Neem seed extract and nanocomposites mixtures’ larvicidal properties against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

By devouring young plant leaves, sabotaging growth, and eventually lowering agricultural yields, the fall armyworm, Spodoptera frugiperda, poses a serious danger to over 90 plant species. Integrated pest management tactics prioritize environmentally conscious methods to reduce damage to non-target creatures. Biological control techniques, such as employing plant extracts and nanoparticles, have demonstrated significant effectiveness in managing the fall armyworm. Methods: The effects of neem extract and mixes of CuO and ZnO nanoparticles on the biological characteristics of Spodoptera frugiperda were evaluated in this study. Fresh castor leaves treated with neem seed oil extract (obtained by Soxhlet extraction from neem seeds) and nanoparticles made by direct precipitation were given to fourth-instar larvae to feed on. Results: Using the second instars, the calculated LC50 values of neem extract + ZnO were 115 ppm, neem extract + CuO were 98 ppm, and ZnO + CuO were 93 ppm. The duration of larvae and pupae was affected by all treatments; they increased by 15% and 1% with neem extract + CuO, 24% and 15% with neem extract + ZnO, and 23% and 33% with ZnO + CuO. Negative effects on adult longevity were also observed with mixes of nerem/CuO, nerem/ZnO, and ZnO/CuO, correspondingly, of 25, 34, and 29%. After treatment, the LC-values of all treatments had a substantial impact on the insects' digestive enzymatic activity. Conclusion: This study concludes that neem seed extract and nanoparticles have strong larvicidal effects against Spodoptera frugiperda. At low doses, all treatments successfully extended the larval and pupal stages and decreased the success of adult emergence. Additionally, these treatments harmed the insects' enzymatic activity, suggesting that they could be used as natural pesticides to control fall armyworms.