CHIRALITY OF ISRAELI PINE BAST SCALE, MATSUCOCCUS-JOSEPHI (HOMOPTERA,MATSUCOCCIDAE) SEX-PHEROMONE

The absolute configuration of the sex pheromone of the Israeli pine ba st scale, Matsucoccus josephi, was determined as (2E,5R,6E,8E)-5,7-dim ethyl-2,6,8-decatrien-4-one, designated here as R-E with 10% (2E,5S,6E ,8E)-5,7-dimethyl-2,6,8-decatrien-4-one, designated as S-E. The chiral ity of the quantitatively minor Z isomer was (2E,5R,6Z,8E)-5,7-dimethy l-2,6,8-decatrien-4-one (R-Z). Chiral assignments were made by compara tive 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. I n gas chromatographic-electroantennographic detection (GC-EAD) analysi s of the racemic Z and E isomers, the latter elicited the stronger ant ennal response by male M. josephi. In GC-EAD of all four stereoisomers , employing the chiral column, R-E was the most active stereoisomer. I n 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 stereoiso mers in approximately equal amounts, attracted as many male M. josephi as did an equivalent amount of R-E, indicating that the other stereoi somers are not inhibitory. The same keto-diene moiety with the same ch iral center and configuration in all three known Matsucoccidae sex phe romones implies a common biosynthetic pathway and phylogenetic relatio nship.