Controlled Release of Trimedlure Isomer C from a Compressed Disk and the Evaluation of Its Attractiveness to the Mediterranean Fruit Fly (Diptera: Tephritidae)

Abstract

Isomer C, the isomer of trimedlure most attractive to Mediterranean fruit flies, Ceratitis capitata (Wiedemann), was obtained in nearly pure form as crystals from aged or refrigerated commercial trimedlure. Crystalline trimedlure-C was compressed into disks with a pellet mold, and the release rate of isomer C from the disks was determined in the laboratory using a volatile collection system. Field-trapping tests comparing pure isomer C in compressed disks, the commercial trimedlure mixture in cotton wicks, and commercial trimedlure in polymeric plugs showed that the isomer C disks were competitive in attractiveness with the two currently used formulations for 8 wk. Trap catches with these three baits did not indicate that the other isomers in the trimedlure mixture added to or reduced the attractiveness of trimedlure-C to male Mediterranean fruit flies. Compressed disks of isomer C provide a method of testing the most attractive trimedlure isomer at precisely controlled release rates and isometric purity, in either laboratory or field tests.