Biopesticide Potential of Camphor, Spearmint, and Tea Tree Essential Oils Through Acetylcholinesterase Inhibition in Musca domestica

ABSTRACT Background:Houseflies (Musca domestica) are major disease vectors, necessitating sustainable biopesticide alternatives. This study evaluates the acetylcholinesterase (AChE) inhibitory potential of essential oils from camphor (Cinnamomum camphora), spearmint (Mentha spicata), and tea tree (Melaleuca alternifolia). Results: A 1:1 camphor–tea tree blend exhibited the highest AChE inhibition (95.76%), comparable to the commercial pesticide profenofos. Synergistic effects were observed in camphor–tea tree and spearmint–tea tree blends, whereas camphor–spearmint showed antagonism. Lethal dose (LD₅₀) assays demonstrated a dose-dependent increase in M. domestica mortality, reaching 100% at a 2% camphor–tea tree concentration. Molecular docking identified caryophyllene oxide (–6.8 kcal/mol), aromadendrene (–6.3 kcal/mol), and allo-aromadendrene (–6.3 kcal/mol) as potent AChE inhibitors. These compounds interact with the enzyme’s peripheral anionic site (PAS), forming strong π-alkyl and π-σ interactions with aromatic residues, thereby may obstruct acetylcholine hydrolysis. Conclusion: Formulations of these essential oils in ethanol (1.75%) can be applied as sprays, offering a stable, eco-friendly alternative to synthetic pesticides. Keywords: Acetylcholinesterase inhibition, biopesticides, essential oils, molecular docking, Musca domestica