Infestation and distribution of chigger mites on Chevrieri's field mouse (Apodemus chevrieri) in Southwest China

Abstract

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 were identified as 107 species, 11 genera and 3 subfamilies in 2 families, which revealed a high species diversity of the mites on A. chevrieri mice. Of 1981 A. chevrieri mice, 633 ones were infested with chiggers with a relatively high overall prevalence ( P M = 31.95%), mean abundance ( MA = 6.32) and mean intensity ( MI = 19.77). Of the 107 chigger species identified from A. chevrieri mice, three ones were the most dominant and they were Leptrombidium scutellare , L. densipunctatum and L. cricethrionis , which showed aggregated distribution among different individuals of the mice. A slightly positive association existed between every two dominant chigger species, which implied that the dominant chigger species tend to co-exist on A. chevrieri . The infestations of A. chevrieri with chiggers varied in different latitudes, altitudes and landscapes and they showed some heterogeneity along different environmental gradients. The logistic regression analysis showed that the risk factors for chigger infestations on A. chevrieri were landscapes, ages and altitudes, which implied that the environmental factors and host ages could influence the infestations of the mice with the mites. A theoretical curve of the species abundance distribution of chigger mites on A. chevrieri was successfully fitted by Preston's lognormal model, suggesting that the species abundance distribution conforms to the lognormal distribution pattern. The expected total species of chigger mites on A. chevrieri was roughly estimated to be 136 species and about 29 rare chigger species were probably missed in the sampling field investigation.

Analysis on infestation and related ecology of chigger mites on large Chinese voles (Eothenomys miletus) in five provincial regions of Southwest China

“…Previously our research group once reported the species composition and infestation of chiggers on two other rodent species, Apodemus agrarius and A. chevrieri , in Southwest China. The previous reports showed that only 14 chigger species were found on A. agrarius with very low infestation indices ( P m = 3.40%, MA = 0.36, MI = 10.63), and 107 chigger species (higher than on A. agrarius ) were found on A. chevrieri with relatively high infestation indices ( P m = 31.95%, MA = 6.32, MI = 19.77) ( Chen et al, 2021b , 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 , 2022 ).…”

“…The previous reports showed that only 14 chigger species were found on A. agrarius with very low infestation indices ( P m = 3.40%, MA = 0.36, MI = 10.63), and 107 chigger species (higher than on A. agrarius ) were found on A. chevrieri with relatively high infestation indices ( P m = 31.95%, MA = 6.32, MI = 19.77) ( Chen et al, 2021b , 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 , 2022 ). The species diversity and infestation of chiggers are often influenced by a series of factors including host species and various environmental factors.…”

“…The majority of chiggers usually have a low host specificity, and cross infestations of chiggers often happen among different host species in different environments ( Shatrov and Kudryashova 2006 ; Peng et al, 2016a ; Li et al, 2022 ). Eothenomys miletus is often distributed in various wild habitats such as farmlands, bushes and woodlands ( Huang et al, 1995 ; Wlison et al, 2017 ), and this may allow E. miletus to harbor abundant chiggers through cross infestations with other animal hosts ( Kaplan and Denno 2007 ; Mu and Zhu 2015 ; Chen et al, 2022 ).…”

“…A certain chigger species can parasitize different animal hosts and a certain host species can harbor different chigger species as well ( Li et al, 1997 ; Peng et al, 2016a ; Xiang and Guo 2021 ). The distribution of chiggers is often influenced by a series of factors including animal hosts and environments, and the host and environment selection of chiggers are different from species to species ( Chen et al, 2021b , 2022 ; Ding et al, 2021 ). On the same host species, the niche breadths of different chigger species can reflect their different ecological adaptability to different environments.…”

“…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 ). …”