Toxicity of bisabolangelone from Ostericum koreanum roots to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae).

The acaricidal activity of materials derived from the roots of Ostericum koreanum (Apiaceae) toward adults of Dermatophagoides farinae and Dermatophagoides pteronyssinus was examined by direct contact and vapor phase toxicity bioassays. Results were compared with those of three acaricides: benzyl benzoate, dibutyl phthalate, and N,N-diethyl-m-toluamide (DEET). The active principle was identified as the sesquiterpenoid bisabolangelone by spectroscopic analysis. In fabric-piece contact toxicity bioassays using adult D. farinae, bisabolangelone (1.88 microg/cm2) was more toxic than benzyl benzoate (11.91 microg/cm2), DEET (62.20 microg/cm2), or dibutyl phthalate (79.54 microg/cm2), based on 24-h LD50 values. Against adult D. pteronyssinus, bisabolangelone (1.79 microg/cm2) was similarly more active than benzyl benzoate (9.65 microg/cm2), DEET (64.45 microg/cm2), and dibutyl phthalate (77.79 microg/cm2). In vapor phase toxicity tests with both mite species, bisabolangelone was equitoxic in closed versus open containers. These results indicate that bisabolangelone was largely toxic through contact action. Bisabolangelone merits further study as a potential contact acaricide or lead for the control of house dust mites.