Inhibitory Effects of Spiracle-Blocking Insecticides on Courtship and Orientation in Sweetpotato Whitefly, Bemisia tabaci（Hemiptera: Aleyrodidae）

Abstract

The sweetpotato whitefly, Bemisia tabaci（Gennadius）（Hemiptera: Aleyrodidae）, is a notorious agricultural pest worldwide. In this study, the inhibitory activities of several spiracle-blocking insecticides on its orientation and courtship were investigated to identify an effective control agent against this pest. The numbers of orientated adults, courting pairs, and eggs were found to decrease on tomato plants that had been sprayed with decanoyloctanoylglycerol, safflower and cotton oil, or rape seed oil. Furthermore, when virgin female and male adults were released on tomato plants, the progeny sex ratio was higher（i.e., a higher percentage of males）on the plants that had been sprayed with decanoyloctanoylglycerol or safflower and cotton oil than on the corresponding control plants. Under greenhouse conditions, a cohort of tomato plants that had been sprayed with 500-fold diluted decanoyloctanoylglycerol four times every 10 days had fewer whitefly adults, lower numbers of eggs and larvae, and a higher sex ratio than the control plants. These results indicate that spiracle-blocking insecticides containing liquid oil, decanoyloctanoylglycerol, safflower and cotton oil, and rape seed oil can inhibit orientation and courtship in B. tabaci and allow this pest species to be maintained at a low density.