Molecular Identification and phylogenetic analysis of Rhipicephalus hard-tick species from different Palestinian districts
رائدة سالم احميدان طقاطقة, سهير عريقات
جامعة القدس · فلسطين
Ticks are obligate blood-sucking hematophagous ectoparasites of terrestrial vertebrates,including amphibians, reptiles, birds, and mammals. Two general families of ticks arerecognized: Argasid (soft ticks) and Ixodid (hard ticks).The family Ixodidae of hard ticks isdivided into two groups based on morphological features: the Metastriata and theProstriata. In the Ixodidae family the genera Ixodes, Amblyomma, Dermacentor, andRhipicephalus are considered medically important. Among Rhipicephalus ticks, R.sanguineus, R. turanicus and R. bursa, are the most common species in Palestine. All threeRhipicephalus species are medically important vectors; therefore their accurateidentification is necessary. Morphological identification of these species is difficult,especially when the specimens are damaged or engorged with blood or in on immaturestage.The objectives of this study are to identify the most common hard-ticks species inPalestine, to establish a molecular approach for discrimination between hard ticks speciesthat infest sheep, and dogs and to study the genetic variation within each species incomparison to local and foreign hard ticks species. By identification of hard tick species,the potential risk to animals as well as humans may be evaluated and thus more adequatelycontrolled.A total of 351 hard ticks (Ixodidae) were collected from sheep, goats and dogs duringMarch to October 2014. Ticks were identified based on morphological features into twomain genus; Rhipicephalus (97.4%) and Haemaphysalis (2.6%). The ticks were furtheridentified down to the species level as following: R. sanguineus (79.2%), R. turanicus(9.7%), R. bursa (3.4%), H. alderi (0.9%) and H. parva (1.6%). All tick samples wereidentified by polymerase chain reaction (PCR) targeting the COX-1 gene followed byRFLP using AluI restriction enzyme. A highly significant correlation was observedbetween RFLP and microscopy identification (p= 0.01). Phylogenetic analysis based onCOX-1 genetic sequences showed four main clusters, R. sanguineus-like cluster, R.turanicus -like cluster G1 and G2, and R. bursa-like cluster.This study is the first of its kind to identify the hard tick species, using COX-1 genefollowed by RFLP as genetic marker. Distinction between the closely relatedRhipicephalus species: R. bursa, R. turanicus and R. sanguineus was successfullyaccomplished.