Abstract:  The aim of the present study was to study the species diversity, community structure, similarity, distribution and niche of chigger mites on the body surface of 3 303 small mammals in the surrounding areas of Erhai Lake in Dali, Yunnan by using Shannon-Wiener, hierarchical cluster analysis (SPSS 13.0) and Levins'niche. The investigated site was located in the wild rodent-type plague focus, one of 11 known plague foci in China and also an important focus of both tsutsugamushi disease and epidemic hemorrhagic fever (EHF), where stand alongside three cordilleras surrounding the Erhai Lake, namely Eastern Wuliang Mountain, Southern Ailao Mountain and Western Cangshan Mountain. The three confined oriented areas with different landscapes are within the same zone with similar longitude, latitude, altitude and zoological location, which forms an inartificial barrier's isolation by Erhai Lake. A total of 3 303 small mammal hosts were captured from the three differently oriented areas belonging to 7 families, 15 genera and 21 species in 4 orders (Rodentia, Insectivora, Scandentia and Carnivora), 56 895 individuals of chigger mites collected from the body surface of the small mammal hosts were identified as 3 subfamilies, 13 genera and 109 species. The abundance, distribution and diversity of chigger mites vary among different populations of host species and habitats. Chigger mites spent a considerable time off hosts (only the larvae are ectoparasites) and so are strongly affected by the off-host environment (temperature, precipitation and habitat). Host-specificity of chigger mites is very low, the similarity of chigger mite communities is not highly consistent with the affinity of small mammal hosts in taxonomy and this implies that the co-evolution between small mammals and chigger mites has not reached a high degree, and the above ecological characteristics of chigger mites might strengthen the chigger mites' potential ability of transmitting some mites born diseases among different small mammal hosts.

Key words: Acari, chigger mite, small mammal, different landscapes within the same zone, community ecology, co-evolution, Yunnan