FUMIGANT TOXICITY OF ESSENTIAL OILS AND THEIR COMBINATIONS TOWARDS Sitophilus oryzae (L.), Tribolium confusum (J. du Val), AND Callosobruchus maculates (FABR.)

Abstract

This study examined the fumigant efficacy of seven essential oils from rosemary, caraway, coriander, thyme, dill, camphor and basil against the adult of Sitophilus oryzae (L.), Tribolium confusum (J. du Val) and Callosobruchus maculates (Fabr.). The rosemary and caraway oil showed the highest fumigant efficacy against the rice weevil at a concentration of LC 50 (26 µl/l air) and (38 µl/l air), respectively. Rosemary (19 µl/l air) and coriander (23 µl/l air), had potent fumigant activities against the T. confusum. The caraway and rosemary were the most effective against C. maculates at LC 50 (19 µl/l air) and LC 50 (25 µl/l air) respectively. In conclusion rosemary and caraway showed strong fumigant toxicity to the S. oryzae, T. confusum and C. maculates. However, thyme and coriander had a lower fumigant activity than rosemary to insects. On the other hand, camphor, dill and basil also showed promising fumigant toxicities on the insects. The toxicity of the essential oils in combination (21 combinations) was investigated. The results obtained indicate that the mixture (caraway + coriander) was the most toxic to the S. oryzae and T. confusum with synergic category 86 and 71.6, respectively. Whereas the mixture (caraway + camphor) was the most toxic to the C. maculates with synergic category 71.2. Therefore, rosemary and other natural volatiles could be safe fumigants to control stored-grain insect pests, and can be used in the IPM programmes.