Abstract

Cut rose growers in the municipalities of Villa Guerrero, Tanancingo, Coatepec Harinas, and Ixtapan de la Sal, in the state of Mexico, Mexico, have reported low effectiveness of abamectin in the control of Tetranychus urticae, possibly due to development of resistance. The objective of this study was to determine the response of 4 field populations and 1 population susceptible to this acaricide. The values of the lethal concentration (LC) at 50% of mortality fluctuated between 0.0012 to 25.37 mg per L, while the relative response (RR) at 50% of mortality of the field populations varied from 2,226 to 21,141. The values of LC at 95% mortality varied from 0.008 to 81,218 mg per L, while the RR at 95% varied from 23,185 to 10,152,250. These results reflect the levels of resistance to abamectin, and therefore, implementation of other alternatives in the management of T urticae are recommended.