Abstract: In order to evaluate the control effect ofEucalyptus camaldulensis, E. maidenii, E.globulus, E. robusta, E. camphora, E. tereticornis, E. triflora, Citrus maxima, C. limon, C. sinensis,andC. reticulataplant essential oils againstSitophilus oryzaeandOryzaephilus surinamensis, the fumigant and contact toxicity activities of essential oils were tested. The essential oils of 11 kinds of plants were extracted by steam distillation. Filter paper impregnation was used for testing fumigant toxicity, topical application method was employed for contact toxicity studies. The fumigant toxicities of essential oils fromE. camaldulensisagainstS. oryzaewere the best, with LC50 of 29.42 mg/L, followed by essential oils fromE. globulus, with LC50 of 39.22 mg/L. The fumigant toxicities of essential oils fromE. camaldulensisagainstO. surinamensiswere the best, with LC50 of 4.97 mg/L, followed by essential oils fromE. globulus, with an LC50 of 11.27 mg/L. The essential oils ofC. maximadisplayed contact toxicity againstS. oryzaewith LD50 values of 29.84 μg/adult, followed by essential oils fromE. camaldulensis, with LD50 of 61.92 μg/adult. The essential oils ofE. camaldulensisexhibited contact toxicity againstO. surinamensiswith LD50 values of 7.74 μg/adult, followed by essential oils fromE. triflora, with LD50 of 16.22 μg/adult. The essential oil ofE. camaldulensisrevealed significant fumigation activity against bothS. oryzaeandO. surinamensis. Its contact activity againstS. oryzaewas second only to that ofC. maxima, and its contact activity againstO. surinamensiswas also the best. The main component of the essential oil fromE. camaldulensiswas (+)-spathulenol (18.48%), while the essential constituent of the essential oil fromC. maximawas D-limonene (37.79%). This study revealed that the essential oils ofE.camaldulensis, C. maximahad the potential to controlS. oryzaeandO. surinamensis, and provided a basis for further understanding the interaction between pests and essential oils.

Key words: essential oils;Sitophilus oryzae, Oryzaephilus surinamensis, fumigant toxicity, contact toxicity