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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

Besides being an important pest in agriculture and forestry, the Himalayan field rat (Rattus nitidus) can be the reservoir host of many zoonoses. Some ectoparasitic gamasid mites on rodents (rats, mice and voles, etc.) are associated with some zoonoses. A field investigation was made in 39 counties in Yunnan Province of southwestern China between 1990 and 2015, and a total of 928 R. nitidus were collected. Based on some strategies of “data mining”, the present paper analyzed the infestation and distribution of gamasid mites on the body surface of R. nitidus in Yunnan for the first time. There were 19,585 individuals of gamasid mites collected, and 18.971 of them were identified as 54 species and 19 genera under seven families. The results indicated that R. nitidus has a high potential to harbor abundant gamasid mites of diverse species. The two dominant mite species, Laelaps nuttalli and Laelaps echidninus, had an aggregated distribution among different individuals of R. nitidus. The identified 54 species of gamasid mites showed a high species diversity on a single rat species (R. nitidus), and the diversity index at the family level was higher than that at the genus level. The infestation of R. nitidus with gamasid mites in the different habitats and altitude gradients was uneven and heterogenic, which reflects the infestation bias in different environments. Most gamasid mites tended to infest male and adult rats rather than female and juvenile ones, which reflects the infestation bias on different sexes and ages. Based on Chao1’s formula, the total number of gamasid mite species on R. nitidus was estimated to be 66.

The Yunnan red-backed vole (Eothenomys miletus) is an endemic and specific wild rodent species in China. From 39 sites across southwest China, a total of 12,536 individuals of gamasid mites were collected from 2,463 voles between 2001 and 2013. The 12,536 mites were identified as comprising 106 species, 26 genera and 9 families. The overall mite prevalence and mean abundance from all the voles were 48.36% and 5.09 mites/per examined vole, respectively. Laelaps chini (Cr= 81.24%) was the dominant mite species. The gamasid mite infestation of E. miletus is common with a very high species diversity (S = 106). The spatial distribution pattern of the dominant species (L. chini) was analyzed by using some indices, including the dispersion coefficient, aggregated indices, Cassie index, patchiness index, mean crowding and negative binomial distribution parameter. The established Iwao’s equation was M* = 5.516 + 2.312M (r = 0.942, P < 0.05) with higher α and β than 0 and 1 (the border values for determining spatial pattern), respectively, and the F value was 81.66 (P < 0.05) in the significance test of random deviation (F-test). The spatial distribution pattern of L. chini among the individuals of E. miletus was then determined as an aggregated distribution, which means that L. chini has a tendency to clump together and form different individual groups on the body surface of E. miletus. The distribution of species-abundance showed that with the increase of gamasid mite individuals, the number of the mite species gradually decreased, which indicates that most mite species are rare species. The curve tendency of species-sample relationship showed that the number of gamasid mite species increased with the increase of the host samples (number of individuals of E. miletus). The results suggest that a large host sample is recommended in the future field investigations for the species composition and species diversity of gamasid mites on rodents.

Together 22,119 individuals and 47 species of mesostigmatic mites, and 485 individuals of fleas belonging to 6 species were obtained from 16 winter nests of mound-building mouse, Mus spicilegus. The most abundant mite species were Laelaps algericus (38.2%), Androlaelaps fahrenholzi (20.9%), Proctolaelaps pygmaeus (16.9%) and Alliphis halleri (8.3%). Ctenophthalmus assimilis (87%) was the highly predominant flea, present in all the positive nests. On the basis of trophic and topic relations, mites were assorted into four ecological groups; parasites had the highest abundance (67% of all individuals). The density peak values of individual ecological mite groups differed the during season. The population peak of the predominant mite species L. algericus was in December, predominance of females was registered throughout the study period. The maximum abundance of fleas was reported in January and May.