ASPECTS OF PHEROMONE BIOSYNTHESIS IN THE HESSIAN FLY, MAYETIOLA-DESTRUCTOR (SAY)

Virgin female Hessian flies biosynthesize sex pheromone in a cyclical fashion throughout their lifetime. Pheromone titre is relatively high early in the photophase, coinciding with the period of sexual activity, and decreases to a low level some 8 h later in the photophase. Mating results in the cessation of pheromone biosynthesis. Injection of male abdomen extract into virgin females suggested that this is due to the transfer of a chemical factor from the male to the female during mating. Decapitated female Hessian flies did not biosynthesize sex pheromone. However, injection of female head extract into these decapitated females resulted in the biosynthesis of sex pheromone, indicating that pheromone biosynthesis is initiated by a factor located in the female head. Injection of synthetic pheromone biosynthesis activating neuropeptide of Heliothis zea into Hessian fly females also initiated some pheromone biosynthesis, and it is believed that this neuropeptide or a related neuropeptide is responsible for initiation of pheromone biosynthesis. Analysis of the fatty acyl groups present in the pheromone gland of virgin female Hessian flies revealed the unusual compound (E)-9-dodecenoate. This compound may be an intermediate in the biosynthesis of the pheromone component (2S)-(E)-10-tridecen-2-yl acetate.