WILD BEE COMMUNITIES IN CENTRAL WISCONSIN VEGETABLE CROPS by Kathryn J. Prince A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science (Agroecology & Entomology) at the UNIVERSITY OF WISCONSIN-MADISON 2016 This thesis is approved by the following members of the advisory committee: Dr. Russell L. Groves, Professor of Entomology (Principal Investigator) Dr. Claudio Gratton, Professor of Entomology Dr. Richard Lindroth, Professor of Entomology i Table of Contents Acknowledgements ................................................................................................................ iii Chapter 1: Literature Review .................................................................................................1 The importance of bees .........................................................................................................2 Challenges facing domestic pollinators .................................................................................5 Land use change increases pollinator stress ..........................................................................6 Pesticide exposure risks for beneficial insects ......................................................................9 Pollinator conservation in central Wisconsin ......................................................................12 Research rationale ...............................................................................................................14 References ...........................................................................................................................16 Chapter 2: The Bee Community of Central Wisconsin Vegetables ..................................24 Abstract ...............................................................................................................................25 Introduction .........................................................................................................................26 The role of landscape in bee conservation ...................................................................... 26 The Central Sands: Wisconsin’s processing vegetable growing region ......................... 28 Research rationale ........................................................................................................... 30 Materials and Methods ........................................................................................................30 Conventional processing vegetable fields ....................................................................... 30 Conventional and organic field margins ......................................................................... 32 Data analysis ................................................................................................................... 33 Results .................................................................................................................................35 Conventional processing vegetable fields ....................................................................... 35 Conventional and organic field margins ......................................................................... 38 Discussion ...........................................................................................................................39 Bees in conventionally grown vegetable fields .............................................................. 39 Bees in field edges .......................................................................................................... 41 Summary ......................................................................................................................... 43 References ...........................................................................................................................44 Chapter 3: Seasonal Variation of Thiamethoxam Concentrations in Central Wisconsin Processing Vegetables ............................................................................................................66 Abstract ...............................................................................................................................67 Introduction .........................................................................................................................68 Neonicotinoid use and insect risk. .................................................................................. 68 ii Unique risks of central Wisconsin .................................................................................. 71 Research rationale ........................................................................................................... 73 Materials and Methods ........................................................................................................73 Tissue collection ............................................................................................................. 73 Thiamethoxam quantification ......................................................................................... 75 Statistical analysis ........................................................................................................... 77 Results .................................................................................................................................77 Thiamethoxam in floral tissue ........................................................................................ 77 Thiamethoxam in leaf tissue ........................................................................................... 78 Discussion ...........................................................................................................................80 Summary ......................................................................................................................... 83 References ...........................................................................................................................84 iii Acknowledgements I would first and foremost like to thank my advisor, Dr. Russ Groves, for taking me on as a student. Being in Russ’ lab has been a great experience and I am grateful for the opportunity to venture into the world of insects and agriculture. I would also like to thank my committee members, Dr. Richard Lindroth and Dr. Claudio Gratton, for their feedback and support in developing this work. I am grateful to my funding sources for this project: The Midwest Food Processors Association and the USDA Specialty Crop Research Initiative provided support for the processing vegetables component of this research, while the Ceres Trust provided support for the organic component. I thank Don Caine and Matthew Badtke of Del Monte Foods, Inc. for their accommodation of the space, seeds, maps, and fields that were necessary for this project to take place. I also thank Tony Whitefeather of Whitefeather Organics, LLC along with Adam Flyte of Flyte Family Farms for their accommodation of this project on their organic farms. I’d like to thank Nick Keuler for providing life-saving statistical consulting, as well as Dr. Jason Gibbs of Michigan State University for identifying for the majority of bee specimens, especially the many difficult to distinguish Lasioglossum species. I’d like to thank my departmental colleagues and the fantastic staff and faculty of the entomology and agroecology departments. I’d especially like to thank Dr. Ned Rubert-Nason for helping me to formulate a tissue analysis procedure and for running all the plant tissue samples. Furthermore, I’d like to thank my field assistants, Katie Chipman and Coralie Deniot, for their help and insight during fieldwork, as well as for their company and map- reading prowess as we struggled to navigate back-country roads. A thank you to my fellow and former Groves Lab members –Ben Bradford, Emily Duerr, Chris Bloomingdale, Linda iv Crubaugh, Justin Clements, and Ryan Bower- for their help with everything from navigating statistical software to learning the subtle nuances of the office coffee-maker… and for that matter, I’d like to thank coffee for getting me through many arduous writing sessions. Finally, I’d like to thank my friends, family, and especially my husband Matt Ledger, for their support and encouragement. 1 Chapter 1: Literature Review 2 The importance of bees Plants are pollinated by many diverse animals. Familiar pollinators like birds and flower flies are active during the day, while nocturnal animals such as bats and moths take the night shift. But the most efficient pollinators – and thus most economically important – are bees (Greenleaf et al 2007, Michener 2007). Bees are nectar and pollen-eating members of the superfamily Apoidea within the insect order Hymenoptera. In North America there are more than 3,300 species of bees (Borror & White 1970). Some bees live socially in colonies founded by a queen, such as honey bees (genus Apis) and bumble bees (genus Bombus). These social genera are perhaps the best-known by the average person, but most bee species are solitary, with females creating individual nest cells that they provision with nectar and pollen (Michener 1967). Still others are nest parasites that lay their eggs in a host species’ nest (Wolf & Ascher 2008). Approximately 35% of the world’s food crop production depends on pollinators like bees (Klein et al 2007), amounting to a current annual value of more than $160 billion worldwide (Potts et al 2010, Gallai et al 2009). Of all bee species, the agricultural