Study on Morphological Changes and Interference in the Development of Aedes aegypti Caused by Some Essential Oil Constituents.

Dengue, Chikungunya and Zika are arboviruses, transmitted by the mosquito Aedes aegypti, that cause high mortality and serious health consequences in human populations. Efforts to control Ae. aegypti are important for preventing outbreaks of these diseases. Essential oil constituents are known to exhibit many activities, such as their use as larvicides. Given their potential, the present study aimed to characterize the larvicidal effect of dihydrojasmone, p-cymene, carvacrol, thymol, farnesol and nerolidol on the larvae of Ae. aegypti and their interference over the morphology of the mosquitos. The essential oil constituents were dissolved in dimethylsulfoxide at concentrations of 1-100 µg/mL and were applied in the breeding environment of third-stage larvae. The larvae from bioassays were fixed, dehydrated and embedded. Ultrathin sections were contrasted using 5% uranyl acetate and 1% lead citrate for observation through transmission electron microscopy. The oil with the highest larvicidal efficiency was found to be nerolidol, followed by farnesol, p-cymene, carvacrol, thymol and dihydrojasmone, with an LC50 of 11, 21, 23, 40, 45 and 66 µg/mL, respectively. The treated Ae. aegypti larvae caused alteration to the tegument or internal portions of larvae. The present study demonstrated which of these oils-dihydrojasmone, farnesol, thymol, p-cymene, carvacrol and nerolidol-have effective larvicidal activity.

Toxicity and Larvicidal Activity of Podophyllum-Based Lignans Against Aedes aegypti (Diptera: Culicidae).

Aedes aegypti L. (Diptera: Culicidae) is a mosquito species that has adapted to urban environments and is the main vector of dengue viruses. Because of the increasing incidence of dengue, a more environmentally acceptable insecticide needs to be found. Natural products have been and continue to be an important source of leading compounds that can be modified in order to develop new drugs. The lignan family of natural products includes compounds with a diverse spectrum of biological activity. Podophyllotoxin and its related lignans represent an exciting class of natural products that can be targeted at different types of biological activity and are therefore worth exploring further. This study had the aim of evaluating the larvicidal activity of an ethanolic extract from the rhizomes and roots of Podophyllum hexandrum (PM-3) and its isolated lignans, podophyllotoxone (1) and desoxypodophyllotoxin (2), on the larvae of the mosquito vector Ae. aegypti. The PM-3 extract and the compounds (1) and (2) were dissolved in a mixture of acetone and dimethylsulfoxide at final concentrations of 1, 10, 30, 50, 100, and 200 µg/ml. After dilution, the solutions were applied (µg/ml) to the larvae-rearing medium. Overall, the ethanolic extract from the rhizomes and roots of P. hexandrum and the compounds (1) and (2) showed larvicidal activity against the larvae of Ae. aegypti According to the results from this study, it can be concluded that podophyllotoxone (1) and desoxypodophyllotoxin (2) exhibited significant toxicity toward Ae. aegypti larvae.

Estratégia de controle da população de Aedes aegypti através da avaliação da atividade larvicida de produtos naturais oriundos de plantas associada a ações de educação em saúde no estado do Rio de Janeiro

Aedes aegypti (Linnaeus, 1762) é reconhecido como transmissor de arboviroses de importância na saúde pública, como a Dengue, Zika, Chikungunya que são responsáveis pelo elevado número de morbidade, mortalidade e consequências severas à saúde da população brasileira. Tem-se reforçado a busca por uma estratégia no controle do mosquito vetor. O presente estudo teve como objetivo avaliar a atividade larvicida de produtos naturais de plantas sobre as larvas de Ae. aegypti na busca de novas alternativas para o seu controle, conciliando ações educativas no controle de Ae. aegypti como ação concreta de apoio ao Plano Brasil sem Miséria. Na busca de um fitolarvicida, utilizou-se como ferramenta de estudo as espécies vegetais Cecropia catharinensis Cuatrec (Urticaceae), Ottonia anisum Sprengel (Piperaceae), Podophyllum hexandrum Royale (Berberidaceae) e óleos essenciais terpenóides. Os resultados demonstraram o potencial larvicida dessas espécies sobre Ae. aegypti. No que tange à proposta de promover a educação para o controle de Ae. aegypti, este trabalho foi desenvolvido através de atividades lúdicas e didáticas nas escolas públicas e particulares do Centro-Sul Fluminense e em centros culturais e espaços públicos do Estado do Rio de Janeiro. Nas ações participaram 2.500 pessoas e os resultados apontaram respostas positivas acima de 80% sobre o tema Aedes-dengue-controle. A proposta de \201Ceducar com diversão\201D forneceu subsídios importantes para o conhecimento sobre o mosquito vetor da dengue e para mudanças de comportamento. Também foi desenvolvido material informativo como livro de atividades \201CO mosquito Dengoso\201D destinado ao público infantil e o \201CCordel do Dr. Mosquitão\201D.