An experimental validation of resistance monitoring techniques for Arizona whitefly

Abstract

Three resistance monitoring methods, leaf disk, sticky trap, and vial, were tested to evaluate their relative reliability, discriminating ability, convenience, and practicality for monitoring insecticide resistance in Arizona whiteflies. Each method was evaluated against two field populations divergent in susceptibility using a mixture of fenpropathrin + acephate and two single chemicals, endosulfan and fenpropathrin. Correlations of field efficacy and leaf disk bioassays resistance estimates were conducted with the Yuma population and a comparatively resistant Maricopa population. At each location egg, immature, and adult whitefly densities were monitored before and after fenpropathrin + acephate treatments. The three methods had advantages and disadvantages. The leaf disk method had the greatest discriminating ability, the vial method was the most practical, and the sticky trap method was good at discriminating populations that had large differences in susceptibility. The field efficacy trials indicated good concordance between the leaf disk assays results and field performance.