The common pistachio psylla, Agonoscena pistaciae, is a serious pest of pistachio. The management of this pest relies on chemical control. We investigated the susceptibility of the fifth instar nymphs to spirotetramat, flonicamid, and lambda-cyhalothrin. as well as the effect of these insecticides on the nymphs' cold tolerance. The effect of sublethal concentrations of pesticides on esterase activity was also examined. Lambda-cyhalothrin, with an LC50 value of 3.3 mg a.i./L, was more toxic to nymphs of A. pistaciae compared to spirotetramat (LC50 = 259.4 mg a.i./L) and flonicamid (LC50 = 1486.8 mg a.i./L). At 0.0 °C lambda-cyhalothrin had no significant effect on the cold tolerance of the nymphs, but the survival rate of nymphs decreased as the temperature dropped from zero to -5 °C across all concentrations. In spirotetramat and flonicamid treatments, the survival of the nymphs significantly decreased with increasing pesticide concentration and decreasing temperature. The esterase activity in nymphs treated with flonicamid and lambda-cyhalothrin was lower than that of spirotetramat. The esterase activity was inhibited by the LC50 and LC25 concentrations of flonicamid and lambda-cyhalothrin, but restrained at LC25 concentration of spirotetramat and induced at LC50 concentration. If lambda-cyhalothrin was the most effective insecticide against the fifth instar nymphs, spirotetramat significantly reduced the cold tolerance of the pest. While lambda-cyhalothrin was the most lethal compound against pistachio psylla, spirotetramat effectively reduced the cold tolerance of the pest.