Abstract
The use of insecticides is one of the effective methods of control of insects in stored foodstuffs, but the presence of residues in the foodstuffs and the emergence of strains of insects resistant to these insecticides are becoming more and more worrying. All these reasons militate in favor of the search for alternative methods, in particular, the use of essential oils with insecticide and/or insect repellent properties. For this purpose, the repellent effect of the essential oils of the aerial part of Origanum glandulosum (Desf.) (Lamiaceae), the seeds of Piper nigrum L. (Piperaceae) and the combination between the two oils (1/2:1/2) against the insect Tribolium confusum (Duval) were evaluated using the preferential area method on filter paper. The essential oils were obtained by hydrodistillation using a Clevenger-type apparatus, then, four different contents of these oils were prepared by dilution in acetone, in the proportions of 2, 4, 8, 12 µl/ml of acetone which corresponds to 0.031, 0.062, 0.125, 0.188 µl/cm2 respectively. The result reveals that the highest dose of O. glandulosum (Desf.) and the combination of the (O. glandulosum (Desf.) and P. nigrum L.) has a strong repellent effect of 93.33% on adults of T. confusum (Duval). Also, the combination of the two essential oils has shown the lowest RD50 (0.0013μl/cm2) followed by the oil of O. glandulosum (0.013μl/cm2). However, the oil of P. nigrum records the highest RD50 (0.025 μl/cm2). From these results, it was concluded that the repulsion percentage of the oils is dose-dependent and the RD50 varies according to the sensitivity of the insect to essential oils.