Microemulsion-based delivery of peppermint essential oil as a sustainable strategy for Aedes aegypti control

Abstract

Arboviral diseases such as dengue, Zika, and chikungunya remain major public health challenges worldwide. In the absence of broadly effective antiviral therapies and considering the limitations of current vaccination strategies, vector control remains the primary approach for reducing disease transmission. Essential oils have emerged as promising alternatives to synthetic insecticides because of their renewable origin, biodegradability, and multiple mechanisms of action. Nevertheless, their practical application is often limited by poor water solubility and physicochemical instability. This study investigated the chemical composition, larvicidal activity, and microemulsion-based formulation of Mentha piperita L. essential oil against Aedes aegypti larvae. The chemical composition of the essential oil was determined by gas chromatography–mass spectrometry (GC–MS). Larvicidal activity against third-instar A. aegypti larvae was evaluated by determining mortality rates and the median lethal concentration (LC 50 ). A pseudoternary phase diagram was constructed to identify suitable microemulsion regions, and selected formulations were characterized according to droplet size, polydispersity index (PDI), and short-term physical stability. The larvicidal activity of the resulting microemulsions was subsequently evaluated at different essential-oil concentrations. A blank microemulsion containing the formulation components without M. piperita essential oil was also evaluated as a control. GC–MS analysis identified 14 compounds representing nearly 100% of the essential oil composition, with menthol (50.17%) and menthone (23.02%) as the predominant constituents. The free essential oil exhibited concentration-dependent larvicidal activity against A. aegypti , with an LC 50 of 175.7 μg/mL and complete larval mortality at 250 μg/mL. Among the tested formulations, PME-05 was selected as the most promising formulation for further development because it achieved complete larval mortality while containing only 5% peppermint essential oil and exhibited the lowest PDI (0.06 ± 0.007), indicating a highly homogeneous dispersed system. The results support the use of microemulsion technology as a suitable delivery system for M. piperita essential oil, facilitating its dispersion and application in aqueous environments while retaining its larvicidal activity. The developed formulation represents a promising platform for the application of botanical larvicides in mosquito control. Further studies are needed to evaluate long-term physicochemical stability, residual activity, effects on non-target organisms, and performance under semi-field and field conditions.