Entomocidal Activity of Powders and Extracts of Four Medicinal Plants Against Sitophilus oryzae (L), Oryzaephilus mercator (Faur) and Ryzopertha dominica (Fabr.)

Powders and extracts of Azadirachta indica, Zanthoxylum zanthoxyloides, Anacardium occidentale and Moringa oleifera were assessed in the laboratory at ambient temperature of 28±2°C and relative humidity of 75±5% for their insecticidal activity against Sitophilus oryzae, Oryzaephilus mercator and Ryzopertha dominica infesting paddy rice. The powders of these plants were tested against these insects at 0.4g, 0.6g, 0.8g and 1g/50g of paddy while the extracts were tested at 2%, 4%, 6% and 8% concentrations. Both the powders and extracts of these botanicals evoked a high mortality effect on the insects. Moreover, both the extracts and powders of A. indica and Z. zanthoxyloides showed greater insecticidal bustle than the powders and extracts of A. occidentale and M. oleifera as they both achieved 100% insect mortality within a short period after treatment. The extracts of these plants were also able to prevent the emergence of adult insects. S. oryzae and R. dominica were more affected with all the powders and extracts of these botanicals than O. mercator which was more vulnerable to the extracts and powders of Z. zanthoxyloides than other botanicals. Moreover, all the plants used showed a greater insecticidal effect and could be integrated into pest management system.