Western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), is a major pest of many greenhouse vegetables, fruits and horticultural crops all over the world. Chemical control is the main strategy to control the thrips population because of the low damage threshold on crops susceptible to TSWV. Knowledge about effective insecticides for F. occidentalis is necessary, in order to provide information important for pesticide resistance management. In this study, diazinon (EC 60%), cypermethrin (EC 40%), fipronil (EC 2.5%), imidacloprid (SC 35%) and oxymatrine (kingbo AS 0.6%) was used to assessing role of exposure time of these insecticides on the mortality. The reaction of the thrips tested was recorded once every 2 hours until the last thrips killed. Findings from this study showed that LT50 for cypermethrin, fipronil, oxymatrine, imidacloprid and diazinon were 5.78, 8.33, 14.41, 15.42 and 15.49 for hour, respectively. Also, amounts of KT50 for cypermethrin, imidacloprid, fipronil and diazinon assessed 5.93, 7.68, 8.59 and 12.18 for hour, respectively. Oxymatrine had no knockdown effect.
