Scale-Dependent Bee (Hymenoptera: Anthophila) Community Patterns and Plant Attractiveness to Pollinators in the Texas High Plains by Samuel Discua, B.Sc., M.Sc. A Dissertation In Plant and Soil Science Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Approved Scott Longing Chair of the Committee Nancy McIntyre Robin Verble Cynthia McKenney Joseph Young Mark Sheridan Dean of the Graduate School May, 2021 Copyright 2021, Samuel Discua Texas Tech University, Samuel Discua, May 2021 ACKNOWLEDGMENTS There are many who helped me along the way on this long and difficult journey. I want to take a moment to thank them. First, I wish to thank my dissertation committee. Without their guidance, I would not have made it. Dr. McIntytre, Dr. McKenney, Dr. Young and Dr. Verble served as wise committee members, and Dr. Longing, my committee chair, for sticking with me and helping me reach my goal. To the Longing Lab members, Roberto Miranda, Wilber Gutierrez, Torie Wisenant, Shelby Chandler, Bryan Guevara, Bianca Rendon, Christopher Jewett, thank you for all the hard work. To my family, my parents, my sisters, and Balentina and Bruno: you put up with me being distracted and missing many events. Finally, and most important, to my wife, Baleshka, your love and understanding helped me through the most difficult times. Without you believing in me, I never would have made it. It is time to celebrate; you earned this degree right along with me. I am forever grateful for your patience and understanding. It is time to close this chapter of my life and start a new one. ii Texas Tech University, Samuel Discua, May 2021 TABLE OF CONTENTS ACKNOWLEDGMENTS ........................................................................................ ii LIST OF TABLES ................................................................................................... vi LIST OF FIGURES ................................................................................................. xi ABSTRACT ........................................................................................................... xiii I. INTRODUCTION ................................................................................................. 1 Value of Pollination Services Provided by Bees .......................................................... 1 Global Pollinator Declines .......................................................................................... 5 Effects of Habitat Quality on Pollinators ..................................................................... 7 Ecological Restoration for Bees and Other Pollinators ................................................ 8 Agriculture and Pollination Services in the Texas High Plains .................................. 10 Native Bees in the Texas High Plains ....................................................................... 12 Research Objectives ................................................................................................. 15 Rationale and Significance ....................................................................................... 16 LITERATURE CITED .......................................................................................... 17 II. POLLINATOR ATTRACTIVENESS OF DROUGHT-TOLERANT PLANTS IN THE TEXAS HIGH PLAINS ............................................................................ 24 Abstract .................................................................................................................... 24 Introduction .............................................................................................................. 25 Materials and Methods ............................................................................................. 27 Site Description and Field Experimental Design ............................................... 27 Plant Selection .................................................................................................. 29 Insect Floral Visitation Counts .......................................................................... 30 Plant Measurements .......................................................................................... 31 Data Analysis ................................................................................................... 31 Results...................................................................................................................... 32 Bee Community ................................................................................................ 32 Plant – Pollinator Associations .......................................................................... 34 Discussion ................................................................................................................ 36 LITERATURE CITED .......................................................................................... 42 iii Texas Tech University, Samuel Discua, May 2021 III. A MULTIVARIATE ANALYSIS OF NATIVE BEES AND FLORAL COMMUNITIES ACROSS AGROECOSYSTEMS IN THE LLANO ESTACADO REGION OF TEXAS ....................................................................... 56 Abstract .................................................................................................................... 56 Introduction .............................................................................................................. 57 Study Area ........................................................................................................ 61 Insect Sampling ................................................................................................ 63 Sample Processing ............................................................................................ 64 Local Habitat Sampling .................................................................................... 65 Pollinator Community Composition .................................................................. 66 Data Analysis ................................................................................................... 66 Results...................................................................................................................... 69 Bee Richness and Abundance ........................................................................... 69 Floral Richness and Abundance ........................................................................ 71 Bee Habitat Data ............................................................................................... 73 PCA Results ..................................................................................................... 73 NMDS Results .................................................................................................. 73 Generalized Linear Mixed Model Results ......................................................... 74 Bee Communities ............................................................................................. 74 Bee Communities and Adjacency to CRP Lands ............................................... 75 Bee Communities and Farm Type ..................................................................... 75 Bee Communities and Playas ............................................................................ 76 Bee Communities and Soil Type ....................................................................... 76 Floral Communities and CRP Lands ................................................................. 78 Floral Communities and Farm Type .................................................................. 78 Floral Communities and Playas ......................................................................... 78 Floral Communities and Soil Types .................................................................. 79 Discussion ................................................................................................................ 79 LITERATURE CITED .......................................................................................... 85 iv Texas Tech University, Samuel Discua, May 2021 IV. HABITAT ANALYSIS OF NATIVE BEES AND FLORAL RESOURCES IN THE LLANO ESTACADO AGRICULTURAL REGION OF TEXAS ......... 137 Abstract .................................................................................................................. 137 Introduction ............................................................................................................ 138 Materials and Methods ........................................................................................... 143 Study Area ...................................................................................................... 143 Insect Sampling .............................................................................................. 144 Land Cover data.............................................................................................. 144 Landscape Composition and Configuration Metrics ........................................ 145 Pollinator Community Composition ................................................................ 146 Data Analysis ................................................................................................. 147 Results.................................................................................................................... 150 Land Cover within Buffers .............................................................................. 150 PCA