Tunisian Eucalyptus essential oils: exploring their potential for biological applications

This study focuses on different chemo-types of Tunisian Eucalyptus essential oils (EOs) and their potential for controlling aphids, phytopathogenic fungi, weed germination and seedling growth.The EOs, obtained from Eucalyptus astringens (Maiden) Maiden and Eucalyptus lehmannii (Schauer) Benth. leaves through hydrodistillation, were analyzed using GC-MS. The chemical analysis revealed a significant presence of oxygenated monoterpenes (ranging from 41.0% to 83.0%), primarily 1,8-cineole (ranging from 30.5% to 58.5%), and oxygenated sesquiterpenes, mainly globulol (19.0%) for E. astringens. In contrast, alpha-pinene (7.0%) was the second most abundant chemical class for E. lehmannii.Statistical analysis demonstrated that both EOs were effective against aphids, fungi, and weeds based on their composition. E. lehmannii showed high efficacy against aphids, causing complete mortality in Aphis fabae Scopoli and an 87.28 +/- 0.65% mortality rate in Aphis nerii Fonscolombe at a concentration of 0.6 mg/mL. E. astringens exhibited antifungal activity with consistent inhibitory effects exceeding 50.59 +/- 0.87% against Fusarium oxysporum Schltdl., and Sclerotinia sclerotiorum (Lib.) de Bary displayed even higher susceptibility with an inhibition rate of 83.33 +/- 1.10%.Similarly, E. lehmannii inhibited fungal growth by nearly 50%, with Fusarium culmorum Schltdl. exhibiting a minimum inhibition rate of 45.59 +/- 0.71%. Both EOs also displayed significant herbicidal potential by impeding weed germination and seedling growth. Sinapis arvensis L. was particularly susceptible, with complete inhibition observed at a concentration of 2 mg/mL. Overall, these findings highlight the potential application of these Eucalyptus EOs for bio-control, underscoring their diverse characteristics.