Green synthesis of zinc oxide nanoparticles using Piper betle leaf methanol extract: Larvicidal, pupicidal, and smoke toxicity activities against Aedes aegypti and impact on goldfish predation efficiency.

Mosquito-borne illnesses, including dengue and chikungunya, pose significant global health risks, with Aedes aegypti resistance to synthetic insecticides increasingly limiting control efficacy. This study investigated an environmentally friendly approach to vector management via the green synthesis of zinc oxide nanoparticles (ZnO NPs) employing Piper betle leaf extract, and evaluated their mosquitocidal activity. Characterization of ZnO NPs was conducted using UV-Visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) analysis. A prominent UV-Vis absorption peak at 420 nm indicated nanoparticle formation. FTIR spectra confirmed functional groups (hydroxyl, carboxyl, sulfonate) implicated in reduction and stabilization processes. SEM images showed uniformly distributed, rod-shaped ZnO NPs with sizes of 1-5 nm; EDX analysis verified zinc as the major elemental component. Larvicidal and pupicidal assessments against A. aegypti revealed concentration-dependent mortality: P. betle extract displayed LC₅₀ values of 253.17-440.74 ppm for various larval instars, while ZnO NPs exhibited greater toxicity (LC₅₀: 189-363 ppm). Pupal LC₅₀ was 492.86 ppm for the extract and 464.4 ppm for ZnO NPs. High predation efficiency (93.1%) of Carassius auratus (goldfish) was maintained in control setups, with minor reduction post-nanoparticle treatment. Smoke toxicity assays showed P. betle-based coil formulations induced 57% adult mosquito mortality within 40 min, indicating strong fumigant potency. These findings suggest P. betle-mediated ZnO NPs as a stable, cost-effective, and eco-safe alternative for sustainable A. aegypti control, supporting their application in integrated vector management strategies.