Ammonium carbonate loss rates from lures differentially affect trap captures of Rhagoletis indifferens (Diptera: Tephritidae) and non-target flies

Abstract

AbstractWestern cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is a pest of cherry (Prunus Linnaeus, Rosaceae) in western North America that can be monitored using traps baited with ammonia. However, ammonia-based attractants also attract non-target Diptera that clutter traps. Here, the hypothesis that ammonium carbonate (AC) loss rates from lures differentially affect numbers of R. indifferens and non-target flies caught on sticky yellow rectangles in sweet cherry trees was tested in Washington State, United States of America. Ammonium carbonate loss rates were varied from seven-dram plastic vials hung ~1 cm above traps. A total of six experiments were conducted in which progressively lower AC loss rates within a range of 0.10–26.19 mg AC/hour were tested. For captures of R. indifferens, no AC loss rate comparisons within 0.19–26.19 mg/hour differed, and captures were not reduced until losses were lowered to 0.10–0.13 mg/hour. In contrast, captures of medium to large (⩾5 mm long) non-target flies, which were mostly Sarcophagidae (Diptera), were reduced at a rate ~30 times higher, at 3.34 or 3.80 mg AC/hour. Results suggest that using lures with an AC loss rate of 0.19 mg/hour can maintain high R. indifferens captures while reducing non-target fly captures and thus can improve monitoring efficiency.