title: The effect of piperonyl butoxide on pyrethroid-resistance-associated esterases in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae).
abstract: Pyrethroid resistance in field populations of Australian Helicoverpa armigera (Hübner) is primarily a consequence of the overproduction of esterase isoenzymes which metabolise and sequester pyrethroid insecticides. Biochemical studies have shown that pyrethroid-resistance-associated esterases in H armigera are inhibited by the insecticide synergist piperonyl butoxide (PBO). Esterase inhibition by PBO did not occur immediately after dosing, but exhibited maximum inhibition 3-4 h after dosage. Esterase activity subsequently recovered until full activity was restored by 24 h. Topical bioassays using a pre-treatment of PBO showed that maximum H armigera mortality was achieved with pre-treatment times corresponding to maximum esterase inhibition. These results demonstrated that, with correct temporal application, PBO can restore pyrethroid efficacy against H armigera. It would also be expected that restoration of efficacy with other conventional insecticides, currently compromised by esterase-based resistance mechanisms, would occur.
authors.affiliation: Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Young
authors.forename: Robin V
authors.initials: RV
authors.lastname: Gunning
authors.forename: Graham D
authors.initials: GD
authors.lastname: Moores
mesh_terms: D000818:Animals; D004357:Drug Synergism; D004950:Esterases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007527:Isoenzymes / Q000378:metabolism; D007814:Larva / Q000201:enzymology; D009036:Moths / Q000201:enzymology*; D010882:Piperonyl Butoxide / Q000494:pharmacology*; D011722:Pyrethrins / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D007306:Insecticides; D007527:Isoenzymes; D011722:Pyrethrins; D004950:Esterases; D010882:Piperonyl Butoxide