thoracic ganglia. Administration of pheromonotropic factors to th e posterior cut-end of VNC can be used as a bioassay for the gypsy mot h and possibly for other species in which these factors are transporte d via the VNC.