A study of fumigation toxicity of horseradish essential oil against two stored grain insects

Horseradish essential oil is a biological fumigant which was extracted from Armoracia rusticana. The effects of different concentrations, temperatures and grain types by fumigation using horseradish essential oil were studied in this paper. The oil had significant fumigation efficacy against pests in stored grain under natural conditions. In the absence of grain, a concentration of 2.25 ppm horseradish essential oil could kill and Rhyzopertha dominica after 12 h at 25oC. Three ppm of horseradish essential oil could kill all the S. zeamais and R. dominica on the surface of maize, wheat and paddy during 72 h exposure at 25oC. The mortalities of S. zeamais placed under maize, wheat and paddy were 100%, 100% and 98%, respectively, using 24 ppm of horseradish essential oil at exposure for 72 h at 25oC. The mortalities of R. dominica were 100%, 93% and 86%, respectively, under the above conditions. Temperature did not result in significant differences on the fumigation efficacy of horseradish essential oil. Different types of stored grain had a significant influence on the fumigation efficacy of horseradish essential oil. The order of fumigation efficacy were maize, wheat and paddy. We concluded that horseradish oil could be used as a sanitary and environmentally user-friendly bio-fumigant within empty granaries or other storage structures.Keywords: Horseradish oil, Stored grain pest, Fumigant toxicity, Fumigatio