title: Acaricidal activity of Thymus vulgaris oil and its main components against Tyrophagus putrescentiae, a stored food mite.
abstract: The acaricidal activities of compounds derived from Thymus vulgaris (thyme) oil against Tyrophagus putrescentiae were assessed using an impregnated fabric disk bioassay, and were compared with those of the synthetic acaricides, benzyl benzoate and N,N-diethyl-m-toluamide. The observed responses differed according to dosage and chemical components. The 50% lethal dose (LD50) value of the T. vulgaris oil against T. putrescentiae was 10.2 microg/cm2. Biologically active constituents derived from T. vulgaris oil were purified by using silica gel chromatography and high-performance liquid chromatography. The structures of acaricidal components were analyzed by gas chromatography-mass spectrometry, 1H nuclear magnetic resonance (NMR), 13C NMR, 1H-13C COSY-NMR, and DEPT-NMR spectra, and were subsequently identified as carvacrol and thymol. Carvacrol was the most toxic compound with LD50 values (4.5 microg/cm2) significantly different from thymol (11.1 microg/cm2), benzyl benzoate (11.3 microg/cm2), and N,N-diethyl-m-toluamide (13.9 microg/cm2). Linalool was as toxic as was N,N-diethyl-m-toluamide. The lower LD50 of carvacrol indicates that it may be the major contributor of the toxicity of T. vulagaris oil against the stored food mite, although it only constitutes 14.2% of the oil. From this point of view, carvacrol and thymol can be very useful as potential control agents against stored food mite.
authors.affiliation: Faculty of Biotechnology and Center for Agricultural Science & Technology, College of Agriculture & Life Science, Chonbuk National University, Chonju 561-756, South Korea.
authors.forename: E Y
authors.initials: EY
authors.lastname: Jeong
authors.forename: J H
authors.initials: JH
authors.lastname: Lim
authors.forename: H G
authors.initials: HG
authors.lastname: Kim
authors.forename: H S
authors.initials: HS
authors.lastname: Lee
mesh_terms: D000818:Animals; D001681:Biological Assay; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D000081007:Cymenes; D004305:Dose-Response Relationship, Drug; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D007306:Insecticides / Q000494:pharmacology*; D007928:Lethal Dose 50; D008925:Mites / Q000187:drug effects*; D039821:Monoterpenes / Q000494:pharmacology; D010572:Pest Control, Biological / Q000379:methods; D010938:Plant Oils / Q000494:pharmacology*; D013943:Thymol / Q000494:pharmacology; D046930:Thymus Plant / Q000737:chemistry*
chemical_list: D000081007:Cymenes; D007306:Insecticides; D039821:Monoterpenes; D010938:Plant Oils; D013943:Thymol; C073316:carvacrol