School of BioSciences - Theses

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    The phenology of outbreaks of the Australian plague locust, Chortoicetes terminifera (Walker), affecting Victoria.
    Berg, Gordon Norris ( 2021)
    This thesis examines the phenology of outbreaks of the Australian plague locust, Chortoicetes terminifera, which have affected the state of Victoria over the period from the mid 1930s to the current time. Victoria is the southern-most limit of the species’ occurrence in eastern Australia but there are episodic outbreaks of it which may cause significant economic damage to agriculture. C. terminifera does not usually survive in high populations in Victoria for more than a few seasons and reinfestation is usually due to migration from the northern states of NSW and Queensland in eastern Australia where it persists more continuously. The key research question investigated in the project asks what determines whether C. terminifera outbreaks will, or will not, affect Victoria when source populations exist in other states? The project explores whether there are identifiable patterns of outbreaks and recessions of C. terminifera in Victoria and seeks to identify the influencing factors such as climate, weather and control interventions in northern source areas which can affect migration to Victoria. Chapter 1 provides a general review of the literature pertaining to locusts, summarising their biology, behaviour and effects and Chapter 2 provides a more detailed review of the Australian plague locust, C. terminifera. These provide necessary context for the data collection, analyses, and conclusions in later chapters. Chapter 3 examines the long-term temporal phenology of C. terminifera outbreaks and recessions affecting Victoria utilising recent and historic data. A long-term phenology of outbreaks of C. terminifera in Victoria is constructed and compared to the overall eastern Australian situation. Chapter 4 examines the phenology of an individual outbreak cycle affecting Victoria using data from the 2009/2010/20011 outbreak which is the most recent major outbreak affecting the state. It identifies influencing factors important to migration into Victoria and the subsequent development and decline of C. terminifera populations in Victoria. Chapter 5 develops methodologies to examine the effects of two critical influencing factors, temperature and wind, which affect locust migration to Victoria. It identifies available data sources which can be used to investigate these in the case studies examined in Chapter 6 which considers several migrations to Victoria and what influences whether C. terminifera outbreaks will, or will not, affect Victoria when source populations exist in other states. Chapter 7 summarises the findings, discusses their significance in achieving the project's objectives, and discusses opportunities for further research. It concludes that whilst climate change is likely to alter the suitability of southern NSW and Victoria for population development and survival as well as the frequency of plague events, there is a continuing need for coordinated surveillance, control capabilities, training, and research and development resources to be maintained.