Bioactivity and biochemical effect of garlic essential oil against Chilo suppressalis Walker

Biopesticides are referred to the naturally existing organisms or plant materials to control major pests through nontoxic mechanisms and environmentally friendly techniques. In fact, biopesticides may derived from animals, plants, and microorganisms containing living organisms and their byproducts, mostly utilized for the control of plant-damaging pests. Essential oils (EOs) and their bioactive constituents—particularly those extracted from plants belonging to the family Alliaceae —have shown significant promise as botanical pesticides capable of targeting a wide range of agricultural pests. In this study, the larvicidal potential of garlic ( Allium sativum ) essential oil and its key sulfur-containing derivatives were evaluated against Chilo suppressalis Walker by larval bioassay and using binary mixture of derivates. Bioassay results demonstrated that diallyl disulfide and diallyl trisulfide exhibited strong toxicity toward C. suppressalis larvae, with LC₅₀ values of 5.72 and 8.42 μg per larva, respectively. When these two compounds were applied in combination, a marked synergistic effect was observed; however, mixtures containing diallyl sulfide with either diallyl trisulfide or diallyl disulfide produced antagonistic interactions. Enzymatic analyses further revealed that exposure to garlic essential oil and its active constituents significantly enhanced esterase and glutathione S-transferase activities, while concurrently inhibiting acetylcholinesterase activity. Collectively, these findings indicate that diallyl disulfide and diallyl trisulfide are potent bioinsecticidal agents with promising potential for integrated pest management of C. suppressalis , owing to their high larvicidal efficacy and favorable compatibility with other insecticidal compounds. • The garlic ( Allium sativum ) essential oil and its constituent, diallyl disulfide and diallyl trisulfide, exhibited strong toxicity toward Chilo larvae. • When these two compounds were applied in combination, a marked synergistic effect. • Enzymatic analyses revealed significantly enhanced esterase and glutathione S-transferase activities. • These compounds inhibited acetylcholinesterase activity.