Inhibition of Insect and Nematode Acetylcholinesterase and Glucosidases by Essential Oils—In Vitro and In Silico Studies

Insects, such as the Mediterranean fruit fly (Ceratitis capitata) and the armyworm (Mythimna unipuncta), and nematodes, including the root-knot nematode (Meloidogyne incognita) and the pine wood nematode (Bursaphelenchus xylophilus), are major agricultural pests. Essential oils (EOs) from aromatic plants are promising botanical pesticides due to their bioactivity. This study evaluated the in vitro effects of EOs from Origanum vulgare, Thymus vulgaris, Ocimum gratissimum, Mentha pulegium, and Cinnamomum cassia, and their main compounds (carvacrol, thymol, eugenol, pulegone, and trans-cinnamaldehyde, respectively), on acetylcholinesterase (AChE) and α- and β-glucosidases using crude enzyme extracts. All EOs inhibited AChE, with no significant effects on glucosidases. M. pulegium EO showed the strongest inhibition in C. capitata (IC50 = 0.022 mg/mL) and B. xylophilus (IC50 = 0.1209 mg/mL), while C. cassia EO was most effective against M. unipuncta (IC50 = 0.0020 mg/mL) and M. incognita (IC50 = 0.0197 mg/mL). In silico analysis revealed selective inhibition of insect AChE by EO-derived compounds, with insignificant effects on electric eel AChE, supporting species-specific interactions. These findings highlight EOs as selective, neurotargeting, and sustainable alternatives to synthetic pesticides.