Physiological, biochemical and histological effects of abscisic acid-synthesized silver and copper oxide nanoparticles on the potato tuber moth, Phthorimaea operculella

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The potato tuber moth (PTM), Phthorimaea operculella, poses a significant threat to potato cultivation in tropical and subtropical regions. Chemical control, though widely used, poses risks to human and environmental health, necessitating safer alternatives. This study investigated eco-friendly alternatives by synthesizing silver (AgNPs) and copper oxide nanoparticles (CuONPs) using abscisic acid (ABA). Characterization through UV–vis spectroscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, X-ray diffraction, Fourier transform infrared spectroscopy, and zeta potential analysis confirmed the successful synthesis of AgNPs with a uniform size of 35.8 nm and a plasmon resonance at 430 nm. CuONPs displayed a porous, rugby sheet-like structure, with a thickness of 68.5 nm and a 290 nm absorption peak. The effectiveness of the nanoparticles against PTM larvae was assessed through larval spraying and leaf-dipping. Larval spraying outperformed leaf-dipping, with median lethal concentration (LC50) values of 670 mg/L for AgNPs and 1320 mg/L for CuONPs. AgNPs and CuONPs significantly altered digestive enzyme activities in treated PTM larvae, reducing α-amylase, β-glucosidase, lipase, protease, and trypsin, and increasing acid phosphatase activity. Histological studies revealed damage to the larvae's midgut epithelial layer and peritrophic membrane, resulting in nuclei dispersion. Our study shows a cost-effective, minimal-impact strategy for synthesizing AgNPs and CuONPs, which can serve as a potential approach for managing PTM.