EXPLORING THE REPELLENT AND INSECTICIDAL EFFECTS OF BLACK PEPPER (Piper nigrum L.) AGAINST SAWTOOTHED GRAIN BEETLE (Oryzaephilus surinamensis L.)

Oryzaephilus surinamensis , also known as the sawtoothed grain beetle, is a widely distributed storage pest that thrives in products with high sugar and carbohydrate contents. Every year, O. surinamensis causes devastating losses in post-harvest and stored products, particularly grain products. The aim of this study was to determined the repellence and toxicity actions of black pepper ( Piper nigrum ) against O. surinamensis . The repellence bioassay was conducted using two types of treatments, hot infusion of black pepper powder at concentrations of 25, 50, 75 and 100 g/L and commercial black pepper oil at 1.25, 2.50, 3.75, and 5.00 mL/L. A toxicity bioassay through contact was also investigated using commercial black pepper oil at the same concentrations. The highest repellence action was recorded at 25 g/L (5.70±1.055) for hot infusion and at 2.50 mL/L (5.40±0.400) for commercial black pepper oil. Meanwhile, in the toxicity bioassay, mortality was recorded to reach 50% after 6 hours and 24 hours of exposure at 3.75 mL/L and 2.50 mL/L concentrations, respectively. The highest mortality was recorded at 3.75 mL/L (20.75±1.315) and reached 83% after 48 hours of exposure. Thus, it can be said that black pepper, despite being prepared in the simplest way possible for use in the home, is a potent insect deterrent and excellent biopesticide against the sawtoothed grain beetle.