Efficacies of Rhagoletis cerasi (Diptera: Tephritidae) Traps and Ammonium Lures for Western Cherry Fruit Fly

Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is a quarantine pest of cherries (Prunus spp.) in western North America that can be detected using sticky yellow rectangle traps. Recently, a related invasive fly from Europe and Asia, the European cherry fruit fly, Rhagoletis cerasi (L.) (Diptera: Tephritidae), was detected in eastern North America, prompting surveys for it in the West. Sticky crossed-panel yellow Rebell and cylindrical-type yellow PALz traps were developed for R. cerasi and are effective for monitoring it, raising the question of efficacies of three-dimensional versus rectangle traps against R. indifferens. Here, efficacies of the Yellow Sticky Strip (YSS) rectangle, thus far the best trap for R. indifferens, and Rebell and PALz traps with ammonium lures were determined for R. indifferens in Washington State. The Rebell and YSS traps caught similar numbers of R. indifferens and more than the PALz trap. Ammonium carbonate (AC) released more ammonia than ammonium acetate and attracted more R. indifferens to all three traps. The large surface area or shape of the Rebell trap was responsible for its high efficacy relative to the YSS. Results suggest that YSS and Rebell traps with AC would be equally useful for detecting R. indifferens, and that a crossed-sheet YSS trap could be even more efficacious than the YSS due to greater surface area. For R. cerasi detection surveys in Washington, the PALz trap would be preferred over the Rebell trap if they are equally efficacious against R. cerasi, as fewer R. indifferens would clutter traps.