Characterization of the physiological condition of Eucalyptus globulus labil by headspace HRGC analysis of the bouquet of odors

The borer Phoracantha semipuntacta originates from Australasia and has spread to Africa, Europe, and America where it attains major pest status on eucalyptus crops. However, in an eucalyptus stand not all trees are equally attractive to females of P. semipunctata searching for ovipositing sites. Previous studies indicate a non‐random host selection process in which olfactory stimuli play an important role. Field experiments, conducted to decode the mechanisms of primary attraction, showed that eucalyptus logs originating from trees already attacked by the borer captured significantly more adults and eggs of P. semipunctata than the ones cut from vigorous trees. A High Resolution Gas Chromatography‐Head Space (HRGC‐HS) technique was used, to analyze and compare the profiles of the volatiles emitted by attacked, and unattacked E. globulus. Identification of the chromatographic peaks was achieved by GC‐MS. Significant differences were found between the two types of trees, particularly in the contents of α‐phellandrene, α‐pinene, and p‐cymene. A relationship between tree physiological condition—attacked or unattacked—and the bouquet of odors emitted was thus established.