Time course of the proteolytic activities exhibited by the four larval instars of Ae. albopictus and influence of pH and temperature on the proteolytic profiles. A. Proteolytic activities were evaluated after 30 min, 60 min, 120 min and 180 min of incubation in 0.1 M Tris–HCl buffer (pH 7.5). B. The effect of pH on the proteolytic activities was evaluated by incubation at 37°C for two hours in 0.1 M sodium acetate buffer pH 3.5, 5,5 or 0.1 M Tris–HCl buffer pH 7.5, 10.0. C. Enzyme activities were detected after incubating the gels for 2 hours at 10°C, 37°C, 50°C, and 60°C in 0.1 M Tris–HCl buffer (pH 7.5). L1, first larval instar; L2, second larval stage; L3, third larval instar; and L4, fourth larval instar. The numbers on the right indicate the apparent molecular masses of the peptidases (kDa).