Insecticide Resistance in the Sweetpotato Whitefly, Bemisia tabaci (Homoptera: Aleyrodidae)1

Abstract
A broad spectrum of resistance to organophosphorus insecticides has evolved in Bemisia tabaci (Gennadius) in southern California. High resistance to sulprofos and methyl parathion, ranging from 20- to 54-fold, was detected in three field populations. The resistance is related to exposure to chemicals used for control of cotton pests. Moderate levels of resistance (3- to 7-fold) were observed to fenthion, malathion, and parathion in the strain from Imperial Valley, California. In addition, two strains showed relatively high levels of resistance to permethrin (12- to 29-fold). Resistance to DDT (6.5- to 9.7-fold) was present in all three strains.