Fauna and distribution of trombiculid mites in relation to the vegetational and geographical environment in northern Kyushu, Japan

Abstract

A total of 33 species of trombiculid mites were identified in northern Kyushu, from 84,413 mites parasitic on captured host mammals at 123 sites, or collected by other methods. The vegetation types, based on the dominant plants or the physiognomies, were arranged into four groups by the trombiculid species structure, namely, the ordinary forest (Cryptomeria-Cypress forest, secondary forest, and evergreen broad-leaved forest), seaside pine forest, grassland, and montane deciduous forest. However, some differences in the structure were detected among sites in each vegetation type. A successive change in the trombiculid structure in accord with the succession of plants, beginning with pioneer species such as Gahrliepia saduski, Leptotrombidium scutellare, and L. pallidum, is discussed. The possibilities of interspecific relationships, such as competition, between two pairs of morphologically related species were suggested in the vertical distribution of L. tanaka-ryoi and L. fuji, and in the horizontal distribution of L. fukuoka and L. kitasatoi. The vector species of Tsutsugamushi disease, L. pallidum and L. scutellare, showed a somewhat restricted distribution. The small number of patients of Tsutsugamushi disease in this region, in comparison with that in southern Kyushu, was attributed to the lesser abundance of the vector trombiculid mites.