Characterization of a New Insecticidal Benzothiazole Derivative from <i>Aspergillus</i> sp. 1022LEF against the Fall Armyworm, <i>Spodoptera frugiperda</i> (Lepidoptera: Noctuidae)

The fall armyworm <i>Spodoptera frugiperda</i> is considered one of the most destructive crop pests, posing a significant threat to food and crop security. In this study, we conducted a chemical investigation of the endophytic fungus <i>Aspergillus</i> sp. 1022LEF, leading to the identification of a previously unreported benzothiazole derivative, 6-(2-hydroxyethyl)benzo[<i>d</i>]thiazol-4-ol (HBT). Its structure was unambiguously characterized using extensive spectroscopic methods, including 1D and 2D NMR data, HRESIMS data, and single-crystal X-ray diffraction analysis. The insecticidal assay revealed that HBT possessed remarkable activity against <i>S. frugiperda</i> with an LC₅₀ value of 0.24 mg/mL. Further transcriptomic and proteomic analyses revealed that HBT induced mortality in <i>S. frugiperda</i> by impeding DNA replication and protein synthesis, influencing mitochondria-mediated autophagy, and perturbing hormone synthesis, thereby disrupting the fundamental biosynthetic processes. HBT demonstrated high activity in controlling <i>S. frugiperda</i>, which highlighted its potential use as a lead in the development of biopesticides.