Evaluation of the larvicidal potential of different fractions of the methanolic extract from Duguetia quitarensis (Annonaceae) leaves against Aedes aegypti (Diptera: Culicidae) immatures

Abstract

Objective: this study evaluated the larvicidal activity of the crude methanolic extract and different fractions (hexanic, acetonic, and ethanolic) obtained from the leaves of Duguetia quitarensis against first-instar larvae of Aedes aegypti. Methods: Larvicidal assays were conducted in 24-well plates containing five first-instar (L1) Ae. aegypti larvae and one milliliter per well of hexane, acetone, and ethanolic fractions, as well as a crude methanolic extract, at concentrations of 500, 1000, and 2000 ppm. Mortality was monitored for up to 96 hours, and experiments were performed in triplicate with six replicates using different generations of the mosquito. Results: all fractions exhibited concentration- and time-dependent effects. The ethanolic fraction showed the highest activity, reaching 86% mortality at the highest concentration, followed by the acetonic (71%), hexanic (65%), and crude methanolic extract (54%). Lethal concentration estimates revealed relatively high values, with LC₅₀ above 1500 ppm for the most active fractions after 48 hours. Conclusions: overall, the results indicate low larvicidal potency, requiring high concentrations and prolonged exposure to achieve significant effects. Nevertheless, the findings highlight the potential of this species as a source of bioactive compounds, supporting further studies focusing on compound isolation and the evaluation of other plant parts.