Objective To determine the host selection and distribution of Ascoschoengastia indica on different small mammal hosts in different areas of Yunnan province. Methods A field survey was carried out in 19 counties of Yunnan province. The small mammal hosts were captured with mice cages and traps with baits. The chigger mites on the surface of two auricles were scraped off by a bistoury and then preserved in 70% ethanol. Species of each specimen of the chigger mites was identified using microscopy. Conventional statistical Methods were adopted to calculate the constituent ratios of A. indica on different hosts and in different areas, together with its prevalence and mean abundance on different hosts. Results A total of 1267 individuals of A. indica (1.36% of the total chigger mite species) were collected from the body surface of 3224 individual small mammal hosts of 7 species. The host specificity of A. indica was relatively high compared to that of other species of chigger mites, of which 94.40% were collected from the body surface of Rattus tanezumi. Conclusion The A. indica species are mainly distributed in southern and midwestern Yunnan with a high abundance, mostly on the body surface of R. tanezumi, a major reservoir host of tsutsugamushi disease.

【Abstract】 Objective To illustrate the similarity， transitional tendency and classification of gamasid mite communities in the surrounding areas of Biluoxueshan in Weixi county of Yunnan province. Methods System clustering analysis was used in this study. Results In 1560 small mammals captured， the dominant species of mites from Apodemus draco， Eothenomys miletus， Niviventer confucianus， Ap.chevrieri, Ap.peninsulae, Rattus norvegicus and R.tanezumi were Laelaps jingdongensis（Dr＝41.32）, L.chin（Dr＝41.87）,  L.traubi （Dr＝63.51） and L.turkestanicus （Dr＝24.78）, L.traubi（Dr＝18.82）,  Eulaelaps huzhuensis（Dr＝14.11） and L.chin（Dr＝11.76）, E.huzhuensis（Dr＝25.00）, E.huzhuensis（Dr＝23.61） and Haemogamasus oliviformis（Dr＝16.67）, Ornithonyssus bacoti（Dr＝71.73） and O.bacoti（Dr＝98.82）, respectively. The result of system clustering analysis indicated that there was prominent similarity between the gamasid mite from R.norvegicus and R.tanezumi, secondly it was the similarity among the mites from Ap.draco, Ap.peninsulae and Ap.chevrieri. Conclusion  The taxonomic relations of mite hosts was nearer, the communities similarity of gamasid mite was higher. The habits distribution of hosts had an effect on communities type of parasitic gamasid mite.

【Abstract】 Objective To study the distribution and its ecological charateristics of medical gamasid mites in the surrounding areas of Biluoxueshan in Yunnan province, China. Methods Some small mammals were captured by mouse traps (or mouse clips) in the surrounding areas of Biluo snow mountain located in Weixi county of Yunnan province. The ectoparasitic gamasid mites were all collected from the body surface of small mammal hosts. The community structure of gamasid mites were illustrated with richness （S）, Shannon?Wiener’s diversity index（H′）, evenness（J′） and dominance index（C′）. The spatial distribution patterns of some dominant species of gamasid mites were measured by disperse coefficient, clumping index, Cassie index and patch index. Results There were 1560 small mammals belonging to 40 species captured, and 35 species of gamasid mites were collected from the body of small mammals. Of which, 8 species were not identified. The community of gamasid mites showed a high diversity with abundant species. The dominant species of gamasid mite were Laclaps traubi, Laelaps chin, Laelaps jingdongensis, Laclaps turkestanicus and Ornithonyssus bacoti. The distribution patterns of 5 dominant gamasid mite species on the body of small mammals were of aggregated distribution. Of the 5 dominant species, the female ratios of most mite species （96.84%, 87.94%, 92.78%, 95.77%） were much higher than the males, but Os.bacoti was an exception （37.25%）. For most mites species, the proportion of the larvae and nympha was much lower with the exception of Os.bacoti Hirst （54.51%）. Conclusion The community of gamasid mites in the surrounding areas of Biluo snow mountain was relatively complicated with abundant species. The spatial distribution of dominant mite species was of aggregated distribution pattern.