Resistance detection and acetylcholinesterase activity on Blattella germanica

Objective To understand the resistance level of 5 conventional insecticides against Blattella germanica and the role of acetylcholinesterase(AChE) in resistance.Methods Medicine film method was used to determine the resistance level of B.germanica,while AChE activity and its kinetic parameters were determined according to the method of Ellman et al.(1961).Results The resistance factor values of 5 insecticides against B.germanica were 1.091 6(propoxur),1.364 7(deltamethrin),4.991 5(high effect cypermethrin),5.251 9(prallethrin) and122.261 8(dichlorvos) fold,respectively.The specific activity of resistant strain was decreased significantly(P 0.01),and Km value was obviously higher than that of susceptible strain(P 0.01).The results suggested that the structure of AChE changed.Therefore,the sensitivity on insecticides was reduced.Conclusion In addition to propoxur and deltamethrin,the field strain of B.germanica had developed high resistance to dichlorvos,high effect cypermethrin and prallethrin in some degree.The biochemistry results indicated that decreased AChE sensitivity was closely correlated to the resistance development of B.germanica.