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Long term application of insecticide phosalone, for controling pistachio psylla, may result in developing resistance in this pest.
Thus, in order to evaluate the susceptibility of overwintering and aestiving adults in various regions of jabalbarez , shahrbabak , kermanand rafsanjan, an experiment
Was conducted during years 1997-1998 . comparison of LC50 For both generations indicated that populations from kerman and rafsanjanwere the least and that of jabalbarez the most susceptible, therefore , the population from shahrbabak was assissed as medium. Although susceptibilities of the populations from different regions were shown to be less than that of the reference , however , due to a low resistance ratio (RR=1.2-1.8) , Developing resistance in the populations appeared to be of low probability.