Targeting the vector of arboviruses Aedes aegypti with nanoemulsions based on essential oils: a review with focus on larvicidal and repellent properties

TL;DR

This review explores how nanoemulsions made from essential oils can effectively target Aedes aegypti mosquitoes, offering a safer and eco-friendly alternative to traditional insecticides.

Contribution

The paper highlights the novel use of nanoemulsions to enhance the larvicidal and repellent properties of essential oils against Aedes aegypti.

Findings

Nanoemulsions significantly improve the efficacy of essential oils compared to free essential oils in larvicidal and repellent activities.

Only three studies in the last decade have explored the repellent activity of nanoemulsions with essential oils.

The review discusses the botanical sources, mechanisms, and formulations of nanoemulsions for mosquito control.

Abstract

Mosquitoes of the Aedes genus are responsible for the transmission of arboviruses that seriously affect public health. Given the increasing resistance to traditional insecticides and their negative environmental impacts, the need for safer alternatives arises. In this context, natural produts such as essential oils (EOs) have been studied for their larvicidal and repellent properties against Aedes aegypti, due to the presence of compounds such as terpenoids and phenols. However, the usage of EOs is limited due to some properties such as poor water solubility, high volatility, and intrinsic oxidation sensitivity. Thus, the development of novel formulations to efficiently deliver bioactives represents an innovative approach for Aedes aegypti control. In this context, nanothecnology provides smart formulations with improved drug solubility, controlled release, and protection against degradation. Nanoemulsions are colloidal systems with droplets of 20 to 500 nm, which improve the dispersion of the compounds, protect their active properties, and enhance their efficacy. This review addresses the potential of nanoemulsions as efficient carriers of EOs, and how this approach could emerge as ecological alternatives to synthetic insecticides. Herein, the focus was kept on targeting larvicidal and repellent activities against Ae. aegypti. For that, 23 studies were analyzed, which demonstrated a significant increase in the efficacy of nanoemulsions with EOs compared to that of free EOs, in both activities. However, the repellent activity has been less explored, present in only three of the studies evaluated, in the last 10 years. Correlatingh with this, other aspects such as botanical species of EOs, mechanisms of action, composition, and characteristics of nanoemulsions are discussed. In addition, this review highlights challenges and perspectives on pharmaceutical nanotechnology towards nanoemulsions as safe, effective, and eco-friendly tools for controlling Ae. Aegypti.

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