Dunkelblum, E., Institute of Plant Protection, Volcani Center, Bet Dagar, 50250, Israel
Gries, R., Centre for Pest Management, Department of Biological Sciences, Simon Fraser University, Burnaby, V5A 1S6, British Columbia, Canada
Gries, G., Centre for Pest Management, Department of Biological Sciences, Simon Fraser University, Burnaby, V5A 1S6, British Columbia, Canada
Mori, K., Department of Agricultural Chemistry, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113, Japan
Mendel, Z., Institute of Plant Protection, Volcani Center, Bet Dagar, 50250, Israel

The absolute configuration of the sex pheromone of the Israeli pine bast scale, Matsucoccus josephi, was determined as (2 E,5 R,6 E,8 E)-5,7-dimethyl-2,6,8-decatrien-4-one, designated here as R-E with 10% (2 E,5 S,6 E,8 E)-5,7-dimethyl-2,6,8-decatrien-4-one, designated as S-E. The chirality of the quantitatively minor Z isomer was (2 E,5 R,6 Z,8 E)-5,7-dimethyl-2,6,8-decatrien-4-one (R-Z). Chiral assignments were made by comparative gas chromatographic (GC) analysis of natural M. josephi pheromone with stereoselectively synthesized stereoisomers on a chiral Cyclodex-B column, which separated the enantiomers with baseline resolution. In gas chromatographic-electroantennographic detection (GC-EAD) analysis of the racemic Z and E isomers, the latter elicited the stronger antennal response by male M. josephi. In GC-EAD of all four stereoisomers, employing the chiral column, R-E was the most active stereoisomer. In field tests R-E attracted 10 times more males of M. josephi than did S-E. The racemic E/Z pheromone mixture, containing all four stereoisomers in approximately equal amounts, attracted as many male M. josephi as did an equivalent amount of R-E, indicating that the other stereoisomers are not inhibitory. The same keto-diene moiety with the same chiral center and configuration in all three known Matsucoccidae sex pheromones implies a common biosynthetic pathway and phylogenetic relationship. © 1995 Plenum Publishing Corporation.