Molecular identification and phylogenetic study of Demodex caprae

Abstract

The DNA barcode has been widely used in species identification and phylogenetic analysis since 2003, but there have been no reports in Demodex. In this study, to obtain an appropriate DNA barcode for Demodex, molecular identification of Demodex caprae based on mitochondrial cox1 was conducted. Firstly, individual adults and eggs of D. caprae were obtained for genomic DNA (gDNA) extraction; Secondly, mitochondrial cox1 fragment was amplified, cloned, and sequenced; Thirdly, cox1 fragments of D. caprae were aligned with those of other Demodex retrieved from GenBank; Finally, the intra- and inter-specific divergences were computed and the phylogenetic trees were reconstructed to analyze phylogenetic relationship in Demodex. Results obtained from seven 429-bp fragments of D. caprae showed that sequence identities were above 99.1% among three adults and four eggs. The intraspecific divergences in D. caprae, Demodex folliculorum, Demodex brevis, and Demodex canis were 0.0-0.9, 0.5-0.9, 0.0-0.2, and 0.0-0.5%, respectively, while the interspecific divergences between D. caprae and D. folliculorum, D. canis, and D. brevis were 20.3-20.9, 21.8-23.0, and 25.0-25.3, respectively. The interspecific divergences were 10 times higher than intraspecific ones, indicating considerable barcoding gap. Furthermore, the phylogenetic trees showed that four Demodex species gathered separately, representing independent species; and Demodex folliculorum gathered with canine Demodex, D. caprae, and D. brevis in sequence. In conclusion, the selected 429-bp mitochondrial cox1 gene is an appropriate DNA barcode for molecular classification, identification, and phylogenetic analysis of Demodex. D. caprae is an independent species and D. folliculorum is closer to D. canis than to D. caprae or D. brevis.

Population identification and divergence threshold in Psoroptidae based on ribosomal ITS2 and mitochondrial COI genes

“…Although rDNA ITS2 and 630-bp mtDNA COI at the 5′ terminal have been used for intra-and interspecies classification and identification in Acari (Zhao et al 2014;Yang et al 2011;Chitimia et al 2009), it is unclear whether the two genes are suitable for intergeneric identification. In the present study, it was confirmed for the first time that rDNA ITS2 can be used not only for intra-and interspecies identification (intraspecific divergences threshold≤5.20 %, interspecific divergences threshold≥6.18 %) but also for interspecies and intergenera identification (interspecific divergences threshold≤14.86 %, intergeneric divergences threshold≥ 15.72 %) with an obvious barcoding gap.…”

Clinical aspects of demodecosis in veterinary and human medicine

“…The invasion of this mite affects mainly older animals and those in a poor body condition (38). The identification and molecular analysis of the gen cox 1 have made it possible to consider D. caprae as a separate species, phylogenetically independent of the other species from the genus Demodex (59).…”

“…The sequences obtained can be compared with those deposited in the GenBank database, which makes it possible to differentiate mite species and create phylogenetic maps of them (21,59). …”

Structure and molecular evolution of the barcode fragment of cytochrome oxidase I (COI) in Macrocheles (Acari: Mesostigmata: Macrochelidae)

“…Species of Macrocheles show a relatively small scale of variability in morphological features, and unknown cryptic diversity can always be uncovered using molecular techniques. Molecular techniques have proven highly effective for exploring the phylogenetic relationships and species boundaries of mites (Dabert et al, 2011 ; Li et al, 2010 ; Skoracka et al, 2012 ; Skoracka & Dabert, 2010 ; Yang et al, 2011 ; Zhao et al, 2014 , 2015 ). However, few studies have used molecular information to explore the phylogenetic relationships of macrochelids.…”