Preliminary analysis of chigger communities associated with house rats (Rattus flavipectus) from six counties in Yunnan, China

This paper presents a preliminary analysis of chigger communities associated with the house rats (Rattus flavipectus) in six counties of Yunnan Province, China. The analysis addresses chigger species composition, infestation rates, community structure and spatial patterns, as well as interspecific relationships of dominant chigger species and species abundance distribution. The Shannon-Wiener method was used in the calculation of community structure. Patch index (m*/m) was used in measuring spatial patterns. The association coefficient was adopted in the analysis of interspecific relationships. In the six counties investigated, 451 individuals of R. flavipectus were captured and 2114 chiggers were collected from these hosts. It was common for R. flavipectus to host chiggers, and 31 chigger species were found on this species of rats. The diversity index of the chigger community was 1.63. Five dominant chigger species accounted for 91.11 % of the total chigger community, and Ascoschoengastia indica was the most abundant species. The overall mite infestation rate and overall mite index were 18.18% and 4.69, respectively. The mutual interspecific relationship between A. leechi and A. indica was determined to be a positive association (V=0.75, P<0.01). A theoretical curve for species abundance distribution was successfully fitted in a semilogarithmic rectangular system, and the species abundance of chiggers conformed to the lognormal distribution pattern. The aggregated pattern of dominant chigger species suggests an uneven distribution of chiggers among individual rat hosts.