Identification of Insecticidal Constituents of the Essential Oil of Acorus calamus Rhizomes against Liposcelis bostrychophila Badonnel

The aim of this research was to determine the chemical composition of the essential oil ofAcorus calamusrhizomes, its insecticidal activity against the booklouse, (Liposcelis bostrychophila) and to isolate any insecticidal constituents from the essential oil. The essential oil ofA. calamusrhizomes was obtained by hydrodistillation and analyzed by GC-FID and GC-MS. A total of 32 components of the essential oil ofA. calamusrhizomes was identified and the principal compounds in the essential oil were determined to be α-asarone (50.09%), (E)-methylisoeugenol (14.01%), and methyleugenol (8.59%), followed by β-asarone (3.51%), α-cedrene (3.09%) and camphor (2.42%). Based on bioactivity-guided fractionation, the three active constituents were isolated from the essential oil and identified as methyleugenol, (E)-methylisoeugenol and α-asarone. The essential oil exhibited contact toxicity againstL. bostrychophilawith an LD50value of 100.21 µg/cm2while three constituent compounds, α-asarone, methyleugenol, and (E)-methylisoeugenol had LD50values of 125.73 µg/cm2, 103.22 µg/cm2and 55.32 µg/cm2, respectively. Methyleugenol and (E)-methylisoeugenol possessed fumigant toxicity againstL. bostrychophilaadults with LC50values of 92.21 μg/L air and 143.43 μg/L air, respectively, while the crude essential oil showed an LC50value of 392.13 μg/L air. The results indicate that the essential oil ofA. calamusrhizomes and its constituent compounds have potential for development into natural fumigants/insecticides for control of the booklice.Keywords:Acorus calamus;Liposcelis bostrychophila;fumigant;contact toxicity;essential oil composition