Variation in temephos resistance in field populations of Aedes aegypti (Diptera: Culicidae) in the State of Sergipe, Northeast Brazil

Abstract INTRODUCTION The organophosphate temephos was first used in Brazil in the 1960s for the control of Aedes aegypti. Because of its extensive and longstanding use worldwide, selection for mosquito populations resistant to the chemical has been observed not only in different regions of Brazil but also in several parts of the world. The objective of this study was to evaluate the susceptibility of Ae. aegypti to the organophosphate temephos, a larvicide used in vector control activities in Sergipe/Northeast Brazil. METHODS This study included mosquito populations from seven municipalities of Sergipe and was carried out from October 2010 to August 2011. Qualitative bioassays of diagnostic dose and dose responses were performed. The resistance ratio was calculated based on lethal concentrations for mosquitoes of the susceptible Rockefeller strain. RESULTS: All populations were classified as resistant to temephos. The resistance ratio ranged from 22.2 to 297.9, the lowest being seen in Aracaju, a coastal area of the state, and the highest in Pinhão, a semi-arid region, 96.6km from Aracaju. CONCLUSIONS: High levels of temephos resistance were observed in the Ae. aegypti populations of Sergipe. The variation between regions indicates that there have been different regimes of insecticide use and also points to the potential of small cities to generate and spread insecticide resistance.

Mosquitos da Caatinga: biodiversidade, aspectos ecológicos e importância epidemiológica da fauna Culicidae do semiárido brasileiro / Mosquitoes of the Caatinga biodiversity, ecology and epidemiological importance of Culicidae fauna of the Brazilian semiarid

Em relação à fauna Culicidae, a Caatinga é um dos biomas mais desconhecidos do Brasil. Há carência de registro de ocorrência de culicídeos, bem como de estudos sobre as interações deles com o ambiente silvestre. Assim, o objetivo deste estudo foi investigar biodiversidade e aspectos ecológicos e epidemiológicos da fauna Culicidae em áreas de conservação do bioma Caatinga. Para isso foram consideradas duas unidades de conservação da Caatinga e realizados 19 levantamentos entomológicos mensais e consecutivos. Foram realizadas coletas de formas imaturas de mosquitos em bromélias, ocos de árvore e criadouros de solo, além da coleta de mosquitos adultos de hábitos diurno, crepuscular e noturno. Ao todo, entre mosquitos adultos e imaturos associados a habitats fitotelmatas, foram coletados 11.456 culicídeos distribuídos em 28 espécies, das quais 11 eram desconhecidas para a ciência. A fauna de imaturos coletados em bromélias e ocos de árvore interferiu na composição da fauna de mosquitos adultos e houve variações na abundância e nos padrões de diversidade de acordo com fitofisionomia do ambiente. Temperatura e umidade foram os parâmetros ambientais mais fortemente associados à abundância de culicídeos. Foram registradas novas ocorrências de anofelinos, coletados em criadouros de solo, ampliando a distribuição das espécies para o semiárido brasileiro

Regarding Culicidae fauna, Caatinga is one of the most unknown biomes of Brazil. There are few records of mosquitoes occurrence, as well as studies on their interactions with the wild environment. Therefore, the aimof this study was to investigate the biodiversity, ecological and epidemiological aspects of Culicidae fauna in conservation areas of the Caatinga biome. Two protected areas were considered for the study and 19 entomological surveys were performed monthly. Immature forms of mosquitoes were collected in bromeliads, tree holes and ground pools, as well as collection of adult mosquitoes with day time, twilight and nocturnal habits. Between adults and immatures associated with phytotelmatas habits, a total of 11,456 mosquitoes were collected, distributed in 28 species, 11 of which were unknown to science. The immature fauna collected in bromeliads and tree holes interfered in the fauna composition of adults and there were variations in the abundance and diversity patterns according to the environment phytophysiognomy. Temperature and humidity were the most strongly environmental factors associated with the abundance of mosquitoes. New records of anophelines collected inground pools were registered, broadening the distribution of species in the Brazilian semiarid region

Identificação e distribuição espacial de imóveis-chave de Aedes aegypti no bairro Porto Dantas, Aracaju, Sergipe, Brasil entre 2007 e 2008 / Identification and spatial distribution of key premises for Aedes aegypti in the Porto Dantas neighborhood, Aracaju, Sergipe State, Brazil, 2007-2008 / Identificación y distribución espacial de recipientes-clave de Aedes aegypti en el barrio Porto Dantas, Aracaju, Sergipe, Brasil entre 2007 y 2008

A melhor forma de evitar novas epidemias de dengue é controlar o vetor, o mosquito Aedes aegypti. Assim, este estudo objetivou identificar e analisar a distribuição espacial dos imóveis-chave para Ae. aegypti em Aracaju, Sergipe, Brasil. Para isso, três levantamentos entomológicos foram realizados em períodos antes, durante e após a epidemia de dengue e em diferentes condições de precipitação: fim do período chuvoso, início da estação chuvosa e estiagem. Para identificar os imóveis-chave, foram consideradas as variáveis: positividade em mais de um levantamento e presença de pupas; e para verificar a distribuição espacial e dispersão dos mosquitos, foi realizada análise de padrões pontuais, por meio do estimador de densidade de kernel e buffer. Constatou-se que os imóveis-chave são responsáveis pela manutenção da infestação na localidade independente das condições ambientais e do período epidêmico e são focos geradores de mosquitos que podem se dispersar para áreas vizinhas ao bairro. Dessa forma, as ações de controle vetorial, para serem mais efetivas, devem ser direcionadas para esses imóveis.

Currently the best way to avoid new dengue epidemics is to control the mosquito vector Aedes aegypti. This study thus aimed to identify and analyze the spatial distribution of "key premises" for Ae. aegypti in Aracaju, Sergipe State, Brazil. Three entomological surveys were performed prior to, during, and after the dengue epidemic and in different conditions of precipitation: the end of the rainy season, beginning of the rainy season, and the dry season. Key premises were identified by positivity in more than one survey and presence of pupae. Spatial distribution and dispersal of mosquitoes used analysis of point patterns, with the kernel and buffer density estimator. Key premises were responsible for maintaining infestation of the area, independently of environmental conditions and the period in the epidemic, serving as foci generating mosquitoes that can spread to areas adjacent to the neighborhood. Thus, in order to be more effective, vector control measures should target these properties.

La mejor forma de evitar nuevas epidemias de dengue es controlar el vector, el mosquito Aedes aegypti. Por ello, este estudio tuvo por objetivo identificar y analizar la distribución espacial de los recipientes-clave para Ae. aegypti en Aracaju, Sergipe, Brasil. Con este fin, tres estudios entomológicos se realizaron en períodos anteriores, durante y después de la epidemia de dengue y en diferentes condiciones de precipitación pluvial: fin del período lluvioso, inicio de la estación de lluvias y período seco. Para identificar los recipientes-clave, se consideraron las variables: positividad en más de un estudio y presencia de crisálidas; y para verificar la distribución espacial y la dispersión de los mosquitos, se realizó un análisis de padrones puntuales, por medio del estimador de densidad de kernel y buffer. Se constató que los recipientes-clave son responsables del mantenimiento de la infestación en la localidad, independientemente de las condiciones ambientales y del período epidémico, además, son focos generadores de mosquitos que pueden dispersarse hacia áreas vecinas del barrio. De esta forma, las acciones de control vectorial, para ser más efectivas, deben estar dirigidas hacia esos inmuebles.

Risk of dengue occurrence based on the capture of gravid Aedes aegypti females using MosquiTRAP

We assessed the risk classification of dengue fever based on the capture of Aedes aegypti adults using MosquiTRAP, a type of sticky trap, in comparison with traditional larval infestation indices. A total of 27 MosquiTRAPs were installed, with one trap per block, and were inspected weekly between November 2008-February 2009. Infestation baseline data were obtained from a survey conducted prior to trap installation. The index generated by MosquiTRAP and house index (HI) classified the area "in alert situation". The set for risk of dengue occurrence proposed by the use of MosquiTRAP classify areas in the same way of the traditional HI.