Bioactivity and Chemical Composition of Essential Oils from Three Chemotypes of Aeollanthus pubescens Benth

Aeollanthus pubescens Benth. (Lamiaceae) is a herbaceous plant that is native to West Africa. It is commonly used in cooking and traditional healing in some parts of Togo and Benin. This study analyzed the chemical compositions of essential oils obtained from different parts of Togo (Kozah, Est-Mono, and Ogou) using gas chromatography-mass spectrometry. Additionally, the study investigated the bioactivity of essential oils and water extracts on the cowpea weevil Callosobruchus maculatus, plant parasitic nematode Meloidogyne incognita, and two plant seeds, Sesamum indicum, and Pennisetum glaucum, regarding germination inhibition. The results showed that the major components of the different essential oils were thymol (55.02%) and thymol acetate (20.03%) for Kozah, D-fenchone (65.05%) for Est-Mono, and thymol (29.48%), carvacrol (20.93%), thymol acetate (16.98%), and carvacryl acetate (13.14%) for Ogou. The Est-Mono essential oil was the most effective in controlling cowpea weevils with an EC50 value of 3.1 ± 0.6 μL/L air. Kozah and Ogou essential oils showed more potent nematicidal activity with ECSUB50/72h/SUB values of 305.4 ± 7.3 mg/L and 275.6 ± 2.6 mg/L, respectively, while Est-Mono essential oil did not exhibit any activity. Finally, the Kozah and Ogou essential oils were found to inhibit the germination of dicotyledonous S. indicum seeds by more than 80% at 10 mg/mL, while less germicidal activity was observed on the monocotyledon P. glaucum from the different essential oils. These findings suggest that extracts of A. pubescens could be used in agriculture as a biopesticide.