Preparation of a Nanoemulsion of Essential Oil of Acroptilon repens Plant and Evaluation of its Larvicidal Activity Agianst Malaria Vector, Anopheles stephensi

Background: Extensive use of chemical larvicides to control larvae, has led to resistance in vectors. More efforts have been conducted the use of natural products such as plant essential oils and their new formulations against disease vectors. Nanoformulation techniques are expected to reduce volatility and increase larvicidal efficacy of essential oils. In this study for the first time, a larvicide nanoemulsion from the essential oil of Acroptilon repens was developed and evaluated against Anopheles stephensi larvae under laboratory conditions. Methods: Fresh samples of A. repens plant were collected from Urmia, West Azarbaijan Prov- ince, Iran. A clevenger type apparatus was used for extracting oil. Components of A. repens essential oil (AEO) were identified by gas chromatography–mass spectrometry (GC–MS). All larvicidal bioassay tests were performed according to the method recommended by the World Health Organization under laboratory condition. Particle size and the morphologies of all pre- pared nanoformulations determined by DLS and TEM analysis. Results: A total of 111 compounds were identified in plant. The LC50 and LC90 values of AEO calculated as 7 ppm and 35 ppm respectively. AEO was able to kill 100% of the larvae in 4 days. Conclusion: The nanoemulsion of AEO showed a weak effect on the larvar mortality. It may therefore be suggested that this kind of nanoemulsion is not appropriate for the formulation as a larvicide. It is important to screen native plant natural products, search for new materials and prepare new formulations to develop alternative interventions with a long-lasting impact.