Methyl benzoate-related compounds as potential repellents and fumigants for the control of cigarette beetle, Lasioderma serricorne (F.)

The cigarette beetle, Lasioderma serricorne (F.), presents a significant management challenge as a stored product pest. The beetle's increasing resistance to conventional fumigants necessitates the search for alternative solutions to mitigate losses in agro-based industries. Here, we constructed a small molecule compounds library containing twenty-eight methyl benzoate-related compounds (MBCs) and evaluated their repellent and toxic effects against cigarette beetles by Y-tube olfactometer behavioral assays, free-choice box assays and fumigation assays. We found that six MBCs (methyl 3-methoxybenzoate, methyl benzoate, methyl 3-formylbenzoate, methyl 2-aminopyridine-3-carboxylate, methyl 2-aminobenzoate and methyl 4-amino-2-methoxybenzoate) act as repellents for cigarette beetles. Notably, methyl benzoate (MeBA) was effective across a broader range of concentrations (200-4000 ppm) compared to other MBCs. Four compounds (methyl 3-formylbenzoate, methyl 2-aminopyridine3-carboxylate, methyl 2-aminobenzoate and methyl 4-amino-2-methoxybenzoate) required higher minimum concentrations (500-4000 ppm) than MeBA for repellence, while methyl 3-methoxybenzoate was effective at a concentration (10 ppm) lower than that for MeBA. Mixtures of MeBA with methyl 3-methoxybenzoate and methyl 3-formylbenzoate enhanced the repellent effect against cigarette beetles when compared to MeBA alone. Additionally, exposure to varying concentrations of MeBA, methyl 3-methoxybenzoate, methyl 3-formylbenzoate, and methyl 2-aminobenzoate resulted in 100% mortality of cigarette beetles. Our findings indicate that specific MBCs offer the potential for their use as repellents and fumigants for this problematic stored product pest.