The Microbiota Changes Of The Brown Dog Tick,Rhipicephalus Sanguineus Under Starvation Stress

Rhipicephalus sanguineus is an obligate blood-sucking ectoparasite that often parasitizes on the surface of vertebrates.It is widely distributed in tropical and subtropical regions.Due to its strong starvation resistance enhances the acquisition and transmission of various opportunities to breed pathogens,causing significant human health and animal husbandry impacts and economic losses.There are few studies on the regulation of microflora and the complex interactions between symbionts and the host during the blood-sucking process of Rh.sanguineus under starvation stress.Compared with insects of the class Insecta,the microbial community of ticks is more known to regulate the nutritional mechanism of the host.Therefore,it is of great reference significance to elucidate the regulation of the microbial community of Rh.sanguinis under starvation stress.The main results of this study are as follows:(1)Using morphological and molecular biology methods to identify the species of Rh.sanguineus collected in Hainan,observe the dorsal scutellum and genital pore,pseudophakic base,basal segment,tooth pattern,and steel groove of female and male ticks.There were noticeable differences among the others,and it was determined that the collected ticks were Rh.sanguineus.Screening under-saturated Rh.sanguinis parasitized on New Zealand white rabbits and mice and compared the changes in blood-sucking rate and life history characteristics between the two methods.Under artificial breeding conditions,it takes about 61-86 d to complete a generation of Rh.sanguineus.(2)The differentially significant genes and metabolic pathways of Rh.sanguineus before and after starvation were analyzed based on transcriptome sequencing technology.A total of 6447 differential genes were classified into 196 known pathways,among which101 differential genes involved 22 KEGG metabolic pathways with significant differences(P<0.05),lipid metabolism and Metabolic vitamin pathways had a higher impact,indicating that Rh.sanguineus had changes in nutrition-related pathways under starvation.(3)The adults of Rh.sanguineus was subjected to starvation stress at different times(one month,two months,four months,six months,and before and after blood feeding).After starvation stress,the composition and diversity of microbial communities in adult samples were evaluated.Found the composition of the microbial community of Rh.sanguineus changed significantly after starvation stress.With the prolongation of starvation stress,the dominant symbiotic bacteria Coxiella sp.of Rh.sanguineus gradually decreased.(4)The commensal microorganism Coxiella sp.was quantitatively analyzed by fluorescence quantitative PCR method,and it was found that it has tissue tropism in Rh.sanguineus,accounting for about 89% in the Malpighian tube and female gonad,and the midgut and salivary gland organs are few.Next,the blood-saturated nymphs were injected with the antibiotic ofloxacin within 24 hours.The blood-sucking rate,blood-saturated weight,fecundity(hatching rate),and blood-sucking rate of the larvae after hatching were all affected to varying degrees,indicating the removal of large amounts of blood.Some symbiotic bacteria have irreversible effects on them.To sum up,this study,on the one hand,clarified the identification of the dominant tick species Rhipicephalus sanguineus in Hainan and the establishment of artificial breeding in the laboratory;It provides an essential reference for tick resistance and development of tick-killing drugs.