Comparative study of the insecticidal effect of essential oils belonging to the Myrtaceae family

Abstract

Our main objective is to evaluate the bioinsecticidal effect of essential oils from two plants, Eucalyptus radiata and Eucalyptus globulus, on the species of Culex pipiens mosquitoes at the L4 stage. An ATR-IR spectral analysis of the essential oils of E. globulus and E. radiata, as well as a chromatographic characterization by gas chromatography of the essential oil of E. radiata, were performed. Biological tests revealed that these two essential oils possess remarkable bioinsecticidal properties. Indeed, individuals treated with E. globulus essential oil at a concentration of 70 mg/L showed a mortality rate of 100% after 96 hours of treatment, whereas populations treated with E. radiata essential oil had a mortality rate of 85%±2.90 after 96 hours of exposure at the highest concentration of 70 mg/L. E. globulus essential oil proved to be slightly more toxic, with a CL50 of 23.98 mg/L and a TL50 of 25 hours, followed by E. radiata essential oil with a CL50 of 53.70 mg/L and a TL50 of 37 hours. ATR-IR spectroscopy results show that E. globulus essential oil contains 15 different compounds, such as 1,8-cineole (eucalyptol), pinene, amyl alcohol, turpentine oil, as well as other compounds like soluble starch and isotactic polypropylene. ATR-IR spectroscopy results show that E. radiata essential oil contains different major compounds such as 1,8-cineole (eucalyptol) and alcohol. The gas chromatography analysis of E. radiata essential oil revealed the presence of 30 distinct compounds, representing 99.98% of the oil's total composition. Among these compounds are viridiflorol (5.20%), globulol (0.74%), piperitone (0.37%), and guaiol (0.27%). These results show that E. radiata and E. globulus essential oils are promising bioinsecticides for preventive control of Culex pipiens and could be an alternative to chemical insecticides.