Use of binary mixtures of three Mentha essential oils for the control of rice weevil Sitophilus oryzae (Curculionidae)

Abstract

Essential oils are well known to act as biopesticides in pest management programs. The main purpose of this research is to explore the insecticidal potential (fumigant and repellent toxicity) of binary mixtures of essential oils extracted from leaves of three Mentha species namely Mentha rotundifolia, M. viridis and M. longifolia collected from north Tunisia against adults of the rice weevil Sitophilus oryzae. Gas chromatography-mass spectrometry analyses revealed quantitative and qualitative variations among oils chemical composition. Three common compounds β-pinene (0.37–1.06%), α-limonene (0.32–18.39%) and pulegone (0.54–68,057%) were detected. Results showed that when applied alone, the oils exhibited a strong gradient of toxicity with M. rotundifolia being the most effective (CL50: 7.67 μL/L air) compared to M. longifolia (CL50: 12.32 μL/L air) and M. viridis oil (CL50: 100.16 μL/L air). In essential oils binary mixtures experiments, the combination M. rotundifolia x M. viridis exhibited the strongest insecticidal activity (CL50: 8.19 μL/L air) followed by M. rotundifolia x M. longifolia (CL50: 12.49 μL/L air) and M. longifolia x M. viridis (CL50: 19.36 μL/L air). Repellent toxicity was highly dependent upon oils binary mixture and concentrations. The mixture M. longifolia x M. viridis was more effective (PR = 40% at the concentration of 0.032 μl/cm2). Overall, this work demonstrates the interest of combing essential oils as a promising alternative to control S. oryzae in storage. This work promotes operating technologies of essential oils to better guide the biopesticide industry towards a sustainable development path.