Hormonal Regulation of Pheromone Biosynthesis in the Silkworm Moth, Bombyx mori (Lepidoptera: Bombycidae)

Abstract

In the silkworm moth (Bombyx mori L.), the sex pheromone [bombykol, (1OE, 12Z)-10, 12-hexadecadien-l-ol] became undetectable 24 hr after decapitation, but its production was restored by the injection of a brain hormone (pheromone biosynthesis activating neuropeptide, PBAN). In order to understand the mode of action of this hormone, 14C-incorporation into pheromone precursors and related compounds was examined by treating the pheromone glands of normal, decapitated, and decapitated and hormone-injected virgin females with 14C-hexadecanoic acid. In the decapitated female moth, conversion of the 14C-acid into bombykol as well as other Ci6-fatty alcohols was very low. The levels of 14C-incorporation observed in normal females were partially recovered in the decapitated female by hormone injection. However, the amount of unsaturated Ci6-fatty acy1 moieties and their levels of 14C-incorporation was not decreased as much by decapitation. This suggests that the main regulatory role of PBAN is in the reduction of an acy1 moiety in the bombykol biosynthetic pathway rather than effecting unsaturation steps. Further, when the gland, which was removed from the decapitated female, was incubated in a Grace's medium with PBAN, the pheromone was again produced indicating the direct regulation of the pheromone gland by this hormone. © 1991, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.