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.

Background: Mosquito assemblages are organized along an ecological gradient, including small habitats where interspecific competition predominates and large permanent habitats where predation predominates. This study aimed to analyze the oviposition behavior of mosquitoes regarding the preference for traps installed at two different heights with regard to ground level and the tendency to share spawning sites in an Atlantic Forest fragment in Nova Iguaçu, State of Rio de Janeiro, Brazil.Methods: The eggs were collected from April 2018 to March 2019. Twelve ovitraps were used, randomly distributed in trees at ground level and at a height of 3 m in a forest environment.Results: They were sequentially numbered, monitored, and replaced every 2 weeks. Among the 5818 eggs collected, 3941 hatched, 3756 reached the pupa stage, and 2370 reached the adult stage. The most abundant species wereAedes albopictus(63%) andHaemagogus leucocelaenus(35%), followed byAedes terrens(2%) andHaemagogus janthinomys(1%). Analyses showed a significant difference of (P = 0.02) between the number of mosquito species collected in the palettes at ground level and the number collected at the height of 3 m. Cluster analysis of species abundance showed that the eggs collected in the palettes at ground level were more abundant than those collected in the palettes at the height of 3 m. We detected co-occurrence of species in the oviposition palettes; according to the null model, such species distribution was not random.Conclusions: The exploitation of oviposition sites by mosquito species can represent an event forced by population density facilitated by the ecological valence of individuals of one species. Understanding the aggregate distribution of larvae at the oviposition site allows us to conduct more in-depth studies of the oviposition behavior of female mosquitoes.Graphical

Aedes aegypti L., 1762, principal vetor reconhecido como transmissor do vírus da dengue. Este vetor, uma vez adaptado aos hábitos humanos, não encontra dificuldades para se reproduzir em ambientes domésticos que disponham de recipientes acumuladores de água, encontrados facilmente nas ruas e nos lixos das cidades. As instituições de ensino têm papel fundamental na formação de jovens como cidadãos disseminadores de práticas a favor da promoção da saúde. Com a finalidade de promover a educação para o controle do mosquito vetor do vírus dengue, este trabalho foi desenvolvido através de atividades lúdicas e didáticas nas escolas públicas e particulares do Centro-Sul Fluminense, cidades, centros culturais e espaços públicos do Estado do Rio de Janeiro. Os resultados apontaram respostas positivas acima de 80% sobre o tema Aedes-dengue-controle. O projeto atendeu a 1883 participantes. O Projeto Educação Antidengue demonstrou que a educação é uma ferramenta eficaz no tripé educação-saúde-meio ambiente.