Characterization and bioassay for larvicidal activity of Anacardium occidentale (cashew) shell waste fractions against dengue vector Aedes aegypti.

Recent studies regarding the harmful effects of synthetic larvicides initiated the need to investigate for unconventional measures that are environmentally safe and target-specific against Aedes aegypti larvae. Thus, the main objectives of the study are to evaluate the larvicidal toxicity of the solvent fractions of Anacardium occidentale shell wastes against the third and fourth instar larvae of A. aegypti and to compare the results with the commercial larvicide product. The shell wastes were extracted with 95% EtOH followed by polarity-based fractionation. The fractions were tested for larvicidal activity according to the World Health Organization bioassay method. These were then characterized by quantitative thin-layer chromatographic (TLC) fingerprinting. The hexane fraction gave the strongest activity among the fractions with an LC50 of 4.01 mg/L and LC90 of 11.29 mg/L highly comparable to the commercial larvicide, which exhibited an LC50 of 1.71 mg/L and LC90 of 8.41 mg/L. The dichloromethane fraction exhibited 9.70 mg/L LC50 and 18.44 mg/L LC90. The remarkable toxicity effects exhibited by these fractions indicate their potential to provide core structures from which sustainable and environmentally safe plant-based larvicidal agents can be synthesized.