In order to find alternatives to chemical synthetic insecticides in the fight against pest of stored products, we evaluate the insecticidal and repellent activities of three essential oils by contact on the adults of R. dominica. Oils were extracted by hydrodistillation technique for 4 h using a Clevenger from the indigenous medicinal plants then the identification of the constituents was carried out on the basis of gas chromatography coupled with the GCMS spectrometry type Shimadzu TQ8030 coupled with a spectrometer. The different plants are S. molle, M. rotundifolia and S. calamintha. Our results of the contact-toxicity test of oils on substrate showed that the essential oil of M. rotundifolia has a highly significant insecticidal effect with a 100 % mortality at a concentration of 3 μL from the first h of treatment, Similarly the essential oil of S. calamintha has a highly significant biocidal effect with a 100 % mortality at a concentration of 5 μL even the first h of treatment also, the essential oil of S. molle that has an insecticidal effect with a mortality of 100 % at a concentration of 25 μL after 96 h of the treatment. The results of the study of the repulsive effect of the oils tested against the insect showed that the three essential oils possess a remarkable repelling effect just after 2 h of exposure with a PR (The percentage of repulsion) of 50 % for S. molle, 100 % for S. calamintha and M. rotundifolia. The toxicity test of dry powders against the adult beetle showed that the powders exerted their biocidal effect (1.2 g) with a mortality rate of 96, 90 and 75 % respectively for S. calamintha, M. rotundifolia and S. molle after 96 h of treatment. Biotechnological control through the use of essential oils extracted from these plants is tested as a bio insecticide has proved very effective in the protection of cereals against such insects that degrade quality and reduce yield and in addition threaten health of the consumer.

No abstract