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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]

In order to investigate the area distribution and host selection of Leptotrombidium scutellare in Yunnan Province, a field survey was carried out during 2001 to 2009, based on different geographic location, topography, climate and ecological characteristics. A total of 16 491 L. scutellare were captured from the body surface of 9 838 small mammal hosts of 7 families, 18 genera, and 30 species in 4 orders, accounted for 17.73% (16,491/92,990) of all chigger mites collected. L. scutellare distributed in 12 counties, more in the northwest and south of the Province. Although L. scutellare could parasitize on different small mammal species, most of them were on Eothenomys miletus and Apodemus chevrieri.

Eothenomys miletus were captured in 19 counties of Yunnan Province. The distribution of species-abundance and the species-plots relationship between E. miletus and chigger mites were analyzed by using ecological statistic method. There were totally 40,052 chigger mites collected from the body surface of 1741 E. miletus. 111 species of chigger mites were identified. The species-abundance distribution showed that with the increase of mite individuals, the number of chigger mite species gradually decreased. Most mite species were rare ones. Species-plot relation indicated that with the number of mouse plots (samples of E. miletus) increasing, the number of chigger mite species increased. E. miletus collected quantity up to date still could not reflect the exact species richness of chigger mite.

Objective: To investigate the distribution of Leptotrombidium deliense among different small mammal hosts in some areas of Yunnan province., Methods: A field survey was carried out in some counties of Yunnan province and the small mammal hosts were captured, using mouse cages and traps with baits. Chigger mites on the surface of two auricles were scraped off by a bistoury, and then preserved in 70% ethanol. Every specimen of the chigger mites on the slides was finally identified into species under a microscope. Some conventional statistical methods were adopted to calculate all the collected chigger mite species and the constituent ratios of Leptotrombidium deliense in different areas and on different hosts, together with its prevalence and mean abundance on different hosts., Results: A total of 10 222 small mammal hosts were captured from 19 counties and identified as 11 families, 34 genera and 62 species in 5 orders, and 92 990 individuals of chigger mites were collected from the body surface of these small mammal hosts. All the collected chigger mites were identified as 3 subfamilies, 22 genera, and 225 species. Meanwhile, Leptotrombidium deliensee only accounted for 1.659% of the total. The host specificity of Leptotrombidium deliense was very low and 1544 individuals of Leptotrombidium deliense collected from 8518 small mammal hosts belonged to 6 families, 13 genera and 19 species in 3 orders. Our results showed that Leptotrombidium delienses were mainly collected from Insectivora and Rodentia. Leptotrombidium deliense had long been considered as the dominant species of chigger mites and the main vector of tsutsugamushi disease in Yunnan province of China, but our results seemed not thoroughly supporting this point of view., Conclusion: Traditionally, Leptotrombidium deliense was the dominant species and the main vectors of scrub typhus in Yunnan province. However, based on our results, the above view might be true in some local places and the composition of chigger mites and the main vector of tsutsugamushi disease might be different in regions and habitats in Yunnan province.