Insecticidal activity of Melaleuca alternifolia (Myrtaceae) essential oil against Tribolium castaneum (Coleoptera: Tenebrionidae) and its inhibitory effects on insecticide resistance development

Pests in stored grains pose a global threat to food security. Tribolium castaneum (Coleoptera: Tenebrionidae) is one of the most serious stored-grain pests in the world, capable of surviving harsh environments and developing resistance to certain classes of insecticides. Fumigation toxicity and the impact of Melaleuca alternifolia Cheel (Myrtaceae) essential oil on T. castaneum were investigated in this study. The 50% lethal concentration (LC50) fumigation toxicity of M. alternifolia essential oil for T. castaneum adults and larvae was 122.7 µL/L at 24 hours and 280 µL/L at 48 hours, respectively. Gas chromatography–mass spectrometry showed that the oil’s major volatile compounds included terpinen-4-ol (31.78%), α-terpineol (20.24%), and terpinolene (17.94%). The treatment disrupted the normal enzymatic activity of acetylcholinesterase, carboxylesterase, and glutathione-S-transferase in T. castaneum adults and caused DNA damage. Melaleuca alternifolia essential oil is a strong fumigant and may be a good substitute for synthetic fumigants used to control pests of stored grain.