Identification of selected South African ticks using morphological traits and DNA barcoding

Abstract

The study aimed to identify and characterise ticks collected from selected wildlife species from selected areas in South Africa using morphological traits and DNA barcoding. The ticks were collected during necropsy and stored at the South African National Biodiversity Institution-National Zoological Gardens (SANBI/NZG) Biobank. A total of 48 individual tick specimens (adult, engorged and nymphs) from 13 hosts of captive wildlife were morphologically identified using appropriate morphological keys. DNA was extracted from whole ticks, followed by amplification of the COI and 16S rRNA genes. Amplification was confirmed by gel electrophoresis, and the amplicons were sequenced. The following tick species were morphologically identified from different species of wild animals: Amblyomma hebraeum, Haemaphysalis elliptica, Amblyomma hebraeum, Amblyomma nuttalli, Ixodes spp., Hyalomma truncatum, Hyalomma rufipes, Otobius megnini, Rhipicentor nuttalli, Rhipicephalus simus, Rhipicephalus evertsi evertsi, Amblyomma (Aponomma) exornatum, Rhipicephalus evertsi mimeticus and Rhipicephalus spp cf. sp nr pravus. Amblyomma spp. were the most common species, and represented 22.9% of the identified ticks. Sequencing results confirmed the morphologically results, and indicated that the new sequences were 95 – 100% similar to published sequences of ticks from wild and domestic animals, and vegetation in different parts of southern Africa. However, sequences of three tick species that were morphologically identified as Rhipicephalus evertsi evertsi, Hyalomma truncatum and Rhipicephalus simus, were closely similar to published sequences of Rhiphicephalus mimeticus, Hyalomma glabrum and Rhipicephalus gertrudae, respectively. The findings of this study confirm previous reports that wildlife in South Africa harbour a wide diversity of ticks of veterinary and public health importance, and that COI and 16S rRNA genes are suitable markers for characterisation of ticks. This study also highlights the risk of transmission of ticks and tick-borne diseases to new areas and hosts during translocation of wild animals. Future work should assess the risk of these ticks as vectors of tick-borne infections of human and livestock in order to inform management of tick-borne diseases, including tick-borne zoonoses, in captive facilities in South Africa.