Abstract

In our screening program for new agrochemicals from local wild plants and Chinese medicinal herbs, the essential oil of Evodia lepta (Rutaceae) root barks was found to possess strong insecticidal activity against the maize weevil, Sitophilus zeamais Motsch. and red flour beetle, Tribolium castaneum Herbst. Essential oil of E. lepta root barks was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 35 components of the essential oil were identified. The main components of the essential oil were α-pinene (26.68%), borneol (7.24%) and trans-pinocarveol (6.82%) followed by evodionol (4.71%), α-terpineol (4.56%) and α-campholenal (4.15%). The essential oil of E. lepta possessed strong fumigant toxicity against S. zeamais and T. castaneum adults with LC₅₀ values of 25.05 and 12.09 mg/L air, respectively. The essential oil also showed contact toxicity against S. zeamais and T. castaneum adults with LD₅₀values of 125.21 and 166.94 μg/adult, respectively.

Key words: Evodia lepta, Sitophilus zeamais, Tribolium castaneum, contact toxicity, fumigant, essential oil composition.