Effect of cypermethrin, dinotefuran, and spinosad insecticides on Thrips tabaci (Thysanoptera: Thripidae) in Osaka prefecture

Onion thrips, Thrips tabaci Lindeman, are a harmful pest of the genus Allium and also damage many other crops and fruits. In Japan, onion thrips developed resistance to pyrethroid and neonicotinoid insecticides, and they may also have developed resistance to other insecticides. We collected onion thrips in Osaka prefecture, Japan, from 2015 to 2018 and examined the effects of cypermethrin, dinotefuran, and spinosad insecticides on adult females using a laboratory bioassay. Most onion thrips populations showed resistance to cypermethrin and dinotefuran, except for a populations from Habikino city. All populations collected in 2015 and 2016 had no resistance to spinosad; however, the populations from Izumisano city collected in 2017 and 2018 and those from Kishiwada city collected in 2017 were found to be spinosad-resistant. This is the first report on the occurrence of spinosad-resistant thrips populations in Osaka.