Optimization and application of a rapid bioassay method of bifenthrin to Bemisia tabaci.
Objectives: The sweetpotato whitefly, Bemisia tabaci (Gennadius) is an important invasive insect pest on the agricultural crops and chemical control is still the main method up to now. In order to get the effective insecticides for the whiteflies, the bioassay method for the whitefly adults through residual film in glass tube was optimized and applied in this study. Methods: The bifenthrin solution was laid on the 1/3 inner wall to the bottom of the glass tube. The B. tabaci adults were released into the glass tubes when the insecticide film were dried and were forced to be kept at the bottom using the cotton plug. The mortality of the tested whiteflies was investigated after several hours determined according to toxicity characters of insecticides. The toxicity of bifenthrin to the whitefly adults were measured using this method and the diagnostic dose was confirmed. The measurement susceptibility of the insecticide film in the glass tube kept at different conditions was monitored finally. Results: The results showed that the residual film method was stable and had good repeatability, and could be used to measure the insecticide susceptibility to the B. tabaci in the field quickly. The residual film in the glass tube can keep its stable sensitivity at 4°C for at least one month. The method in this study was confirmed to be quick and simple. Conclusion: Few tested insects were needed in this bioassay method and the insecticide quantities tested were also low due to the 1/3 volume inner wall being covered by the insecticide film. This bioassay method could also be used on the other flying insects, which provides a quick practical method for the insecticide selection in the field.