Environmentally friendly botanical larvicides are commonly considered as an alternative to synthetic larvicides against Aedes aegypti Linn. In addition, mosquito resistance to currently used larvicides has motivated research to find new compounds acting via different mechanisms of action, with the goal of controlling the spread of mosquitos. Essential oils have been widely studied for this purpose. This work aims to evaluate the larvicidal potential of Syzygium aromaticum and Citrus sinensis essential oils, either alone or in combination with temephos, on Ae. aegypti populations having different levels of organophosphate resistance. The 50% lethal concentration (LC50) of the essential oils alone and in combination with temephos and the influence of essential oils on vector oviposition were evaluated. The results revealed that essential oils exhibited similar larvicidal activity in resistant populations and susceptible populations. However, S. aromaticum and C. sinensis essential oils in combination with temephos did not decrease resistance profiles. The presence of the evaluated essential oils in oviposition sites significantly decreased the number of eggs compared to sites with tap water. Therefore, the evaluated essential oils are suitable for use in mosquito resistance management, whereas their combinations with temephos are not recommended. Additionally, repellency should be considered during formulation development to avoid mosquito deterrence.

Este trabalho teve como objetivo a avaliação da toxicidade aguda do extrato aquoso de folhas de Erythrina velutina, espécie vegetal muito usada na medicina popular principalmente como tranqüilizante. O protocolo experimental utilizado seguiu o Guia para a Realização de Estudos de Toxicidade Pré-clínica de Fitoterápicos da Agência Nacional de Vigilância Sanitária (Anvisa, 2004). Ratos Wistar adultos foram tratados por via oral com a dose limite de 5 g/kg do extrato e observados por 14 dias consecutivos. Nenhum animal veio a óbito e nenhum sinal de toxicidade foi detectado nas observações comportamentais ou nas autópsias, indicando uma razoável atoxicidade do extrato.

The aim of this work was to evaluate the acute toxicity of the aqueous extract of Erythrina velutina leaves, which is frequently used in folk medicine as a tranquilizer. The experimental design followed the Guide for Preclinical Toxicity Studies of Herbal Medicines from the Agência Nacional de Vigilância Sanitária (Anvisa, 2004). Adult Wistar rats were treated per os with the limit dose of 5g/kg of the extract and then observed for 14 consecutive days. No animals died and no signs of toxicity were detected either during the behavioral observations or at the autopsies, what indicates a reasonable lack of toxicity for the extract.