Fabrication of Silver Nanoparticles From <i>Caryota Urens</i> and Their Effects on the Microscopy Characteristics of Tissues in <i>Spodoptera Litura</i>

This study presents the green synthesis of silver nanoparticles (AgNPs) using Caryota urens leaf extract, emphasizing its role as a reducing and stabilizing agent. The synthesized AgNPs, characterized by UV-vis spectroscopy, FTIR, XRD, and SEM, were predominantly spherical, ranging from 10 to 50 nm. Biochemical assays revealed that bioactive molecules like flavonoids and phenolics contributed significantly to the formation and stability of AgNPs. The bioassay results demonstrated potent larvicidal effects against Spodoptera litura. The mortality rate was dose-dependent, with 95% mortality achieved at 100 mg/mL after 48 h (p < 0.001). The LC50 and LC90 values were 40 and 80 mg/mL, respectively. The nanoparticles also inhibited feeding and egg-laying behaviors in S. litura, reducing oviposition by 82% at the highest concentration. Biochemical studies indicated significant inhibition of acetylcholinesterase (AChE) and elevated glutathione S-transferase (GST) activity, suggesting oxidative stress and disrupted neuromuscular coordination. Histopathological analyses showed severe tissue damage in larval midguts, including epithelial disintegration, mitochondrial swelling, and necrosis. These structural changes were consistent with nanoparticle-induced oxidative damage and enzymatic inhibition.