title: Standardization of laboratory bioassays for the study of Triatoma sordida susceptibility to pyrethroid insecticides.
abstract: BACKGROUND
  Increasing reports of high-resistant Triatominae populations concerns scientists and sanitarians as little is known about the factors behind the occurrence of such phenotype and its real impact on vector control strategies. Moreover, the utilization of a large variety of methodologies hinder the comparison of the reported studies.
  
  
  METHODS
  This work aims to review laboratory bioassays, redefining the assessed biological features (age, generation and insecticide application area) and technical procedures (mortality recording time and the ideal diagnostic dose).
  
  
  RESULTS
  Results were not influenced by the insecticide application area in nymphs or by their generation. Three days-old specimen's revealed lower susceptibility to the tested insecticide. We determined that it is more appropriate to record mortality 72 h after treatment with insecticide, as well as using a diagnostic dose of 1xDL₉₉.
  
  
  CONCLUSIONS
  This work suggests more adequate methodological parameters for assessing insecticide resistance in triatomines, which also allows the comparison of results obtained by different research groups. For laboratory bioassays, we recommend: 1) the use of first instar nymphs from first or second generation; 2) 3 day-old specimens; 2) application of insecticide in the dorsal or ventral abdomen area; 3) mortality recording 72 h after treatment with pyrethroids and 4) a diagnostic dose of 1x LD₉₉.
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisa René Rachou, Av Augusto de Lima, 1715 Barro Preto, Belo Horizonte, MG, CEP 30190-002, Brazil. grasielle@cpqrr.fiocruz.br.
authors.forename: Grasielle Caldas D'Ávila
authors.initials: GC
authors.lastname: Pessoa
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisa René Rachou, Av Augusto de Lima, 1715 Barro Preto, Belo Horizonte, MG, CEP 30190-002, Brazil. leticia.pinheiro@cpqrr.fiocruz.br.
authors.forename: Letícia Cavalari
authors.initials: LC
authors.lastname: Pinheiro
authors.affiliation: Secretaria de Saúde do Estado de Minas Gerais, Rodovia Prefeito Américo Gianetti, s/n., 0 - Serra Verde, Belo Horizonte, MG, CEP 31.630-901, Brazil. marcela.ferraz@saude.mg.gov.br.
authors.forename: Marcela Lencine
authors.initials: ML
authors.lastname: Ferraz
authors.affiliation: Secretaria de Saúde do Estado de Minas Gerais, Rodovia Prefeito Américo Gianetti, s/n., 0 - Serra Verde, Belo Horizonte, MG, CEP 31.630-901, Brazil. bernardinovazdemelo@yahoo.com.br.
authors.forename: Bernardino Vaz
authors.initials: BV
authors.lastname: de Mello
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisa René Rachou, Av Augusto de Lima, 1715 Barro Preto, Belo Horizonte, MG, CEP 30190-002, Brazil. diotaiuti@cpqrr.fiocruz.br.
authors.forename: Liléia
authors.initials: L
authors.lastname: Diotaiuti
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000592:standards*; D005260:Female; D006801:Humans; D007303:Insect Vectors / Q000187:drug effects* / Q000254:growth & development; D007305:Insecticide Resistance / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology*; D009758:Nymph; D011722:Pyrethrins / Q000494:pharmacology*; D014224:Triatoma / Q000187:drug effects* / Q000254:growth & development
chemical_list: D007306:Insecticides; D011722:Pyrethrins