Abstract: The regression method was adopted to establish mathematical models for the selection of most effective combination of pH value of buffer, constant temperature, reaction time and substrate concentration, that are four major factors affecting activity of phosphatase, either acidic or alkaline, in Tetranychus cinnabarinus. The models are: Y_acidic=0.456380+0.107889X²+0.069027X³-0.026836X₁²-0.030794X₃², F=24.98，P<0.01; Y_alkaline=0.267286-0.200736X₁+0.049541X₂+0.030930X₃-0.049063X₁X₂+0.053585X₁²-0.049665X₂², F=57.68, P<0.01. It reveals that the acid phosphatase has the highest activity under the combination of buffer pH 4.4, temperature 42℃, reaction time 42 minutes and substrate concentration 8.5×10^-3 mol/L. The reaction time is a key factor affecting acid phosphatase. The key factor affecting alkaline phosphatase is the buffer pH. The best combination is pH 9.0, 37℃, 30 minutes and 7.5×10^-3 mol/L.

Key words: Tetranychus, phosphatase, effect factors, models