Bio-efficacy of green synthesized silver nitrate and zinc oxide nanoparticles against Spodoptera litura (Fabricius)

The development of high resistance in the polyphagous insect pest Spodoptera litura to conventional insecticides highlights the pressing need to find alternative environmentally friendly control measures. This study demonstrates the insecticidal potency of green-synthesized silver nitrate (AgNO3 NPs) and zinc oxide nanoparticles (ZnO NPs) against 2nd-instar larvae of S. litura. The larval leaf-dip bioassay revealed a significant mortality, depending on concentration and exposure time. The nanoparticles were synthesized by using 6 different plant extracts and tested in distilled water and ethanol (solvent) at three concentrations (3, 5, and 7 ml). Data was noted at 24, 48, and 72 h intervals. The highest mortality of larvae (90.3%) was recorded for AgNO3 NPs synthesized from a Z. officinale. Also, ethanol-based suspensions of ZnO NPs showed high efficiency, resulting in 83.3% mortality. In contrast, O. basilicum nanoparticles suspended in distilled water established the lowest insecticidal activity for AgNO3 and ZnO nanoparticles, both after 72 h interval. These results demonstrate that green synthesis is a rapid and non-toxic method for generating an effective nanoparticle. The high potency of these green synthesized nanoparticles, particularly nanoparticles derived from Z. officinale spots them as a promising and sustainable implement for the integrated management of S. litura. Furthermore, these findings provide a foundation for the development of plant-mediated nanoparticle-based bioinsecticides that could reduce reliance on conventional chemical insecticides and contribute to environmentally sustainable pest management. Future studies should evaluate their field performance, long-term stability, and potential effects on non-target organisms before large-scale application.