title: Contact and fumigant toxicity of Armoracia rusticana essential oil, allyl isothiocyanate and related compounds to Dermatophagoides farinae.
abstract: BACKGROUND
  The toxicity to adult Dermatophagoides farinae of allyl isothiocyanate identified in horseradish, Armoracia rusticana, oil and another 27 organic isothiocyanates was evaluated using contact + fumigant and vapour-phase mortality bioassays. Results were compared with those of two conventional acaricides, benzyl benzoate and dibutyl phthalate.
  
  
  RESULTS
  Horseradish oil (24 h LC(50), 1.54 µg cm(-2)) and allyl isothiocyanate (2.52 µg cm(-2)) were highly toxic. Benzyl isothiocyanate (LC(50) , 0.62 µg cm(-2)) was the most toxic compound, followed by 4-chlorophenyl, 3-bromophenyl, 3,5-bis(trifluoromethyl)phenyl, cyclohexyl, 2-chlorophenyl, 4-bromophenyl and 2-bromophenyl isothiocyanates (0.93-1.41 µg cm(-2)). All were more effective than either benzyl benzoate (LC(50) , 4.58 µg cm(-2)) or dibutyl phthalate (24.49 µg cm(-2)). The structure-activity relationship indicates that types of functional group and chemical structure appear to play a role in determining the isothiocyanate toxicities to adult D. farinae. In the vapour-phase mortality bioassay, these isothiocyanates were consistently more toxic in closed versus open containers, indicating that their mode of delivery was, in part, a result of vapour action.
  
  
  CONCLUSIONS
  In the light of global efforts to reduce the level of highly toxic synthetic acaricides in indoor environments, the horseradish oil-derived compounds and the isothiocyanates described herein merit further study as potential acaricides for the control of house dust mite populations as fumigants with contact action.
authors.affiliation: Entomology Major, Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yeon-Kyeong
authors.initials: YK
authors.lastname: Yun
authors.forename: Hyun-Kyung
authors.initials: HK
authors.lastname: Kim
authors.forename: Jun-Ran
authors.initials: JR
authors.lastname: Kim
authors.forename: Kumnara
authors.initials: K
authors.lastname: Hwang
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Ahn
mesh_terms: D056810:Acaricides / Q000633:toxicity*; D000818:Animals; D031215:Armoracia / Q000737:chemistry*; D040001:Dermatophagoides farinae / Q000187:drug effects*; D005651:Fumigation; D017879:Isothiocyanates / Q000633:toxicity*; D009822:Oils, Volatile / Q000633:toxicity*; D010936:Plant Extracts / Q000633:toxicity*; D010938:Plant Oils / Q000633:toxicity*; D013329:Structure-Activity Relationship
chemical_list: D056810:Acaricides; D017879:Isothiocyanates; D009822:Oils, Volatile; D010936:Plant Extracts; D010938:Plant Oils; C004471:allyl isothiocyanate