Toxicological Evaluation of Mucin-Capped Silver Oxide (Ag₂O) Nanomaterials in the Land Snail Lissachatina fulica: Histological Alterations in the Brain and Ovotestis

Abstract

The present study investigates the toxicological impact of mucin-capped silver oxide nanoparticles (Ag₂O NPs) on the brain and ovotestis histology of Lissachatina fulica, a major invasive agricultural pest and intermediate host of parasitic diseases. Ag₂O nanoparticles were synthesized using a mucin-assisted method and characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis (EDX), and high-resolution transmission electron microscopy (HR-TEM), confirming their crystalline, phase-pure, and nanoscale nature. Adult snails were exposed to varying concentrations (5, 10, and 15 ppm) of Ag₂O NPs for 24, 48, and 72 hours, respectively. Histological analysis of cerebral ganglia revealed progressive neurodegenerative alterations, including disruption of connective tissue layers, vacuolation, neuronal necrosis, neuropil disorganization, and degeneration of giant nerve cells in a dose- and time-dependent manner. Similarly, the ovotestis exhibited marked structural damage such as degeneration of seminiferous tubules, rupture of basement membranes, fusion of acini, vacuolation, reduction in spermatogenic stages, and loss of oocytes under higher exposure conditions. Severe necrosis and architectural disintegration were evident at the highest concentration and prolonged exposure. The findings demonstrate that Ag₂O nanoparticles exert significant neurotoxic and reproductive toxicity in L. fulica, suggesting their potential application in targeted pest management strategies while also highlighting ecological considerations regarding nanoparticle exposure in terrestrial invertebrates.