Sex pheromone of the oak processionary moth Thaumetopoea processionea. Identification and biological activity.

The sex pheromone of the oak processionary moth Thaumetopoea processionea has been characterized from female gland extracts as a mixture of (Z,Z)-11,13-hexadecadienyl acetate (1), (E,Z)-11,13-hexadecadienyl acetate (3) and (Z,Z)-11,13-hexadecadienol (2) in 88:7:5 ratio. The amount of the major compound 1 was 20-30 ng/gland. No trace of (Z,Z)-11,13-hexadecadienal was found in the extract, and therefore, T. processionea appears to be the only "summer" processionary moth lacking this compound as a pheromone compound. The alcohol 2 had also been previously found but is electrophysiologically inactive, and in wind tunnel assays it lowers the number of contacts with the source when mixed with the major compound 1. The major component 1 elicited males to display the complete behavioral sequence, but the amount of chemical needed was unexpectedly high in comparison to the activity displayed by virgin females and gland extracts. (E,E)-11,13-hexadecadienyl acetate (5) inhibits the attractant activity of the major component 1 when mixed with 1 in 1:10 and 1:1 ratios. The main constituent 1 is active in the field, but its tendency to isomerize into the corresponding E,E isomer (5) must be considered if effective formulations are to be prepared.