Chirality of israeli pine bast scale,Matsucoccus josephi (homoptera: Matsucoccidae) sex pheromone.

The absolute configuration of the sex pheromone of the Israeli pine bast scale,Matsucoccus josephi, was determined as (2E,5R,6E,8E)-5,7-dimethyl-2,6,8-decatrien-4-one, designated here asR-E with 10% (2E,5S,6E,8E)-5,7-dimethyl-2,6,8-decatrien-4-one, designated asS-E. The chirality of the quantitatively minorZ isomer was (2E,5R,6Z,8E)-5,7-dimethyl-2,6,8-decatrien-4-one (R-Z). Chiral assignments were made by comparative gas chromatographic (GC) analysis of naturalM. 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 racemicZ andE isomers, the latter elicited the stronger antennal response by maleM. josephi. In GC-EAD of all four stereoisomers, employing the chiral column,R-E was the most active stereoisomer. In field testsR-E attracted 10 times more males ofM. josephi than didS-E. The racemicE/Z pheromone mixture, containing all four stereoisomers in approximately equal amounts, attracted as many maleM. josephi as did an equivalent amount ofR-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.