A 4-component sex pheromone of the Chilean fruit leaf roller <i>Proeulia auraria</i> (Lepidoptera: Tortricidae)

Abstract:
The Chilean fruit leaf roller Proeulia auraria is a pest of economically important fruit species. Two compounds attractive to males have been identified as (E)-11-tetradecenyl acetate (E11-14:OAc) and (E)-11-tetradecenol (E11-14:OH) and are currently being used in Chile to monitor this species. Preliminary experiments carried out by our group suggested that the 2-compound mixture might not be optimal for the attraction of males, which prompted us to reinvestigate the sex pheromone of P. auraria in the present study. The pheromone component candidates were extracted from pheromone glands with hexane and identified by gas chromatography (GC) with electroantennographic detection (BAD), GC-mass spectrometry, and a comparison of the analytical data of the natural compounds with those of authentic reference substances. The EAD active compounds were identified as tetradecyl acetate (14:OAc), E11-14:OAc, (Z)-11-tetradecenyl acetate (Z11-14:OAc), and E 11-14:OH in a relative ratio of 11:100:4:37, respectively. Field tests showed that all four compounds are behaviorally active. The most attractive blend, which is more attractive than the 2-component mixture that is currently in use, contained the main compound E11-14:OAc, I% of the geometric isomer Z11-14:OAc, and both of the other minor compounds. Increasing the relative amount of Z11-14:OAc to 4% of the major component resulted in a significant reduction of attraction. An analysis of the fatty acid content of the pheromone gland revealed the presence of (E)-11-tetradecenoate but not of (Z)11-tetradecenoate. The possible role in species isolation and the possible biosynthetic origin of this strongly E-biased pheromone are discussed.