Search

Based on the field investigation in five provincial regions of Southwest China between 2001 and 2019, the present paper reports the infestation and distribution of chigger mites on the Confucian white-bellied rat Niviventer confucianus in China for the first time. A total of 11,017 chigger mites were collected from the body surface of 911 N. confucianus rat hosts, and 10,161 of them were identified as 166 species and 16 genera in three subfamilies under two families with high species diversity (S = 166, H' = 3.19, E = 0.62). Of 911 N. confucianus rats, 341 individuals were infested with chiggers with high overall prevalence (PM = 37.43%), mean abundance (MA = 12.09 mites/rat) and mean intensity (MI = 32.31 mites/rat). On the body surface of N. confucianus, Ascoschoengastia sifanga was the most dominant chigger species followed by Walchia ewingi and Leptotrombidium rupestre. All the three dominant chigger species showed an aggregated distribution pattern among different individuals of N. confucianus. Chigger infestations on the same rat host (N. confucianus) showed some heterogeneity under different environmental conditions such as latitudes, longitudes, altitudes and landscapes. Based on Preston's lognormal model, the species abundance distribution of chiggers on N. confucianus conformed to a lognormal distribution pattern, and the predicted total species of chiggers on N. confucianus in Southwest China was estimated to be 228 species. [ABSTRACT FROM AUTHOR]

The Yunnan red-backed vole (Eothenomys miletus) is an endemic rodent species in China and it often harbors two groups of mites, chigger mites and gamasid mites, on its body surface. A few species of chigger mites and gamasid mites are transmitting vectors of some zoonoses. Based on abundant original data from a long-term field ecological investigation in Yunnan Province of southwest China between 2001 and 2015, the present study made a detailed analysis on the infestation of E. miletus with mites. From 14 to 30 investigated counties, 53,958 mites were collected from 1,900 E. miletus voles with relatively high infestations. Of 232 mite species identified, there were 152 species of chigger mites (44,797 individuals) and 80 species of gamasid mites (9,161 individuals). The overall infestation prevalence (PM) and mean abundance (MA) reached 76.84 % and 28.40 mites/vole, respectively. The chigger mite Leptotrombidium scutellare (the constituent ratio, Cr = 18.60 %), gamasid mite Laelaps chini (Cr = 12.16 %) and chigger mite Leptotrombidium sinicum (Cr = 10.57 %) were three dominant species of mites. The three dominant mite species had an aggregated distribution among the different individuals of E. miletus. Eothenomys miletus in the mountainous landscape harbored much more individuals and species of mites with a higher prevalence (PM = 82.25 %), mean abundance (MA = 38.26 mites/vole) and species richness (Mf = 19.59) than in the flatland landscape (p < 0.05). The infestation of E. miletus with mites in different altitude gradients was uneven and heterogenic, which reflects the infestation fluctuations in different environments. Mites tended to infest male and adult voles with higher PM and MA than female and juvenile ones, which reflects the infestation bias on different sexes and ages of vole hosts. There is no obvious interspecific coexistence, cooperation or competitive exclusion between chigger mites and gamasid mites on E. miletus. Based on iChao1's formula, the total number of mite species on E. miletus was estimated to be 285. [ABSTRACT FROM AUTHOR]

The Norway rat, Ratttus norvegicus, is a common agricultural pest and an important reservoir host of many zoonoses. A long-term field investigation on gamasid mites was made in 39 counties of Yunnan province, southwest China from 1990 to 2015. A total of 1448 Norway rats were captured, and 10,034 individuals of gamasid mites were collected from the body surface of the rats, which were identified as 42 species and 16 genera under 6 families. Based on some strategies of "data mining", the present paper took advantage of the long-term accumulated original data and made an ecological analysis of gamasid mites on the Norway rat. The results showed that the infestation of gamasid mites on 1448 Norway rats was common with an overall prevalence (48.55%), mean abundance (6.93) and mean intensity (14.27). Of 42 species of gamasid mites, Laelaps nuttalli, Laelaps echidninus and Ornithonyssus bacoti were three dominant species, and they showed an aggregated distribution among different individuals of their rat host, R. norvegicus. There were much more species (39 species) of gamasid mites on the outdoor rats with a higher prevalence (65.12%), mean abundance (10.24) and mean intensity (15.72) than on the indoor rats (p < 0.001). The Norway rats in the lower altitude gradients showed a higher infestation prevalence and intensity of the mites, but lower species diversity. The adult rats had higher infestations (prevalence, mean abundance and mean intensity) of the mites than the juvenile rats. Most gamasid mites showed a predominantly male-biased sex ratio on Norway rats. The association coefficient was used to analyze the interspecific relationship between any two dominant mite species, and a positive association was found between L. nuttalli and L. echidninus. The curve tendency of species-sample relationship showed that the numbers of mite species still kept increasing without an eventual "platform" stage when the sampled rats reached 1200 individuals, and this implies a great heterogeneity of the mite community on the rat. Preston's lognormal distribution model successfully fitted the theoretical curve of species abundance distribution of gamasid mites on R. norvegicus, which illustrated the distribution of the dominant, common and rare species of the mites. [ABSTRACT FROM AUTHOR]