Insecticide resistance of Frankliniella occidentalis
Over recent years, growers in the USA have reported the failure of chemical control programmes to control Frankliniella occidentalis (EPPO A2 pest). Laboratory experiments were conducted in California to detect a possible insecticide resistance in field populations of F. occidentalis to commonly used insecticides in ornamental production.
In this·experiment field populations of western flower thrips showed high levels of resistance to several classes of insecticides, expressed as resistance ratios at LC90 (compared to susceptible populations). Very high levels of resistance were observed to pyrethroids. Permethrin resistance ranged from 178-fold to 8716-fold and for bifenthrin a 138-fold to 1279-fold resistance were observed.
Methomyl resistance was moderate to high with a range between 41-fold to 378-fold resistance ratio and also a high resistance to abamectin was observed with a resistance ratio between 18-fold and 798-fold.
The resistance to chlorpyrifos was rather low with a 17-fold to 31-fold resistance ratio, but that might be due to the fact that this compound is hardly used in ornamental. production because of its phytotoxic effect on most ornamentals.
Sources
Immaraju, J.A.; Paine, T.D.; Bethke, J.A.; Robb, K.C.; Newman, J.P. (1992) Western flower thrips (Thysanoptera: Thripidae) resistance to insecticides in coastal California greenhouses.
Journal of Economic Entomology 85, 9-14.