Avaliação do potencial larvicida de extratos etanólicos do caule de Croton argyrophyllus (Euphorbiaceae: Crotonoideae) sobre Aedes aegypti (Diptera: Culicidae)

Plants are natural sources of bioactive compounds that may possess larvicidal properties against Aedes aegypti, a vector of the dengue, Zika and Chikungunya viruses. A number of studies have been conducted to identify botanical insecticides that can be used to control that vector. We aimed to evaluate the larvicidal activity of Croton argyrophyllus extracts obtained from stems collected during the rainy (RSE) and dry (DSE) seasons against A. aegypti, as well as to perform a phytochemical screening on both extracts. For the bioassays, third-instar larvae of A. aegypti were exposed to five extract concentrations (four replicates per treatment and 30 larvae per replicate). The extract obtained from stems collected during the rainy season showed higher toxicity against A. aegypti larvae than the extract obtained from stems collected during the dry season. The phytochemical screening of ethanol extracts revealed the presence of flavones, flavonoids, flavanones and xanthones in the RSE, and of strong fixed acids, free steroids and triterpenoids in the DSE. Our findings demonstrated the larvicidal potential of the Croton argyrophyllus stem against Aedes aegypti.