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Habitat-based drivers of arthropod abundance and richness in an intensively farmed agricultural landscape by Aleksandra Dolezal A Thesis presented to The University of Guelph In partial fulfilment of requirements for the degree of Master of Science in Integrative Biology Guelph, Ontario, Canada © Aleksandra Dolezal, July 2019 ABSTRACT HABITAT-BASED DRIVERS OF ARTHROPOD ABUNDANCE AND RICHNESS IN AN INTENSIVELY FARMED AGRICULTURAL LANDSCAPE Aleksandra Dolezal Advisor: University of Guelph, 2019 Dr. A. S. MacDougall Habitat is critical for sustaining arthropod populations, but its influence in agricultural landscapes where arthropods are declining is unclear. In a heavily farmed area of Ontario, I examined habitat effects on arthropods at two scales: landscape (habitat isolation) and local (farm cover type -crop, prairie, forest). Additional analyses tested differences in arthropod communities among cover types, how prairie addition affects leaf defoliation, whether crop type influences arthropods (soy, corn, orchard, mixed organic), and whether arthropod richness differs between farm and non-farm sites. I found arthropod richness and abundance to be determined locally, via the presence of restored high-quality prairie habitat. Prairie addition did not affect leaf defoliation but influenced the spatial distribution of herbivores in crops. Crop type influenced arthropod groups, especially herbivores, which preferred mixed organic cover. Lastly, farm and non-farm sites revealed similar family-level richness, suggesting that conventional farms can support arthropod biodiversity if habitat is not limiting. iii ACKNOWLEDGEMENTS This thesis would not have been possible without the researchers who came together to initiate an extraordinary project that was the basis for my work. It’s their guiding idea and the efforts of all the participating scientists and non-scientists which make this project an on-going success. Being a part of this collaborative effort has been a great privilege. I want to express my gratitude to my supervisor Dr. Andrew MacDougall, who gave me the opportunity to do my MSc under his guidance. I am especially thankful that he encouraged me in skill-building activities such as workshops and conferences which added great experiences to my time as a graduate student. I am also grateful to my committee members Kevin McCann and Alex Smith for giving me input throughout my research journey. I would also like to acknowledge Steve Marshall whose passion for entomological research has motivated me to start my own journey as an entomologist. I look forward to following his work. I wholeheartedly thank the MacDougall lab team for creating a positive and supportive working atmosphere which cannot be taken for granted. A big thanks to Dr. Ellen Esch for all her consulting days in the office for stats help. Thank you to all my field technicians who helped during the summer of 2017. Thank you Brianna Maher for being so hardworking, Sam Kloke for teaching me plant taxonomy in the field, Brock Roth for your dedication and work ethic, and Bernal Arce for your expertise in all things arthropods. I learned from all of you as I hope you took a piece of my work with you. Thank you Margeret Visser for putting in the time to edit my work. I cannot forget Kevin, the love of my life, who held me together when I fell apart. iv I also want to thank the awesome participants in the ALUS program who gave us the permission to do research on their farms. I hope my study contributes to the conservation of these lands. Bryan Gilvesy was a huge contributor to the passion and work these participants had, as well as Casey Whitelock and Alyssa Cousineau. Thank you to Sage Handler of the Nigel Raine bee lab for identifying my bee species to genus level, you don’t know how many hours this saved me, Sage. I am thankful for the funding provided by the OMAFRA Highly Qualified Personnel Scholarship that made this research possible. Tall Grass Ontario, and Food from Thought also provided partial support for this work through travel grants. Lastly, I would like to thank my family for their love and support for all my various endeavors over the years, and not freaking out when bags of arthropods appeared in the freezer. Planting wildflowers, caring for insect pets, running barefoot outside…. the childhood you gave me has made me who I am today. “Nature holds a key to our aesthetic, intellectual, cognitive and even spiritual satisfaction” -E.O. Wilson v TABLE OF CONTENTS Abstract…………………………………………………………………………………………....ii Acknowledgements ........................................................................................................................ iii Table of Contents ............................................................................................................................ v List of Tables ................................................................................................................................. vi List of Supplementary Tables ....................................................................................................... vii List of Figures .............................................................................................................................. viii List of Supplementary Figures ........................................................................................................ x List of Appendices ........................................................................................................................ xii 1. Introduction ................................................................................................................................. 1 2. Methods....................................................................................................................................... 4 2.1 Site selection and description ................................................................................................ 4 2.2 Arthropod and habitat sampling ............................................................................................ 9 2.3 Main analysis ...................................................................................................................... 12 2.3.1 Landscape and local factors of habitat on 13 agricultural sites ................................... 12 2.3.2 Within-prairie habitat factors ....................................................................................... 14 2.4 Complementary analyses .................................................................................................... 16 2.5 Statistical analysis ............................................................................................................... 17 2.5.1 Landscape and local factors of habitat on 13 agricultural sites ................................... 18 2.5.2 Within-prairie habitat factors ....................................................................................... 19 2.5.3 CA1: Arthropod community composition among cover types .................................... 20 2.5.4 CA2: Assessment of arthropod-derived ecosystem service mediated by habitat ........ 20 2.5.5 CA3: Crop type differences for arthropod abundance and richness (family-level) ..... 21 2.5.6 CA4: Regional family pool comparison ...................................................................... 21 3. Results ....................................................................................................................................... 22 3.1 Landscape and local factors of habitat on 13 agricultural sites .......................................... 23 3.2 Within-prairie habitat factors .............................................................................................. 25 3.3 CA1: Arthropod community composition among cover types ........................................... 27 3.4 CA2: Assessment of arthropod-derived ecosystem service mediated by habitat ............... 27 3.5 CA3: Crop type differences for arthropod abundance and richness ................................... 28 3.6 CA4: Regional family pool comparison ............................................................................. 28 4. Discussion ................................................................................................................................. 29 5. Conclusion ................................................................................................................................ 39 6. References ................................................................................................................................. 40 List of Tables ................................................................................................................................ 66 List of Figures ............................................................................................................................... 72 List of Appendices ........................................................................................................................ 84 vi LIST OF TABLES Table 1: Results of linear models between percentage of landcover type of buffer radii (500, 1000, 1500, 2000 m) and total arthropod abundance and richness for 13 farms in Southern Ontario, Canada. .............................................................................................................. 66 Table 2: Mantel test r-values (Pearson’s product-moment correlation) for the correlation between similarity matrices for functional group abundance