An evaluation of alternative insecticides to diazinon for control of tephritid fruit flies (Diptera: Tephritidae) in soil.

Diazinon has been used extensively in the past as part of California eradication programs for tephritid fruit flies (Diptera: Tephritidae) as a soil drench, but it is being phased out for this purpose in the United States. Therefore, in this study, the toxicity of Platinum, Force, Admire, Regent, and Warrior was estimated after application to sand and soil as drenches for control of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann); melon fly, Bactrocera cucurbitae (Coquillett); and oriental fruit fly, Bactrocera dorsalis (Hendel), in Hawaii. Susceptibility of each species differed. In sand, the order of toxicity at LC50 based on the 95% confidence limit overlap approach for C. capitata from most toxic to least toxic was diazinon > Force = Warrior > Admire = Platinum > Regent. The order of toxicity for B. dorsalis was diazinon > Platinum = Warrior = Force > Regent = Admire. The order of toxicity for B. cucurbitae was Warrior = diazinon > Force = Regent = Platinum = Admire. Based on the dose ratio method, Warrior was not significantly different at LC50 than diazinon for B. cucurbitae only. All other insecticides were significantly different from diazinon at LC50. Studies in sand were followed by an evaluation of specific concentrations of Warrior and Force in soil collected from two sites on the island of Kauai. Average concentrations that caused at least 95% mortality in soil in all three fruit fly species were 121 g active ingredient (AI)/ha for Force and 363 g (AI)/ha for Warrior compared with 182 g (AI)/ha for diazinon. These results indicate that Force and Warrior could be used as soil treatments for control of tephritid fruit flies.