Identification and biosynthesis of (E,E)-10,12-tetradecadienyl acetate in Spodoptera littoralis female sex pheromone gland.

A minor component of the sex pheromone gland of the Egyptian cotton leafworm, Spodoptera littoralis, has been identified as (E,E)-10,12-tetradecadienyl acetate. Structural elucidation has been carried out by isobutane-chemical ionization mass spectrometry of the fatty acyl biosynthetic precursor-derived methyl ester. To assign the stereochemistry of the double bonds, the four isomers of both 10,12-tetradecadienyl acetates and methyl 10,12-tetradecadienoates have been synthesized and their gas chromatography retention times and mass spectra have been compared to those of the corresponding natural compounds. Mass-labeling experiments showed that the (E,E)-10,12-tetradecadienoyl moiety is biosynthetically derived from (Z)-11-tetradecenoic acid in the insect pheromone gland.