Influence of Eucalyptus spp. essential oils and tannins on herbivory

Abstract

Eucalyptus (family Myrtaceae), a native plant from Australia, is a genus cultivated due to its oil, gum, pulp and timber used worldwide for different commercial applications. It is a plant with significant economic importance and possibly its cultivation, in Brazil and other countries, has reduced the exploitation of native trees. The secondary metabolism of Eucalyptus, as usually found in plants, produces essential oils and tannins, which may interfere in the consumption of plants by wild animals. The goal of the present work was to investigate the influence of essential oil and tannins concentration on the herbivory of seven Eucalyptus taxa. Essential oils composition for all species investigated were characterized by CG MS HS-Trap analysis. The lowest hebivory rate were associated to Urocam, Grancam and Eucalyptus benthamii. Those taxa were associated with the presence of mix oil compounds, α/β-Pinene, Pinocarveol, α-Terpineol and Tannins. Tannins concentrations and essential oil are an important factor that contributes to the plant protection against herbivory.

Myrtaceae anther glands: morphology, anatomy and variation in glandular contents

“…Oil was examined in only six species, but the intention was to compare the oil content of leaves with that of anther glands in species from several different Myrtaceae tribes. E. conferruminata contained 1-8 cineole, which is consistent with other studies on eucalypts (Dunlop et al 1997;King et al 2006;Müller et al 2022). This monoterpene was found in both the leaves and anthers but not in any of the other species.…”

“…One of the characteristics of the family Myrtaceae is the presence of oil glands in the leaves, even in the pith of stems and in various floral parts (Johnson and Briggs 1984). It is generally considered that the oils are unpleasant/poisonous to animals that might be attracted to consume plant parts, and so, they are a protection against herbivory (Rafferty and Lamont 2021;Müller et al 2022). For example, the monoterpene 1,8 cineole, which is a common component of Eucalyptus oil, was considered a deterrent to hares from eating balsam poplars in Alaska (Reichardt et al 1990).…”