2 - Lepidoptera: Female sex pheromone biosynthesis and its hormonal regulation

Abstract

The first insect sex pheromone, bombykol (E10, Z12-hexadecadien-1ol) from the silkworm moth, Bombyx mori, was identified in 1959 and since then around 2000 species of moths have been investigated with regard to identification of their sex pheromone. The first moth sex pheromone biosynthetic pathway was described by Bjostad and Roelofs in 1983 and since then a number of biosynthetic pathways have been identified as modifications of fatty acid biosynthesis. The pathway in most moths uses a series of enzymes including desaturases, chain shortening enzymes, fatty acyl-CoA reductases, oxidases, and acetyltransferases. The genes encoding desaturases and reductases have been characterized providing a great deal of information not only about the specifics of pheromone biosynthesis but also the evolution of sex pheromones in Lepidoptera. Some moths also utilize hydrocarbons as sex pheromones and their production occurs in oenocyte cells and then subsequent transport to pheromone glands for release. Moth sex pheromones are usually produced following a circadian rhythm, being released from the pheromone gland during a certain time of the scotophose. The timing of biosynthesis and release indicates hormonal regulation and a neuropeptide termed pheromone biosynthesis activating neuropeptide (PBAN) was identified in 1987 by the Raina lab. Since then research has shown that the peptide belongs to a large family of peptides conserved in insects. The G-protein coupled receptor for the neuropeptide has been identified as well as the signal transduction cascade in several species of moth pheromone glands. This chapter will provide an up to date review of pheromone biosynthesis and its hormonal regulation in moths.