Identification of resistance mechanisms in Culex pipiens (Diptera: Culicidae) from southern France: insensitive acetylcholinesterase and detoxifying oxidases.

J. Ecan. Entomd 79: 14521458 (1986) ABSTRACï Resistance mechanisms of a strain (MSE) of Culex pipiens L., collected in sauthern France in 1979 and highiy resistant to chlorpynfos. were investigated by comparing the resistance characteristics to vanous organophasphates and carbamates in the absence or presence of synergists and determining the biochemical characteristics of four enzymes (esterases. glutathione-S-transferases, mixed function oxidases, and acetylcholinesterase) compareci with a susceptible strain and a chlorpyrifas-resistant strain (S54) collected in the same area in 1960 and 1974, respectively. Cblorpyrifos resistance in S54 was due to a detoxifying esterase as previously dexribed, whereas resistance in MSE was associateci with an acetylcholinesterase insensitive to the inhibition by chlorpyrifoxon and some carbamates (propoxur, carbosulfan. and carbaryl), and with an increase of oxidative metabolism.