PHYTOCHEMICAL-CAPPED COPPER OXIDE NANOPARTICLES FROM OCIMUM SANCTUM: STRUCTURAL ELUCIDATION AND MULTIMODAL LARVICIDAL MECHANISM AGAINST CULEX QUINQUEFASCIATUS

Abstract

Mosquito-borne diseases remain a major public health threat, necessitating the development of eco-friendly larvicides to overcome insecticide resistance and environmental toxicity. In the study, Copper Oxide nanoparticles (CuONPs) were synthesized using aqueous leaf extract of Ocimum sanctum (Tulsi) via a green chemistry approach and evaluated the larvicidal activity against Culex quinquefasciatus larvae. Copper nanoparticle formation was confirmed by UV–Vis spectroscopy, FTIR, and XRD biosynthesis. The green synthesis approach of copper nanoparticles (CuONPs) via Ocimum sanctum extract leverages the phytochemicals and functional groups present in the plant to reduce and stabilize Cu²⁺ ions to CuO and promote the surface reactivity of the CuONPs nanoparticles. Larvicidal bioassays demonstrated dose- and time-dependent activity with cumulative mortality reaching 100% at 125 ppm after 48 hours during the study. The LC₅₀ values were recorded as 71.54 ppm at 24 hours and 49.55 ppm at 48 hours respectively indicating enhanced potency with prolonged exposure. The analysis yielded a marked increase in larvicidal potency with extended exposure duration. The results of present study highlighted that Tulsi-mediated CuONPs can be used as sustainable, cost-effective larvicidal agent for controlling mosquito populations.