[Breeding control and immobilizing effects of wood microingredients on house dust mites]

The possible effects of essential oils as wood microingredients on house dust mites (Tyrophagus putrescentiae, Dermatophagoides farinae and Dermatophagoides pteronyssinus) were investigated. 1. Whether small pieces of 5 types of wood had any control effect on mite breeding was studied. Mite breeding using only normal feed was compared with breeding using feed mixed with small pieces of wood. In addition, mite breeding using feed mixed with small pieces of wood with no essential oil was studied. 2. Effects of 6 different wood essential oils in immobilizing mites were studied with regard to respired and contact toxicities. 3. The immobilizing effects of 10 ingredients in Hinoki oil were also specifically studied with regard to contact toxicity. The results of the 3 experiments were as follows: 1) It was confirmed that the small pieces of Hinoki, cedar, pine and Lauan had control effects on mite breeding. However, the small pieces of spruce did not demonstrate an effect. Woods which had no essential oils had reduced or no breeding control effects. 2) It was confirmed that the 6 different wood essential oils had mite immobilizing effects associated with respired and contact toxicities. Rosewood oil, White Pine oil and Taiwan Hinoki oil had strong immobilizing effects. Hinoki oil, however, had only a weak effect. 3) Among the 10 ingredients of Hinoki oil, specifically Linalool, Geranyl acetate and alpha-Terpineol had strong mite immobilizing effects.