The organophosphate temephos has been the main insecticide used against larvae of the dengue and yellow fever mosquito (Aedes aegypti) in Brazil since the mid-1980s. Reports of resistance date back to 1995; however, no systematic reports of widespread temephos resistance have occurred to date. As resistance investigation is paramount for strategic decision-making by health officials, our objective here was to investigate the spatial and temporal spread of temephos resistance in Ae. aegypti in Brazil for the last 12 years using discriminating temephos concentrations and the bioassay protocols of the World Health Organization. The mortality results obtained were subjected to spatial analysis for distance interpolation using semi-variance models to generate maps that depict the spread of temephos resistance in Brazil since 1999. The problem has been expanding. Since 2002-2003, approximately half the country has exhibited mosquito populations resistant to temephos. The frequency of temephos resistance and, likely, control failures, which start when the insecticide mortality level drops below 80%, has increased even further since 2004. Few parts of Brazil are able to achieve the target 80% efficacy threshold by 2010/2011, resulting in a significant risk of control failure by temephos in most of the country. The widespread resistance to temephos in Brazilian Ae. aegypti populations greatly compromise effective mosquito control efforts using this insecticide and indicates the urgent need to identify alternative insecticides aided by the preventive elimination of potential mosquito breeding sites.

Foi detectada, por meio de bioensaios, alteração dos níveis de suscetibilidade do Aedes aegypti a organofosforados em municípios do Estado de São Paulo

Baseline data on susceptibility of Aedes aegypti to organophosphates detected alterations in cities of the state of S. Paulo, Brazil

Foi detectada, por meio de bioensaios, alteração dos níveis de suscetibilidade do Aedes aegypti a organofosforados em municípios do Estado de São Paulo

Baseline data on susceptibility of Aedes aegypti to organophosphates detected alterations in cities of the state of S. Paulo, Brazil

Uma das estratégias de controle do Aedes aegypti é o uso do larvicida temephós, cujo efeito residual prolongado permite a programação de tratamentos focais. O objetivo deste estudo é verificar a duração do efeito residual do temephós simulando-se uma situação de campo. Recipientes plásticos com capacidade de um e cinco litros, foram tratados com temephós e seu efeito residual testado a cada trinta dias. Foram observadas diferentes durações do efeito residual, o qual foi maior nos recipientes localizados no interior do laboratório comparados aos expostos fora do laboratório. Nos recipientes de um litro o efeito residual foi superior ao de cinco litros. O pH e a salinidade da água, durante o período de estudo, não interferiram com o efeito do larvicida.

One of the most used strategies for controlling Aedes aegypti is the use of the larvicide temephos (Abate). This larvicide has a prolonged residual effect which allows planning the focal treatments. This study aims to verify the duration of the laivicide residual effect simulating a field situation. Plastic containers of one arid five liters were treated with temephos and the residual effect was evaluated every 30 day after the treatment. Different residual effect was observed in the containers placed outside attd inside the laboratory. The containers of one liter showed a longer residual effect than the five liters containers. The water salinity as well as the pH, during the test did not affect the larvicide effect.