Whether sugar mixed with insecticides enhances kill of western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), may depend on insecticide rate and food availability. Here, we tested the hypothesis that sucrose mixed with the insecticide spinosad (in the Entrust® SC formulation) enhances kill of adults and reduces oviposition when food is scarce. Three- to 5-d-old flies were exposed to a low or high rate of dried spinosad or spinosad mixed with sucrose in the presence of (a) supplemental food in the form of yeast extract sucrose (YE S) and sweet cherries (Prunus avium [L.] L.) or (b) only sweet cherries. Cherries were a food source and an oviposition substrate. At the low spinosad rate, sucrose enhanced fly kill over spinosad alone under both food conditions the first 4 d or during all 7 d of experiments. At the high spinosad rate, sucrose enhanced kill only when supplemental food was absent. Sucrose-enhanced spinosad did not reduce oviposition versus spinosad alone at either spinosad rate when supplemental food was present but it did at both spinosad rates when only cherries were present. Results suggest that sucrose mixed with the formulation of spinosad tested here in low-volume sprays could be useful for managing R. indifferens in low-food environments, but it offers no benefit in preventing oviposition when applied in food-rich environments.
ACCESS THE FULL ARTICLE

Journal of Entomological Science
Vol. 51 • No. 2
April 2016
Vol. 51 • No. 2
April 2016
oviposition
spinosyn insecticide
sweet cherries
western cherry fruit fly
yeast extract sucrose