title: Oxidases responsible for resistance to pyrethroids sensitize Helicoverpa armigera (Hübner) to triazophos in West Africa.
abstract: Helicoverpa armigera (Hübner) is the major insect pest of cotton in Africa, Turkey, Asia, India, Indonesia and Australia. Populations recently developed resistance to pyrethroids in West Africa via the overproduction of cytochrome P450 (oxidases) increasing pyrethroid metabolism. One way to overcome pyrethroid resistance is to use compounds that show negative cross-resistance to pyrethroids. Triazophos is one of these compounds: it is slightly more toxic against pyrethroid resistant larvae of H. armigera than against susceptible ones. Overproduced oxidases transform the non active triazophos into its active form, triazophos-oxon, since this form was significantly more often found in larvae from pyrethroid resistant strain (23%) than in susceptible strain (15%). This suggests that oxidases, which provide resistance by degradation of pyrethroids in the resistant individuals, also activate triazophos in its toxic oxon form resulting in a negative cross-resistance.
authors.affiliation: CIRAD-CA, 34398 Montpellier, France. thibaud.martin@cirad.fr
authors.forename: Thibaud
authors.initials: T
authors.lastname: Martin
authors.forename: Ochou G
authors.initials: OG
authors.lastname: Ochou
authors.forename: Maurice
authors.initials: M
authors.lastname: Vaissayre
authors.forename: Didier
authors.initials: D
authors.lastname: Fournier
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000349:Africa; D000818:Animals; D002800:Cholinesterase Inhibitors; D007305:Insecticide Resistance / Q000502:physiology*; D007306:Insecticides; D007814:Larva / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D007915:Lepidoptera / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D009946:Organothiophosphorus Compounds; D010088:Oxidoreductases / Q000378:metabolism / Q000494:pharmacology*; D011722:Pyrethrins; D014230:Triazoles
chemical_list: D002800:Cholinesterase Inhibitors; D007306:Insecticides; D009946:Organothiophosphorus Compounds; D011722:Pyrethrins; D014230:Triazoles; D010088:Oxidoreductases; D000110:Acetylcholinesterase