Abstract:

Objective: To explore the inhibitory effect of pesticides on the activity of acetyl cholinesterase (AChE) in the
head of Periplaneta americana, and to provide a new susceptible enzyme source for the quick detection of pesticides.
Methods: The activity of AChE was determined by Ellman’s colorimetric method. An orthogonal array design was used to
establish the optimum reaction conditions for determining AChE activity. The susceptibility of the AChE activity to organic
phosphorus pesticides and carbamate pesticides was measured using enzymatic inhibition by calculating IC50. Electric eel
AChE was used as a control under the same experimental conditions. Results: The IC50 values of trichlorfon, dichlorvos,
carbaryl, carbofuran and metolcarb to Periplaneta americana head AChE were 5.495, 5.943, 0.290, 0.160, 1.897 μmol/L,
respectively. The susceptibility of AChE from the head of Periplaneta americana to dichlorvos, carbaryl and metolcarb were
slightly higher than that from electric eel. The IC50 values of trichlorfon, dichlorvos, carbaryl, carbofuran, and metolcarb to
electric eel AChE were 3.990, 7.656, 1.002, 0.007, 7.568 μmol/L, respectively. Conclusion: Periplaneta americana head
AChE shows good susceptibility to five pesticides and thus can be used as a new susceptible enzyme.

Key words: Periplaneta americana, acetyl cholinesterase, pesticides, susceptibility