Female Sex Pheromone of the Cone Moth, Dioryctria mendacella: Investigation of Synergism between Type I and Type II Pheromone Components

Polyunsaturated hydrocarbons (Type II pheromone components) have been reported to be synergists for unsaturated acetates, alcohols or aldehydes (Type I components) in the sex pheromones of several species of Lepidoptera. However, there is some debate over whether the active components are the hydrocarbons themselves or more volatile degradation products. Extracts of pheromone glands of adult females of the cone moth, Dioryctria mendacella (Lepidoptera: Pyralidae), contain (Z,E)-9,11-tetradecadienyl acetate (ZE9,11–14:Ac) and at least ten times as much (Z,Z,Z,Z,Z)-3,6,9,12,15-pentacosapentaene (ZZZZZ3,6,9,12,15–25:H). The former elicits a strong electroantennogram response from males while no response could be recorded to the latter. In field trapping tests, both compounds were individually unattractive to male D. mendacella moths, but blends of the two compounds containing at least a 10:1 ratio of ZZZZZ3,6,9,12,15–25:H : ZE9,11–14:Ac were highly attractive. The relatively involatile hydrocarbon was shown to be released from the dispensers used and no significant degradation could be detected. Furthermore, blends of ZE9,11–14:Ac and analogs of ZZZZZ3,6,9,12,15–25:H with fewer carbons and/or double bonds that might be expected to produce similar degradation products to ZZZZZ3,6,9,12,15–25:H were unattractive. This indicated a specific response to the hydrocarbon itself, further substantiated by the observation that related hydrocarbons did not interfere with the activity of ZZZZZ3,6,9,12,15–25:H. Thus a three-step conversion of fish oil was used to produce a blend of unsaturated hydrocarbons containing ZZZZZ3,6,9,12,15–25:H as the major component, albeit only 30% of the total, and a blend of this material with ZE9,11–14:Ac was as attractive to male D. mendacella moths as blends with an equivalent amount of the purified material. This mixture of unsaturated hydrocarbons is much cheaper to produce than the pure pentaene, and may be useful in lures for other species using these compounds. Dioryctria mendacella is a major constraint to production of edible pine kernels throughout the Mediterranean region. Pheromone traps will provide a means to improve monitoring of seasonal flight patterns and changes in population abundance of this pest.