The ectoparasitic gamasid mites found on small mammals are important arthropods in the field of medical entomology. This paper studied the distribution and ecological niches of ectoparasitic gamasid mites on small mammal hosts in Yunnan Province of southwest China. Levins' niche breadth and Colwell-Futuyma's method were used to quantitatively evaluate host-specificity and similarity of host selection, and hierarchical analysis was used to illustrate niche overlap among gamasid mite species. Species diversity of both small mammals and gamasid mites was lower in indoor habitats than that in outdoor habitats. Most gamasid mite species were found on the body surface of the host species and niche breadths varied from species to species. A species with low niche breadth indicates high host specificity and most gamasid mites showed a relatively low niche overlap. The results suggest that a coevolutionary relationship may exist between some species of gamasid mites and their small mammal hosts. 1. Introduction Ectoparasitic gamasid mites (Acari: Mesostigmata) on the body surface of small mammals (especially rodents and insectivores) are generally regarded as an important group of medical arthropods because some are suspected as potential vectors of more than 20 zoonoses. Besides dermatitis caused by feeding ectoparasitic gamasid mites, it has been proved that some gamasid mites could be vectors of rickettsial pox and hemorrhagic fever with renal syndrome (HFRS) [1–3]. Yunnan Province in southwest China (Figure 1) has been a persistent focal point for HFRS in recent years . It is therefore deemed meaningful to investigate the distribution of ectoparasitic gamasid mites on small mammals in Yunnan Province. In recent years, Guo and his colleagues have made a series of studies on gamasid mites parasitic on small mammals in Yunnan, their research covered the fauna, geographical distribution, community structure, and other related issues concerning gamasid mites in that region [5–8]. Our intention was to expand on the distribution and ecological niches of ectoparasitic gamasid mites on small mammals ignored in Guo’s former reports by quantitatively evaluating host specificity and the possible coevolutionary relationship between ectoparasitic gamasid mites and their small mammal hosts. Mite ectoparasitism is a complicated phenomenon involving mutual adaptations between parasites and their hosts. As a result of long-term evolutionary and ecological processes, these complicated mutual interactions have important ecological and evolutionary implications [9, 10].
T. A. Younis, M. E. Fayad, M. A. El Hariry, and T. A. Morsy, “Interaction between acari ectoparasites and rodents in Suez Governorate, Egypt,” Journal of the Egyptian Society of Parasitology, vol. 25, no. 2, pp. 377–394, 1995.
Q. H. Yuan, H. L. Zhang, Y. Z. Zhang, et al., “Analysis of results in monitoring of hemorrhagic fever with renal syndrome in Yunnan Province in 2006. China,” Tropical Medcine, vol. 7, no. 8, pp. 1404–1408, 2007 (Chinese).
X. Y. Men, X. G. Guo, W. G. Dong, A. Q. Niu, T. J. Qian, and D. Wu, “Ectoparasites of Chevrier's field mouse, Apodemus chevrieri, in a focus of plague in southwest China,” Medical and Veterinary Entomology, vol. 21, no. 3, pp. 297–300, 2007.
B. R. Krasnov, G. I. Shenbrot, I. S. Khokhlova, and R. Poulin, “Relationships between parasite abundance and the taxonomic distance among a parasite's host species: an example with fleas parasitic on small mammals,” International Journal for Parasitology, vol. 34, no. 11, pp. 1289–1297, 2004.
M. V. Vinarski, N. P. Korallo, B. R. Krasnov, G. I. Shenbrot, and R. Poulin, “Decay of similarity of gamasid mite assemblages parasitic on Palaearctic small mammals: geographic distance, host-species composition or environment,” Journal of Biogeography, vol. 34, no. 10, pp. 1691–1700, 2007.
D. Simberloff and J. Moore, “Community ecology of parasites and free-living animals,” in Host-Parasite Evolution: General Principles and Avian Models, D. H. Clayton and J. Moore, Eds., pp. 174–197, Oxford University Press, 1997.
Y. F. Meng, X. G. Guo, X. Y. Men, and D. Wu, “Ecological niches of sucking lice (Phthiraptera: Anoplura) and their coevolution relationship with small mammal hosts in Yunnan, China,” Chinese Journal of Parasitology & Parasitic Diseases, vol. 26, no. 1, pp. 25–29, 2008 (Chinese).