Thesis aims

The overarching aims of this thesis are to understand the ticks parasitising urban wildlife and to characterise the microbial community associated with these ticks and their wildlife hosts. To address these aims, this thesis is divided into three major themes.

1. Australian ticks

Chapter 2 reviews records of Australian ticks in respect to distribution, hosts and genetic information. This chapter reviews and curates records of Australian ticks collected from museum collections, public databases (e.g. living atlas Australia) and the literature. Records of tick species from humans is also provided, and expands the number of tick species recorded biting humans in Australia. Updated distribution maps are provided for three common and wide spread species in Australia; the ornate kangaroo tick Amblyomma triguttatum, Australian paralysis tick Ixodes holocyclus and the marsupial tick Ixodes tasmani. Genetic information of Australian ticks is synthesised and new data is presented. In this chapter, a high-throughput sequencing approach using the 12S rRNA gene was developed and applied to the identification of hard ticks.

2. Bacteria and haemoprotozoa present in wildlife and ticks

For Chapters 3 and 4, samples were collected from Australian wildlife. Small mammal trapping was carried out in Perth, Western Australia and Sydney, New South Wales and blood, tissue and tick samples were collected from animals. Amplicon metabarcoding on the Illumina MiSeq platform and targeted Sanger sequencing were used to characterise a suite of bacteria and selected haemoprotozoa. This method provides an unbiased approach to investigate (i) the microbes present in these wildlife samples and (ii) uncover any overlap between sample types in order to identify microbes that may be transmitted by ticks into wildlife, which potentially act as reservoir hosts.

3. Molecular characterisation microbes

Chapters 5 and 6 provide targeted information about selected haemoprotozoa from wildlife. Trypanosoma lewisi identified in Chapter 5 was identified in blood samples. As Chapter 4 made use of data collected over an extended period of time, Chapter 5 was written as a short communication to allow rapid dissemination of this result. Additionally, Chapter 5 includes a near full length characterisation of the 18S rRNA gene that informs the phylogenetic position of this Tr. lewisi-like species. A collaborative research opportunity arose during my candidature to provide the first molecular screening of blood parasites from the iconic Tasmanian devil (Chapter 6). While this paper presents a Tasmanian devil-centric view of haemoprotozoa, it also describes a surveillance method for potential zoonotic pathogens in previously neglected areas.