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

Authors: Yee, Wee

Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2016
Publication Date: 10/3/2016
Citation: Yee, W.L. 2016. Ammonium carbonate loss rates from lures differentially affect trap captures of Rhagoletis indifferens (Diptera: Tephritidae) and non-target flies. The Canadian Entomologist. 149:241-250.

Interpretive Summary: Western cherry fruit fly is a quarantine pest of sweet cherry in the Pacific Northwest of the U.S. that can be monitored using traps baited with ammonia. However, ammonia-based attractants also attract non-target flies that clutter traps and reduce trap efficiency. Personnel at the USDA-ARS Yakima Agricultural Research Laboratory in Wapato, WA, determined whether ammonium carbonate (AC) loss rates from lures differentially affect numbers of cherry fruit fly and non-target flies caught on sticky traps in cherry trees. Results showed that lures with an AC loss rate of 0.19 mg/hour maintained high cherry fruit fly captures while reducing non-target fly captures. This rate thus should be used for monitoring cherry fruit flies in areas where there are many non-target flies.

Technical Abstract: Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is a pest of cherry (Prunus spp.) 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, U.S.A. AC loss rates were varied from 7-dram plastic vials hung ~1 cm above traps. Six experiments were conducted in which progressively lower AC loss rates within a range of 0.10–26.19 mg AC/h were tested. For captures of R. indifferens, no AC loss rate comparisons within 0.19–26.19 mg/h differed, and captures were not reduced until losses were lowered to 0.10–0.13 mg/h. In contrast, captures of medium to large (>5 mm long) non-target flies, which were mostly Sarcophagidae, were reduced at a rate ~30 times higher, at 3.34 or 3.80 mg AC/h. Results suggest that using lures with AC loss rates of 0.19 mg/h can maintain high R. indifferens captures while reducing non-target fly captures and thus can improve monitoring efficiency. Results also suggest that altering release rates of chemical attractants as a method to reduce catches of non-target insects in other trapping systems merits consideration.