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Medical Entomology and Zoology
Vol. 15 (1964) No. 4 p. 233-244



Towards making a research of fauna of Acarina on the floors of school buildings during the summer season, a new method was tested. This was done by means of examining the dust collected within vacuum-cleaners by using a mixed solvent (ethyl-ether/chloroform or ethyl-ether/carbon chloride combination). The schools where this new method was tested were : 6 public schools (3 Grade, 2 Junior High, and 1 Senior High) and 3 private girls' schools. The mites collected totalled 6, 766 spp., all belonging to 29 different families (or 20.5 WMI, which means the whole number of mites per one gram of dust). The WMI figure of the mites, as broken down according to schools, is as follows : 66.6-Private Girls' Schools, 7.9-Public (Senior High) School, 4.5-Public (Grade) Schools and 1.9-Public (Junior High) Schools. The numbers of families of the mites are : 23 families in Senior, 20 families in Grade, 19 families in Junior High and 15 families in Private Girls' Schools. The higher the ratio of the number of Acaridiae is, the higher the ratio of the number of active live mites is. The ratio of this particular cohort according to different types of schools is as follows : 98.6% in private Girls', 72.9% in Public Senior High, 47.5% in Grade and 43.1% in Junior High Schools. As for the Oribatids ratio, the above order of schools is reverse. As for Mesostigmatids and Trombidiformids, the orders of schools are as that for the Oribatids ratio, except that Junior High and Grade Schools are reversed. It is considered at this stage of the research that the different floor cleaning methods are contributing factors for the difference in WMI figures and the suborders. It is added that the numbers of mites were the highest for retarded pupils' classrooms and sewing-rooms. No statistic significance of difference was noted in the average WMI among the schools of the same age groups (e.g. among the three Public Grade Schools). The difference was noted, however, between the three grade schools and the two Junior high schools and also between the public and private schools. Both Dermatophagoides farinae Hughes, 1961, and Dermatophagoides scheremetewskyi Bogdanow, 1864 (Epidermotidae), are definitely dominant species on the floors of the school buildings aforementioned. They comprise 89.9% in the Acarina fauna on the floors. It seems that they act as agents for pruritic dermatosis (insect bites) for the reason that there are many reports on the relationship between D. scheremetewskyi and dermatosis. The symptoms of these bites at the above-mentioned schools were seen on the exposed feet and arms of the pupils accompanied by itching red papules each ranging from several millimeters to several ten millimeters in diameter, and no one recognized the agents, although 78% of the pupils in a girls' schools suffered from the bites. This indicates that the agents might have been too small to be visible. Mites other than described heretofore were found as follows : 91 spp. of Cheyletids (1.3%) (percetage of mites total), 87 spp. of Melichares sp. (1.3%), 68 spp. of Acarids (1.0%), 66 spp. of Tetranychids (1.0%), 61 spp. of Hypochthoniids (0.9%), 38 spp. of Glycyphagids (0.6%), 38 spp. of Hypoaspis sp. (0.6%), 33 spp. of Lohmanniids (0.5%), 20 spp. of Tarsonemids (0.3%), 18 spp. of Ornythonyssus bacoti (0.3%), 16 spp. of Pyemotids (0.2%), and others. Meanwhile, as a result of this new testing method, not only the mites but also other arthropods such as Insecta, Araneina, and Cheliferidae were found. Hemiptera, an order of Insecta (larvae of shell worms and jumping plant lice), totalling 120 spp., which was 1.8% of the mites total. 30 spp. of larvae of beetles (0.4%), 21 spp. of book-lice (0.3%) and 16 spp. of thrips (0.2%) were found also. The latest investigation by the Educational Committee of Yokohama shows that 56 out of 216 public schools (26%) have suffered from both rodents and mites

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Copyright © 1964 The Japan Society of Medical Entomology and Zoology

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