Chemical Composition of Essential Oil Extracted fromLaggera pterodontaand its Bioactivities Against Two Stored Product Insects

Abstract

The essential oil was extracted from aerial parts of Laggera pterodonta. Twenty-three components were identified in the essential oil with gas chromatography-mass spectrometry (GC-MS). The main constituents included isoeugenol (34.06%), [S,(-)]-2,3,4,4a,5,6-Hexahydro-1, 4a-dimethyl-7-(1-methylethyl)naphthalene (24.78%), α-caryophyllene (8.19%), eudesm-7(11)-en-4-ol (5.51%), eudesma-3,7(11)-diene (4.43%) and β-caryophyllene (3.70%). Contact and repellent activities of the essential oil and three individual constituents were evaluated. It was found that the essential oil possessed contact activity against Lasioderma serricorne and Liposcelis bostrychophila adults (LD50 = 32.97 µg/adult and 28.53 μg/cm2, respectively). Isoeugenol, α-caryophyllene and β-caryophyllene also exhibited various levels of bioactivities. The results indicate that the essential oil of L. pterodonta and the three selected constituents might be developed into natural insecticides or repellents for control of insects in stored products. Practical Applications The essential oil extracted from aerial parts of Laggera pterodonta, which was traditionally used as Chinese medicinal materials, processed strong contact toxicity against Liposcelis bostrychophila adults. And its LD50 (28.53 μg/cm2) was merely higher than that of the positive control pyrethrins (LD50 = 18.72 µg/cm2). All the essential oil and three selected compounds (isoeugenol, α-caryophyllene and β-caryophyllene) exhibited over 80% repellency against L. bostrychophila adults at 63.17 nL/cm2. The results indicate that the essential oil of L. pterodonta and the selected constituents might be developed into natural insecticides or repellents for control of insects in stored products.