Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2005
Publication Date: October 1, 2005
Citation: Yee, W.L., Chapman, P.S. 2005. Effects of GF-120 fruit fly bait concentrations on attraction, feeding, mortality, and control of Rhagoletis indifferens (Diptera: Tephritidae). Journal of Economic Entomology. 98(5):1654-1663. Interpretive Summary: Cherry growers in the Pacific Northwest need alternative methods to control cherry fruit fly because there continues to be a zero tolerance for infested fruit. At the same time many effective insecticides used in the past may soon be lost. Personnel at the Yakima Agricultural Research Laboratory in Wapato, WA, are evaluating spray baits for the cherry fruit fly. It was found that fresh commercial GF-120 bait is not highly attractive to flies, but that flies readily feed on the bait and that it is highly toxic to them. Flies may find the bait through normal movement within trees. The new information on how flies contact and feed on the bait may facilitate the development of improved methods to apply the bait or of improved bait chemistries to make it more attractive to the flies.
Technical Abstract: Effects of different concentrations of GF-120 NF Naturalyte Fruit Fly Bait on attraction and feeding responses, mortality, and control of the western cherry fruit fly, Rhagoletis indifferens Curran, were determined. In the laboratory, flies that had been exposed to sugar and yeast and then deprived of all food for 16-20 h were not attracted to 0.6% and 4.8% GF-120 (vol:vol) (2.2 and 3.6% responses, respectively), but were slightly attracted to 40.0% GF-120 (8.1% response). Non-starved flies were not attracted to any concentration. In the field, flies were not attracted to 2,500 and 5,000 µl volumes of 55.6% GF-120 on cherry leaves, and few flies fed on the bait. In the laboratory, males fed for shorter durations on and ingested lower amounts of 0.6% than 4.8 or 40.0% GF-120, but females fed equally on all concentrations. Spinosad in ingested GF-120 was highly toxic to flies. Starved flies exposed to 100 µl of 10 concentrations of GF-120 from 0.6 to 40.0% inside containers for one hour showed greater mortality than non-starved flies, with effective concentrations50 of spinosad at 1-4 d being 1.2-0.6 ppm and 110.1-11.8 ppm, respectively. When gravid flies were exposed to cherries treated with 0.6, 4.8, and 40.0% GF-120, mortality was greater at each higher concentration, but none prevented oviposition. Larvae emerged from cherries treated with 0.6% GF-120, but not from those treated with 4.8 and 40.0% GF-120. Field spray tests comparing 0.6, 4.8, and 40.0% GF-120 in 225 ml of spray per cherry tree resulted in 79-94% lower larval infestations than in controls, but no significant differences were seen among the three concentrations. Results indicate fresh GF-120 is not highly attractive to R. indifferens and that its mechanism of control may be related to foraging behaviors. Although the effects of aged GF-120 on fly responses still need to be determined, the results suggest the efficacy of GF-120 needs to be improved by reformulating it with more attractive components.