(Oreixenica Ptunarra) from the Threat of Predation by Introduced Vespid Wasps in Tasmania, Australia
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Conservation management to protect the threatened ptunarra brown butterfly (Oreixenica ptunarra) from the threat of predation by introduced vespid wasps in Tasmania, Australia Josephine Potter-Craven BSc (Hons) Thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy (Geography & Environment) School of Technology, Environments and Design University of Tasmania, Australia May 2019 Declaration This thesis contains no material which has been accepted for a degree or diploma by the University or any other institution, except by way of background information and duly acknowledged in the thesis, and to the best of my knowledge and belief no material previously published or written by another person except where due acknowledgement is made in the text of the thesis, nor does the thesis contain any material that infringes copyright. The publishers of the paper comprising Chapter Three hold the copyright for that content and access to the material should be sought from the respective journal. The remaining non-published content of the thesis may be made available for loan and limited copying and communication in accordance with the Copyright Act 1968. The research performed on O. ptunarra associated with this thesis was performed under the authority of Threatened Fauna Permit numbers TFA 11061 and TFA 12060 and complied with the DPIPWE Translocation Policy. Fipronil used for wasp control was used under the authority of permit numbers PER9326 and PER13184 issued by the Australian Pesticides and Veterinary Medicines Authority. Josephine Potter-Craven 15 May 2019 Conservation management to protect the threatened ptunarra brown butterfly (Oreixenica ptunarra) from the threat of predation by introduced vespid wasps in Tasmania, Australia ii Statement of Co-Authorship The following people and institutions contributed to the publication of work undertaken as part of this thesis: • Josephine Potter-Craven, School of Technology, Environments and Design = Candidate • James Kirkpatrick, University of Tasmania, Supervisor = Author 1 • Peter McQuillan, University of Tasmania, Supervisor = Author 2 • Phillip Bell, University of Tasmania = Author 3 Paper incorporated in Chapter 3: Potter-Craven J, Kirkpatrick JB, McQuillan PB, Bell P (2018) The effects of introduced vespid wasps (Vespula germanica and V. vulgaris) on threatened native butterfly (Oreixenica ptunarra) populations in Tasmania. J Insect Conserv 22:521-532. https://doi.org/10.1007/s10841-018-0081-9 JPC was the primary author, and contributed approximately 80 per cent of the planning, research and writing of the paper. JPC led the conceptualisation, literature review, fieldwork, data collection, analysis, writing up and liaising with the journal. JK contributed by assisting with data analysis, providing knowledge on ecology through several decades of knowledge, support, and assisting with the written manuscript. PM and PB contributed by assisting with the conceptualisation, providing knowledge on butterflies through their several decades of local knowledge, and to improving the written manuscript. We the undersigned state that the “proportion of work undertaken” specified above for the published peer- reviewed manuscript contributing to this thesis is correct: Signed: ______________________ ______________________ James Kirkpatrick Mark Hunt Supervisor Head of School School of Technology, Environments & Design School of Technology, Environments & Design University of Tasmania University of Tasmania 15 May 2019 22 May 2019 Date: ______________________ ______________________ Conservation management to protect the threatened ptunarra brown butterfly (Oreixenica ptunarra) from the threat of predation by introduced vespid wasps in Tasmania, Australia iii Acknowledgements Thanks to my supervisor, Distinguished Professor Jamie Kirkpatrick, for supporting and encouraging me, always having time to discuss matters, for hours of analysis, and for coming to leech-ridden Surrey Hills to assist with the vegetation surveys! Thank you for believing in me and for your firm conviction that nothing is too hard, actually it can be quite easy. Thanks for your approachable manner, exuberant spirit and bold laugh, that made it such fun to come to uni. I will always treasure the honour of having had the opportunity to learn from such a knowledgeable mentor and remarkable individual. Thanks to my supervisor, Dr Peter McQuillan, for your enthusiasm for the project and insights into butterflies and other invertebrates. Thanks also for coming to assist with the vegetation surveys, our combined plant knowledge made the task much faster and more enjoyable. Thanks to my mentor, Dr Phil Bell, who sparked my interest in ptunarra brown butterflies to begin with and whose continued enthusiasm assisted throughout the project. Thank you for sharing your wealth of knowledge about ptunarra and wasps and for assisting with some butterfly surveys and translocations. Thanks to my wonderful husband, Leigh Craven, who came and did lengthy hours of fieldwork in the far northwest, supported me, encouraged me and gave me time to study by doing extra kid wrangling and less of his beloved golf and surfing! Thank you so much, without your love and support I would not have been able to finish this project. Thanks to my family, Potters, Cravens and Pauses, for all your support and encouragement! As well as the assistance in the field with all manner of butterfly and wasp surveys, translocations, wasp control, set-up and pack-down. Thanks also for the dinners, watching the kids, the financial assistance and to Dod for the editing! Thanks to James Dick for sharing his knowledge about ptunarra and wasp control, as well as assisting with surveys and providing background data on the sites. Thanks for providing access to the sites through the previous landowners, Gunns, and for the accommodation and the support during car breakdowns. Thanks to Denna Kingdom and the Tasmanian Land Conservancy for providing access to the Vale of Belvoir and permission to conduct butterfly and wasp trials within the reserve. Thanks for your company on some extended stays in the bush and for access to background data on the site. Thanks to Clare Hawkins for introducing me to the Surrey Hills site on a rare foray into the field to perform some butterfly and wasp surveys and translocations. Thanks also for providing some background data on early work in this area. Thanks to the Department of Primary Industries, Parks, Water & Environment for allowing me study leave and in-kind support in the form of loaned equipment and the use of a vehicle during the fieldwork component of the project. Thanks also to the Threatened Species Section of DPIPWE for encouragement and assistance. Thanks to Sue Botting and Natural Resource Management Cradle Coast for their grant to support food and accommodation for the volunteers, which was invaluable and assisted in the success of the project. Thanks for Mick Statham for donating his collection of wasp traps to this project and for teaching me about wasp control and how to best use the traps. A big thanks to all of the volunteers who assisted, without whom this study would not have been possible. Thanks for coming out into the field during rain or shine to count, catch and move butterflies and control wasps. Thanks for your company and cheerfulness, picnics in the sun, swims, and platypus spotting! I dedicate this thesis to my two children Genevieve and Madeleine, who came along the way, and who deserve to live in a world that contains butterflies. Conservation management to protect the threatened ptunarra brown butterfly (Oreixenica ptunarra) from the threat of predation by introduced vespid wasps in Tasmania, Australia iv Abstract Butterfly numbers are declining worldwide primarily due to habitat loss and habitat degradation, resulting in many species now being classified as threatened. Many butterfly species are further endangered by the additional threats of fragmentation, agricultural chemicals, climate change and introduced predators. In Tasmania, Australia, the threatened ptunarra brown butterfly (Oreixenica ptunarra) has recently come under threat from predation by introduced vespid wasps, which have the potential to further reduce their numbers, possibly causing local extinctions. The nature of this new threat and possible conservation actions to mitigate it are the subject of this thesis. The present study investigated whether vespid wasps were having a significant impact on O. ptunarra numbers, ways of controlling the wasps or excluding them from O. ptunarra’s habitat, and methods of creating new populations of O. ptunarra by translocating individuals within its historical range. Vespid wasp control was performed by using toxic baits containing fipronil, as well as directly poisoning wasp nests. Transect surveys to count vespid wasp and O. ptunarra numbers performed at wasp control sites and monitoring sites, were compared to determine whether the wasp control was effective and whether the wasps were having a negative effect on O. ptunarra numbers. Vegetation transect surveys were also performed at sites with and without O. ptunarra to determine the relationship between flora species and O. ptunarra numbers and which species O. ptunarra prefers. Translocations of O. ptunarra were attempted by moving female imagoes and eggs to suitable sites within the species’ historical range to create new, self-sustaining populations. The buffer size necessary to exclude wasps from O. ptunarra habitat