title: Effects of piperonyl butoxide on the toxicity of the organophosphate temephos and the role of esterases in the insecticide resistance of Aedes aegypti.
abstract: The effects of piperonyl butoxide (PBO) on the toxicity of the organophosphate temephos (TE) and the role of esterases in the resistance of Aedes aegypti to this insecticide were evaluated.
  
  
  
  A. aegypti L4 larvae susceptible and resistant to TE were pre-treated with PBO solutions in acetone at concentrations of 0.125, 0.25, 0.5, 1, and 2% for 24h and subsequently exposed to a diagnostic concentration of 0.02 mg/L aqueous TE solution. The esterase activity of the larvae extracts pre-treated with varying PBO concentrations and exposed to TE for three time periods was determined.
  
  
  
  At concentrations of 0.25, 0.5, 1, and 2%, PBO showed a significant synergistic effect with TE toxicity. High levels of esterase activity were associated with the survival of A. aegypti L4 larvae exposed to TE only.
  
  
  
  The results of the biochemical assays suggest that PBO has a significant inhibitory effect on the total esterase activity in A. aegypti larvae.
authors.affiliation: Departamento de Saúde Ambiental, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Boscolli Barbosa
authors.initials: BB
authors.lastname: Pereira
authors.affiliation: Departamento de Saúde Ambiental, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Jean Ezequiel
authors.initials: JE
authors.lastname: Limongi
authors.affiliation: Departamento de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Edimar Olegário de
authors.initials: EO
authors.lastname: Campos
authors.affiliation: Departamento de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Denis Prudencio
authors.initials: DP
authors.lastname: Luiz
authors.affiliation: Departamento de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Warwick Estevam
authors.initials: WE
authors.lastname: Kerr
mesh_terms: D000330:Aedes / Q000187:drug effects* / Q000201:enzymology*; D000818:Animals; D004950:Esterases / Q000502:physiology*; D007305:Insecticide Resistance; D007814:Larva / Q000187:drug effects; D010755:Organophosphates; D010574:Pesticide Synergists / Q000494:pharmacology*; D010882:Piperonyl Butoxide / Q000494:pharmacology*; D000002:Temefos / Q000633:toxicity*
chemical_list: D010755:Organophosphates; D010574:Pesticide Synergists; D004950:Esterases; D010882:Piperonyl Butoxide; D000002:Temefos