PHEROMONE STEREOCHEMISTRY AND PURITY EFFECT FIELD CATCHESOF MALE APHIDS (HOMOPTERA: APHIDIDAE)
Diane W. M. Smiley,1 Jim Hardie,2 Lynn Peace,2John A. Pickett,1 J. Robert Storer,2 Lester J. Wadhams1
1 IACR-Rothamsted, Harpenden, Hertfordshire, AL5 2JQ, U.K.
2 Aphid Biology Group, Department of Biology, Imperial Collegeat Silwood Park, Ascot, Berkshire SL5 7PY, U.K.
A range of aphid sex pheromones have been previously identified as comprisingthe cyclopentanoids (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol,and these compounds have been obtained by extraction from plants with minorsynthetic modification. A synthetic route to these compounds hasbeen developed from (3S)-citronellol, where the required (7S) stereochemistryof the products is provided by the 3S stereochemistry of the citronellol. Various levels of enantiomeric purity of (3S)-citronellol are available:99, 95 and 50% (3S), at reducing cost, and a range of enantiomeric puritiesof synthetic (4aS,7S,7aR)-nepetalactones and (1R,4aS,7S,7aR)-nepetalactolswere prepared. Field studies with synthetic and plant-derived componentshave illustrated that high enantiomeric purity and chemical purity arerequired for biological activity.