Infestation and related ecology of chiggers on the large-eared field mouse (Apodemus latronum), an endemic rodent species in southwest China

Abstract

Abstract 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.