Phytochemical composition, toxicity, and repellent effects of medicinal plants Peganum harmala, Pterocarya fraxinifolia, and Tanacetum parthenium extracts against Sitophilus oryzae L.

Abstract

Sitophilus oryzae is an important pest of stored rice and is usually controlled by the use of aluminum phosphide, which is dangerous to humans. Botanical insecticides deemed promising alternatives in controlling this pest. In this study, extracts of Peganum harmala seeds, Pterocarya fraxinifolia leaves, and Tanacetum parthenium flowers were evaluated against S. oryzae adults. Phytochemical analyses showed that steroid, terpenoid, tannin, alkaloid, and flavonoid are present in the extracts. Bioassays revealed repellency effects of all extracts, besides, P. harmala extract exerted significant mortality (93.33 ± 6.6%, LC50: 521.06 mg/ml) hence it may have applications in preventing infestation of stored rice by S. oryzae. Highlights Plant extracts studied in this research efficiently repel rice weevil. These plant extracts show significant toxicity against rice weevil. Alkaloid, steroid, terpenoid, tannin, and flavonoid are present in extracts of these plants.