Morphological and molecular evidence of Linognathus vituli infestation in yaks from Ganzi Tibetan Autonomous Prefecture, China.

Louse infestations pose a serious threat to yak production, affecting animal health and causing substantial economic losses. However, until now there has been limited information available regarding yak lice infestations. Herein, we collected lice samples from Ganzi Tibetan yaks and amplified the nuclear small subunit ribosomal 18S and mitochondrial cytochrome c oxidase subunit 1 (cox1) genes for evolutionary and phylogenetic analyses. Stereoscopic and scanning electron microscope observations showed high morphological similarity between the yak lice and the cattle sucking louse Linognathus vituli (Phthiraptera: Anoplura: Linognathidae). Pairwise nuclear and mitochondrial DNA comparisons, genetic distance analysis and phylogenetic relationships strongly supported that the yak lice belonged to the same species, L. vituli and together shared a sister-species relationship with congeneric other species in the genus Linognathus. This was the first study to report L. vituli in yaks, based on combined micromorphological (scanning electron microscope) and molecular (nuclear-plus-mitochondrial DNA) evidence, and this finding should contribute to a more complete understanding of evolutionary biology, diagnostics and control of this sucking louse in the plateau yaks and other bovine animals.