Bioactivity of Zanthoxylum armatum fruit extract against Spodoptera frugiperda and Tuta absoluta

In Africa and Asia, fall armyworm ( Spodoptera frugiperda ) and South American tomato pinworm ( Tuta absoluta ) have become severe invasive pests of maize and tomato, respectively. They rapidly develop resistance to commercial pesticides. Therefore, there is an urge to integrate new eco-friendly pesticides into the management programs. Bamboo-leaf prickly ash, Zanthoxylum armatum ( Za ), is known to have insecticidal activities. We tested Za ’s n -hexane extract against these two pests. Median lethal concentrations (LC 50 ) at 96 h after treatment (HAT) against second-instar S. frugiperda and T. absoluta larvae were 4.41 and 4.42 mL/L, respectively. At ≥ 22.0 mL/L concentration, the extract showed a 100% ovicidal effect against both the pest species. LCQTOF analysis revealed that fatty acids constituted ~ 95% of this extract; carboxylic acids and secondary metabolites such as alkaloids and flavonoids accounted for the remaining portion. Extract’s foliar application also showed oviposition deterrence against these two pests. At ≥ 22.0 mL/L extract concentration, no S . frugiperda oviposition was observed. At ≥ 6.0 mL/L, extract reduced the T . absoluta oviposition by > six folds. To understand the basis of this deterrence, we conducted Za extract’s GCMS analysis. It revealed that monoterpenes, sesquiterpenes, and their derivatives were the most abundant constituents (55%), followed by fatty acids and their derivatives (34%), and aromatic compounds (10%). We infer that this extract is a unique combination of antibiosis- and antixenosis-causing, shelf life-increasing, and activity-enhancing compounds. It can be a highly useful biopesticide for integrating into the S. frugiperda and T. absoluta management programs.