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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]

Chigger mites are a large group of arthropods and the larvae of mites are ectoparasites. Some species of ectoparasitic mites (larvae) can be the transmitting vectors of tsutsugamushi disease (scrub typhus). Yunnan Province is located in the southwest of China with complicated topographic landform and high biodiversity, where there are five zoogeographical subregions. Rodents and some other small mammals were trapped and examined for ectoparasitic chigger mites in 29 investigation sites in Yunnan during 2001-2013. From 13,760 individuals and 76 species of small mammal hosts, we collected 274 species of mites, which were identified as comprising 26 genera in two families. The species diversity of chigger mites (274 species) in the present study were not only much higher than that from other provinces of China but also largely exceeded that recorded from other regions and countries in the world. Of the five zoogeographical subregions, both the species diversity and Shannon-Weiner's diversity of mites were the highest in subregion II (southern subregion of Hengduan Mountains) with middle altitudes and middle latitude. Both the species diversity of mites and Shannon-Wiener diversity index showed a parabolic tendency from the low altitude (<500 m) to the high altitude (>3500 m) along the vertical gradients with the peak occurring in the middle-altitude regions (2000-2500 m). Of four dominant hosts, the species richness of mites was highest on Eothenomys miletus ( S = 165) and Shannon-Wiener diversity index was highest on Rattus norvegicus ( H = 3.13). Along latitude gradients, species richness of chigger mites increased first and then decreased, peaking at 25° to 26° N with 193 mite species. The geographical location, complex topography, and landscape with diverse small mammal hosts in Yunnan Province have contributed to the extremely high species diversity of mites in the province. The large sampling size of small mammal hosts in a wide geographical scope within a long time span also made it possible to have collected so many species of chigger mites. [ABSTRACT FROM AUTHOR]

Understanding factors that shape host selection has been a classic issue in ecology, evolutionary biology, and epidemiological investigation. During the survey from 2000 to 2009, a total of 11,216 individuals of small mammals were captured from Yunnan Province in southwestern China. The captured small mammalian hosts belong to five orders, ten families, 35 genera, and 65 species and from their body surface, 38,885 individuals of ectoparasitic sucking lice were collected, which represent five families, seven genera, and 31 species. Based on niche overlap of dominant sucking lice on their primary hosts, we used hierarchical cluster analysis to sort different sucking louse species' resource utilizations of similar kind into respective categories. Given λ < 5, there are only two groups clustered, however, sucking louse species' resource utilization was sorted into eight respective categories at λ = 15. The results revealed that most species of sucking lice usually had high host specificity and a certain species of sucking louse usually restricted to one or few small mammalian species as their dominant hosts. Correspondence analysis was used to visualize associations between parasitic sucking lice and their small mammalian hosts, which suggested three different patterns of host resource utilization: species specialists, genera generalists, and multiple selections. For example, Sathrax durus (Johnson) only parasitized on species of Tupaia belangeri (Wagner), Hoplopleura edentula (Fahredholz) predominatly on genus of Eothenomys, and Polyplax reclinata (Nitzsch) on Family of Soricidae. Our results demonstrate that sucking lice have high host specificity and this might be due to coevolution between sucking lice and their hosts. [ABSTRACT FROM AUTHOR]

Highlights: [•] The diorite porphyry in the Hongniu-Hongshan Cu deposit formed at 200Ma. [•] The quartz monzonite porphyry in the Hongniu-Hongshan Cu deposit formed at 77Ma. [•] The molybdenite Re–Os isotopic date of the ore is 78.9Ma. [•] The quartz monzonite porphyry formed by the remelting of the residual oceanic slab. [ABSTRACT FROM AUTHOR]