Insecticidal activity of the essential oil of Lonicera japonica flower buds and its main constituent compounds against two grain storage insects

Abstract

The aim of this research was to determine acute toxicity of the essential oil of Lonicera japonica Thunb. (Caprifoliaceae) flower buds against the booklouse (Liposcelis bostrychophila Badonnel) and the maize weevils (Sitophilus zeamais Motschulsky). Essential oil of L. japonica flower buds was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 25 components of the essential oil were identified. The principal compounds in the essential oil were estragole (80.17%) and linalool (6.05%). The essential oil exhibited strong contact toxicity against S. zeamais and L. bostrychophila with LD50 values of 21.54 µg/adult and 64.04 µg/cm2, respectively. The constituent compounds, estragole (LD50 = 49.95 µg/cm2) and linalool (LD50 = 172.54 µg/cm2) also possessed contact toxicity against L. bostrychophila. L. japonica essential oil and its constituent compounds (estragole and linalool) exhibited fumigant toxicity against S. zeamaiswith LC50 values of 13.36, 14.10 and 10.46 mg/L, respectively. The essential oil of L. japonica(LC50 = 0.20 mg/L) and its constituent compounds, estragole (LC50 = 0.16 mg/L) and linalool (LC50 = 0.41 mg/L) possessed fumigant toxicity against L. bostrychophila. The results indicated that the essential oil of L. japonica and its constituent compounds showed potential in terms of contact and fumigant toxicity against grain storage insects. Key words: Lonicera japonica, Liposcelis bostrychophila, Sitophilus zeamais, contact toxicity, fumigant, essential oil composition, estragole, linalool.