Effects of Landscape Heterogeneity and Land Use on Interacting Groups of Solitary Bees, Wasps and Their Flying
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Effects of landscape heterogeneity and land use on interacting groups of solitary bees, wasps and their flying and ground-dwelling antagonists Dissertation zur Erlangung des naturwissenschaftlichen Doktorgrades der Julius-Maximilians-Universität Würzburg vorgelegt von Juliane Steckel geboren in Bad Homburg v.d.H., Deutschland Würzburg, Juli 2013 Eingereicht am: 02. Juli 2013 Mitglieder der Promotionskommission Vorsitzender: Gutachter : Prof. Dr. Ingolf Steffan-Dewenter Gutachter: Prof. Dr. Jürgen Tautz Tag des Promotionskolloquiums: 03. September 2013 Doktorurkunde ausgehändigt am: When the ripe pears droop heavily, The yellow wasp hums loud and long His hot and drowsy autumn song: A yellow flame he seems to be, When darting suddenly from high He lights where fallen peaches lie. Yellow and black – this tiny thing’s A tiger-soul on elfin wings. ‘The Wasp’ by William Sharp (1856 – 1905) Hiermit erkläre ich ehrenwörtlich, dass ich die vorliegende Dissertation mit dem Titel “Effects of landscape heterogeneity and land use on interacting groups of solitary bees, wasps and their flying and ground-dwelling antagonists“ selbständig, am Lehrstuhl für Tierökologie und Tropenbiologie (Zoologie III) der Julius- Maximilians-Universität Würzburg, unter der Anleitung und Betreuung durch Herrn Dr. Marcell K. Peters, Frau Dr. Catrin Westphal und Herrn Prof. Dr. Ingolf Steffan- Dewenter angefertigt habe und dabei keine anderen als die von mir angegebenen Quellen und Hilfsmittel verwendet habe. Ich erkläre außerdem, dass die vorliegende Dissertation weder in gleicher, noch in ähnlicher Form bereits in einem Prüfungsverfahren vorgelegen hat. Des Weiteren habe ich außer den mit dem Zulassungsantrag urkundlich vorgelegten Graden keine weiteren akademischen Grade erworben oder zu erwerben versucht. Würzburg, 02.07.2013 Juliane Steckel TABLE OF CONTENTS TABLE OF CONTENTS 1 SUMMARY _____________________________________________________________________________ 1 2 ZUSAMMENFASSUNG ________________________________________________________________ 4 3 CHAPTER I – GENERAL INTRODUCTION __________________________________________ 7 3.1 AGRICULTURAL INTENSIFICATION ______________________________________________________ 8 3.2 LANDSCAPE HETEROGENEITY ___________________________________________________________ 8 3.3 POLLINATOR POPULATIONS __________________________________________________________ 10 3.4 STUDY REGIONS _____________________________________________________________________ 10 3.5 STUDY DESIGN _______________________________________________________________________ 12 3.6 STUDY SYSTEM ______________________________________________________________________ 13 3.7 SPECIES PORTRAIT ___________________________________________________________________ 14 3.8 CHAPTER OUTLINE AND MAIN HYPOTHESES ___________________________________________ 14 3.8.1 Chapter II ____________________________________________________________________ 15 3.8.2 Chapter III ____________________________________________________________________ 16 3.8.3 Chapter IV ____________________________________________________________________ 16 4 CHAPTER II – HABITAT MANAGEMENT MEDIATES SHIFTS IN THE IMPACT OF GROUND-DWELLING AND FLYING ANTAGONISTS ON SOLITARY BEES AND WASPS ____________________________________________________________________________________ 17 4.1 ABSTRACT ___________________________________________________________________________ 18 4.2 INTRODUCTION ______________________________________________________________________ 19 4.2.1 Land use intensification _____________________________________________________ 19 4.2.2 Vegetation structure & habitat heterogeneity _____________________________ 19 4.2.3 Trap nest system _____________________________________________________________ 21 4.3 MATERIALS AND METHODS __________________________________________________________ 22 4.3.1 Study plots and experimental design _______________________________________ 22 4.3.2 Local land use intensity _____________________________________________________ 23 4.3.3 Trap nest system _____________________________________________________________ 24 4.3.4 Statistical analyses __________________________________________________________ 24 4.4 RESULTS ____________________________________________________________________________ 25 4.4.1 Effects of mowing and predator exclusion _________________________________ 26 TABLE OF CONTENTS 4.4.2 Effects of habitat management _____________________________________________ 28 4.4.3 Effects of closure type as a protection against antagonists _______________ 30 4.5 DISCUSSION _________________________________________________________________________ 33 4.6 CONCLUSIONS _______________________________________________________________________ 35 4.7 APPENDIX ___________________________________________________________________________ 36 5 CHAPTER III – LANDSCAPE COMPOSITION AND CONFIGURATION DIFFERENTLY AFFECT TRAP-NESTING BEE AND WASP HOSTS AND THEIR ANTAGONISTS ___________________________________________________________________________ 42 5.1 ABSTRACT ___________________________________________________________________________ 43 5.2 INTRODUCTION ______________________________________________________________________ 44 5.3 MATERIALS AND METHODS __________________________________________________________ 46 5.3.1 Study plots ___________________________________________________________________ 46 5.3.2 Trap nests ____________________________________________________________________ 46 5.3.3 Metrics of local land use intensity __________________________________________ 47 5.3.4 Landscape heterogeneity metrics ___________________________________________ 48 5.3.5 Statistical analyses __________________________________________________________ 49 5.4 RESULTS ____________________________________________________________________________ 50 5.4.1 Regional differences in hymenoptera communities and land use intensity51 5.4.2 Local and landscape scale effects ___________________________________________ 54 5.5 DISCUSSION _________________________________________________________________________ 59 5.6 APPENDIX ___________________________________________________________________________ 63 6 CHAPTER IV – SPATIALLY COMPLEX LANDSCAPES ENHANCE THE FORAGING EFFICIENCY OF A SOLITARY BEE (OSMIA BICORNIS) _________________ 66 6.1 ABSTRACT ___________________________________________________________________________ 67 6.2 INTRODUCTION ______________________________________________________________________ 68 6.3 MATERIALS AND METHODS __________________________________________________________ 69 6.3.1 Experimental setup __________________________________________________________ 70 6.3.2 Local and landscape metrics ________________________________________________ 70 6.3.3 Foraging flight efficiency ____________________________________________________ 71 6.3.4 Measurement of reproductive success ______________________________________ 72 6.3.5 Statistical analyses __________________________________________________________ 72 6.4 RESULTS ____________________________________________________________________________ 73 TABLE OF CONTENTS 6.5 DISCUSSION _________________________________________________________________________ 77 6.5.1 Landscape configuration & scales __________________________________________ 77 6.5.2 Local land use intensity and resource abundance _________________________ 79 6.5.3 Nest building activity ________________________________________________________ 79 6.5.4 Reproductive success ________________________________________________________ 79 6.6 CONCLUSIONS _______________________________________________________________________ 80 6.7 APPENDIX ___________________________________________________________________________ 81 7 CHAPTER V – GENERAL DISCUSSION ____________________________________________ 82 7.1 SPECIES INTERACTIONS ON LOCAL LAND USE (CHAPTER II) _____________________________ 83 7.2 LANDSCAPE EFFECTS (CHAPTER III) __________________________________________________ 84 7.3 FORAGING SUCCESS (CHAPTER IV) ____________________________________________________ 84 7.4 REPRODUCTIVE SUCCESS (CHAPTER IV) _______________________________________________ 85 7.5 SPECIES TRAITS (CHAPTER II & CHAPTER IV) __________________________________________ 85 7.6 CONCLUSIONS _______________________________________________________________________ 86 8 REFERENCES ________________________________________________________________________ 89 9 AUTHOR CONTRIBUTIONS _____________________________________________________ 101 9.1 CHAPTER II _________________________________________________________________________ 101 9.2 CHAPTER III ________________________________________________________________________ 102 9.3 CHAPTER IV ________________________________________________________________________ 103 10 PUBLICATION LIST ______________________________________________________________ 105 11 CURRICULUM VITAE _____________________________________________________________ 107 12 ACKNOWLEDGEMENTS _________________________________________________________ 110 SUMMARY 1 SUMMARY Within the last decades, land use intensification reduced the heterogeneity of habitats and landscapes. The resulting pauperization led to habitats and landscapes that are spatially or temporally limited in food and nesting resources for solitary bees and wasps. Hence, biodiversity and ecosystem processes are seriously threatened. The impacts of changing resource conditions for valuable pollinators and (pest) predators remain poorly studied as well as their top-down