The greater rice weevils, Sitophilus zeamais, are one of the devastating insect pests of stored cereals. Since they reside in stored product, mainly food, synthetic insecticides are not favorable choice to control them, as which botanical pesticides can be alternatives in this particular situation. In the present study, contact and fumigant activity of twenty-three plant essential oils against the adults S. zeamais were examined. To identify the chemical compositions of potent essential oils, Gas chromatography-mass spectrometry was performed. Interestingly, essential oils which showed great contact toxicity did not always produce fumigant toxicity accordingly. Among the twenty-three oils assessed, seventeen oils displayed acute contact toxicity and only six oils exhibited fumigant effect. Cinnamon oil was the most toxic in both fumigant and contact assays (LC50 = 10.02 μL/L air, 0.04 μL/cm2, respectively). Cinnamaldehyde in cinnamon oil and terpinen-4-ol in tea tree and majoram oils were identified as the most abundant components, respectively.

• Yunho Yang(Department of Agricultural Biotechnology, Seoul National University)
• Jun-Hyung Tak(Department of Agricultural Biotechnology, Seoul National University)