| Ticks are an obligate blood-feeding arthropods which are widely distributed all over the world.Ticks can parasitize diverse animals and can adapt to the environment well.Most notably,ticks are the storage host and transmission medium of a variety of pathogens,which can cause a variety of zoonosis.Rhipicephalus microplus is a key tick species studied in China.The characteristics of microflora and pathogens carried by the whole insect of Rhipicephalus microplus and the factors affecting the composition of microflora have not been studied.In this study,204 microfloras carried by the whole insect of Rhipicephalus microplus from3 regions and 13 provinces and cities in China were sequenced.Firstly,the dominant bacteria carried by Rhipicephalus microplus were studied;secondly,the effects of sampling regions,host,blood-sucking state and gender were analyzed;then,the characteristics of microflora at the genus level of Rhipicephalus microplus were characterized;finally,the distribution characteristics of six tick borne pathogens were studied.The main results are as follows:(1)The dominant phyla carried by Rhipicephalus microplus were Proteobacteria,Firmicutes and Actinobacteria;the dominant bacteria genera were Staphylococcus,Acinetobacter,Rickettsia,Corynebacterium.(2)The sampling region was the main factor affecting the composition of its microflora,followed by the host animal,blood-sucking state and gender of Rhipicephalus microplus.(3)There was no significant difference in alpha diversity of microflora of Rhipicephalus microplus from Southwest China,South China and Central China;but there was significant difference in beta diversity;the genus Ehrlichia was specifically enriched in Rhipicephalus microplus in South China,and the genus Rickettsia was specifically enriched in Rhipicephalus microplus in Southwest China.(4)There was no linear correlation between the alpha diversity of the microflora of Rhipicephalus microplus and the nine environmental factors characterizing climate;however,some bacteria genus were negatively correlated with the environmental factors characterizing temperature and air pressure,and positively correlated with the environmental factors characterizing humidity and precipitation.(5)The alpha diversity of the microflora of ticks in free-living state was significantly higher than that of ticks parasitizing on the surface of bovinae or caprinae;Coxiella was enriched in Rhipicephalus microplus parasitizing on the surface of caprinae.(6)The microflora composition of the ticks in blood sucking tended to be similar;Rickettsia was specifically enriched in not blood sucking Rhipicephalus microplus,and Coxiella was specifically enriched in the blood sucking Rhipicephalus microplus.(7)The alpha diversity of microflora carried by male Rhipicephalus microplus was significantly higher than that of female ticks;Coxiella was specifically enriched in female ticks.(8)According to the species abundance at the genus level of microflora,204 samples of ticks can be clustered into 9 clusters of different dominant bacteria.(9)Among the Rhipicephalus microplus,Rickettsia and Coxiella had the highest prevalence,followed by Ehrlichia and Anaplasma,and Borrelia and Francisella had the lowest prevalence.In this study,metagenomic sequencing technology was used for the first time to study the microflora characteristics and pathogen characteristics of the whole insect of Rhipicephalus microplus in China.This study can not only understand the characteristics of microflora and tick borne pathogens of Rhipicephalus microplus in China,but also provide some theoretical basis for the prevention and control of tick borne pathogens and tick borne diseases at the microflora level,which has important public health significance. |
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