Abstract: To investigate the relationship between different tree age/insect infection status and chemical constituents of essential oil from the leaves of Eucalyptus grandis×E.urophylla, aiming to empolder it efficiently. Eucalyptus essential oil was extracted by steam distilling (SD) and analyzed by GC-MS method.The results showed that along with the increasing of tree age,the amount of Eucalyptus oil increased year by year.However,the composition and relative contents of essential oil varied yearly.The changes of relative content of main component was:Cineole and terpinyl acetate increased with time increments;Camphene,β-pinene and α-terpineol decreased annually;d-Limonene and α-pinene reached a peak in 4 to 5 years,and then began to decline.While infected by Batocera horsfieldi (HoPe),the amount of cineole,α-pinene, β-pinene and camphene was relatively decreased,but the contents of d-limonene,α-terpineol and terpinyl increased.

Key words: Eucalyptus grandis×, E.urophylla, essential oil, age, Batocera horsfieldi (HoPe)