Avaliação do efeito residual de piretróides sobre anofelinos da Amazônia brasileira

Abstract

OBJECTIVE:To evaluate the residual effect of pyrethroids on the mortality rates of Anopheles in order to check their effi cacy in indoor residual spraying in the Amazon Region, Brazil. METHODS:The study was conducted in public housing unities in the city of Belem, Northern Brazil, in 2003. Twelve houses were randomly chosen, three in each of the four established areas. Pyrethroids cypermethrin wettable powder, deltamethrin suspension concentrate, lambda-cyhalothrin wettable powder, and etofenprox wettable powder, were sprayed on the indoor wall surface of local houses. Their effects on the mortality of Anopheles were assessed from July to November. Wall bioassay was performed using plastic cones attached to insecticide and wild mosquitoes from the town of Peixe Boi. RESULTS:Mortality rate varied according to the type of wall that received the insecticide. Those inseticides applied to wood and non-plastered brick surfaces were more stable and lasted longer. Lambda-cyhalothrin presented shorter effect than the other insecticides, and Etofenprox had residual effects up to four months and was more effective in non-plastered brick surfaces. There was no statistical difference between the effect of deltamethrin and cypermethrin in all surfaces tested, and the duration of the residual effect was satisfactory up to three months after spraying. CONCLUSIONS:Deltamethrin and Etofenprox presented grater performance when compared to the others. For these insecticides and formulations, a threemonth interval between successive applications can be considered safe. In communities with predominance of houses with plastered brick surfaces, the smaller effectiveness of formulations should be considered, together with the importance of residual spraying as a vector control method in the area.

Impact of Indoor Residual-Sprayed Deltamethrin on Different Surfaces in a Malaria Endemic Area in Balai Ringin, Sarawak

“…One of the main reasons for the loss of deltamethrin activity is the fast absorption by porous surfaces. Brick surfaces are porous and may degrade the molecule of the insecticide faster [9].…”

Amazonian malaria: Asymptomatic human reservoirs, diagnostic challenges, environmentally driven changes in mosquito vector populations, and the mandate for sustainable control strategies

“…Santos et al, 2007), in Amazonian Brazil) on the size of anopheline populations is to measure the effective population size ( N e ), or simply put, the number of reproductive females, at distinctive temporal points (Pinto et al, 2002; Pinto et al, 2003). This measure is indirect, in that it depends on temporal variation in allele frequencies ( i.e ., genetic drift) and population size (Wondji et al, 2005).…”

Fenitrothion Bio-Efficacy on Different Intradomicile Surface Types Against Anopheles (Nyssorhynchus) Albimanus in the Main Malaria Endemic Regions of Panama

“…In similar studies, the application of deltamethrin on different types of surfaces, among them wood, bamboo and brick, found that the smooth surface of a bamboo presented the longest duration of insecticide toxicity and residuality. On the contrary, the rapid absorption by the brick porous surfaces led to a much faster loss of deltamethrin activity [58]. Several other studies have also found similar results with insecticides losing their toxicity much faster on porous surfaces than on smooth surfaces such as wood panels, and ceramic tiles [59][60].…”