Search Results (7)

Chiggers (chigger mites) and gamasid mites are two groups of ectoparasites on rodents, and they can be the vectors or potential vectors of scrub typhus and hemorrhagic fever with renal syndrome (HFRS), while Bower’s white-toothed rat (Berylmys bowersi) can serve as the reservoir host of the diseases. Based on field investigations at 117 survey sites of southwest China, a total of 2512 mites were collected from 55 B. bowersi rats. Under a microscope, these mites were taxonomically identified as 56 distinct species, comprising 37 chigger mite species and 19 gamasid mite species. The mite infestation burdens on B. bowersi were heavy, with a high prevalence (P_M = 85.45%), mean abundance (MA = 45.67), and intensity (MI = 53.45). Of 56 mite species identified, 7 are vectors of scrub typhus and HFRS. Of the seven vector mite species, Leptotrombidium scutellare was one of dominant chigger species, with a higher infestation index on rats (P_M = 21.82%, MA = 7.76) than the other six vector mite species. The sex ratio of female gamasid mites was higher than that of males. The number and infestation of adult gamasid mites were higher than those of immature mites. The infestation indexes of mites on B. bowersi hosts varied with the host’s sex and age and fluctuated along different environmental gradients. The association coefficient (V) showed a slight positive association between chiggers and gamasid mites, suggesting that these two groups of mites may coexist on B. bowersi rats. Spearman correlation coefficients showed positive correlations among some dominant and vector mite species, indicating that some mite species tend to select the same hosts. A total of 69 mite species (47 chigger mite species and 22 gamasid mite species) on B. bowersi were estimated by species rarefaction and extrapolation curves. In conclusion, Berylmys bowersi has a high susceptibility to mite infestation, and it has the potential to harbor abundant mites, with heavy mite burdens. The occurrence of vector mite species, especially L. scutellare (the dominant species), increases the potential risk of transmission and the focus persistence of scrub typhus and HFRS in southwest China. Full article

Gamasid mites (Acari: Mesostigmata) are ecologically diverse arthropods, many of which act as vectors for zoonotic diseases such as rickettsial pox and hemorrhagic fever with renal syndrome. This study investigates the faunal and ecological patterns of gamasid mites across five zoogeographic microregions in Yunnan Province, China, a biodiversity hotspot with complex topography. From 1990 to 2022, 18,063 small mammal hosts (primarily rodents) were surveyed, yielding 167 mite species (141,501 specimens). The key findings include the following: (1) Low host specificity: most mite species parasitized >10 host species, with Laelaps nuttalli, L. echidninus, Dipolaelaps anourosorecis, L. guizhouensis, L. turkestanicus, and L. chini dominating (>76.59% abundance). (2) Environmental heterogeneity: mountainous and outdoor habitats exhibited higher mite diversity than flatland/indoor environments. (3) Zoonotic risks: thirteen vector species with low host specificity were identified, potentially amplifying disease transmission. (4) Ecological niche dynamics: high niche overlaps (e.g., Laelaps guizhouensis vs. L. xingyiensis: O_ik = 0.997) and positive interspecific correlations (e.g., L. echidninus vs. L. nuttalli: R = 0.97, p < 0.01) suggest co-occurrence trends on shared hosts. (5) Biogeographic patterns: mite communities were clustered distinctly by microregion, with the highest similarity being obtained between western/southern plateaus (IV and V) and unique diversity in the Hengduan Mountains (I). (6) Chao 1 estimation predicted 203 total mite species in Yunnan, 36 of which were undetected in the current sampling. These results highlight the interplay of biogeography, host ecology, and environmental factors in shaping mite distributions, with implications for zoonotic disease surveillance in biodiverse regions. Full article

The study of the ectoparasite fauna of the insectivores—Sorex araneus, Sorex minutus, Neomys fodiens, and Neomys anomalus (subfamily Soricinae)—was carried out in three locations in Poland: Białowieża National Park, Kosewo Górne in the Masurian Lake District, and in vicinity of Warsaw. Three species of Ixodidae ticks, eleven species of fleas, and four species of mites from the order Mesostigmata were noted. The most numerous ectoparasites are ticks Ixodes ricinus (larvae), Dermacentor reticulatus (nymphs), and fleas Palaeopsylla soricis, Megabothris walkeri, and Hystrichopsylla orientalis. These species show the highest prevalence and show the highest dominance index. The parasitofauna of S. araneus is much richer in species than other shrew species. The structure and dominance of parasite assemblages differ between locations. Full article

(1) Background: Gamasid mites are a large group of arthropods, and some of them are of medical importance. Besides directly biting humans and causing dermatitis, some gamasid mites are the vector of rickettsialpox and potential vector of hemorrhagic fever with renal syndrome (HFRS). The Three Parallel Rivers Area of China is one of the hotspots of biodiversity research in the world, with complicated topographic landforms, different types of vegetation, special elevation gradients and high biodiversity. (2) Methods: Species richness (S): the Shannon–Wiener diversity index (H), Simpson dominance index (D) and Pielou evenness index (E) were used to analyze the basic community structure. The β diversity (Cody index) was used to reflect the diversity difference between any two adjacent elevation gradients. The method based on Preston’s lognormal model for species abundance distribution was used to estimate the total number of gamasid mite species. (3) Results: A total of 3830 small mammal hosts captured from the nine survey sites were identified as 44 species, 27 genera and nine families in five orders. Apodemus chevrieri, Eothenomys miletus and A. draco were the dominant host species with a total constituent ratio C_r = 52.037%. From the body surface of the hosts, 26,048 gamasid mites were collected and identified as 10 families, 21 genera and 82 species (excluding 847 unidentified specimens) with high species richness (S = 82) and diversity (H = 2.33). The three dominant mite species were Dipolaelaps anourosorecis, Laelaps nuttalli and L. echidninus, with a total C_r = 64.46% (16,791/26,048). There are significant differences in the species composition, species diversity and dominant species of gamasid mites on different hosts. The species diversity of the mite community fluctuated greatly in different elevation gradients. The highest peaks of species richness and β diversity appeared at altitudes of 3000–3500 m (S = 42) and 1500–2000 m (β = 17.5), respectively. The species abundance distribution of the mites was successfully fitted by Preston’s lognormal model with $\widehat{S}\left(R\right)=19e^{-{\left[0.22\left(R-0\right)\right]}^2}$ (α = 0.22, R² = 0.9879). Based on fitting the theoretical curve by Preston’s model, the total number of gamasid mite species was estimated to be 153 species. (4) Conclusions: Gamasid mites on small mammals are abundant with complex community structures and high species diversity in the Three Parallel Rivers Area of China. There is an apparent community heterogeneity of the mites on different hosts and in different environments. Full article

In montane environments, as elevation increases, the combination of hydrothermal factors changing and vegetation types changing can cause changes to the soil mite community. To reveal the influence of different vertical vegetation types on the structure and diversity of soil mite communities in the Shibing Karst World Natural Heritage Property, in September 2021, specimen collection and identification of soil mites were carried out under the four typical vegetation zones of coniferous broad-leaved mixed forests (CBF), evergreen broad-leaved forests (EBF), deciduous broad-leaved forests (DBF), and river beach scrubs (RBS) in the Heritage Property. This occurred in order to analyze the community structure of soil mites. A total of 10,563 soil mites were captured in this region, belonging to 3 orders, 67 families, 137 genera; Perscheloribates and Scheloribates are the dominant groups in the area. The number of soil mite genera (CBF > EBF > DBF > RBS) and the number of individuals (RBS > DBF > CBF > EBF) differed between vegetation types. The dominant soil mite genera were not entirely consistent, with the highest values for each soil mite community diversity parameter being in the EBF habitat. The number of soil mite genera and individuals differed among vegetation types in different soil layers. It showed an apparent aggregation towards the surface layer, with complex diversity and richness indices changes. The highest community similarity indices were found between CBF and DBF, which were moderately similar. The cluster analysis results further showed that soil mite communities differed in different vegetation zones and among the same vegetation zones. The predatory gamasid mite structure is mainly r-selective. The ecological groups of oribatid mites are all O-type in the number of groups and P-type in the number of individuals. Lasiobelba, Nanhermannia, Tectocepheus, and Mochlozetes, among others, represent the group of nutrient functions that make up the soil mites in the study area. The study shows that the soil mite community of the Shibing Karst World Natural Heritage Property is rich in groups and shows gradient differences with the vegetation spectrum, and based on the unique subtropical canyon karst habitat of the Heritage Property, the community structure of soil mites will be in the process of adaptation and dynamic change, so long-term dynamic monitoring and in-depth study of the soil mites community structure of the Heritage Property are needed. Full article

A 12-month consecutive investigation was made at Jingha village in southern Yunnan of southwest China from April 2016 to March 2017. A total of 2053 Indochinese forest rats (Rattus andamanensis Blyth, 1860) were captured and examined, which account for 84.69% (2053/2424) of all the animal hosts (rodents and other small mammals) at the investigation site. And 39.82% (13,531/33,980) of gamasid mites were identified from the body surface of R. andamanensis and they belong to 41 species, 10 genera, 3 subfamilies and 2 families. Of the 41 species of gamasid mites identified from R. andamanensis, Laelaps nuttalli Hirst, 1915 and Laelaps echidninus Berlese, 1887 were the most dominant with 70.63% and 20.67% of constituent ratios respectively. In monthly fluctuations of all the gamasid mites on R. andamanensis, the constituent ratio (C_r) and overall infestation mean abundance (MA) of the mites in 12 months showed two obvious peaks in January (winter season) and June (summer season). However, the two dominant mite species, L. nuttalli and L. echidninus, showed different patterns of seasonal fluctuations. Laelaps nuttalli occurred throughout the year, and its C_r and MA showed two prominent peaks in winter season (December and January) and summer season (June), which belongs to the summer-winter type of seasonal fluctuation. Laelaps echidninus also occurred on R. andamanensis throughout the year, but its C_r and MA showed only one peak in winter season (December and January), which belongs to the winter type of seasonal fluctuation. A negative correlation existed between two climatic factors (temperature and rainfall) and the infestations (C_r, prevalence P_M and MA) of two dominant mite species (L. nuttalli and L. echidninus) on R. andamanensis (p < 0.05). Temperature and rainfall are considered to be two key factors that influence the seasonal fluctuations of the mites on the studied rat species. Full article

(1) Background: As a species of gamasid mite, the tropical rat mite (Ornithonyssus bacoti) is a common ectoparasite on rodents and some other small mammals. Besides stinging humans to cause dermatitis, O. bacoti can be a vector of rickettsia pox and a potential vector of hemorrhagic fever with renal syndrome (HFRS). (2) Objective: The present study was conducted to understand the host selection of O. bacoti on different animal hosts and the distribution in different environmental gradients in Yunnan Province of Southwest China. (3) Methods: The original data came from the investigations in 39 counties of Yunnan, between 1990 and 2015. The animal hosts, rodents and some other small mammals were mainly trapped with mouse traps. The O. bacoti mites on the body surface of animal hosts were collected and identified in a conventional way. The constituent ratio (Cr), prevalence (P_M), mean abundance (MA) and mean intensity (MI) were used to reflect infestations of animal hosts with O. bacoti mites. The patchiness index and Taylor’s power law were used to measure the spatial distribution pattern of O. bacoti mites on their hosts. (4) Results: A total of 4121 tropical rat mites (O. bacoti) were identified from 15 species and 14,739 individuals of hosts, and 99.20% of them were found on rodents. More than half of O. bacoti mites (51.78%) were identified from the Asian house rat (Rattus tanezumi), and 40.09% of the mites from the Norway rat (R. norvegicus) (p < 0.05). The infestations of R. tanezumi (P_M = 7.61%, MA = 0.40 and MI = 5.31) and R. norvegicus (P_M = 10.98, MA = 1.14 and MI = 10.39) with O. bacoti mites were significantly higher than those of other host species (p < 0.05). The infestations of two dominant rat hosts (R. tanezumi and R. norvegicus) with O. bacoti mites varied in different environmental gradients (latitudes, longitudes, altitudes, landscapes and habitats) and on different sexes and ages of the hosts. The prevalence of juvenile R. norvegicus rats with O. bacoti mites (P_M = 12.90%) was significantly higher than that of adult rats (P_M = 9.62%) (p < 0.05). The prevalence (P_M = 38.46%) and mean abundance (MA = 2.28 mites/host) of R. tanezumi rats with O. bacoti mites in the high latitude were higher than those in the low latitudes (p < 0.05). The majority of the total collected 4121 O. bacoti mites was found in the flatland landscape (91.28%) and indoor habitat (73.48%) (p < 0.05). The P_M (10.66%) and MA (0.49 mites/host) of R. tanezumi rats with O. bacoti mites were significantly higher in the indoor habitat than in the outdoor habitat (p < 0.05). The tropical rat mites showed an aggregated distribution pattern on their first dominant host, R. tanezumi. Conclusion: The tropical rat mite (O. bacoti) is a widely distributed species of gamasid mite in Yunnan Province, Southwest China, and its dominant hosts are two synanthropic species of rats, R. tanezumi and R. norvegicus. It is mainly distributed in the flatland landscape and indoor habitat. It has some host-specificity, with a preference to rodents, especially R. tanezumi and R. norvegicus. The O. bacoti mites are of aggregated distribution on R. tanezumi rats. Full article