Abstract: Objective: This study was carried out to investigate the insecticidal activity of Citrus aurantium (Rutaceae), Eruca sativa (Brassicaceae), Zingiber officinale (Zingiberaceae) and Origanum majorana (Lamiaceae) volatile oils (EO) and organophosphate insecticide (Chlorpyrifos) against R. dominica. Materials and Methods: The wheat grains were treated by plant oil extracts and chlorpyrifos with different concentrations, then they were given as food for the insect pests to record mortality percentages and identify the LC25, LC50 and LC90 for each one. Also, different enzymes, DNA concentration and DNA damage for treated insects were estimated. Results: The data was showed that the activity ratios of AChE, acid, alkaline phosphatase, lactate dehydrogenase and Phenol Oxidase (PO) ranged from 0.97-0.75, 1.08-0.71, 1.09-0.60, 1.39-0.57 and 1.37-0.67, respectively. The DNA tail (%), tail moment, olive-tail moment and tail length were all greater in case of treatment with chlorpyrifos compared with the control. Conclusion: The tested plant oils could play a significant role as safer insecticide than chemical one. Tested plant oils could be used as a practical tool of integrated pest management program as insecticides for the stored-grain insects.