Nanoemulsion of cashew nut shell liquid bio-waste: Mosquito larvicidal activity and insights on possible mode of action

Abstract

Cashew nut (Anacardium occidentale) shell liquid (CNSL) is a massive waste generated from the cashew nut processing industry. The Disposal of large volume of CNSL may become a concern in terms of ecological issues. CNSL is having insecticidal properties despite of this fact it has not been utilized to its full extent. CNSL is poorly soluble in water; in this context, we have utilized CNSL to develop a nanoemulsion for larvicidal applications; using spontaneous emulsification method. The monodispersed micelles of CNSL with mean diameter of 52 nm were produced. The comparative bioefficacy of bulk and nano CNSL was evaluated against the 3rd instar larva of Anopheles culicifacies, which was recorded with LC50 of 18.1 mg/L and 1.4 mg/L, respectively. Morphological damages to the larva post exposure to CNSL nanoemulsion were examined using scanning electron microscope (SEM). Histopathological examination revealed detailed mode of toxicity of nano CNSL on larva. The result obtained showed that the CNSL nanoemulsion has enhanced larvicidal activity compared to bulk CNSL which allows effective utilization of waste. The utilization of CNSL nanoemulsion may also resolve disposal related issues of massive waste generated by cashew nut industry. Such approach may be suitable for enhanced efficacy against mosquito vector, at lower doses and also contribute towards reduced use of synthetic pesticides.