Phytogenic nanoparticles: A novel strategy for sustainable crop protection

• Green nanoparticle synthesis provides a sustainable crop protection alternative to destructive pesticides. • Phytogenic nanoparticles have potent antibacterial, antifungal, and insecticidal activities via biocidal processes. • The synergistic effect of bioactive phytochemicals and metal ions makes plant-based nanoparticles more effective. • Nano formulations, targeted drug delivery, and regulatory harmonization for secure agricultural integration are among the potential future applications. The increasing use of chemical pesticides has led to insect resistance, non-target harm, and ecological imbalance, motivating interest in eco-friendly alternatives. This review summarizes recent findings related to the use of biologically synthesized (phytogenic and microbial) metal nanoparticles to control various agricultural pests and diseases. We outline strategies for green production and physicochemical characterization, evaluate insecticidal and antimicrobial modes of action, including physical disruption, ROS generation, metabolic disruption, and reproductive inhibition, and compare efficacy parameters used in the studies of field and storage pests, e.g., LC₅₀, anti-feedant activity, fecundity, and enzymatic markers. In several investigations, biogenically capped nanoparticles often demonstrate enhanced bioefficacy and lessened required dosages compared to chemically produced alternatives, perhaps attributable to synergistic phytochemicals. We also critically assess non-target effects, viz., phytotoxicity and germination on crops and stored grain, and reveal significant gaps: no standardization in synthesis/characterization, little field-scale and long-term ecotoxicity testing, and insufficient regulatory frameworks. Finally, we propose a roadmap for research and regulation via standardized testing, mechanistic studies, safe-by-design nano formulations, and life-cycle assessment that would support the responsible translation of green nanotechnologies to sustainable pest management.