Plant diversity and landscape-scale effects on multitrophic interactions involving invertebrates Dissertation zur Erlangung des mathematisch-naturwissenschaftlichen Doktorgrades "Doctor rerum naturalium" der Georg-August-Universität Göttingen im Promotionsprogramm Biologische Diversität und Ökologie der Georg-August University School of Science (GAUSS) vorgelegt von Julia Tiede aus Hildesheim Göttingen, 2017 Betreuungsausschuss Prof. Dr. Christoph Scherber Arbeitsgruppe Tierökologie und Multitrophische Interaktionen, Institut für Landschaftsökologie, Westfälische Wilhelms- Universität Münster Prof. Dr. Teja Tscharntke Abteilung Agrarökologie, Department für Nutzpflanzenwissenschaften, Georg-August-Universität Göttingen Prof. Dr. Rolf Daniel Genomische und Angewandte Mikrobiologie und Göttinger Genomlabor, Institut für Mikrobiologie und Genetik, Georg- August-Universität Göttingen Mitglieder der Prüfungskommission Referent: Prof. Dr. Christoph Scherber Korreferent: Prof. Dr. Teja Tscharntke 2. Korreferent: Prof. Dr. Rolf Daniel Weitere Mitglieder der Prüfungskommission Prof. Dr. Stefan Scheu Arbeitsgruppe Tierökologie, Blumenbach-Institut für Zoologie und Anthropologie, Georg-August-Universität Göttingen Prof. Dr. Johannes Isselstein Abteilung Graslandwissenschaften, Department für Nutzpflanzenwissenschaften, Georg-August-Universität Göttingen Prof. Dr. Stefan Vidal Abteilung Agrarentomologie, Department für Nutzpflanzenwissenschaften, Georg-August-Universität Göttingen Tag der Disputation: 15.11.2017 “What escapes the eye, however, is a much more insidious kind of extinction: the extinction of ecological interactions.” Daniel H. Janzen, 1974, The deflowering of Central America. Nat. Hist. 83:48–53 “Round and round as the nature flows It's like one big ring Caterpillars eat plants Small birds eat caterpillars Big birds eat small birds Bacteria eats the dead- big bird From there plants grow Again, caterpillar eats the plant! How natural, no waste It is an endless chain What an amazing, wonderful, and excellent! How harsh, not careless It's an endless chain What an amazing, wonderful, and excellent food... food chain!” The food chain song, Adventure Time, Season 6, Episode 7 iii TABLE OF CONTENTS TABLE OF CONTENTS ....................................................................................................................................... IV ABBREVIATIONS ............................................................................................................................................ VIII SUMMARY ...................................................................................................................................................... IX CHAPTER 1 ....................................................................................................................................................... 1 1.1 GENERAL INTRODUCTION ..................................................................................................................................... 2 1.2 STUDY SYSTEMS AND REGIONS .............................................................................................................................. 4 1.2.1 Landscape approach - Agroecosystems in the Midwestern USA .......................................................... 4 1.2.2 Experimental approach - The Jena Experiment .................................................................................... 6 1.2.3 Virtual ecologist approach - A simulation ............................................................................................. 8 1.3 RESEARCH OBJECTIVES AND CHAPTER OUTLINE ......................................................................................................... 9 Chapter 2 ....................................................................................................................................................... 9 Hypothesis for chapter 2 ............................................................................................................................................ 9 Chapter 3 ..................................................................................................................................................... 10 Hypothesis for chapter 3 .......................................................................................................................................... 10 Chapter 4 ..................................................................................................................................................... 10 Hypothesis for chapter 4 .......................................................................................................................................... 10 Chapter 5 ..................................................................................................................................................... 11 Hypothesis for chapter 5 .......................................................................................................................................... 11 1.4 ORIGINAL ARTICLES .......................................................................................................................................... 12 Chapter 2 .................................................................................................................................................................. 12 Chapter 3 .................................................................................................................................................................. 12 Chapter 4 .................................................................................................................................................................. 12 Chapter 5 .................................................................................................................................................................. 13 Author affiliations ..................................................................................................................................................... 13 CHAPTER 2 ..................................................................................................................................................... 14 ABSTRACT ............................................................................................................................................................ 15 2.1 INTRODUCTION ................................................................................................................................................ 15 2.2 MATERIAL AND METHODS ................................................................................................................................. 17 2.2.1 Feeding experiment ............................................................................................................................ 17 2.2.2 Field study ........................................................................................................................................... 17 2.2.3 Sample processing .............................................................................................................................. 19 2.2.3.1 Gut dissections .............................................................................................................................................. 19 2.2.3.2 Analysis of gut bacteria ................................................................................................................................. 19 2.2.3.3 Estimation of body fat content ...................................................................................................................... 20 2.2.4 Statistical analyses ............................................................................................................................. 20 2.2.4.1 Feeding experiment ...................................................................................................................................... 20 2.2.4.2 Field study ..................................................................................................................................................... 20 2.2.4.2 | .1 Bacterial richness .............................................................................................................................. 20 2.2.4.2 | .2 Bacterial community structure ......................................................................................................... 21 2.2.4.2 | .3 Body fat content ............................................................................................................................... 21 2.3 RESULTS......................................................................................................................................................... 22 2.3.1 Feeding experiment ............................................................................................................................ 22 2.3.2 Field study ........................................................................................................................................... 23 3.2.1 Bacterial richness ............................................................................................................................................. 23 2.3.2.2 Bacterial community structure ...................................................................................................................... 23 2.3.2.3 Body fat content ..........................................................................................................................................