Field and Laboratory Tests of New Insecticides Against the Apple Maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae)

Abstract

Laboratory bioassays and field tests were conducted to compare the effectiveness of the new insecticides, imidacloprid, indoxacarb, pyriproxyfen, spinosad, thiacloprid, and thiamethoxam, against apple maggot. The activity ranking of the compounds in reducing oviposition in laboratory bioassays was: imidacloprid, 95% reduction at 11 ppm 〉 thiamethoxam, 91% and thiacloprid, 89% reduction at 100 ppm 〉 spinosad, 98% reduction at 316 ppm 〉 indoxacarb, 80% reduction at 1000 ppm 〉 pyriproxyfen, 0% reduction at 38 ppm. In laboratory bioassays, the only insecticides that were toxic to flies at concentrations equal to or below the recommended field rates were imidacloprid, (50% of flies at 11 ppm), spinosad (90% of flies at rates >10 ppm), and thiamethoxam (≈50% of flies at 32 ppm). In field trials, thiacloprid was the only material that consistently controlled apple maggot fruit infestation that was comparable to standard treatments of organophosphate insecticides. Spinosad applied at weekly intervals, and indoxacarb applied as biweekly sprays provided adequate control of apple maggot damage when infestation levels in the field were low, but were not effective in preventing damage in small plots when apple maggot pressure was high.