Sex pheromone of the pine sawfly Macrodiprion nemoralis (Hymenoptera : Diprionidae): Identification of (2S,3R,7R,9S)-3,7,9-trimethyl-2-tridecanol as the precursor for the active pheromone acetate

The main component of the sex pheromone precursor in females of Macrodiprio n nemoralis was identified as a threo-3,7,9-trimethyl-2-tridecanol isomer, approximately 800 pg per female, by gas chromatography-mass spectrometry. C omparison of mass spectrometric ion chromatograms showed that the natural c ompound in the female extract has the same retention time and mass spectrum as one of the two synthetic three peaks. The acetate of the synthetic 16-i somer mixture caught a large number of males in the field. confirming the s tructure of the active pheromone. Comparison of gas chromatograms of the na tural female extract with the eight synthetic three stereoisomers showed th at the pheromone is the (2S,3R,7R,9S)-stereoisomer of 3,7,9-trimethyl-2-tri decyl acetate.