Examining host specificity of Chrysochus spp. (Coleoptera: Chrysomelidae) to inform management of invasive dog strangling vine Vincetoxicum rossicum (Apocynaceae) by Rhoda Bernadette deJonge A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Faculty of Forestr University of Torontoy © Copyright by Rhoda B. deJonge 2018 Examining host specificity of Chrysochus spp. (Coleoptera: Chrysomelidae) to inform management of invasive dog strangling vine Vincetoxicum rossicum (Apocynaceae) Rhoda Bernadette deJonge Doctor of Philosophy Faculty of Forestry University of Toronto 2018 Abstract Native insects have the capacity to form novel associations with invasive plants, which in some cases may allow them to exploit the invaders as hosts. To date, little work has been done to predict these novel associations and their outcomes before they occur. By conducting host- specificity tests on native North American Chrysochus spp. ( C. auratus , C. cobaltinus , and their hybrid) with the European invasive vine, Vincetoxicum rossicum and North American Apocynaceae plants, this thesis: (1) addresses the question as to whether native Chrysochus spp. will form a novel association with the vine; (2) predicts the outcomes of such an association; (3) suggests ways to improve the potential biotic resistance of these beetles to reduce the spread of this vine; (4) compares host specificity results of these North American beetles with their European congener C. asclepiadeus , in order to enhance predictions of its ecological host range. Feeding, survival, oviposition, and development tests with North American Chrysochus at all life stages demonstrate: (1) V. rossicum may act as an ovipositional sink for eastern C. auratus ; ii (2) the vine could be a source of food for C. cobaltinus when the plant expands its range westward; and (3) Chrysochus hybridization will not increase use of this invasive vine. In addition, host-specificity tests conducted here show that C. auratus , which does not feed or develop on Asclepias spp . in its natural ecological host range , will complete development on plants in this genus when exposed under lab conditions. This false positive for host plant specificity suggests that, in this genus, the predicted ecological host range of the European congener (C. asclepiadeus) of the two North American species may have been overestimated. Overall, my findings highlight: (1) the importance of predicting novel associations before they occur in the field; (2) demonstrate how the testing of native relatives of biological control candidates can enhance ecological host-range predictions for classical agents; and (3) increase our knowledge about the potential outcomes of novel associations between introduced V. rossicum and North American Chrysochus spp. iii Acknowledgments I learned early on in my graduate career that a PhD thesis is something that will never be finished without the help and support of an excellent supervisor, committee, family, friends and colleagues. First I want to thank my supervisor, Sandy Smith. She accepted me as a graduate student and has continually supported me financially, intellectually and with helpful insights and advice. Without her positivity, guidance, and encouragement, the prospect of tackling a PhD thesis would have seemed insurmountable. Acting as a co-supervisor, I also have Rob Bourchier so much to thank. For financial support, helpful critiques, advice in test design, and always finding the practical angle in the research. Both Sandy and Rob’s constant availability and helpful feedback has improved this thesis immeasurably. I also want to thank my committee members, Peter Kotanen and Marc Cadotte. Both gave up much of their time to offer insightful suggestions for the thesis and had time to meet with me one-on-one to instruct me in areas where I needed more help. In particular, Marc’s class in how to use the statistical software R has been invaluable. I also appreciated the time, comments and critique from my external reviewers Danijela Puric-Mladenovic (Faculty of Forestry) and Steve Murphy (University of Waterloo). Staff at the Faculty of Forestry have been incredibly helpful and patient over the years, particularly Tony Ung, Deborah Paes, and Ian Kennedy (minus the patience for this last fella). I want to thank Jay Malcolm and Marie-Josée Fortin for their help with statistics, as well as Terry Carleton, Andy Kenney, Danijela Puric-Mladenovic, Kathleen Ryan, Sandy Smith, and Sean iv Thomas for teaching such interesting and helpful classes that have all grounded my research. I also want to thank René Sforza at EBCL-France and André Gassman at CABI-Switzerland for introducing me to this fascinating study system back in 2010. As well, Merrill Peterson, Janis Dickinson, and Aaron Weed are owed my great thanks for help in assisting in my learning ‘all things Chrysochus’. I am indebted to all the property owners who allowed myself and research assistants to collect insects and plant material on their land: The City of Toronto’s High Park, Koffler Scientific Reserve, Royal Botanical Gardens, Riley Wilderness Park, Yosemite National Park, Hastings Scientific Reserve, La Primavera Farms, as well as the Harrop and Loewith families. This research was funded by the Invasive Species Centre, Agriculture and Agri-Food Canada, Faculty of Forestry, Ontario Ministry of Natural Resources and Forestry, as well as the Ontario Graduate Scholarship and Jeanne F. Goulding Fellowship. There are a number of undergraduate students who have helped with the project in varying capacities over the years: Elpidio Chavez, Atheena Dy, Jeremy Gautherot, Iris Hu, Rosemary Martin, Felicity Ni, Ariane Pouet, Nina Sokolov, Alex Stepniak, and particularly, Frank Oukhouia, who did so much to improve the testing methods early on in the project. I owe mountains of thanks to all my friends and colleagues at the Faculty of Forestry including Melissa Apostoli, Kira Borden and Anjali Karve for all our great chats at the GSU pub in those early days and for continuing to be good friends (when we actually get to see each other!). My lab and office mates over the years: Sadia Butt, Amy Choi, Eric Davies, Yicheng Du, Alexa Feldberg, Susan Frye, Justin Gaudon, Nurul Islam, Amany Mansour, Bo Patankar, Paul Piascik, v Lucas Roscoe, Tara Sackett, Lukas Seehausen, Janani Sivarajah, Tim Skuse, Graham Watt, and in particular Richard Dickinson to whom I owe so much for all the chats over noodles and long days in the field where we solved all the world’s invasive species problems. Without these friends and colleagues, I would have felt completely lost navigating the foreign world that is graduate school. Last, I want to express my love and gratitude to my family and friends. Many thanks to Joanne Feddes and Angela Reitsma for all their encouragement over the years. Thanks particularly to Joanne for her help along with little Margot to collect beetles on hot summer days. Thanks to all my many siblings, in particular Sara, Dave and Jess who spurred me on by making me feel like I was accomplishing this thesis not just for myself, but for them as well. To my in-laws, Henk and Anna, I owe special thanks for all the much-needed childcare and taking an entire weekend to attend a conference in Montreal with me so I could present and still take care of Willa when she was yet so small. I owe so much gratitude to my amazing parents; first to my mom, who encouraged my love of the outdoors and showed me how to sew malaise traps before I even finished high school. I think she would have gotten a big kick out of this whole ‘PhD thing’. Thanks to my Dad and Linda for giving up weeks upon weeks to collect and measure insects all over California, and in particular Dad for introducing me to insects in the swamps of Southwestern Ontario when I was little. We make such a great team. The support from both Dad and Linda has been invaluable over the years including their help with childcare and all the random tasks I’ve assigned. My greatest thanks I save for my amazing husband Johan. He has given up every summer for the last few years to be my number one field assistant. His love and support for me undertaking vi this grand adventure has been without equal. Many thanks to my daughter Willa for her help in the field (her tiny stature gives her a great angle to find all the beetles hiding under leaves!) and for her extreme interest in all things larvae. Both Johan and Willa have slogged through hours in the field, the humid greenhouse, and have put up with getting kicked out of the house so I can write in peace. Thank you all. vii Table of Contents Acknowledgments ........................................................................................................................ iv Table of Contents ........................................................................................................................ viii List of Tables ................................................................................................................................ ix List of Figures ............................................................................................................................... xi List of Appendices ...................................................................................................................... xiii Chapter 1: An Introduction to Novel Associations and Biological Control ................................ 1 Novel Associations .................................................................................................................................