Aedes aegypti is a species of mosquito with wide distribution worldwide, involved in the cycles of transmission of dengue, Zika and chikungunya. The lack of vaccines for most of these arboviruses highlights the importance of vector control as a measure to reduce the incidence of these diseases. Several researches have been carried out in order to find substances of plant origin that are candidates for the control of A. aegypti. In this sense, medicinal plants that also have an insecticidal action have shown promise for the development of new products, environmentally safer than traditional chemical insecticides. The objective of this work was to evaluate the larvicidal activity of the essential oil of the leaves of Croton rhamnifolioides and its formulation in nanocapsules for A. aegypti. The essential oil was extracted by hydrodistillation and analyzed by gas chromatography coupled to a mass spectrometer (CG/MS). Formulations were produced containing concentrations of pure oil, which ranged from 40 to 80 μg/mL and polycaprolactone nanocapsules with concentrations from 30 to 120 μg/mL. Larvicide tests were performed using varying concentrations of an aqueous suspension, in triplicates, containing 20 larvae / concentration, in addition to an untreated control. As a result, the essential oil had an average content that varied between 1.4% and 0.58%, depending on the time of collection and, as main constituents, eucalyptol (16.57%) and (E) -cariophylene (11, 32%). LC50 values ranged from 26.3 μg/mL to 52.2 μg/mL and CL90 from 37.8 μg/mL to 68.7 μg/mL for pure oil. In encapsulated oil, the LC50 = 63.4 μg/mL and the LC90 = 104.8 μg/mL. The pure oil of Croton rhamnifolioides was considered more active against the larvae of A. aegypti than the encapsulated one, although both have great potential for application as a larvicide.

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