title: Temporal synergism can enhance carbamate and neonicotinoid insecticidal activity against resistant crop pests.
abstract: BACKGROUND
  Piperonyl butoxide (PBO) effectively synergises synthetic pyrethroids, rendering even very resistant insect pests susceptible, provided a temporal element is included between exposure to synergist and insecticide. This concept is now applied to carbamates and neonicotinoids.
  
  
  RESULTS
  A microencapsulated formulation of PBO and pirimicarb reduced the resistance factor in a clone of Myzus persicae (Sulzer) from >19 000- to 100-fold and in Aphis gossypii (Glover) from >48 000- to 30-fold. Similar results were obtained for a strain of Bemisia tabaci Gennadius resistant to imidacloprid and acetamiprid, although a second resistant strain did not exhibit such a dramatic reduction, presumably owing to the presence of target-site insensitivity and the absence of metabolic resistance. Synergism was also observed in laboratory susceptible insects, suggesting that, even when detoxification is not enhanced, there is degradation of insecticides by the background enzymes. Use of an analogue of PBO, which inhibits esterases but has reduced potency against microsomal oxidases, suggests that acetamiprid resistance in whiteflies is largely oxidase based.
  
  
  CONCLUSIONS
  Temporal synergism can effectively enhance the activity of carbamates and neonicotinoids against resistant insect pests. Although the extent of this enhancement is dependent upon the resistance mechanisms present, inhibition of background enzymes can confer increased sensitivity against target-site resistance as well as increased metabolism. .
authors.affiliation: Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
authors.forename: Georgina
authors.initials: G
authors.lastname: Bingham
authors.forename: Robin V
authors.initials: RV
authors.lastname: Gunning
authors.forename: Giovanna
authors.initials: G
authors.lastname: Delogu
authors.forename: Valerio
authors.initials: V
authors.lastname: Borzatta
authors.forename: Linda M
authors.initials: LM
authors.lastname: Field
authors.forename: Graham D
authors.initials: GD
authors.lastname: Moores
mesh_terms: D000818:Animals; D001042:Aphids / Q000187:drug effects*; D002219:Carbamates / Q000494:pharmacology*; D004357:Drug Synergism; D006430:Hemiptera / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology; D007305:Insecticide Resistance / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000494:pharmacology; D010882:Piperonyl Butoxide / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D002219:Carbamates; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D011725:Pyridines; D011743:Pyrimidines; C011994:pirimicarb; C082359:imidacloprid; C464485:acetamiprid; D010882:Piperonyl Butoxide