Development of Herbal Mosquito-Repellent Formulations and Their Comparative Evaluation

Abstract

Objective: The present research work aimed to develop herbal mosquito repellents as gels, incense sticks, and liquids for plug-in devices and also to assess their performance characteristics. Methods: Herbal materials possessing mosquito-repellent activity were selected from the literature review based on percentage repellency and protection period. In this study, lavender, rosemary, lemongrass, and cedarwood oils were selected as actives. Span 20 and tween 80 were used to emulsify the volatile materials and then incorporated into Carbopol 934 base to form F1 and F2 gels which were evaluated for homogeneity, pH, spread ability, viscosity, and extrudability. Incense sticks were developed using charcoal and jigat as base materials. The prepared incense sticks F3 and F4 were evaluated for burning time, ash weight, and smoke. Solutions F5 and F6 were prepared using surfactants and cosolvents and were evaluated for phase separation. All formulations were screened for their mosquito repellency by screen cage method and their performance was compared to that of the marketed herbal repellents. Results: Reared mosquitoes were identified as Culex species by microscopical observations of the antenna and maxillary palps. Mosquito repellency in 4 h is 93%, 87%, 89%, 79%, 89%, and 85% for F1, F2, F3, F4, F5 and F6, respectively. Among all, gel formulation F1 expressed the highest mosquito-repellent activity with 93% and is a better candidate. Conclusions: Gel, incense sticks, and liquids prepared for use in plug-in devices exhibited reasonably good percentage repellency comparable to that of the standard. All the developed formulations are suitable for indoor protection from mosquito bites. However, safety, stability, and field studies need to be carried out to demonstrate suitability for regular use.