STUDIES ON SPATIAL DISTRIBUTION PATTERNS AND SPECIES OF CHIGGER MITES ON SMALL MAMMALS IN THE SURROUNDING AREAS OF NORTH JINSHA RIVER OF YUNNAN

[Objective] To understand the species composition,the dominant species and the spatial distribution pat-terns of Chigger Mites on the body surface of Small Mammals in the surrounding areas of North Jinsha River of Yunnan.[Methods] Different oriented areas surrounding North Jinsha River were selected as investigate spots.Small mammals were randomly captured with baited mouse cages.Two auricles and hip 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 pre-served 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.Dispersion coefficient,clumping index,cassie index and patchiness index were used to analyze the spatial patterns of Chigger Mites.[Results] The captured 302 small mammals were identified as 16 species and 13 genera in 7 families.4 550 individuals of Chigger Mites were collected from the two auricles of 302 small mammal hosts and then they were identified as 63 species and 12 genera in 3 subfamilies of Trombioulidae.The amount of six dominant Chigger Mites species accounted for 75.68% of the total Mites,which were W.ew-ing,W.micropelta,L.sinicuum,L.scutellare,Helenicula simena,L.scutellare and so on.Most small mammal host had abun-dant Chigger Mites on their body surface and the highest one reached 42 mite species.All the values from four kinds of indices regarding the spatial patterns were much higher than their border values(0 or 1).The spatial distribution patterns of the dom-inant Chigger Mites species were therefore determined as the aggregated patterns among the different individuals of their hosts.[Conclusion] The Chigger Mite parasitism on small mammals is very common in the surrounding areas of North jinsha River of Yunnan.The species of Chigger Mites are very abundant in the areas.Aggregated pattern on the body surface of hosts forms ag-gregated Ectoparasitic groups of the Chigger Mites on small mammal hosts.