Larvicidal Activity of Anacardium occidentale Against Aedes aegypti

Dengue is the most serious vector-borne disease in the Philippines. This crucial fact led to the main objectives of the study which were to evaluate the toxicity of the ethanol and hexane extracts of Anacardium occidentale (cashew) shell wastes toward 3rd and 4th instars larvae of Aedes aegypti and to characterize the ethanol extract by qualitative phytochemical analysis. The shell wastes were processed for crude extraction using 95% EtOH and n-hexane. The crude extract was bio-assayed for larvicidal activity against A. aegypti following the WHO standard bioassay method. The mortality was observed 24 and 48 hours after treatment and data were subjected to probit analysis to determine lethal concentrations (LC50 and LC90). The ethanol extract was characterized by phytochemical analysis. Both the hexane and ethanol extracts of A. occidentale shell wastes exhibited evidence of larvicidal toxicity. The crude ethanol and hexane extracts yielded an LC50 of 2.35 mg/L and 6.93 mg/L, and LC90 of 5.36 mg/L and 11.97 mg/L, respectively. Phytochemical screening of the crude ethanol extract of cashew shell wastes indicated the presence of unsaturated steroids and triterpenoids, free fatty acids, fats and oils, γ-benzopyrone nucleus (flavonoids), leucoanthocyanins, anthraquinones, and tannins. Both the hexane and ethanol extracts of A. occidentale showed promising potential as an alternative source of a more sustainable, non-toxic, and environmentally friendly solution for the control of dengue vector, A. aegypti.