Biosynthesis of lepidopteran pheromones

Research on lepidopteran sex pheromone component biosynthetic pathways has revealed general systems that may have significance in understanding the evolution of these moth mating communication signals. Studies with the redbanded leafroller moth, cabbage looper moth, and the domestic silkworm showed that they all possess a unique delta-11 unsaturated acid precursor. Radiolabeled precursor acids were used to show that various combinations of limited beta-oxidation chain-shortening or chain-elongation steps with the desaturase enzyme could produce most of the pheromone components identified for noctuid, pyralid, and tortricid moths. Evolution of the delta-11 desaturase enzyme from the ubiquitous delta-9 desaturase enzyme was suggested by finding primitive species that use the intermediate delta-10 desaturase enzyme. It is suggested that pheromone components of other primitive species are produced by using only the chain-shortening steps on available oleate, linoleate, and linolenate. Pheromone componets of some more advanced species appear to be produced by chain elongation of these available acids, with subsequent reductive decarboxylation to hydrocarbon.