SEX-PHEROMONE OF THE PINE SAWFLY DIPRION PINI (HYMENOPTERA, DIPRIONIDAE) - CHEMICAL-IDENTIFICATION, SYNTHESIS AND BIOLOGICAL-ACTIVITY

The main component of the sex pheromone secretion of female Diprion pi ni L. (Hymenoptera: Diprionidae) from insects collected both in Finlan d and in France has been identified as a threo-3,7-dimethyl-2-tridecan ol (8 ng per female) stereoisomer by GC-MS and synthesis. The secretio n also contains lower and higher homologues in small amounts (1-4% of the main component). Combined gas chromatographic-electroantennographi c detection showed activity in both natural and esterified extracts (a cetates and propionates); the esters of the main component gave the la rgest responses. The acetates and propionates of the eight stereoisome rs of 3,7-dimethyl-2-tridecanol were synthesized from enantiomerically highly enriched (> 99% ee) building blocks. The stereochemistry of th e main component was established to be (2S,3R,7R) -3,7-dimethyl-2-trid ecanol by GC analysis of the natural material. It was purified by liqu id chromatography prior to the GC analysis of both its pentafluorobenz oates and its isopropylcarbamates on a nonchiral polar column (ECD) an d a chiral column (NPD), respectively. Field tests demonstrated that b oth the acetate and propionate of the main component (100 mu g of each applied on cotton roll dispensers) were active in attracting males, w ith or without the presence of several of the minor compounds. Experim ents with smaller amounts of the acetate and the propionate (1 mu g in France and 50 mu g in Finland) demonstrated that the propionate was m ore active than the acetate, and that it also caught more males than a blend of the two compounds.