@techreport{oai:soar-ir.repo.nii.ac.jp:00016994, author = {内川, 公人 and 熊田, 信夫}, month = {Mar}, note = {To improve the knowledge of population densities of Leptotrombidium pallidum in non.endemic areas of tsutsugamushi disease,a s eries of surveys were carried out on altitudes and in Suwa.gun,Nagano Prefecture in 1987 and 1988. Soil samples(20cm x 20cm x 5cm) were taken on the eastern slope of Mt No rikura(alt. 1,100 1,600m),Kamikochi(1,500m) and on the downhill ski course on Happo.one(800・1,400m)Jor separating chiggers with Tullgren funnels. L.ρσllidum was distributed sparsely up to as high as 1,600m above the sea level,w hile trombiculid faunas of Kamikochi and Happo.one were limited,l acking L.aρllidum. It is, thus,p resumed that L.pallidum is depopulated on altitudes,a nd that faunistic composition of chiggers varies according to the differences in topography,v egetation,so il nature and degrees of disturbance of survey areas Of the soil samples taken from paddy banks and grass lands(alt. 1,000.1,150m) of Fujimi Town and Hara Village,Suwa.gun,w here tsutsugamushi disease patient has never been reported,t hose from the paddy banks located at about 1,000m above the sea level included so many individuals of L.pallidum. This indicates that the vector chigger is populated densely even in the non.endemic 'area of tsutsugamushi disease. Infltienceof aerially applied pesticides on the population densitiesof L.pallidum and other chigger's was also studied, having the use oftwo areas well.demarcated by a farm road in a paddy zone. Aerial applicationof many kinds of pesticides(BPMC,d iazino .,nMPPa nd/or MEP) had been done to one of these areas for more than 20 years, while the other area had never received such application. Chiggers consisting of predominantL.pallidum and 3other species wefe found from paddy banks regardless of the pesticide treatment,a nd,m oreover,a m aximum population density was encountered on a bank in the treated area. This indicates that the pesticides in current use have no distinguishable effect on the population density of the vector chigger., Article, 環境科学年報11:91-97(1989)}, title = {恙虫病媒介性恙虫類の分布特性に関する補充調査}, year = {1989} }