Effects of insecticides on immature and adult western flower thrips (Thysanoptera: Thripidae) in Israel

A bioassay confining Frankliniella occidentalis (Pergande) to insecticide-treated kidney bean leaves in a modified Munger cell was used to test the effects of insecticides on fecundity, feeding activity, and mortality. Adult thrips were exposed to various concentrations of abamectin, carbosulfan, methiocarb, monocrotophos, methamidophos, cypermethrin, and acrinathrin; and immature thrips were exposed to abamectin, carbosulfan, methiocarb, and acrinathrin. Cypermethrin had no direct effect on adult thrips at concentrations up to 2,000 ppm. Carbosulfan had the highest efficacy against adults in terms of suppression of feeding activity and fecundity, and the lowest LC,, (11.3 ppm). Additionally, F. occidentalis were collected from newer greenhouses in 4 locations where growers reported problems controlling their populations; thrips were tested with abamectin, carbosulfan, and methiocarb. At only 1 collection site was there moderate resistance to carbosulfan and methiocarb; moderate resistance to abamectin was observed only in immature thrips from 1 site.