RELATIONSHIP BETWEEN BIOASSAY DATA AND THE SIMULATED FIELD PERFORMANCE OF INSECTICIDES AGAINST SUSCEPTIBLE AND RESISTANT ADULT BEMISIA-TABACI (HOMOPTERA, ALEYRODIDAE)

Adults from seven strains of Bemisia tabaci (Gennadius) were tested wi th nine insecticides or combinations in both leaf-dip bioassays and th e Rothamsted field simulators. A statistical model was used to describ e the survival of the insects in the field simulators and comparisons made to the resistance factors from leaf-dip assays. Strains of B. tab aci shown to be susceptible in bioassays were well controlled by field rates of the insecticides in the field simulators. For each insectici de or combination, the degree of adult survival in field simulators af ter insecticide treatment was positively related to the resistance fac tor. However, similar resistance factors for different insecticides ga ve quite different adult field simulator survival. In populations with high resistance factors, adult mortality in the field simulators afte r insecticide application was not different to untreated controls. The se data provide information about the implications of B. tabaci resist ance on the field performance of insecticides.