RESISTANCE OF AEDES AEGYPTI TO ORGANOPHOSPHATES IN SEVERAL MUNICIPALITIES IN THE STATE OF RIO DE JANEIRO AND ESPíRITO SANTO, BRAZIL

Abstract

Chemical insecticides have been widely used in Brazil for several years. This exposes mosquito populations to an intense selection pressure for resistance to insecticides. In 1999, the Brazilian National Health Foundation started the first program designed to monitor the resistance of Aedes aegypti to insecticides. We analyzed populations from 10 municipalities (from 84 selected in Brazil) in the states of Rio de Janeiro and Espírito Santo. Exposure of larvae to a diagnostic dose of temephos showed in alterations in susceptibility in all populations. Mosquitoes from eight municipalities exhibited resistance, with mortality levels ranging from 74% (Campos dos Goytacazes, Rio de Janeiro) to 23.5% (São Gonçalo, Rio de Janeiro). The resistance ratios of mosquitoes from three municipalities ranged from 3.59 to 12.41. Adults from only one municipality (Nova Iguaçu, Rio de Janeiro) remained susceptible to both fenitrothion and malathion. These results are being used to define new local vector control strategies.

Aedes aegypti resistance to temephos during 2001 in several municipalities in the states of Rio de Janeiro, Sergipe, and Alagoas, Brazil

“…Ovitraps were prepared according to Fay and Eliason (1966), using black plastic jars filled with hay infusion (Reiter et al 1991, Braga et al 2000. The number of ovitraps placed in the field was based on the number of buildings in each locality, as described previously (Lima et al 2003). Field collection of eggs was done in September 2001 in municipalities from SE (Aracaju, Barra dos Coqueiros, and Itabaiana) and AL (Arapiraca and Maceió) and between January and July 2001 in the state of RJ (Campos dos Goytacazes, Duque de Caxias, Niterói, Nova Iguaçu, Rio de Janeiro, São Gonçalo, and São João de Meriti).…”

“…Bioassays were done with the recommended World Health Organization (WHO) protocol, described elsewhere (WHO 1981a, Lima et al 2003, using 0.006 mg/l temephos as the diagnostic dose (twice the concentration of the dose that kills 99% of a susceptible strain -LC 99 -, as defined by WHO (1981a, b). Susceptibility of larvae from a total of 19 localities, comprising 8 districts from the municipality of Rio de Janeiro and 11 municipalities at RJ, SE, and AL was determined.…”

“…In the first round of monitor-ing, in 1999, our group, responsible for the analysis of ten municipalities at both RJ and Espírito Santo states, detected alterations in temephos susceptibility in vector populations from all municipalities examined. Furthermore, resistance ratios three to 12 fold were found (Lima et al 2003).…”

Current resistance status to temephos in Aedes aegypti from different regions of Argentina

“…aegypti in Argentina has not been systematically verified; only sporadic reports for some areas are available. Given the present epidemiological situation and that susceptibility levels to the larvicide are beginning to decrease, it is recommended that the country start an integrative program to monitor the resistance of this dengue vector to insecticides with a strategy similar to the one carried out in Brazil since 1999 (Lima et al 2003).…”

Leaf extracts of Melia azedarach Linnaeus (Sapindales: Meliaceae) act as larvicide against Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae)

“…However, constant use of synthetic insecticides induces resistance in populations of Aedes species. In Brazil, resistance of Aedes aegypti to organophosphates has been reported in Brasília 3 , Goiás 8 , São �aulo 7 , Rio de Janeiro and Espírito Santo 6 , Manaus 14 and other regions of Brazil 11 .…”