TOXICOLOGICAL AND PHYSIOLOGICAL EFFECTS OF ESSENTIAL OILS AGAINST TRIBOLIUM CASTANEUM (COLEOPTERA:TENEBRIONIDAE) AND CALLOSOBRUCHUS MACULATUS (COLEOPTERA: BRUCHIDAE)

The aim of this study was to investigate the toxicity and physiological effect of cardamom, cinnamon and nutmeg oils against egg, larva, and adult of Tribolium castaneum Herbst and Callosobruchus maculatus F. Further biochemical tests were conducted to assess the impact of essential oils on total carbohydrate, protein, fat contents and also assess the enzymes esterase and glutathione s-transferase activity. The mortality results indicated that cinnamon oil has the highest efficacy against egg, larva, and adult of C. maculatus with an LC50 of 0.01%, 0.132%, and 0.186%, respectively compared with T. castaneum, which recorded 1.051%, 0.109%, and 1.239% respectively. Furthermore, all essential oils reduce the total carbohydrate, protein, and fat contents, and cinnamon oil demonstrated to be the most effective among the three essential oils. On the same note, cinnamon oil had a greater impact of inhibiting esterase and glutathione s-transferase activity compared to nutmeg and cardamom oils. Thus, from the results, all the tested essential oils produced a significant range of biological effect on T. castaneum and C. maculatus. However, cinnamon oil was the most effective making it suitable botanical extract to develop fumigant to control and manage T. castaneum and C. maculatus with less environmental hazards.