P450 monooxygenases are an important mechanism of permethrin resistance inCulex quinquefasciatusSay larvae

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.

Role of cytochrome P450s in insecticide resistance: impact on the control of mosquito-borne diseases and use of insecticides on Earth

“…[84,85]. In C. quinquifasciens , four P450s have emerged as candidates for permethrin resistance: CYP6AA7 , CYP9J40 , CYP9J34 and CYP9M10, with overexpression levels closely correlated to their levels of resistance in laboratory strains from Alabama, USA (table 4).…”

Permethrin Resistance Mechanisms in the Beet Armyworm (Spodoptera exigua (Huebner))

“…Bioassays and synergism studies showed that resistance to permethrin in the TR-strain is due to decreased cuticle penetration, and target site insensitivity (kdr) to some extent, but enhanced metabolic detoxification by cytochrome P450 monooxygenase is the major mechanism involved. On the other hand, it was reported that susceptibility to permethrin after phenobarbital (cytochrome P450 inducer) treatment was reduced in the TS- 43) and Culex quinquefasciatus 44) was reported to be due to enhanced metabolic detoxification by cy- tochrome P450 monooxygenase. The cytochrome P450 monooxygenase is extremely important in the metabolism of endogenous compounds and xenobiotics including insecticides.…”

Gene silencing through RNAi and antisense Vivo-Morpholino increases the efficacy of pyrethroids on larvae of Anopheles stephensi

“…In the wild, mosquito larvae are exposed to the residues of insecticides used in agriculture or in the control of adults, where these residues flow to the breeding sites [7]. These low amounts of insecticides, creating a toxic stress, could induce tolerance by the upregulation of genes involved in the xenobiotic metabolism/detoxification of chemicals [74, 75]. Notably, this low dose insecticide exposition is regarded as one of the major causes for the onset of resistant forms in mosquitoes [76, 77].…”