[Geographical distribution of chigger mites on Rattus flavipectus in Yunnan Province]

To investigate species composition of chigger mites on Rattus flavipectus in different zoogeographical subregion of Yunnan Province.

The field investigation was carried out in 25 counties of Yunnan Province during 2001-2012. Some conventional statistical methods were adopted to calculate the species of collected chigger mites, constituent ratio (Dr), mite infestation rate (RM), mean abundance (MA), mean intensity (MI), species richness (S) and species diversity index (H') of chigger mites in five zoogeographical subregions. The hierarchical cluster analysis was used to compare the similarity of chigger mite communities on the rats in the subregions.

A total of 2 118 R. flavipectus were captured. 11 040 individuals of chigger mites were identified as 3 subfamilies, 17 genera and 114 species. The overall RM, MA and MI of chigger mites were 19.6% (416/2 118), 5.2 mites per examined rat and 26.5 mites per infested rat, respectively. The species richness, species composition and dominant species of chigger mites on R. flavipectus were not identical among the subregions. The RM (28.9%, 179/620), MA (10.6) and MI (36.6) of chigger mites in the mountainous subregion of southern Yunnan were the highest among the five subregions. There was a significantly linear positive correlation between the number of R. flavipectus and the species of chigger mites (r = 0.942, P < 0.05). The similarity of chigger mite communities between plateau subregion of western Yunnan and mountainous subregion of southern Yunnan was the highest, and the dominant species of chigger mites was Leptotrombidium deliense. The main dominant species of chigger mites in middle subregion and southern subregion of Hengduan Mountains, and eastern plateau subregion of Yunnan were Ascoschoengastia indica and Schoengastiella ligula.

The infestation of chigger mites on R. flavipectus is common with a high species diversity. The composition of chigger mite community in different geographical subregions is significantly different.