Resistance in field populations of Tetranychus urticae to acaricides and characterization of the inheritance of abamectin resistance

Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important mite pests in the world. This mite is mainly controlled with synthetic acaricides, and abamectin is one of the most widely used ones. However, control failures have occurred in the field that may be associated with the development of acaricide resistance. Studies were carried out to evaluate resistance to abamectin in four T. urticae populations using dipping test. Also, cross-resistance was assessed to nine acaricides and the genetic basis to the abamectin resistance was determined. Reciprocal crosses between resistant and susceptible populations were carried out to test the inheritance of resistance. Populations from Bonito and Brejão (state of Pernambuco, Brazil) were highly resistant to abamectin and to other acaricides tested, including METI group. Cross-resistance observed between abamectin and milbemectin was likely due to similar modes of action because milbemectin was not used in the field. The inheritance findings of this work indicate that resistance to abamectin in Bonito and Brejão populations was autosomal, incomplete recessive and polyfactorial.