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Exploring Predator-Prey Interactions in Agroecosystems Through Molecular Gut-Content Analysis

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Exploring Predator-Prey Interactions in Agroecosystems Through Molecular Gut-Content Analysis University of Kentucky UKnowledge Theses and Dissertations--Entomology Entomology 2017 Exploring Predator-Prey Interactions in Agroecosystems through Molecular Gut-Content Analysis Kacie J. Athey University of Kentucky, [email protected] Author ORCID Identifier: http://orcid.org/0000-0003-1790-6530 Digital Object Identifier: https://doi.org/10.13023/ETD.2017.116 Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Athey, Kacie J., "Exploring Predator-Prey Interactions in Agroecosystems through Molecular Gut-Content Analysis" (2017). Theses and Dissertations--Entomology. 35. https://uknowledge.uky.edu/entomology_etds/35 This Doctoral Dissertation is brought to you for free and open access by the Entomology at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Entomology by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained needed written permission statement(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine) which will be submitted to UKnowledge as Additional File. I hereby grant to The University of Kentucky and its agents the irrevocable, non-exclusive, and royalty-free license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known. I agree that the document mentioned above may be made available immediately for worldwide access unless an embargo applies. I retain all other ownership rights to the copyright of my work. I also retain the right to use in future works (such as articles or books) all or part of my work. I understand that I am free to register the copyright to my work. REVIEW, APPROVAL AND ACCEPTANCE The document mentioned above has been reviewed and accepted by the student’s advisor, on behalf of the advisory committee, and by the Director of Graduate Studies (DGS), on behalf of the program; we verify that this is the final, approved version of the student’s thesis including all changes required by the advisory committee. The undersigned agree to abide by the statements above. Kacie J. Athey, Student Dr. John Obrycki, Major Professor Dr. Charles Fox, Director of Graduate Studies EXPLORING PREDATOR-PREY INTERACTIONS IN AGROECOSYSTEMS THROUGH MOLECULAR GUT-CONTENT ANALYSIS _________________________________ DISSERTATION _________________________________ A dissertation submitted in partial fulfillment of the Requirements for the degree of Doctor of Philosophy in Entomology in The College of Agriculture, Food and Environment At the University of Kentucky By Kacie Jo Athey Lexington Kentucky Director: Dr. John J. Obrycki, Professor of Entomology Lexington Kentucky 2017 Copyright © Kacie Jo Athey 2017 ABSTRACT OF DISSERTATION EXPLORING PREDATOR-PREY INTERACTIONS IN AGROECOSYSTEMS THROUGH MOLECULAR GUT-CONTENT ANALYSIS Generalist predators can contribute to vital ecosystem services by potentially inducing trophic cascades as natural enemies of pests in agroecosystems. As the human population of the world gets larger, we need to produce more food on ever-smaller swaths of available land relying on ecosystem services, in the form of pest control, that may contribute to agricultural sustainability. Teasing apart the exact trophic linkages between predators and prey is a vital first step and essential to uncovering which predators are inducing trophic cascades and should be enhanced through conservation biological control. Combined with ecological experimentation, the main tool used throughout my research to identify trophic linkages is molecular gut-content analysis. I began by investigating mass sampling techniques and found they do not cause contamination in gut-content analysis and may be a simple method for collecting large numbers of cryptic predators for use in determining trophic linkages. Additionally, my research uncovered trophic interactions between stink bugs and generalist predators at multiple scales. Overall, I successfully designed molecular methods to investigate relationships between agricultural pests and generalist predators. A multi-year field study uncovered low predation on stink bug pests in contrast to previous research suggesting that generalist predators were contributing highly to biological control. This research highlights the need for replicated studies before making broad conservation biological control decisions. Although generalist predators were not consuming stink bugs in large numbers, my field cage study showed evidence of superfluous killing by spiders on adult stink bugs, highlighting the need to combine ecological studies with molecular methods to understand consumptive and non-consumptive effects on prey items. Gut-content analysis showed no evidence of consumption, but the field cage study allowed me to uncover the complicated relationships between spiders and stink bugs. In addition, I showed an invasive species can be detected in new areas through molecular gut-content analysis of predators before other sampling methods. KEYWORDS: Agroecosystems, Pentatomidae, Food Webs, Generalist Predators ___Kacie Jo Athey _______ ___April 26, 2017______________________ Date EXPLORING PREDATOR PREY INTERACTIONS IN AGROECOSYSTEMS THROUGH MOLECULAR GUT-CONTENT ANALYSIS By Kacie Jo Athey ___John Obrycki ___ Director of Dissertation __Charles Fox__ ________________ Director of Graduate Studies ___April 26, 2017 _____________ ACKNOWLEDGMENTS This dissertation, although an individual work, would not have been possible without the assistance and support of many people. First and foremost, my advisor, Dr. John Obrycki, whose selflessness and willingness to step in in a time of crisis I will always be grateful for. Members of my committee, Dr. Ricardo Bessin, Dr. Mark Williams and Dr. Jennifer White, were also integral to this work as they provided valuable guidance and never hesitated to help me when I showed up at their offices with a question. I have also benefited from several collaborators, including Dr. John Ruberson, Dr. Dawn Olson and Dr. Eric Chapman. In particular, Dr. Eric Chapman has been a constant collaborator and mentor, teaching me several of the methods integral to this dissertation. Additionally, none of this would have been possible without many members of my lab, past and present. Dr. Katelyn Kesheimer, Dr. Hannah Penn, Dr. Jamin Dreyer, Dr. Michael Sitvarin, Dr. Julie Peterson and Leslie Potts were very important for academic and moral support during difficult academic times. The department of entomology has been very supporting and helpful through the process of this degree. Finally, I am grateful to my family. To my parents, who were supportive of me moving to Kentucky to become the first person in my family to achieve a graduate degree. To my husband Mark, who is an equal partner in the raising of our children, Padric and Evelyn, and who has dealt with lots of uncertainty during my time here and has handled it in the best way possible. iii Table of Contents ACKNOWLEDGMENTS ................................................................................................. iii Table of Tables ................................................................................................................. vii Table of Figures ................................................................................................................. ix Chapter 1: Introduction ....................................................................................................... 1 1.1 Role of generalist predators in trophic cascades in agroecosystems ........................ 1 1.2 Molecular gut-content analysis ................................................................................. 4 1.2.1 Uses for molecular gut-content analysis ............................................................ 4 1.2.2 Limitations to molecular gut-content analysis ................................................... 5 1.3 Stink bugs and relatives as pests in agroecosystems ................................................ 8 1.3.1 Brown Marmorated Stink Bug ........................................................................... 9 1.3.2 Southern Green Stink Bug ................................................................................... 10 1.3.3 Green Stink Bug ............................................................................................... 10 1.3.4 Brown Stink Bug.............................................................................................. 11 1.3.5 Kudzu Bug ....................................................................................................... 11 1.4 Objectives ............................................................................................................... 13 Chapter 2: Investigating cross contamination of liquid storage methods in molecular gut- content analysis ................................................................................................................. 15 2.1 Summary ................................................................................................................. 15 2.2 Introduction ............................................................................................................
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