Use of Oil, Aqueous Extracts, and Formulations of Azadirachta indica A. Jussieu against Spodoptera frugiperda: A Systematic Review (2015–2026)

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is one of the most economically damaging cereal pests globally, with yield losses exceeding 30%. The neem tree, Azadirachta indica A. Jussieu (Meliaceae), contains over 200 bioactive secondary metabolites, with azadirachtin A (C₃₅H₄₄O₁₆) as the most potent insecticidal compound. This review systematizes scientific evidence published between 2015 and 2026 on the use of oil, aqueous extracts, and formulations of A. indica against S. frugiperda under laboratory and field conditions, analyzing formulation efficacy, multi-target mechanisms of action, and the influence of high-altitude climatic conditions on biopesticide performance. Formulated neem oil at 500–1,500 µL/L achieves larval mortality exceeding 70% in early instars (L1–L3), with LC₅₀ = 580–703 µL/L and LT₅₀ = 21–67 h. Metabolite modes of action include ecdysteroid antagonism, gustatory inhibition, intestinal cytotoxicity, immunosuppression, and enzymatic inhibition of detoxification systems (Tables 1 and 3), constituting a multi-target strategy that minimizes resistance development risk in S. frugiperda . Emerging nanoformulations (microencapsulation, chitosan-azadirachtin nanoparticles) show LC₅₀ values up to 2.5-fold lower and extended environmental half-lives of 7–21 days compared with conventional emulsifiable concentrates, constituting a priority area for future research and commercial development.