Metabolite-Guided Evaluation of Strophanthus gratus Reveals an Environmentally Safer Multitarget Botanical against Spodoptera frugiperda

The fall armyworm, Spodoptera frugiperda, is a globally damaging invasive pest of maize, and sustainable control tools targeting multiple toxic endpoints remain limited. Here, we evaluated Strophanthus gratus (poison arrow vine) as a metabolite-rich botanical candidate for fall armyworm management by integrating solvent-fraction bioassays, antifeedant phenotyping, enzyme profiling, GC–MS metabolomics, molecular docking, and short molecular dynamics simulations. Sequential solvent fractionation revealed concentration-dependent bioactivity, with the ethyl acetate fraction showing the strongest overall response, including 50.0 ± 2.0% larval mortality and 93.3 ± 1.5% antifeedant activity at 3000 mg L –1 (ppm equivalent). Biochemical assays showed that active fractions reduced the activities of key detoxification enzymes [(glutathione-S-transferase (GST), mixed-function oxidase/cytochrome P450 (MFO/CYP)-associated activity, and carboxy esterase (CE)], digestive hydrolases (amylase, lipase, and protease), and the neurophysiological target acetylcholinesterase (AChE). GC–MS profiling resolved a partial but chemically informative metabolite profile dominated by derivatizable sterols, triterpenoids, and phenylpropanoid-associated metabolites, with multivariate analyses revealing distinct fraction-specific chemical signatures. In silico screening was used as a hypothesis-generating layer to prioritize putative ligand-target interactions, highlighting favorable predicted interactions such as ergosterol-amylase (–31.8 kcal mol –1 ), clionasterol-CYP (–30.3 kcal mol –1 ), and ergosterol-lipase (–29.1 kcal mol –1 ). A 5 ns molecular dynamics simulation supported retention of the selected docked ligand within the predicted binding pocket. Collectively, these results indicate that S. gratus acts primarily through strong feeding deterrence and coordinated disruption of detoxification, digestion, and neurophysiological pathways, supporting its further isolation-guided development as a botanical tool for fall armyworm management.