title: Toxicological profile of deltamethrin in Triatoma brasiliensis (Hemiptera: Reduviidae) in State of Ceará, Northeastern Brazil.
abstract: BACKGROUND
  Triatoma brasiliensis is the species of greatest epidemiological relevance in the semi-arid region of Brazil. This species is predominantly found in domestic environments, and it has the ability to build large colonies with high levels of natural infection via Trypanosoma cruzi. Thus, T. brasiliensis is one of the most efficient transmitters of Chagas disease (CD) to humans. Despite household spraying with residual insecticides, many areas report persistent reinfestations for reasons that remain poorly understood. Therefore, this study sought to characterize the toxicological profile of deltamethrin in T. brasiliensis from areas with persistent reinfestation in State of Ceará, Brazil.
  
  
  METHODS
  The susceptibility reference lineage (SRL) was derived from Umari. 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 (0.851 nanograms of active ingredient per treated nymph) of the SRL.
  
  
  RESULTS
  The susceptibility profile characterization of the T. brasiliensis populations revealed 50% resistance ratios (RR50) that ranged from 0.32 to 1.21. The percentage of mortality in response to the diagnostic dose was 100%.
  
  
  CONCLUSIONS
  We demonstrated that T. brasiliensis was highly susceptible to deltamethrin. The control difficulties found might be related to the recolonization of the triatomines originating from neighboring environments and the possible operational failures related to the process of spraying that enabled specimens less susceptible to deltamethrin to survive.
authors: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil.
authors: Grasielle Caldas D'Ávila
authors: GC
authors: Pessoa
authors: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil.
authors: Nathália Abreu Borges
authors: NA
authors: Trevizani
authors: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil.
authors: Letícia Sena
authors: LS
authors: Dias
authors: Secretaria de Saúde do Estado do Ceará, Fortaleza, CE, Brazil.
authors: Claudia Mendonça de
authors: CM
authors: Bezerra
authors: Secretaria de Saúde do Estado de Minas Gerais, Belo Horizonte, MG, Brazil.
authors: Bernardino Vaz de
authors: BV
authors: Melo
authors: Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil.
authors: Liléia
authors: L
authors: Diotaiut
mesh_terms: D000818:Animals; D001938:Brazil; D014355:Chagas Disease / Q000635:transmission; D007303:Insect Vectors; D007305:Insecticide Resistance; D007306:Insecticides; D007928:Lethal Dose 50; D009570:Nitriles; D011722:Pyrethrins; D014224:Triatoma
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin