Susceptibility to insecticides in adults of whitefly Trialeurodes vaporariorum (West.) (Homoptera: Aleyrodidae) from Tepoztlan, Morelos, Mexico.

In order to determine the level of susceptibility, expressed as LC50 and LC95, for Trialeurodes vaporariorum (West.) from Chapingo, Mexico, and Tepoztlan, Morelos, six insecticides of different toxicological groups were tested on adults 2-6 days old. The method of bioassay was application by immersion. Comparison of LC´s of the populations of whiteflies studied showed that the Chapingo strain was susceptible to endosulfan, imidachloprid, methamidophos, dimethoate, methomyl and permethrin. The strain from Tepoztlan was susceptible to endosulfan and imidachloprid; tolerant to dimethoate, methomyl and permethrin, and resistant to methamidophos. Although resistance to methamidophos is a serious problem in this specie, satisfactory control should be possible using insecticides that are not metabolized by esterases, such as endosulfan or imidachloprid.