Baccharis reticularia DC. and Limonene Nanoemulsions: Promising Larvicidal Agents for Aedes aegypti (Diptera: Culicidae) Control

Abstract

<i>Baccharis reticularia</i> DC. is a plant species from the Asteraceae family that is endemic to Brazil. Despite the great importance of <i>Baccharis</i> genus, no study has been carried out regarding either the phytochemical composition of <i>B. reticularia</i> or the evaluation of its larvicidal potential. Considering the intrinsic immiscibility of essential oils, this study shows larvicidal nanoemulsions containing the <i>B. reticularia</i> phytochemically characterized essential oil and its main constituent against <i>Aedes aegypti</i>. The major compound found was d-limonene (25.7%). The essential oil inhibited the acetylcholinesterase, one of the main targets of insecticides. The required hydrophile-lipophile balance of both nanoemulsions was 15.0. The mean droplet sizes were around 90.0 nm, and no major alterations were observed after 24 h of preparation for both formulations. After 48 h of treatment, the estimated LC₅₀ values were 118.94 μg mL^-1 and 81.19 μg mL^-1 for <i>B. reticularia</i> essential oil and d-limonene nanoemulsions, respectively. Morphological alterations evidenced by scanning electron micrography were observed on the larvae treated with the d-limonene nanoemulsion. This paper demonstrated a simple and ecofriendly method for obtaining <i>B. reticularia</i> essential oil and d-limonene aqueous nanoemulsions by a non-heating and solvent-free method, as promising alternatives for <i>Aedes aegypti</i> control.