Community Structure of Chigger Mites on Small Mammals in the Surrounding Areas of Erhai Lake in Dali of Yunnan

Objective To understand the distribution of chigger mites on the body surface of small mammals,together with the species diversity and community structure of the chigger mites,in the surrounding area of Erhai Lake in Dali of Yunnan,China. Methods Different oriented areas surrounding the Erhai Lake in Dali were selected as investigated spots. Small mammals were randomly captured with baited mouse cages. Two auricles of every small mammal host were chosen as a fixed site for collecting chigger mites. All the chigger mites on the surface of two auricles were scraped off by a bistoury at first and then preserved in 70% of ethanol. Hoyer's medium was used to mount the chigger mites onto glass slides and the specimens of the chigger mites on the slides were finally identified into species under a microscope. Richness (S),Shannon-Wiener diversity index (H′) and dominance index (C′) were adopted to measure the community structure of chigger mites on small mammals. Results The captured 3 313 small mammals were identified as 21 species and 14 genera in 7 families. 56 150 individuals of chigger mites were collected from the two auricles of 3 313 small mammal hosts and then they were identified as 109 species and 13 generain 3 subfamilies of Trombiculidae . Theindividuals of eight dominant chigger mite species account for74 .42 %of the total mites . Most small mammals host have abundant chigger mites (more than eight species of chigger mites)on their body surface (exactly auricle surface) and the highest one reaches 58 mite species . Most species of chigger mites canparasitize different species of small mammals hosts si multaneously ( more than five host species at least) and the highest onereaches 15 host species . The infestation rate and the mite index of dominant chigger mites on their corresponding hosts varyfrom2 .06 %to 59 .02 %and from0 .462 7 to 68 .560 6 respectively . Of 17 main species of small mammal hosts ,the richness(S) of chigger mite community on 13 host species is beyond 10 and the highestSreaches 58 while the diversity index on 15host species is beyond 1 with the highestH′=2 .583 4 .Conclusion The chigger mite parasitismon small mammals is verycommonin the surrounding area of Erhai Lakein Dai pf Yunnan.The species of chigger mites are very abundant inthe area andtheir community structure is complicated . Most chigger mite species have abundant small mammal hosts with low hostspecificity .