Ruta chalepensis L. Essential Oil Has a Biological Potential for a Natural Fight against the Pest of Stored Foodstuffs: Tribolium castaneum Herbst

Chemical pesticides used against insect pests of stored food have adverse effects on both health and the environment. So, the present study aims to evaluate the insect repulsive and insecticidal power of Ruta chalepensis L. essential oil (EO) from the region of Oulmes (Central plateau of Morocco); the ultimate objective is to develop a biological and ecological control strategy against pests. Thus, the EO obtained by hydrodistillation from the aerial parts of Ruta chalepensis L. was identified by GC-MS; its repellent and fumigant toxicity effects on adults of Tribolium castaneum Herbst were, respectively, investigated by the preferential area method on a filter paper and the inhalation test. The insecticide power was estimated by determining the percentage of mortality as a function of the duration of exposure and concentration of the EO. The essential oil obtained is characterized by the dominance of 2-undecanone (64.35%), piperonyl piperazine (11.9%), 2-decanaone (5.12%), 2-dodecanone (4.52%), decipidone (3.9%,) and 2-tridecanone (2.36%). This EO is endowed with a very repulsive power belonging to class V, which is strongly due to its majority compound 2-undecanone. The dose 0.038 μl/ml gave a repellent power of 100% after 15 min. The tests also revealed a considerable insecticidal effect, which reached 100% after 48 hours at a dose of 0.62 μl/ml. The calculation of the lethal dose causing 50% mortality (LD50) and the lethal times after which there is 50% mortality (LT50) allowed deducing that the insecticidal effect of Ruta chalepensis L. is time- and dose-dependent. Hence, the effectiveness of Ruta chalepensis L. EO attests that it can constitute a healthy alternative to fight against Tribolium castaneum Herbst.