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用分光光度计终点测定法和酶标仪动力学测定法对3个抗性水平不同的棉蚜品系和1个敏感品系的羧酸酯酶进行了研究。以α-乙酸萘酯（α-NA）为底物时，敏感品系（S）和抗性品系R1，R2，R3终点测定法所需的最适酶量分别为1／2，1／20，1／33和1／100头蚜虫，β-乙酸萘酯（β-NA）为底物时分别为1／3，1／20，1／33和1／100头蚜虫。S品系对β-NA的水解活性明显高于α-NA，而抗性品系相反，对α-NA的活性明显高于β-NA。对α-NA水解的活性在不同品系间差异较大（近60倍），而对β-NA水解的活性差异小于对α-NA，最大约为14倍。用酶标仪动力学测定法研究表明，4个棉蚜品系间羧酸酯酶活性具有明显的差异，S，R1，R2和R3分别为38，85，198和762mOD·min-1·虫-1；与4个品系的抗性程度比较，酶动力学方法的测定结果更可靠。
Carboxylesterase activities of three susceptible cotton aphid strains and one susceptible strain were studied by spectrophotometer endpoint assay and microplate reader kinetic assay. When the α-NA was used as the substrate, the optimum amount of enzyme required for the endpoint determination of the susceptible strain (S) and the resistant strains R1, R2, and R3 were respectively 1/2, 1/20, 1/33 and 1/100 aphids, and β-NA was 1/3, 1/20, 1/33 and 1/100 aphids, respectively. S strain hydrolyzed β-NA significantly higher than α-NA, whereas the resistant strain had a higher α-NA activity than β-NA. The activity of α-NA hydrolysis varied greatly among different lines (nearly 60-fold), while the difference in β-NA hydrolysis was less than that of α-NA, up to a maximum of about 14-fold. The kinetic assay of microplate reader showed that the carboxylesterase activity of four cotton aphid strains was significantly different. The values of S, R1, R2 and R3 were 38, 85, 198 and 762 mOD · min- 1; Compared with the resistance of 4 strains, the results of enzyme kinetic method are more reliable.