Ultrastructural Observation Of Four Dominant Dermacentor Species(Acari:Ixodidae) And Molecular Detection Of Anaplasma Ovis Carried By Dermacentor,Xinjiang

Tick is an arthropod that rely on sucking blood of animal`s derm for living.Its spreading hazard to transmitting pathogen is just after mosquitoes,meanwhile it's also the storage host and carrier of multiple animal and human diseases.Tick is belong to Arthropoda,Arachnida,Acari,Parasitiformes and Ixodida.The Dermacentor and Hyalomma are dominant species in Xinjiang area,which could lead to Anaplasmosis,Q fever,Babesiosis,Theileriosis,Forest encephalitis,Xinjiang hemorrhagic fever and Lyme disease etc.It causes huge damage to animal husbandry industry and human health.There are quite few reports about Dermacentor in Xinjiang,particularly in terms of ultramicroscopic morphology.In this study,the stereoscopic microscope and scanning electron microscope were undertaken to carry out a observation on the morphological feature of the dominant species Dermacentor in Xinjiang and the molecular diagnose of its carrier Anaplasma ovis,which provides scientific basis for the accurate identification of the vector tick and the integrated control of the tick-borne diseases.(?)To determine the ultrastructural characteristics for diagnosis of dominant Dermacentor species,tick-borne vectors,in Xinjiang,northwestern China.four dominant Dermacentor species,i.e.,Dermacentor niveus,Dermacentor silvarum,Dermacentor nuttalli and Dermacentor marginatus,were observed by scanning electronic microscope on the basis of observation and identification with stereo microscope.Differences existed in the idiosoma and the enamel color of scutum among the four species.There are three odontoid processes on the ventral podomere ?(femur,tibia and metatarsus)of D.niveus and D.marginatus,and the odontoid processes are present on both tibia and metatarsus of D.nuttalli,but only present on the metatarsus of D.silvarum.Notable differences were also found in the seta arrangement of ventral palpus' s medial margin,the length of claws,and the claw-pulvillus length ratios of the four dominant Dermacentor species.The number and location of the odontoid processes on ventral podomer ?and the morphology of spiracular plate are diagnostic characteristics for the four Dermacentor species,and a rapid species identification could be made by combining these characteristics with the seta arrangement of ventral palpus,the claw length and the claw-pulvillus length ratio.(?)This experiment explained the difference between developmental stage and characteristics,and also provided a reference for the prevention and treatment in various instar of D.niveus.At the first time,the D.niveus of the Dermacentor was taken as the type species and a detailed ultrastructural study was carried out to the polypides at ages with the microscopes such as the stereoscopic microscope and scanning electron microscope.The ultrastructures of D.niveus had significantly difference between eggs,larvae,nymphs and adults.Eggs looked like oval,the color and internal structures of eggs would obviously change in incubation time.Larvae can be distinguished by dental formula 2|2;3 pairs of podomere;none of spiracular plate,genital aperture and anal groove;anal vaives with 1 pair of setae.Nymphs can be distinguished by dental formula 3-2|2-3,4 pairs of podomere;spiracular plate;none of genital aperture;anal vaives with 3 pairs of setae;basis capitulum,with triangle.Male of adult ticks can be identified by dental formula 3|3;spiracular plate,genital aperture;surface of anal vaives,with 5.5 pairs of setae;ventral idiosoma of podomere ?(femur,tibia and metatarsus),with 3 odontoid processes.Female of adult ticks can be also distinguished by dental formula 4-3|3-4;dorsal of basis capitulum,each side of the porose area with a seta;the surface of anal vaives,with 5 pairs of setae;none of ventral idiosoma of podomere?.(?)The specific primers of Anaplasma ovis was designed,according to the gene order of GenBank login MSP4(major surface protein 4),the dominant species Dermacentor carrier Anaplasma ovis is detected by PCR method,the specificity could be amplified to the segment of 322 bp,the comparative analysis of the homology with the Anaplasma ovis(KU497712.1)reached 98% after sequencing.The result showed the carrying rate of the Anaplama ovis of the surface tick from Altay Prefecture,Turpan Prefecture and Urumqi periphery in Xinjiang was 14.4%.For the tick-borne pathogen Anaplasma ovis by PCR in the above collecting area,only the D.niveus and D.niveus carried the Anaplasma ovis,with their carrying rate of 33.6%(42/125)and 24.0%(30/125)respectively.It could be determined that the D.niveus and D.marginatus were the vector ticks of the Anaplasma ovis.