C-7-1
CONTROL OF PHEROMONE BIOSYNTHESIS IN VIRGIN AND MATEDFEMALES OF TWO CHORISTONEURA SPECIES.
Johanne Delisle1 and Jean-François Picimbon2
1 Natural Resources Canada, P. O. Box 3800, 1055 du P.E.P.S.Québec, Canada
2 National Institute of Sericultural and Entomological Science,Tsukuba, Japan.
The physiological regulation of pheromone synthesis was investigatedin the oligophagous, migratory species, Choristoneura fumiferana andthe polyphagous, non-migratory species, C. rosaceana. Decapitationof newly-emerged females totally inhibited pheromone synthesis. However,injection of Hez-PBAN (pheromone biosynthesis neuropeptide of Heliothiszea) or a brain extract of either species induced pheromone production.Thus the brain of both C. fumiferana and C. rosaceana hasthe ability to release a PBAN-like substance that stimulates pheromoneproduction. Severing the ventral nerve cord (VNC) or removing the terminalabdominal ganglion (TAG) following decapitation did not affect pheromoneproduction after injection of either PBAN or a brain extract in eitherspecies, suggesting that the neuropeptide is released from the suboesophagealganglion (SOG) into the hemolymph rather than passing through the VNC.Following mating, pheromone production declined markedly in both species,however injection of either PBAN or brain extract restores pheromone production,suggesting that a factor associated with mating inhibits the release ofPBAN. Injections of blood from virgin and mated females, or the accessoryglands secretions from virgin males, had no effect on pheromone productionin virgins. On the other hand, pheromone production did not decline followingmating in females when the VNC was transected prior to mating. These resultsindicate that the inhibition of pheromone production in mated females isunder neural regulation in both species. However, while treatment withJH or JH analogs did not affect pheromone production in C. fumiferanavirgin females a significant decline was observed in C. rosaceana,suggesting that in the latter species there is also a hormonal componentto pheromone production.