Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2006
Publication Date: 10/1/2006
Citation: Yee, W.L., Alston, D.G. 2006. Effects of spinosad, spinosad bait, and chloronicotinyl insecticides on mortality and control of adult and larval western cherry fruit fly, rhagoletis indifferens (diptera: tephritidae). Journal of Economic Entomology 99(5):1722-1732. Interpretive Summary: Western cherry fruit fly is a serious pest of cherry in the Pacific Northwest, but organophosphate and carbamate insecticides used in the past will no longer be available for use by growers in the near future. Thus, knowledge about the effects of newer insecticides on fly mortality is needed. Personnel at the Yakima Agricultural Research Laboratory in Wapato, WA and at Utah State University in Logan, UT are determining the effects of these newer and safer insecticides on mortality and control of the flies. Spinosad (Success and Entrust), spinosad bait (GF-120), and imidacloprid (Provado) were effective in the laboratory in causing high adult fly mortality. Thiacloprid (Calypso) was not very effective in killing adults, but it was effective in killing immature stages in fruit. Field tests confirmed the effectiveness of spinosad, spinosad bait, and imidacloprid in controlling adults and larvae of cherry fruit fly. The results of this study are important in that they show these three newer and safer materials can replace the harsher insecticides used in the past for controlling the fly.
Technical Abstract: Effects of spinosad, spinosad bait, and the chloronicotinyl insecticides imidacloprid and thiacloprid on mortality of the adults and larvae of western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), were determined in the laboratory and the field. Spinosad and spinosad bait caused higher adult mortality than imidacloprid, which caused higher mortality than thiacloprid. Only spinosad bait killed flies early enough to prevent oviposition. All materials were toxic to adults when topically applied or ingested, except for thiacloprid, which was toxic only when ingested. Spinosad bait had the greatest residual toxicity on leaves, killing 100% of adults after 14 d of aging in the field. When materials were sprayed on infested cherries, numbers of live larvae in fruit after 8 d were lower in imidacloprid and thiacloprid than in spinosad and spinosad bait treatments, which did not differ from the control, but all materials reduced larval emergence, with imidacloprid having the greatest effect. In the field, spinosad, spinosad bait, and imidacloprid were more effective in suppressing larval infestations than thiacloprid, and were nearly as effective as azinphosmethyl and carbaryl. Overall results show that spinosad and chloronicotinyl insecticides differed significantly in their effectiveness against adults and larvae of R. indifferens, but that spinosad, spinosad bait, and imidacloprid seem to be acceptable substitutes for organophosphate and carbamate insecticides for controlling this fruit fly.