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The 91 investigation sites and the captured sites where Chevrieri's field mice (Apodemus chevrieri) were captured in southwest China (2001-2019).
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Based on a long-term field investigation on chigger mites in southwest China from 2001 to 2019, the present study analyzed the infestation and distribution of chigger mites on the Chevrieri's field mouse (Apodemus chevrieri) in the region. A total of 12,516 individuals of chigger mites were collected from 1981 A. chevrieri mice, and 12,281 chiggers...
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... total of 1981 A. chevrieri mice were captured from 30 sites of 91 investigated ones in southwest China. The result showed that A. chevrieri mice were not distributed in all the region of southwest China and they were mainly from Yunnan, Sichuan and Guizhou ( Fig. 1, Table 1). From the body surface of 1981 A. chevrieri mice, 12516 individuals of chigger mites (chiggers) were collected. Of 12,516 collected mites, 12,281 ones were identified as 107 species, 10 genera in 3 subfamilies under 2 families (Table 2), and the rest 235 mites remained unidentified because of broken body, dirt-covered body, ...
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Chigger mites are the exclusive vector of scrub typhus. Based on field investigations of 91 survey sites in 5 provincial regions of Southwest China, this paper reported variations of chigger infestation on the oriental house rat (Rattus tanezumi) along various environmental gradients. A total of 149 chigger species were identified from 2919 R. tane...
As a group of ectoparasites, chiggers (larvae of chigger mites) are the exclusive vector of scrub typhus (tsutsugamushi disease). Rodents are the most important hosts of chiggers. The Anderson's niviventer rat, Niviventer andersoni, is an endemic species of rodent in China. However, few studies have involved this endemic rodent species and its ecto...
Chigger mites (Acari) are common ectoparasites on rodents, and they are the exclusive vector of scrub typhus. South China field mouse (Apodemus draco) and Lantsang field mouse (A. ilex) are two sibling rodent species. Based on field investigations in southwest China (2001–2015), this paper compared the infestation of these two mouse species with ch...
Based on the field investigations in 91 investigation sites (counties) in southwest China between 2001 and 2019, the present paper reported the chigger mites on A. agrarius mice in southwest China for the first time by using a series of statistical methods. From 715 striped field mice captured in 28 of 91 investigated sites, only 255 chiggers were...
Based on a long-term field investigation in the five provincial regions of Southwest China between 2001 and 2019, the present paper studied the infestation and related ecology of chigger mites (chiggers) on the large Chinese vole (Eothenomys miletus), an endemic and dominant rodent species in the regions. A total of 52331 chiggers were collected fr...
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... The original data of this study came from the field investigation in 91 survey sites of five provincial regions (Yunnan, Guizhou, Sichuan, Chongqing, and Tibet) in southwest China from 2001 to 2019 Chen et al. 2022). Ryukyu mice, M. caroli, were collected in 18 sites out of 91 ones (Fig. 1). ...
... sinicum Yu et al., 1981) and on A. chevrieri (L. scutellare and L. densipunctatum Yu et al., 1982), which further support the opinion that different host animals have different susceptibility to chiggers with different dominant chigger species, and different chigger species (especially dominant ones) have different host selection (Ding et al. 2021;Li et al. 2022;Chen et al. 2022). In the complex life cycle of chigger mites, all stages live freely in the topsoil except the larval stage (chigger), and chiggers usually show a relatively low host specificity when choosing hosts. ...
Chiggers are a group of ectoparasites and they are the vector of scrub typhus. Although the Ryukyu mouse (Mus caroli) is a common species of rodent in some outdoor habitats, few studies are about the mouse itself and its ectoparasites. To date, there has been no specific report on chiggers of M. caroli. Based on the field investigation in southwest China from 2001 to 2019, this paper reported the infestation and distribution of chiggers on M. caroli for the first time. Among the 91 sites investigated, 263 Ryukyu mice were captured at 18 sites, and 678 chiggers were collected from the mice. The collected chiggers were identified to be one family, two subfamilies, six genera, and 16 species with relatively low species diversity. The overall infestation prevalence (PM), mean abundance (MA), and mean intensity (MI) were PM = 27.38%, MA = 2.58 chiggers/per mouse, and MI = 9.42 chiggers/per mouse respectively. The dominant chigger species are Walchia ewingi and W. micropelta with a total constituent ratio of Cr = 94.10% (638/678), and they were of aggregated distribution among different individuals of the host M. caroli. The distribution of two dominant chigger species seemed to be mutually independent with the association coefficient V ≈ 0 (p < 0.001). The infestation (PM, MA, and MI) of M. caroli with chiggers greatly fluctuated in different geographical landscapes, altitudes, and latitudes with an obvious environmental heterogeneity. The male and adult M. caroli harbored much more chigger mites with significantly higher infestations (PM, MA and MI) than the female and juvenile mice. The theoretical curve of species abundance distribution of the chigger mite community on M. caroli was fitted by Preston lognormal distribution model with fitting goodness R2 = 0.77. Based on the iChao1 formula, the expected total number of chigger species on the mice was estimated to be 24 species.
... The original data came from the field investigations in 91 survey sites of five provincial regions in southwest China from 2001 to 2015 [29,30]. Among the 91 sites investigated, there are 8 sites where A. draco was captured, and 3 sites where A. ilex was captured, totaling 11 sites (Figure 1). ...
... Chevrier's field mouse (A. chevrieri Miline-Edwards, 1868) is a mouse species in the same genus (Apodemus) as A. draco and A. ilex, and it is one of the dominant rodent species in southwest China [30]. A special study on chiggers of A. chevrieri in southwest China showed that its overall infestation prevalence (P M = 31.95%), ...
... mites/mouse) with chiggers were significantly higher than the corresponding infestation indexes on the two mouse species of Apodemus in this study. The dominant chigger species on A. chevrieri are L. scutellare, L. densipunctatum and L. cricethrionis Wen, Sun and Sun, 1984, which are also obviously different from A. draco and A. ilex in this study [30]. The above differences reflect the different susceptibility of different mouse host species to chigger infestation. ...
Chigger mites (Acari) are common ectoparasites on rodents, and they are the exclusive vector of scrub typhus. South China field mouse (Apodemus draco) and Lantsang field mouse (A. ilex) are two sibling rodent species. Based on field investigations in southwest China (2001–2015), this paper compared the infestation of these two mouse species with chiggers. Of 42 chigger species identified from two mouse species, 36 were found on A. draco, 11 on A. ilex and 5 common species on both mice. Jaccard similarity index (J = 0.12, J < 0.25) showed a very different species composition of chiggers on two mouse species, and some parameters of the chigger community were also different. The overall mean intensity of chiggers on A. draco (MI = 4.26) was higher than that on A. ilex (MI = 3.91, p < 0.05). The dominant chigger species on A. draco were Trombiculindus yunnanus, Leptotrombidium scutellare (a major vector species in China) and L. sinicum with a total constituent ratio Cr = 42.9% (106/247). Leptorombidium sinicum and L. scutellare independently occurred on A. draco with an association coefficient V = 0.09 (V ≈ 0). The dominant chigger species on A. ilex were L. rusticum, L. densipunctatum and L. gongshanense, with a total Cr = 58.14% (25/43). Leptorombidium rusticum and L. densipunctatum on A. ilex had a slight positive association (V = 0.49, 0.5 < V < 1). All dominant chigger species were unevenly distributed among different individuals of two mouse species. Chigger infestation showed sex bias on different sexes of two mouse species. The species abundance of the chigger community on A. draco was revealed as a log-normal distribution pattern.
... The above statistical analyses were performed under the statistical software SPSS (v. 25). p values < 0.05 were considered statistically significant. ...
... Compared with other rodent species in the same region, R. tanezumi harbored more individuals and species of chiggers with a high rate of infestation. In the present study, the species richness (S) of chiggers on R. tanezumi was higher than that on the Chevrier's field mouse, Apodemus chevrieri (S = 107 species), in Southwest China [25]. Some infestation indices of chiggers on R. tanezumi in the present study (MA = 7.01 and MI = 33.20) ...
... Some infestation indices of chiggers on R. tanezumi in the present study (MA = 7.01 and MI = 33.20) were also higher than those on A. chevrieri (MA = 6.32 and MI = 19.77) in the same region (Southwest China) between 2001 and 2019 [25]. The species richness and infestation indices of chigger mites on R. tanezumi in the present study were much higher than those on the striped field mouse, Apodemus agrarius (S = 14 species, PM = 3.40%, MA = 0.36, and MI = 10.63), in Southwest China [26]. ...
Chigger mites are the exclusive vector of scrub typhus. Based on field investigations of 91 survey sites in 5 provincial regions of Southwest China, this paper reported variations of chigger infestation on the oriental house rat (Rattus tanezumi) along various environmental gradients. A total of 149 chigger species were identified from 2919 R. tanezumi in the 5 provincial regions, and Leptotrombidium deliense (a major vector of scrub typhus in China) was the first dominant chigger species, followed by Ascoschoengastia indica and Walchia ewingi. Rattus tanezumi had a stable overall prevalence (PM = 21.10%), mean abundance (MA = 7.01), and mean intensity (MI = 33.20) of chiggers with the same dominant mites in the whole Southwest China in comparison with a previous report in Yunnan Province, but chigger infestations on R. tanezumi varied along different environmental gradients. Rattus tanezumi in mountainous landscape had a higher infestation load of chiggers with higher species diversity than in flatland landscape. The infestation was higher at lower altitudes and latitudes. A high intensity of vegetation coverage was associated with high infestations. The results reflect the environmental heterogeneity of chiggers on the same host species. Warm climate and high relative humidity are beneficial to chigger infestation on R. tanezumi.
... In China, 531 species of chigger mites have been identified, of which six transmit scrub typhus (including Leptotrombidium deliense, L. scutellare, L. rubellum, L. sialkotense, L. wenense and L. insulare). A total of 274 species of chigger mites have been identified in Yunnan, five of which transmit scrub typhus (Leptotrombidium deliense, L. scutellare, L. rubellum, L. wenense and L. insulare) (Lv et al., 2018;Xiang & Guo, 2021;Chen et al., 2022). Chigger mites are thought to be the only vector of scrub typhus; however, in addition to the transmission of tsutsugamushi, chigger mites are suspected of transmitting the virus that causes hemorrhagic fever in China (Lee et al., 2009;Peng et al., 2016a;Liu & Ren, 2022). ...
... Random sampling was conducted at various longitudes, latitudes and altitudinal gradients, and in different ecosystems. Traps were set at each survey site at 17:00-18:00 and checked in the next morning between 07:00-08:00, with captured animal hosts placed individually in premarked white cloth bags and then transferred to a temporary laboratory where they were anesthetized with ether, Small mammals were identified based on characteristics such as fur color and external morphology, chiggers were collected from each host and preserved in 70% ethanol vials to make slide specimens, and all chigger specimens were eventually identified by microscopy Peng et al., 2016b;Chen et al., 2022). Representative animal hosts and chigger mite specimens were deposited in the Herbarium of the Institute of Pathogens and Vectors, Dali University, Yunnan Province, China. ...
... All chiggers on the surface of each host were considered a community unit, and mite community structure was described using abundance (S), the Shannon-Wiener diversity index (H'), community evenness (J') and Simpson's dominance index (D). In this study, the infection rate (Pm) was statistically determined using the chi-square test (c 2 ), and mean multiplicity (MA) and intensity (MI) were analyzed for significance using the Mann-Whitney test or Kruskal-Wallis test (Zhang et al., 2009;Ding et al., 2021b;Chen et al., 2022). ...
Chigger mites are arthropods and are the sole vectors of scrub typhus, and rodents as well as other small mammals are the most common hosts of chigger mite larvae. Therefore, it is of great medical significance to study the ecology of chigger mites. In this study, a detailed analysis of chigger mites was conducted based on field survey data. A total of 4,941 chigger mites were collected from 86 hosts at 34 survey sites in Ruili, Yunnan Province, China. Among the 4,941 chiggers, five genera in one subfamily were identified; Schoengastiella ligula was the dominant chigger species with the highest infestation index, prevalence (Pm, 42.86%) and mean intensity (MI, 59.09%) (P<0.001). The association coefficient (V) between S. ligula and Gahrliepia radiopunctata was positively correlated (P<0.05), indicating the tendency of chiggers to select and coexist on the same host at the same time. The dominant species Leptotrombidium kunmingense, Ascoschoengastia indica, S. ligula and G. radiopunctata showed aggregation distribution patterns, indicating that the distribution of chiggers among different hosts was not uniform. Low altitudes and low latitudes appeared to be more favorable for the growth and reproduction of chigger mites (P<0.05). It is suggested to collect as many host samples as possible in future field investigations to better understand the dynamics of chigger mite populations and their primary hosts.
... According to the fitting result of the theoretical curve of species abundance, the expected total number of chigger species on E. miletus (S T ), together with the number of probably missed chigger species in the sampling investigation (S M ), were roughly estimated with the following formulae (Ding et al., 2021;Chen et al., 2022). In the above formulae, S A = the number of actually collected chigger species, π = 3.1415… (the circumferential rate), and S 0 and α are the same as before. ...
... MI = 19.77) (Chen et al., 2021b(Chen et al., , 2022. The chigger species diversity and infestation indices on E. miletus in the present study were obviously higher than those on A. agrarius and A. chevrieri in the same region (Chen et al., 2021b(Chen et al., , 2022. ...
... (Chen et al., 2021b(Chen et al., , 2022. The chigger species diversity and infestation indices on E. miletus in the present study were obviously higher than those on A. agrarius and A. chevrieri in the same region (Chen et al., 2021b(Chen et al., , 2022. The species Annotation: In the above table, n = the total number of animal hosts (E. ...
Based on a long-term field investigation in the five provincial regions of Southwest China between 2001 and 2019, the present paper studied the infestation and related ecology of chigger mites (chiggers) on the large Chinese vole (Eothenomys miletus), an endemic and dominant rodent species in the regions. A total of 52331 chiggers were collected from 2661 voles, and 52261 mites were identified as 185 species and 13 genera in the family Trombiculidae with very high species diversity. The identified 185 chigger species on E. miletus (a single rodent species) even exceeded those recorded in some countries. The overall infestation prevalence (Pm = 53.96%), mean abundance (MA = 19.64) and mean intensity (MI = 36.39) on E. miletus were much higher than those on some other rodent species in the same regions. Although the species composition showed a moderate similarity (J = 0.63) between male and female hosts (E. miletus), the infestation indices (Pm = 56.25%, MA = 21.67) of chiggers on male hosts were higher than those on the females (Pm = 51.23%, MA = 17.09) (P
Chiggers generally refer to the larvae of chigger mites, and they are the exclusive vector of scrub typhus. Based on the field surveys in the five provincial regions of southwest China between 2001 and 2022, the present paper first reported the infestation and related ecology of chiggers on the large-eared field mouse ( Apodemus latronum ), an endemic rodent species in the region. A total of 501 A. latronum were captured and examined, and 933 chiggers collected from the mice were identified as 2 families, 8 genera, and 61 species. The overall infestation prevalence ( PM ) and mean abundance ( MA ) of A. latronum with chiggers reached 19.76% and 1.86 mites/host, respectively. Of 61 chigger species identified from the mice, Leptotrombidium bayanense , Neotrombicula tongtianhensis , L. rupestre and L. yongshengense were four dominant species, which were of aggregated distribution among the different individuals of their host, A. latronum . The interspecific relationship analysis showed that a positive or negative correlation existed between any two of the four dominant chigger species. The male A. latronum harbored more chiggers with higher infestation prevalence ( PM = 20.25%), mean abundance ( MA = 2.31 mites/host) and mean intensity ( MI = 11.42 mites/host) than the female mice ( PM = 18.68%, MA = 1.11 mites/host, MI = 5.94 mites/host) with p > 0.05. The infestation indices of chiggers on adult A. latronum ( PM = 38.28%, MA = 5.11) were higher than those on juvenile mice ( PM = 12.63%, MA = 0.97) with p < 0.01, showing an age bias in the infestation. The relative fatness ( K ) was introduced to reflect the nutrition status of the mouse host. The mouse hosts with good nutrition ( K = 3.4±0.89g/cm3) harbored fewer chiggers than the hosts with poor nutrition (K = 2.2±0.90g/cm3) (p < 0.01). Based on Preston’s lognormal model, the theoretical curve of the species abundance distribution of chigger community on A. latronum was successfully fitted, the expected theoretical total number of chigger species on A. latronum in southwest China was estimated to be 93 species.
As a group of ectoparasites, chiggers (larvae of chigger mites) are the exclusive vector of scrub typhus (tsutsugamushi disease). Rodents are the most important hosts of chiggers. The Anderson's niviventer rat, Niviventer andersoni, is an endemic species of rodent in China. However, few studies have involved this endemic rodent species and its ectoparasites including chiggers. According to the field investigation in five provincial regions of southwest China between 2001 and 2019, this paper retrospectively analysed the infestation and distribution of chiggers on the body surface of N. andersoni in southwest China for the first time. From 77 Anderson's niviventer rats captured, a total of 527 chiggers were collected and they were identified as 39 species and nine genera in two subfamilies of family Trombiculidae. Of 39 chigger species identified, Leptotrombidium deliense and L. scutellare are the most important vectors of scrub typhus in China. The overall infestation indexes were PM = 29.87%, MA = 6.84 and MI = 22.91, and the indexes of chigger mite community were Mf = 39, H' = 2.60, E = 0.71 and D = 0.12. The dominant chigger species are L. wenense, L. xiaguanense and L. fujianense with a total Cr = 51.04%, among which L. wenense is one of the six main vectors of scrub typhus in China. The dominant chigger species are of aggregated distribution among different individuals of the rats.
Chigger mites are the vector of scrub typhus. This study estimates the infestation status and ecological characteristics of chiggers on the chestnut white-bellied rat Niviventer fulvescens in Southwest China between 2001 and 2019. Chiggers were identified under the microscope, and infestation indices were calculated. The Preston’s log-normal model was used to fit the curve of species abundance distribution. A total of 6,557 chiggers were collected in 136 of 342 N. fulvescens rats, showing high overall infestation indices (prevalence=39.8%, mean abundance=19.2, mean intensity=48.2) and high species diversity (S=100, H’=3.0). Leptotrombidium cangjiangense, Neotrombicula japonica, and Ascoschoengastia sifanga were the three dominant chigger species (constituent ratio=42.9%; 2,736/6,384) and exhibited an aggregated distribution among different rat individuals. We identified 100 chigger species, with 3 of them (Leptotrombidium scutellare, Leptotrombidium wenense, and Leptotrombidium deliense) as the main vectors of scrub typhus in China and nine species as potential vectors of this disease. Disease vector occurrence on N. fulvescens may increase the risk of spreading scrub typhus from rats to humans. Chigger infestation on N. fulvescens varied significantly in different environments. The species abundance distribution showed a log-normal distribution pattern. The estimated number of chigger species on N. fulvescens was 126 species.
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.
(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 Cr = 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 Cr = 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 S^(R)=19e−[0.22(R−0)]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.
