Chemical composition and insecticidal, repellent and antifungal activities of essential oil of Mentha rotundifolia (L.) from Algeria

The biological struggle by the use of the natural substances that have a pesticide effect may be an alternative to harmful chemicals; among these natural substances are the extracts of aromatic plants especially essential oils. The present work aims to highlight the fungicidal and insecticidal effect of the essential oil (EO), of an aromatic plant Mentha rotundifolia, against respectively, a phytopathogenic mold (Fusarium culmorum) and the adults of two pests (Sitophilus granarius and Tribolium confusum) of stored grains. The evaluation of the chemical composition of the EO was carried out by gas chromatography coupled to mass spectrometry (GC/MS). The analysis made it possible to identify 27 compounds, which corresponds to 97.93 % of the totality of the oil of which the majority compounds are: Piperitenone oxide 35.49 +/- 0.08, Caryophyllene oxide 35.27 +/- 0.13 and cisCinerolone 10.95 +/- 0.05. The bioassays to assess the EO toxicity towards the pest insects revealed a very high effect, which increases significantly with the dose and the time of exposure. Similarly, the test for the repellent effect shows that this extract is a powerful insect repellent. In addition, we found that both the liquid and vapor phases of the EO present an inhibitory effect of the growth of the fungal strain. In the light of the results obtained, the plant studied is promising as a source of natural pesticides and lends itself well to research in the field of pest control using biochemical alternatives.