The effects of semi-natural habitat and wildflower plantings on ecosystem services, bee communities, and tick populations Christopher T. McCullough Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy In Horticulture Megan O’Rourke - Chair Thomas Kuhar Sarah Karpanty Jacob Barney May 8th, 2020 Blacksburg, Virginia Keywords: biological control, natural habitat, yield, pollinators, lone star tick Creative Commons, CC BY-NC The effects of wildflower plots and diverse landscapes on ecosystem services, bee communities, and on-farm tick abundance Christopher T. McCullough ABSTRACT Conservation of natural habitats and planting wildflower plots are two commonly promoted tactics to enhance pollination services and biological control of crop pests, which are ecosystem services that can improve agricultural outputs. There are several programs at various levels of government in the United States that landowners can use to defray the costs of implementing these conservation strategies. Studies of European Agricultural Environmental Schemes have shown these tactics to have positive outcomes for crop production. However, real-world applications of cost-sharing programs have not been evaluated in the United States on pollination services and biological control. Furthermore, these tactics may inadvertently perform ecosystem disservices, like increasing crop pests or creating habitat for disease vectors. In this study, we evaluated the effects of natural habit and wildflower plots on biological control, pollination services, bee communities, and tick populations in Eastern Virginia and Maryland. This research was conducted on 22 farms. 10 of these farms had wildflower plots that were designed by Natural Resource Conservation Service personnel, and implemented by cooperating farmers. Collards, strawberries, tomatoes, and squash were used as model systems. We measured pest density, sentinel egg predation, crop damage, seed pollination, biomass production, marketable crop yield, sampled the bee community, and recorded tick abundance in wildflower plots. Many of the measures of biological control and pollination services had idiosyncratic results in regards to the wildflower plots and natural habit in the landscape. However, the proportion of high quality yield for all four crops increased with increasing natural habitat in the landscape. Bee communities between sites with and without wildflower plots were not different. Bee abundance did increase at wildflower sites when natural habitat comprised a certain proportion of the habitat around the site. Ticks were sampled from wildflower plantings, but not in greater abundance compared to field margins. In this study, the effects of wildflower plots were overshadowed by the landscape effects of natural habitat. Government personnel that oversee these programs may need to consider the surrounding landscape when helping implement on-farm conservation measure like wildflower plots. Such measures, do not perform an ecosystem disservice in regards to ticks. The effects of wildflower plots and diverse landscapes on ecosystem services, bee communities, and on-farm tick abundance Christopher T. McCullough GENERAL AUDIENCE ABSTRACT Conservation of natural habitats and planting wildflower plots are two strategies to enhance pollination services and biological control of crop pests. These two ecosystem services are of needed to improve agricultural production without further damaging the environment. There are several programs at various levels of government in the United States that landowners can use to subsidize the costs of implementing these strategies. European studies have shown these government programs to be successful. However, these programs have not been evaluated in the United States on their ability to enhance pollination services and biological control. Furthermore, studies investigating potential ecosystem disservices these strategies. In this study, we evaluated the effects of natural habit and wildflower plots on biological control, pollination services, bee communities, and tick populations in Eastern Virginia and Maryland. This research was conducted on 22 farms. 10 of these farms had wildflower plots that were designed by Natural Resource Conservation Service personnel, and implemented by cooperating farmers. Collards, strawberries, tomatoes, and squash were used as model systems. We measured pest density, egg predation, crop damage, seed pollination, and yield. We also sampled the bee community, and recorded tick abundance in wildflower plots. There were no consistent trends for many measures of biological control and pollination services in response to the wildflower plots and natural habit. However, the proportion of high quality yield for all four crops increased with increasing natural habitat in the landscape. Bee communities between sites with and without wildflower plots were not different. Bee abundance did increase at wildflower sites when natural habitat comprised a certain proportion of the habitat around the site. Ticks were sampled from wildflower plantings, but not in greater abundance compared to field margins. In this study, the effects of wildflower plots were overshadowed by the landscape effects of natural habitat. Government personnel that oversee these programs may need to consider the surrounding landscape when helping implement on-farm conservation measure like wildflower plots. Such measures, do not perform an ecosystem disservice in regards to ticks. Acknowledgements There are many people that I need to thank for their contributions to the project, as well as my own development. First and foremost, is Megan, my adviser. Thank you for taking me on with this project, riding through my highs and lows, and holding me accountable to a higher standard. You have helped me realize the approach and forethought that is necessary for conducting research., as well as trying to help me improve my writing along the way. Next, thank you to Gina for being on the Eastern Shore and handling so much of the logistical side of this work. It certainly helped ease the transition from Blacksburg to Painter each year. I know I have to say on behalf of Laura, thanks for putting up with me for all those hours driving around in the truck. Thank you for the feedback and suggestions on different aspects of this work, and providing some inspiration to sample for ticks. I appreciated the various conversations about a plethora of things while riding in the truck. Thank you to everyone else in the lab. Velva, baked goods aside, thanks for helping get stuff done through the university’s various systems, and running around to buy up all the coolers from our local retailers. Jennie, thanks for helping pin and wash those ~900 bees that were unearthed. I guess thanks for sharing your mom’s cookies, but her recipe could use some adjustments. I guess I ate them anyway. Mike, it is difficult to type sarcastically, so…Thanks. Thank you to all the people who helped collect and process the data, Erika, Sarah, Monique, Courtney, Brook, Brian, and Mika. Thank you to my committee members for the various roles you all have played. There was a lot of reshuffling with people coming iv and going from the university. Thank you to all of our cooperators that let us do this work on their land. Thank you to Tom and Linda for being gracious hosts and local experts on all things related to the Eastern Shore. Thank you to Bob and Jane from the NRCS who helped implement the wildflower plots and find cooperators to work with. Thank you to Don for providing us with the stink bug egg. Thank you Sam for providing species determinations for the bees, and showing me the collaborative spirit that exists in the bee conservation community. Finally, thank you Laura. Thank you for putting up with the summers apart, but also visiting the Eastern Shore twice. Thank you for being supportive throughout this endeavor. v Table of contents Introduction ......................................................................................................................... 1 References ....................................................................................................................... 4 Chapter 1: Diverse landscapes increase marketable yields of four crops in the Eastern U.S. ..................................................................................................................................... 7 Introduction ..................................................................................................................... 8 Materials and Methods .................................................................................................. 10 Results ........................................................................................................................... 15 Discussion ..................................................................................................................... 17 References ..................................................................................................................... 22 Supplemental Appendix 1.1. ......................................................................................... 30 Supplemental Appendix 2 ............................................................................................. 35 Chapter 2: Landscape context influences the bee conservation value of wildflower plantings ...........................................................................................................................