Insecticidal activity of the root bark essential oil of Periploca sepium Bunge and its main component.

During our screening programme for agrochemicals from Chinese medicinal herbs, the root bark essential oil of Periploca sepium was found to possess strong contact toxicity against the fruit flies, Drosophila melanogaster with a LD(50) value of 1.22 µg/adult. The main component of the essential oil was identified to be 2-hydroxy-4-methoxy-benzaldehyde (78.8%), followed by linalool (2.8%) and (-)-α-terpineol (2.7%). The 2-hydroxy-4-methoxy-benzaldehyde was further isolated and identified by bioassay-directed fractionation. The compound showed strong contact toxicity against D. melanogaster and the maize weevil (Sitophilus zeamais) with LD(50) values of 1.47 and 6.99 µg/adult, respectively.