The interaction between the gall wasp Leptocybe invasa and Eucalyptus camaldulensis leaves: A study of phyto-volatile metabolites

A comparative study of the volatile terpene fraction isolated from the leaves of Eucalyptus camaldulensis attacked by the gall wasp (Leptocybe invasa) and from the healthy leaves of the plant was carried out using gas chromatography-mass spectrometry. A total of 59 components representing 89.13 and 88.6%, respectively, of their total volatile fraction contents were analyzed. Of these volatiles, 26 compounds with concentrations greater than (0.1± 0.02%) have been used for statistical comparison. A number of 21of these compounds were identified, in different concentrations, in the leaves volatile fraction of both healthy plants and plants attacked by the wasps. The other 5 volatiles: p-mentha-2-4(8) diene, δ-elemene, β-elemene, E-caryophyllene and bicyclogermacrene, were exclusively found in the volatile fraction of the attacked leaves. The newly produced compounds in the attacked leaves or the change in concentration of those commonly found in that fraction, could be part of the plant defense mechanisms, or/and an element of the plant allelopathic and communication mechanisms. Identifying the components of the gall wasp-damaged leaves can help in their recycling for different physiological, pharmacological and medicinal uses. Key words: Eucalyptus, gall wasp, plant defense mechanisms, plant recycling, terpene fraction.