Acaricidal Activities of Major Constituents of Essential Oil of Juniperus chinensis Leaves against House Dust and Stored Food Mites

The acaricidal activities of major constituents from the oil of Juniperus chinensis (var. globosa) leaves were compared with those of DEET (N,N-diethyl-m-toluamide) by using impregnated fabric disk bioassay against Dermatophagoides spp. and Tyrophagus putrescentiae. Toxicity varied with doses as well as chemical composition. The 50% lethal doses (LD50) of J. chinensis oil against Dermatophagoides farinae, Dermatophagoides pteronyssinus, and T. putrescentiae were 21.60, 19.89, and 38.10 mu g/cm(2), respectively. The active constituent was purified using silica gel chromatography and high-performance liquid chromatography. The acaricidal component was identified as bornyl acetate through gas chromatography-mass spectrometry, H-1 nuclear magnetic resonance (NMR), C-13-NMR, H-1-C-13 shift correlation spectrum-NMR, and distortionless enhancement by polarization transfer-NMR. The LD50 of bomyl acetate (2.94 mu g/cm(2)) against D. farinae was significantly lower than those of DEET (37.13 mu g/cm(2)) and alpha-eudesmol (29.72 mu g/cm(2)). Similar results were observed when bomyl acetate and alpha-eudesmol were tested against D. pteronyssinus and T. putrescentiae. The lower LD50 of bomyl acetate indicates that it may be responsible for the major acaricidal activity against house dust and stored food mites, even though it constitutes only 19.5% of J. chinensis oil. Overall, these findings indicated that bomyl acetate and alpha-eudesmol have potential for use as control agents against house dust and stored food mites.