author(s)
Syed Najeer E Noor Khadri and N Srinivasa

abstract
Culture of Tetranychus urticae Koch successfully maintained under laboratory conditions unexposed to acaricidal stress for more than two years was designated as the susceptible reference population. Susceptibility of the mite to four major acaricides i.e., dicofol, fenazaquin, propargite and spiromesifen was ascertained after every 10 generations starting from 20th to 91st generation. The susceptibility of T. urticae by 91st generation was found increased to 282, 89, 31 and 221 folds for dicofol, fenazaquin, propargite and spiromesifen, respectively as compared to the susceptibility of the initial population at the 20th generation. This baseline susceptibility data could be helpful in monitoring as well as in the management of acaricide resistance of T. urticae. It is inferred that propargite can be included in the control program of T. urticae more conveniently, due to its more consistent toxicity to the mite with a novel mode of action of inhibiting mitochondrial ATPase and its faster reversion rate.