Abstract: The threshold value R0,which determines the dynamical behaviour of a model of a non-autonomous predator-prey system with impulsive effects,was obtained and we show that if R0 < 1 the pest-free periodic solution is globally stable.The effects of seasonality and the optimum timing of integrated pest management interventions on the threshold value R0 are also addressed.Our numerical results indicate that there are some optimum timings for applications of IPM strategies when the pest population exists with seasonal fluctuations.