Combating Spodoptera frugiperda (Lepidoptera: Noctuidae) with Moringa-Synthesized Silica Nanoparticles and Its Combination with Some Insecticides

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is a major agricultural pest known for developing resistance to insecticides. This study investigated a novel approach to manage FAW by silica nanoparticles (SiNPs) synthesized from eco-friendly leaf extract of Moringa oleifera Lam. (Moringaceae). This green synthesis method offers a sustainable and potentially safer alternative to traditional chemical processes. SiNP formation was confirmed by various techniques: UV-visible spectrophotometer, X-ray spectroscopy with energy-dispersive (EDX), scanning electron microscopy (SEM), and dynamic light scattering (DLS). The effectiveness of SiNPs alone and their combination with three common insecticides (emamectin benzoate, indoxacarb, and chlorpyrifos) were evaluated against third instar larvae of fall armyworm. While SiNPs after 24 h by leaf dipping method recorded limited insecticidal activity (LC₅₀ = 9947.59 mg/L), it significantly enhanced the potency of all three insecticides. Combining SiNPs with emamectin benzoate resulted in the most dramatic increase in effectiveness compared to the insecticide alone with LC₅₀ = 0.295 mg/L and 0.42 mg/L, respectively. This research suggests that moringa extract can be a valuable resource for the green synthesis of nanoparticles potentially useful in pest control. This approach could potentially reduce the amount of insecticide needed for effective pest control, leading to a more sustainable and environmentally friendly agricultural practice.