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Abstract
The B-strain (MEAM1) of sweetpotato whitefly, Bemisia tabaci (Gennadius), is a key pest of vegetable and agronomic crops in the Southeastern USA. Insecticide resistance is one of the major concerns for management of this pest in commercial crops. Four whitefly bioassay methods (tube, cup, petri dish, and clip cage) were evaluated under leaf and root drench application routes across five whitefly insecticides compared with a water check. The application route (root or leaf drench) made no significant difference on whitefly mortality. The clip-cage bioassay resulted in less overall whitefly mortality and the best separation of insecticide treatments and rates followed by the cup and tube methods, respectively. High rates of cyantraniliprole, dinotefuran and flupyradifurone insecticides resulted in the highest whitefly mortality. Interactions occurred between the methodology and insecticide treatment in both populations. Whole-plant bioassays in 2018 and 2020 showed that these same insecticides significantly reduced adult and egg numbers using a lab colony, but results were more variable when using the whole plant exposure method. Insecticide response provided greater separation when using the clip cage technique. Finally, a modified tube bioassay method was tested for obtaining LC50 values resulting in promising preliminary results.