Efficacy of Selected Insecticides as Replacement for Neonicotinoids in Managing Sweetpotato Whitefly on Poinsettia

Abstract

Management of sweetpotato whitefly (Bemisia tabaci), one of the most economically important pests of poinsettia (Euphorbia pulcherrima), relies heavily on neonicotinoid insecticides. Growers are seeking insecticide alternatives to neonicotinoids due to market demands. Although several systemic and translaminar insecticides have been suggested as alternatives to neonicotinoids, no published study has simultaneously compared their efficacies against sweetpotato whiteflies. This study compared the efficacies of 10 systemic and translaminar alternative insecticides with those of two systemic neonicotinoids, when all products were applied as foliar spray (twice at 14 d) or substrate drench (once) against sweetpotato whiteflies on poinsettia plants. Sweetpotato whitefly nymph and adult densities were examined 2 weeks before the first application (pretreatment), and weekly after the application for 8 weeks. Results showed that insecticides varied greatly in their efficacy, particularly against adults, and that spray application provided more effective suppression of nymphs than drench application. Spray and drench applications of imidacloprid and dinotefuran were consistently the most effective against sweetpotato whitefly nymphs and adults. Among the neonicotinoid alternatives, cyantraniliprole was the most effective insecticide in reducing sweetpotato whitefly nymph densities by both spray and drench application methods, with efficacy comparable to those of imidacloprid and dinotefuran. Although less effective than cyantraniliprole, foliar sprays of afidopyropen, chloratraniliprole, cyclaniliprole, flonicamid, flupyradifurone, pyrifluquinazon, spirotetramat, and sulfoxaflor + spinetoram were also effective against nymphs and could serve as partners in an insecticide rotation program.