Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2008
Publication Date: 12/12/2008
Citation: Yee, W.L. 2008. Mortality of Rhagoletis indifferens exposed to hydrolyzed protein baits and spinosad in the absence and presence of yeast extract. Entomologia Experimentalis et Applicata 129:77-86.
Interpretive Summary: Cherry fruit fly is a quarantine pest of commercial cherries in the Pacific Northwest. Knowledge about the effects of various factors on efficacy of bait sprays used for fly control is needed to optimize management of the fly. Personnel at the Yakima Agricultural Research Laboratory in Wapato, WA, are determining the effects of protein foods in the environment on mortality of cherry fruit flies. In the presence of protein bait + spinosad insecticide, we found that flies exposed to protein food (yeast extract) suffered lower mortalities than flies not exposed to protein food (sugar only). However, in the presence of the insecticide alone, flies exposed to and not exposed to protein food suffered similar mortalities. The results of this study are important in that they suggest insecticide alone may have an advantage over baits with insecticide because it kills equal numbers of flies regardless of protein food in the environment.
Technical Abstract: Western cherry fruit fly, Rhagoletis indifferens Curran, is the major quarantine pest of sweet cherry, Prunus avium L. (L.), in the Pacific Northwest of the USA and in British Columbia in Canada. Although spinosad bait (GF-120 NF Naturalyte® Fruit Fly Bait, Dow AgroSciences, Indianapolis, IN, USA) is used for control of R. indifferens in this region, the factors responsible for its effectiveness are not well known. In this study, experiments were conducted to determine mortalities of flies exposed to hydrolyzed protein baits in the absence and presence of sugar + yeast extract food, a source of amino acids and peptides. All baits contained Entrust® (Dow AgroSciences, Indianapolis, IN, USA) (termed ‘spinosad alone’). When flies were exposed to GF-120 with or without added ammonia compounds (uric acid [UA], ammonium acetate [AA], and ammonium carbonate [AC]) for 48 h, mortalities were greater in the absence (sugar only) than presence of sugar + yeast extract food, but when flies were exposed to spinosad alone, mortalities were similar in the absence and presence of it. Also, mortality was highest in flies exposed to spinosad alone. In another experiment comparing GF-120, Nu-Lure, Mazoferm, yeast extract (as the bait), and spinosad alone, mortalities in the GF-120, Mazoferm, and yeast extract bait treatments were greater in the absence than presence of sugar + yeast extract food, but in the Nu-Lure and spinosad alone treatments, mortalities were similar in the absence and presence of yeast extract food. Overall results suggest that effects of yeast extract food on mortality are dependent on bait type and that mortalities caused by spinosad alone and baits are similar. Nu-Lure and spinosad alone may have an advantage over other treatments for fly control because their effects do not appear to be affected by the presence of proteinaceous food.