Investigation and analysis of chigger mites on Apodemus chevrieri in Yunnan Province

Abstract

Objective To investigate and analyze the infestation status of chigger mites on a single rodent species,Apodemus chevrieri.Methods The field investigation was done in 25 counties of Yunnan Province.Food bait was placed in mouse traps to prey on A.chevrieri.The parasitic chigger mites on the body surface of the animals were collected,and then mounted on slides with Hoyer's medium,classified,and identified under a microscope.Some conventional statistical methods were used in the analysis of chigger mites on the rat (A.chevrieri),including constituent ratio,rate of mite infestation,mean abundance,mean intensity,species richness and Shannon-Wiener's index.The spatial distribution indices were used to determine the spatial pattern of the dominate chigger mites among different individuals of the host (A.chevrieri).Preston's lognormal model was used to describe the species-abundance distribution of chigger mite communities on A.chevrieri.Based on the species-abundance distribution,the total species number of chigger mites was estimated.Results From the body surface of 1 620 individual rats (A.chevrieri),8 038 individuals of chigger mite were collected,which were identified to comprise 88 species in 11 genera of 3 subfamilies (including 7 unidentified species).The overall rate of mite infestation and mean abundance of chigger mites from all the rats were 28.83％ and 4.93 (mites/per examined rat) respectively.A linear correlation existed between rate of mite infestation and mean abundance with the correlation coefficient r =0.87.Of the collected 88 species of chigger mites,five species were determined as the dominant species.The constituent ratio of the main dominant species of chigger mites,Leptotrombidium scutellare,reached 27.05％.All the dominant species of chigger mites showed an aggregated distribution among different individuals of A.chevrieri.The species-abundance distribution of chigger mite communities was successfully fitted to Preston's lognormal model (R2=0.89).The total number of chigger mite species was approximately estimated as 110 species,and therefore about 22 species were missed in the sampling process.Conclusions As a single rodent species,A.chevrieri has a great potential to harbor abundant chigger mites with high species diversity in Yunnan Province of China.L.scutellare is the main mite species on A.chevrieri.A large host sample is recommended in the future field investigation in order to find more mite species. Key words: Acari ; Chigger mite(Trombiculid mite) ; Apodemus chevrieri ; Yunnan ;