Exploring the application of mosquito iDNA for monitoring Australian mammals and birds

<p dir="ltr">Globally, biodiversity is declining at an alarming rate. This includes extensive declines in Australia’s unique mammals, with a third of all modern mammalian extinction events occurring in Australia, despite being home to only 6% of the world’s mammalian diversity. Australia has also observed a 60% decline in threatened birds over the last 40 years. To reduce the rate of decline in the world’s biodiversity, there is a pertinent need for reliable and robust biodiversity data. Technological advances such as passive acoustic monitors (PAM), camera traps, and more recently environmental DNA (eDNA), are providing sensitive and minimally invasive alternatives to traditional monitoring techniques. This includes a growing sub-discipline within the field of eDNA, ingested DNA (iDNA), an approach employing the use of 'invertebrate samplers' to collect the DNA of an area’s vertebrate diversity. Early studies using carrion flies and leeches have shown great promise, detecting more orders of chordates than established methods, including difficult to detect taxa such as small and arboreal mammals. However, other 'samplers', such as mosquitoes have not been as extensively explored, but may be suitable in many parts of Australia, where they are diverse and abundant. Furthermore, mosquitoes may offer an advantage over other 'samplers', providing a higher degree of both temporal and spatial accuracy associated with the iDNA signal.</p><p dir="ltr">This thesis examined several aspects of mosquito iDNA application and aimed to: a) understand what terrestrial vertebrate diversity can be detected with iDNA; b) explore how iDNA can be used to provide ecologically relevant information on birds and mammals within Kakadu National Park; c) compare iDNA against other minimally invasive approaches (PAM and camera traps); and d) understand the temporal and spatial variation in mosquito communities within a region of Kakadu.</p><p dir="ltr">The findings from this thesis clearly highlights the application of iDNA on varying scales from citizen science projects to large scale monitoring programs. Demonstrating its capacity to detect a diverse range of birds and mammals, both native and introduced of varying body sizes and ecologies. With notable detections in Kakadu including the threatened white-throated grasswren (<i>Amytronis woodwardi</i>), ghost bat (<i>Macroderma gigas</i>) and leaf-nosed bats (<i>Hipposideros sp</i>.), along with the elusive spectacled hare-wallaby (<i>Lagorchestes conspicillatus</i>). Additionally, highlighting the capability of iDNA to provide ecologically relevant information critical to the management of Kakadu National Park, including the influence of fire regimes and vegetation on avian and mammalian communities. Moreover, demonstrating the sensitivity of iDNA, detecting twice as many mammals as camera traps and offering a complimentary approach to PAM for bids. Our findings emphasise the importance of understanding the ecology of the ‘invertebrate sampler’, with seasonal conditions driving distinct mosquito communities, with different taxa having differential feed preferences, thereby influencing the detection of targeted taxa. Collectively, the research captured in this thesis clearly demonstrated the utility of mosquito iDNA as a sensitive approach that can provide biodiversity data in an ethical and cost-effective manner. With it envisioned that this sensitive data will be utilised to inform management decisions and improve the trajectory of threatened fauna.</p>