Antimicrobial and insecticidal activity of Myrtus communis essential oils: Biological potential and ecological applications

Abstract

This study aims to investigate the bioactive molecules in Myrtus communis essential oil (MCEO) using the GC-MS method, and to assess their antibacterial, antifungal, and insecticidal activities. The insecticidal evaluation focuses on toxicity via inhalation and contact, examining adulticidal (adult mortality), ovicidal (impact on egg laying), and larvicidal (reduction in offspring emergence) effects. Biochemical analysis identified 24 compounds, accounting for 99.3% of the total oil content, with major components being 1,8-cineole (32.5%), α-pinene (18.6%), myrtenyl acetate (18%), limonene (10.9%), and α-terpenyl acetate (7.3%). Antibacterial and antifungal activities were evaluated against pathogenic strains using MIC and MBC assays. Results indicate significant inhibition of fungal growth, with a notably low MIC of 1.03% recorded against the Aspergillus niger HO32. Conversely, MIC values for bacterial strains remained relatively high, suggesting some resistance to MCEO. Regarding insecticidal activity, the inhalation test showed higher efficacy (LC50 = 1.38 ± 0.15 μL/L air) compared to the contact test (LC50 = 2.48 ± 0.39 μL/100 g) after 24 hours of exposure. Furthermore, the contact test showed a significant reduction in fertility and insect emergence at a dose of 20 μL/mL.