Bioactivity of Poincianella bracteosa (Tul.) L.P. Queiroz (Fabaceae) roots on larvae of Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae)

Abstract

Aedes aegypti has an epidemiological importance, as it is the main vector of the ‘dengue’-causing virus. In order to control this vector, the search for botanical insecticides that are more selective and have lower impact on the environment and on human health has been intensified. We aimed to evaluate the larvicidal potential of Poincianella bracteosa roots on A. aegypti, as well as to perform a phytochemical screening on the root ethanol extract. To conduct the biological assays, we used third and fourth instar larvae of A. aegypti, which were subjected to five different concentrations of the ethanol extract and of the dichloromethane, hexane, ethyl acetate and hydroalcoholic fractions (13.3 mg•ml-1, 6.7 mg•ml-1, 4.0 mg·ml-1, 2.0 mg·ml-1, and 0.7 mg·ml-1). Simultaneously, we performed a phytochemical screening on the ethanol extract. The dichloromethane fraction was significantly more toxic to A. aegypti (LC50 = 0.241 mg·ml-1) in comparison with the ethanol extract and the ethyl acetate and hexane fractions. The phytochemical screening indicated the presence of strong fixed acids, alkaloids, quaternary bases, flavonols, flavanonols, flavanones, resins, condensed tannins, triterpenoids, and xanthones. The bioassays revealed the larvicidal potential of the dichloromethane fraction on A. aegypti.