Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2007
Publication Date: 12/15/2007
Citation: Yee, W.L. 2007. Attraction, Feeding, and Control of Rhagoletis pomonella (Diptera: Tephritidae) Using GF-120 with Added Ammonia in Washington. Florida Entomologist 90(4):665-673. Interpretive Summary: Apple maggot fly is a major quarantine pest of apples in the Pacific Northwest. Local pest boards need alternatives to conventional insecticides for control of the fly because of the potential harmful effects of these insecticides to the environmental. Personnel at the Yakima Agricultural Research Laboratory in Wapato, WA, are evaluating GF-120 protein baits with the environmentally safe insecticide spinosad for fly control. It was found that GF-120 alone was not highly attractive to flies, but that when ammonia was added to the bait, more flies were attracted to it and fed. However, when the baits were sprayed on whole trees to kill flies and protect apples from infestations, there were no differences between GF-120 alone and GF-120 with added ammonia and all reduced larval infestations >90%, perhaps because ammonia dissipated quickly from drops on the leaves. Results are important because they show that GF-120 alone can greatly reduce fly populations. Future studies need to determine how long ammonia in baits remain attractive and if timed release of ammonia can improve GF-120 performance in eliminating larval infestations.
Technical Abstract: Experiments were conducted in 2005 and 2006 in western Washington State to determine effects of adding ammonium carbonate (AC) and ammonium acetate (AA) to GF-120 Fruit Fly Bait (Dow AgroSciences, Indianapolis, IN) on attraction, feeding, and control of the apple maggot fly, Rhagoletis pomonella (Walsh). In the field, sticky yellow panel traps baited with GF-120 and 10% AC attracted more flies than those baited with GF-120 and 10% AA or GF-120 alone, but 10 g AC alone caught the most flies. In the laboratory, females responded more frequently to apples with sucrose and GF-120 treatments than with water, but addition of AA and AC lowered the frequency of feeding, suggesting ammonia in bait may be repellent soon after application in small spaces. In the field, fly attraction and feeding were greater to and on GF-120 + 10% or 2.5% AC or AA than GF-120 alone on apple leaves. In three spray tests comparing 100 or 200 ml of GF-120 alone and GF-120 + 10% or 2.5% AC or AA applied on single apple trees, larval infestations in fruit were reduced up to 99% compared with controls, but there were no differences among treatments and none was different from spinosad only. Our overall results indicate the attractiveness of GF-120 to R. pomonella can be increased with added ammonia, but that this does not necessarily result in greater control, perhaps because the added ammonia volatilizes too quickly to make the enhanced GF-120 different over time than GF-120 alone. Our results suggest that at the spray volumes used, GF-120 alone or even spinosad only can greatly reduce local R. pomonella populations in Washington.