Varroa mite management among small-scale beekeepers: Characterizing factors that affect IPM adoption, and exploring drone brood removal as an IPM tool THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science In the Graduate School of The Ohio State University By Hannah R. Whitehead Graduate Program in Environmental Science The Ohio State University 2017 Master’s Examination Committee: Dr. Casey Hoy, Advisor Dr. Reed Johnson Dr. Anna Willow Copyrighted by Hannah R. Whitehead 2017 ABSTRACT Varroa mites (Varroa destructor) are the most damaging pest in modern beekeeping, and have been linked with elevated levels of colony loss. Experts increasingly recommend an integrated pest management (IPM) strategy to manage Varroa, which incorporates both preventative and therapeutic controls. However, Varroa IPM is complicated and knowledge-intensive. Small-scale beekeepers in particular seem to have difficulty adopting effective Varroa control strategies, and suffer especially high rates of colony loss. This study took an interdisciplinary approach to understanding the adoption of Varroa IPM among small-scale beekeepers. First, I used surveys and interviews to characterize mite management strategies among Ohio small-scale beekeepers, and to explore the effect of experience and risk perception on behavior. Second, as a case study, I took a closer look at the efficacy and adoption of one complex IPM tool – drone brood removal (DBR) – through interviews, surveys, and an on-farm trial. Overall, I found no relationship between beekeeping experience and mite management strategies, but sampling (risk perception) was associated with the use of “soft” miticides (organic acids/essential oils) and DBR. I also found that most beekeepers who used DBR combined it with drone sampling (adjusting DBR based on sampled mite levels), and that labor was the biggest barrier to DBR use. In the on-farm trial, DBR significantly reduced mites in year one but not year two. These results suggest that mite management failures ii among small-scale beekeepers are not due to inexperience and may indicate a broader communication breakdown. They also suggest that risk perception – beekeepers’ understanding that they even have mites – may be a key factor driving adoption of mite management practices. Finally, they point to the fact that DBR is already being used in nuanced ways as a combined management and sampling strategy. They suggest that DBR is not a silver bullet, but can be an effective tool to reduce mites if used consistently, intensively, and in combination with other management tactics. iii Dedicated to my family iv ACKNOWLEDGEMENTS This project would not have been possible without help from so many people. Thanks first to my advisor, Casey Hoy, who was open to advising a project outside his typical area of research, and who offered endless support, thoughtful edits and a systems perspective all along the way. Many thanks also to my committee members: Reed Johnson, who introduced me the beekeeping scene in Ohio and allowed me to become an honorary member of the Bee Lab – borrowing equipment, attending bee events, and tagging along for beekeeping activities. And Anna Willow for providing thoughtful feedback and pushing me to consider the broader social implications of this research. Thanks also to fellow graduate students – Natalie, Julie, Fred, Matt, as well as the entomology crew – with whom I’ve had many passionate discussions about sustainable agriculture and beekeeping, and who made graduate school much more fun. Many thanks to the beekeepers who volunteered their bees, their knowledge and their time in order to make the field experiment a reality: Dave Noble, Phil Young, Laura Urban, Al Blyth, Randall Westfall and Rod and Dru Pritchard. Thanks to Chia Hua Lin for help with research design and set-up, to Alia Dietsch for help with survey analysis, and to Meghan Blackson, Sreelakshmi Suresh, Laura Bond, Natalie Riusech and Andrea Wade for patiently helping me collect data. Special thanks to Willi for invaluable support and insightful feedback throughout this v project and to my family, for their support and encouragement in all of my academic endeavors. Finally, this work would not have been possible without funding from an Ohio State SEEDS grant. vi VITA 2007……………………Hawken High School, Gates Mills, OH 2007-2011……………...B.A. History, The University of Chicago 2011-2012……………..Administrative Assistant, Common Threads 2012……………………Intern, Coonridge Organic Goat Cheese 2013-2014……………...Research Assistant, Agroecosystem Management Program, The Ohio State University 2014……………………Farm Manager, Muddy Fork Farm 2014-2016……………..Graduate Fellow, Environmental Science Graduate Program, The Ohio State University 2016……………………Graduate Teaching Associate, Environmental Science Graduate Program, The Ohio State University Fields of Study: Major Field: Environmental Science Specialization: Agroecosystem Science vii TABLE OF CONTENTS ABSTRACT .......................................................................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................................................. v VITA ..................................................................................................................................................................... vii TABLE OF CONTENTS .............................................................................................................................. viii LIST OF FIGURES ............................................................................................................................................ x LIST OF TABLES ............................................................................................................................................. xi CHAPTER 1 ........................................................................................................................................................ 1 1.1 Introduction ........................................................................................................................................... 1 1.2 The big picture: why we should care about honey bees ......................................................... 6 1.3 Ecology of honey bees and Varroa destructor ........................................................................... 8 1.4 Varroa mite IPM (integrated pest management) .................................................................... 13 1.5 The beekeeping industry ................................................................................................................ 16 1.6 Varroa management among backyard beekeepers ................................................................ 20 1.7 Varroa IPM and the Diffusion of Innovation Framework .................................................. 22 1.8 Drone brood removal ...................................................................................................................... 25 1.9 Research Objectives ........................................................................................................................ 31 CHAPTER 2 ..................................................................................................................................................... 34 2.1 INTRODUCTION ............................................................................................................................... 34 2.2 MATERIALS AND METHODS .................................................................................................... 41 2.2.1 Study Region ................................................................................................................................ 41 2.2.2 Interview Process ........................................................................................................................ 42 2.2.3 Survey Administration ............................................................................................................... 43 2.2.4 Data Analysis ................................................................................................................................ 44 2.3 RESULTS ............................................................................................................................................... 45 2.3.1 Survey Response ......................................................................................................................... 45 2.3.2 Demographic Characteristics .................................................................................................. 46 2.3.3 Characterize mite management strategies (Objective 1) ................................................ 48 2.3.4 Effect of years beekeeping on management and sampling (Objective 2) ................ 55 2.3.5 Effect of sampling on mite management (Objective 3) .................................................. 57 2.4 DISCUSSION ....................................................................................................................................... 59 CHAPTER 3 ..................................................................................................................................................... 63 3.1 INTRODUCTION ............................................................................................................................... 63 3.2 MATERIALS AND METHODS .................................................................................................... 68 3.2.1 Study region .................................................................................................................................. 68 3.2.2 Experimental design ................................................................................................................... 69 3.2.3 Interview process ......................................................................................................................... 73 3.2.4 Survey administration ................................................................................................................ 73 3.2.5 Statistical analysis ....................................................................................................................... 74 3.3 RESULTS ............................................................................................................................................... 76 viii 3.3.1 Experimental results ................................................................................................................... 76 3.3.2 Interview results ........................................................................................................................... 81 3.3.3 Survey results ............................................................................................................................... 83 3.4 DISCUSSION ....................................................................................................................................... 89 CHAPTER 4 .................................................................................................................................................. 102 LITERATURE CITED ................................................................................................................................ 111 APPENDIX A: INTERVIEW GUIDE ................................................................................................... 120 APPENDIX B: SURVEY INSTRUMENTS ........................................................................................ 123 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