Susceptibility of the two-spotted spider mite collected from grape crop (Vitis spp.) in Pilar do Sul, São Paulo, Brazil, to some acaricides

Abstract

The experiment was carried out in order to study the susceptibility to some acaricides in two-spotted spider mite Tetranychus urticae (Koch, 1836) Boudreaux & Dossé, 1963 (Acari: Tetranychidae) collected from a grape crop in Pilar do Sul, SP, Brazil, in comparison with T. urticae collected from nature forest of Jundiaí, SP. After the mites were picked up in the field, they were reared on bean plants (Phaseolus vulgaris, L.) in a greenhouse for the toxicity bioassays with the acaricides dimethoate, cyhexatin, propargite, naled and mevinphos. The slide-dip method was used in this study, making the mortality evaluations 24 hours after treatment. Concentration-mortality regression lines and median lethal concentrations (LCso) on the products were determined. The mites from grape crop showed to be 5.02 times more resistant to dimethoate than mites from forest. Nevertheless, there was a small difference in the susceptibility of mites coming from the both places to the remaining products. The mites from the crop showed to be up to 1.24 times more resistant to these products.