Culex quinquefasciatus Say from Saudi Arabia (JPal-per) showed high levels of resistance (2,500-fold) to permethrin. A major contribution of cytochrome P450 monooxygenases as a mechanism of resistance was suggested by the large synergistic effects of oxidase inhibitors such as 2-propynyl 2,3,6-trichlorophenyl ether (PTPE) and piperonyl butoxide (PBO) on the toxicity of permethrin in the resistant strain. Contents of cytochrome P450 and b 5 were about 2.5 times higher in the JPal-per strain than those in the susceptible strain. P450 monooxygenase in the microsomes of gut and other parts of the body metabolized permethrin to 4´-HO-permethrin and other metabolites. Degradation of permethrin by microsomal P450 enzymes was much greater in the resistant JPal-per strain and was inhibited by PBO and PTPE. In addition to a kdr type mechanism which seems to work in the larvae, cytochrome P450 monooxygenase is clearly shown to play an important role as a mechanism of permethrin resistance in JPal-per strain larvae. Arch. Insect Biochem. Physiol. 37:47-56, 1998. © 1998 Wiley-Liss, Inc.Key words: resistance; pyrethroid; permethrin; mosquito; Culex quinquefasciatus; metabolismAbbreviations used: DEF = S-S-S-tributylphosphorotrithioate; DMC = 1,1-bis (p-chlorophenyl) ethanol; DTT = threo-1,4-dimercapto-2,3-butanediol; p-APMSF = p-amidinophenyl-methanesulfonyl fluoride hydrochloride; PB acid = 3-phenoxy-benzyl acid; PB alc. = 3-phenoxy-benzyl alcohol; PBO = piperonyl butoxide; PTPE = 2-propynyl 2,3,6-trichlorophenyl ether; PTU = 1-phenyl-2-thiourea.

No abstract

Culex quinquefasciatus Say from Saudi Arabia (Jpal‐per) showed high levels of resistance (2,500‐fold) to permethrin. A major contribution of cytochrome P450 monooxygenases as a mechanism of resistance was suggested by the large synergistic effects of oxidase inhibitors such as 2‐propynyl 2,3,6‐trichlorophenyl ether (PTPE) and piperonyl butoxide (PBO) on the toxicity of permethrin in the resistant strain. Contents of cytochrome P450 and b5 were about 2.5 times higher in the Jpal‐per strain than those in the susceptible strain. P450 monooxygenase in the microsomes of gut and other parts of the body metabolized permethrin to 4′‐HO‐permethrin and other metabolites. Degradation of permethrin by microsomal P450 enzymes was much greater in the resistant Jpal‐per strain and was inhibited by PBO and PTPE. In addition to a kdr type mechanism which seems to work in the larvae, cytochrome P450 monooxygenase is clearly shown to play an important role as a mechanism of permethrin resistance in Jpal‐per strain larvae. Arch. Insect Biochem. Physiol. 37:47–56, 1998. © 1998 Wiley‐Liss, Inc.

No abstract

No abstract