title: Deltamethrin pyrethroid susceptibility characterization of Triatoma sordida Stål, 1859 (Hemiptera: Reduviidae) populations in the Northern Region of Minas Gerais, Brazil.
abstract: BACKGROUND
  Triatoma sordida is the most captured Triatomine species in the Brazilian artificial environment. In 2008, the discovery of three Triatomine populations with altered susceptibilities to deltamethrin highlighted the importance of investigating the genetic potential for resistance in triatomines. The purpose of this study was to characterize the susceptibility to deltamethrin of peridomestic T. sordida populations in Minas Gerais, Brazil.
  
  
  METHODS
  A susceptibility reference lineage derived from Uberaba, Minas Gerais, Brazil was used. Serial dilutions of deltamethrin were prepared and applied to the dorsal abdomen of first instar nymphs. The control group received only pure acetone. Mortality was evaluated after 72h. Qualitative tests assessed mortality in response to a diagnostic dose of 1xLD99 of the susceptibility reference lineage.
  
  
  RESULTS
  Susceptibility profile characterization of T. sordida populations revealed resistance ratios (RR50s) ranging from 0.42 to 3.94. The percentage mortality in response to the diagnostic dose varied from 70% to 100%. A comparison of the results obtained in the quantitative and qualitative assays demonstrated a lack of correspondence for some populations.
  
  
  CONCLUSIONS
  We demonstrated that only T. sordida populations that present a RR50>1.0 have altered susceptibility, and the execution of simultaneous field and laboratory tests is required to understand the actual effect of vector control. A possible cause of the observed resistance ratios might be the continuous use of pyrethroids in Brazil since the 1980s.
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, BRAZIL.
authors.forename: Grasielle Caldas Dávila
authors.initials: GC
authors.lastname: Pessoa
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, BRAZIL.
authors.forename: Letícia Sena
authors.initials: LS
authors.lastname: Dias
authors.affiliation: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, BRAZIL.
authors.forename: Liléia
authors.initials: L
authors.lastname: Diotaiuti
mesh_terms: D000818:Animals; D001938:Brazil; D014355:Chagas Disease / Q000635:transmission; D007303:Insect Vectors; D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D014224:Triatoma
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin