Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2003
Publication Date: 1/10/2004
Citation: Yee, W.L., Landolt, P.J. 2004. Responses of apple maggot (Diptera:Tephritidae) to ammonium hydroxide lures in Washington. The Canadian Entomologist. 136:139-142. Interpretive Summary: The apple maggot is a major threat to the apple industry in Washington state. Personnel at the Yakima Agricultural Research Laboratory in Wapato Washington conducted studies in 2001 and 2002 to determine the effects of ammonia on fly responses to traps. Results indicated that flies responded best to ammonia of a specified release rates. The identification of an effective ammonia lure may improve detection of apple maggot and thus help with its management and control.
Technical Abstract: Responses of female and male apple maggots, Rhagoletis pomonella (Walsh), to ammonium hydroxide lures were determined in three experiments conducted at six sites in four western Washington counties in 2001 and 2002. In experiment 1, a lure made of a 15-ml polypropylene bottle containing 10 ml of 1.9, 3.6, 7.3, 14.6, 20.8, or 29.3% ammonia with a 0.5-mm diameter hole was hung above a sticky yellow panel. The strength of the ammonia concentration-fly response relationship varied among sites, but overall female and male responses followed a similar pattern, although subtle sex differences were seen. Females and males were weakly attracted to 1.9% ammonia, which released 0.1 mg ammonia/bottle/h (mg/h) at 21 ºC in the laboratory. Females were most attracted to 20.8 and 29.3% ammonia, which released 1.4-4.7 mg/h. Males were equally attracted to these concentrations and 14.6% ammonia, which released 1.1-1.2 mg/h. The percentages of flies captured on ammonia-baited traps were 64.8% female and 35.2% male. In experiment 2, a lure made of three bottles containing 29.3% ammonia, with a release rate of about 10-15 mg/h in the laboratory, slightly increased responses to yellow panel but not to red sphere traps in one of three sites. In experiment 3, lures made of bottles containing 29.3% ammonia with 1.6, 3.2, and 6.4 cm hole sizes, which released 5.1-12.0, 16.0-35.7, and 47.0-99.9 mg/h in the laboratory, respectively, generally did not increase fly responses to yellow panels or red spheres, suggesting the 1.6 mm size released enough ammonia for maximum responses. Based on results of all experiments, the lure that most consistently elicits maximum female responses is the one bottle containing the 20.8% or 29.3% ammonia with a 0.5-mm hole. Lures containing between 14.6 and 29.3% ammonia seem to elicit maximum male responses.