Monday, December 10, 2007 - 9:53 AM

Isolation of a marking pheromone from the oviposition plug of the pepper weevil, Anthonomus eugenii Cano

Karla M. Addesso, addesso@ufl.edu1, Heather J. McAuslane, hjmca@ufl.edu1, and Hans T. Alborn, halborn@gainesville.usda.ufl.edu2. (1) University of Florida, Entomology and Nematology, P.O. Box 110620, Gainesville, FL, (2) USDA, Agricultural Research Service, 1600-1700 SW 23RD DRIVE, Gainesville, FL

Female pepper weevils demonstrate a clear preference for oviposition in uninfested pepper fruit over fruit containing pepper weevil eggs. Further behavioral studies identified the plug deposited by females over newly oviposited eggs as the main source of the observed deterrent effect. We hypothesized that this plug contains a host marking pheromone. The compounds comprising the marking pheromone blend were isolated by solvent extraction, column separation and HPLC fractionation in concert with behavioral bioassay. In the behavioral bioassays, females were presented with extract-treated pepper fruit and/or solvent-treated control fruit in choice and no-choice tests, respectively, and allowed to oviposit for 12 h. Three solvents, methanol: water (80:20), methylene chloride and pentane were able to extract marking pheromone compounds but the pentane extract had the highest deterrent activity. Sequential extraction of plugs confirmed that pentane removed all active compounds. Further separation of the pentane extract was performed by passing the crude extract through a silica column and eluting the compounds with pentane, pentane: ethyl acetate (95:5) and pentane: ethyl acetate (70:30). The pentane: ethyl acetate (70:30) fraction retained activity indicating the active compounds are slightly polar. Further separation of the compounds was done using normal phase HPLC under gradient elution with pentane and ethyl acetate as the mobile phase.

Species 1: Coleoptera Curculionidae Anthonomus eugenii (pepper weevil)