Sex pheromone precursors in Spodoptera littoralis (Lepidoptera: Noctuidae)

Abstract

Female pheromone gland extracts of Spodoptera littoralis were analyzed for pheromone precursors. Large amounts of fatty methyl esters were found and a positive relationship between the methyl esters and the pheromonal components was observed. The esters were identified on the basis of capillary gas chromatography, coupled gas chromatography with mass spectroscopy and dimethyl disulfide derivatization, and subsequent gas chromatography with mass spectrometry. The characteristic fatty esters of S. littoralis are methyl ( Z)-9-tetradecenoate, ( E)- and ( Z)-11-tetradecenoate, ( Z, E)-9,12-tetradecadienoate, ( Z, E)-9,11-tetradecadienoate, and ( Z)-11-hexadecenoate. The biosynthesis of the monosaturated acids involves probably the common E11 and Z11 desaturases and chain shortening. For the biosynthesis of the novel diene acids, we propose a second, specific desaturation of ( Z)-9-tetradecenoate by an E11 desaturase to produce ( Z, E)-9,11-tetradecadienoate or by an E12 desaturase to produce ( Z, E)-9,12-tetradecadienoate.