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Attempts have been made in recent years to reduce the use of synthetic pesticides and seek alternative and innovative methods for pest control. We conducted a study on the chemical composition of Eucalyptus occidentalis essential oil and investigated the fumigant, contact and repellent effects against Tribolium castaneum （Herbst） （Col: Tenebrionidae） and Rhyzopertha dominica （F.） （Col: Bostrichidae）. The major components were τ-cadinol （17.20）, 1,8-cineol （15.5%）, α-cadinol （14%） and α-pinene （9.21%）. The contact toxicity experiment showed that the oil was more toxic to R. dominica （LD 50 value 0.82 μL/cm） than to T.?castaneum （LD 50 value 0.99 μL/cm） and showed the same fumigant toxicity for both insects according to the 95% confidence limit of LC 50 . The repellency against T. castaneum was more than for R. dominica and increased from 14 to 75% for R. dominica and 22 to 78% for T. castaneum after 2 h. These results suggest that E. occidentalis essential oil is a potential candidate for use as a natural repellent and insecticide for stored-product insect pests.
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