Comparative Pesticidal Activities of Essential Oils Extracted from Indigenous Plants Against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae)

Abstract

Background and Objectives:Tribolium castaneum is a major pest of stored grains that developed resistance against synthetic insecticides. This study was aimed to compare and evaluate the pesticidal activities of essential oils of Piper nigrum, Syzygium aromaticum and Monodora myristica against 4th instars of T. castaneum. Materials and Methods: Extracted essential oils of these 3 botanicals were tested for repellency and larvicidal activities against 4th instar larvae of T. castaneum at different doses for specific exptl. periods. The 4th instars were subjected to repellency bioassay of 5, 10, 15 and 20 μL ML-1 test solutions at intervals of 1 h for 4 h in 3 replicates. While the larvicidal activities were assayed using 5, 10, 15 and 20 μL mL-1 test solutions for 24, 48, 72 and 96 h. Results: The 3 essential oils exhibited repellency degree in order of P. nigrum>S. aromaticum>M. myristica, resp. at 20 μL mL-1 within 4 h exposure time. Piper nigrum has the highest and significant toxicity (p<0.05) at 20 μL mL-1 for 96 h. The P. nigrum exhibited the lowest lethal concentration (20.4 μL mL-1) to attain 50% mortality of 4th instar larvae of T. castaneum within 24 h of treatment exposure time as compared to S. aromaticum and M. myristica, resp. Conclusion:Piper nigrum exhibited highest repellent and larvicidal activities against 4th instars of T. castaneum compared to S. aromaticum and M. myristica. Based on this study, P. nigrum essential oil is recommended for indigenous adoption as an aspect of integrated pest management strategies to protect local stored grains in south west Nigeria.