Comparison of toxicological bioassays for whiteflies

Authors: SPARKS, TANNER - University Of Georgia; RILEY, DAVID - University Of Georgia; Simmons, Alvin; GUO, LIANGZHEN - Guangdong University

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2020
Publication Date: 11/12/2020
Citation: Sparks, T.C., Riley, D.G., Simmons, A.M., Guo, L.G. 2020. Comparison of toxicological bioassays for whiteflies. Insects. 11:789. https://doi.org/10.3390/insects11110789.
DOI: https://doi.org/10.3390/insects11110789

Interpretive Summary: Insecticides are commonly used to manage whiteflies in many crops including vegetables, but frequent use can cause these pests to become resistant to insecticides. Resistance can lead to control failure and severe crop damage, thus the need for insecticide efficacy testing and insecticide resistance monitoring. A study was conducted to determine if any current methods of toxicity assays are better than others for testing whiteflies for insecticide resistance and efficacy. Although most methods were found to be similar, the clip cage method was highly sensitive while the dish method was the least responsive to insecticide dose. For both the Florida and Georgia whiteflies tested, high rates of cyantraniliprole, dinotefuran and flupyradifurone insecticides resulted in the highest adult whitefly mortality while imidacloprid provided only intermediate control. These data provide a starting point for regional monitoring of resistance which will provide growers with better information to make effective pest control decisions. The resulting toxicological information will be useful to both the scientific and agricultural communities to improve the management of whiteflies in multiple cropping systems.

Technical Abstract: Two Bemisia tabaci populations from Georgia and Florida, USA were tested for their response to insecticides across different toxicological bioassay methods. Five insecticides in four Insecticide Resistance Action Committee (IRAC) Groups [imidacloprid (4A), dinotefuran (4A), flupyradifurone (4D), pyriproxyfen (7C) and cyantraniliprole (28)], were evaluated against a water check. The routes of application to the plant used were either leaf drench or (systemic) root drench. The four different whitefly bioassay methodologies tested were two published IRAC methods, a clip cage method, and a new tube method. A split-split experimental design was used to assess any interactions between the application route, bioassay method and insecticide treatment. Application route had no significant effect on efficacy. However, bioassay method affected overall whitefly mortality with dish method having reduced mortality compared to other methods, except for the clip cage method. High rates of cyantraniliprole, dinotefuran and flupyradifurone insecticides resulted in the highest incidence of adult whitefly mortality. Significant interactions relative to percent adult mortality were found between insecticide and bioassay method for both populations assayed. The clip cage method was more sensitive in terms of dose mortality response followed by the tube method. The dish method was the least responsive to insecticide dose. Other interactions are discussed.