title: Susceptibility profile of Aedes aegypti from Santiago Island, Cabo Verde, to insecticides.
abstract: In 2009, Cabo Verde diagnosed the first dengue cases, with 21,137 cases reported and Aedes aegypti was identified as the vector. Since the outbreak, chemical insecticides and source reduction were used to control the mosquito population. This study aimed to assess the susceptibility of A. aegypti populations from Santiago, Cabo Verde to insecticides and identify the mechanisms of resistance. Samples of A. aegypti eggs were obtained at two different time periods (2012 and 2014), using ovitraps in different locations in Santiago Island to establish the parental population. F1 larvae were exposed to different concentrations of insecticides (Bacillus thuringiensis var israelensis (Bti), diflubenzuron and temephos) to estimate the lethal concentrations (LC90) and calculate the respective rate of resistance (RR90). Semi-field tests using temephos-ABATE(®) were performed to evaluate the persistence of the product. Bottle tests using female mosquitoes were carried out to determine the susceptibility to the adulticides malathion, cypermethrin and deltamethrin. Biochemical and molecular tests were performed to investigate the presence of metabolic resistance mechanisms, associated with the enzymes glutathione S-transferases (GSTs), esterases and mixed-function oxidases (MFO) and to detect mutations or alterations in the sodium channel and acetylcholinesterase genes. A. aegypti mosquitoes from Santiago exhibited resistance to deltamethrin, cypermethrin (mortality<80%) and temephos (RR90=4.4) but susceptibility to malathion (mortality≥98%), Bti and diflubenzuron. The low level of resistance to temephos did not affect the effectiveness of Abate(®). The enzymatic analysis conducted in 2012 revealed slight changes in the activities of GST (25%), MFO (18%), α-esterase (19%) and β-esterase (17%), but no significant changes in 2014. Target site resistance mutations were not detected. Our results suggest that the A. aegypti population from Santiago is resistant to two major insecticides used for vector control, deltamethrin and temephos. To our knowledge, this is the first report of temephos resistance in an African A. aegypti population. The low level of temephos resistance was maintained from 2012-2014, which suggested the imposition of selective pressure, although it was not possible to identify the resistance mechanisms involved. These data show that the potential failures in the local mosquito control program are not associated with insecticide resistance.
authors: Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz, PE, Brazil; Unidade de Ciências da Natureza, da Vida e do Ambiente, Universidade Jean Piaget, Cabo Verde. Electronic address: heliorocha4@gmail.com.
authors: Hélio Daniel Ribeiro
authors: HDR
authors: Rocha
authors: Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz, PE, Brazil; Centro Acadêmico do Agreste, Núcleo de Ciências da Vida, Universidade Federal de Pernambuco, PE, Brazil. Electronic address: marcelohspaiva@gmail.com.
authors: Marcelo Henrique Santos
authors: MHS
authors: Paiva
authors: Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz, PE, Brazil; Departamento de Biologia Celular, Embriologia e Genética - BEG, Universidade Federal de Santa Catarina, SC, Brazil. Electronic address: normamsilva@yahoo.com.br.
authors: Norma Machado
authors: NM
authors: Silva
authors: Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz, PE, Brazil. Electronic address: ana.araujo@cpqam.fiocruz.br.
authors: Ana Paula
authors: AP
authors: de Araújo
authors: Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz, PE, Brazil; Unidade de Ciências da Natureza, da Vida e do Ambiente, Universidade Jean Piaget, Cabo Verde. Electronic address: denisecamacho799@gmail.com.
authors: Denise Dos Reis da Rosa de Azevedo
authors: DDRDRA
authors: Camacho
authors: Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz, PE, Brazil; Unidade de Ciências da Natureza, da Vida e do Ambiente, Universidade Jean Piaget, Cabo Verde. Electronic address: aires_fm@hotmail.com.
authors: Aires Januário Fernandes da
authors: AJFD
authors: Moura
authors: Unidade de Ciências da Natureza, da Vida e do Ambiente, Universidade Jean Piaget, Cabo Verde. Electronic address: lara.ferrero.gomez@gmail.com.
authors: Lara Ferrero
authors: LF
authors: Gómez
authors: Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz, PE, Brazil. Electronic address: tans@cpqam.fiocruz.br.
authors: Constância Flávia Junqueira
authors: CFJ
authors: Ayres
authors: Departamento de Entomologia, Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz, PE, Brazil. Electronic address: mavarjal@cpqam.fiocruz.br.
authors: Maria Alice Varjal de Melo
authors: MAVM
authors: Santos
mesh_terms: D000330:Aedes / Q000187:drug effects*; D000818:Animals; D055726:Cabo Verde / Q000453:epidemiology; D003715:Dengue / Q000453:epidemiology / Q000517:prevention & control*; D004199:Disease Vectors; D005260:Female; D007305:Insecticide Resistance / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects*; D007928:Lethal Dose 50; D009032:Mosquito Control / Q000379:methods
chemical_list: D007306:Insecticides
keywords: Aedes aegypti; Dengue; Insecticide resistance; Kdr; Metabolic enzymes; Temephos; Vector control