Chemical composition and bioactivity of essential oil from Eucalyptus occidentalis leaves against two stored product pests
AbstractAttempts 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 ofEucalyptus occidentalisessential oil and investigated the fumigant, contact and repellent effects againstTribolium castaneum(Herbst) (Col: Tenebrionidae) andRhyzopertha 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 toR. dominica(LD50value 0.82 μL/cm) than toT. castaneum(LD50value 0.99 μL/cm) and showed the same fumigant toxicity for both insects according to the 95% confidence limit of LC50. The repellency againstT. castaneumwas more than forR. dominicaand increased from 14 to 75% forR. dominicaand 22 to 78% forT. castaneumafter 2 h. These results suggest thatE. occidentalisessential oil is a potential candidate for use as a natural repellent and insecticide for stored-product insect pests.