Comparison of Chiggers (Acari: Trombiculidae, Leeuwenhoekiidae) on Two Sibling Mouse Species, Apodemus draco and A. ilex (Rodentia: Muridae), in Southwest China

SIMPLE SUMMARY: Chigger mites (Acari) are common ectoparasites and the exclusive vector of scrub typhus. South China field mouse (Apodemus draco) and Lantsang field mouse (A. ilex) are two sibling rodent species. The investigation in southwest China (2001–2015) showed that chigger infestations on two mouse species were quite different, including different species composition, overall infestation, community parameters and dominant chigger species. There were 36 chigger species found on A. draco and 11 on A. ilex, and 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). Dominant chiggers were unevenly distributed among different individuals of mouse hosts, and chigger infestation showed sex bias on different mouse sexes. The species abundance of the chigger community on A. draco was revealed as a log-normal distribution pattern. ABSTRACT: 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 C(r) = 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 C(r) = 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.