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Chemically Mediated Interactions Between Hosts, Parasitic Plants and Insect Herbivores

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Chemically Mediated Interactions Between Hosts, Parasitic Plants and Insect Herbivores University of Massachusetts Amherst ScholarWorks@UMass Amherst Doctoral Dissertations Dissertations and Theses July 2016 Chemically Mediated Interactions Between Hosts, Parasitic Plants and Insect Herbivores Muvari C. Tjiurutue University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/dissertations_2 Part of the Integrative Biology Commons, Plant Biology Commons, and the Weed Science Commons Recommended Citation Tjiurutue, Muvari C., "Chemically Mediated Interactions Between Hosts, Parasitic Plants and Insect Herbivores" (2016). Doctoral Dissertations. 671. https://doi.org/10.7275/8412502.0 https://scholarworks.umass.edu/dissertations_2/671 This Open Access Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks@UMass Amherst. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. CHEMICALLY MEDIATED INTERACTIONS BETWEEN HOSTS, PARASITIC PLANTS AND INSECT HERBIVORES A Dissertation Presented by MUVARI C. TJIURUTUE Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY MAY 2016 Plant Biology Graduate Program © Copyright by Muvari C. Tjiurutue 2016 All Rights Reserved CHEMICALLY MEDIATED INTERACTIONS BETWEEN HOSTS, PARASITIC PLANTS AND INSECT HERBIVORES A Dissertation Presented by MUVARI C. TJIURUTUE Approved as to style and content by: ______________________________________ Lynn S. Adler, Chair ______________________________________ Anne L. Averill, Member ______________________________________ Hilary A. Sandler, Member ______________________________________ Peter Alpert, Member ___________________________________ Elizabeth R. Dumont, Director Interdepartmental Graduate Programs, CNS DEDICATION To my loving parents Konstancia Tjimoma Ngutjinazo & Rudolf Kapee Ngutjinazo and grandparents Simon Tjiurutue & Naomi Uandjua Tjiurutue. ACKNOWLEDGMENTS A special thanks goes to my advisor Lynn Adler for her support and patience throughout all these years. Thank you for never giving up on me and for always saving the day. I would also like to thank my committee members for their support and understanding. Special thanks to Anne Averill for all the encouragement and kind words, Hilary Sandler for her never-ending help and patience, and Peter Alpert for attending all my poster presentations and providing good advice for the future. Thanks to Fulbright, Faculty for the Future Fellowship (Schlumberger Foundation), the Plant Biology Graduate Program, USDA/CSREES and USDA-NRI for financial support. My sincere thanks goes to Susan Capistran for her tremendous help and unwavering support. Thanks to the Adler lab, especially Evan Palmer-Young, for helping me in so many ways and making this more fun. Thanks to the entire undergraduate team, Diana Chan, Lauren Azuela, Suzanne Nicholson, Ari Soleil and my friend Mjeke Kinyota for all their help on the various projects. My sincere gratitude goes to Chris Joyner, our CNS greenhouse manager, for his dedication and caring of my plants. I am grateful to Scott Lee for always being willing to help, and for the continued support throughout all this years. Finally I would like to thank all my friends, family and loved ones. Thanks to my mother, Konstancia Ngutjinazo, for always believing in me and for her strong support, my grandmother Naomi Tjiurutue for her prayers and unconditional love, Juvelino Tavares for holding my hand when things got tough, and Faith Ndlovu, a fellow companion in this journey who made graduate school more bearable. v ABSTRACT CHEMICALLY MEDIATED INTERACTIONS BETWEEN HOSTS, PARASITIC PLANTS AND HERBIVORES MAY 2016 MUVARI C. TJIURUTUE, B.SC UNIVERSITY OF NAMIBIA, WINDHOEK Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Lynn S. Adler Species interactions, by changing phenotypic traits, can alter the outcome of subsequent interactions. Plant-mediated responses to herbivores have been extensively studied, but little is known about plant-mediated responses involving parasitic plants within a broader community context that also includes herbivores. Because parasitic plants are important components of many ecosystems and can shape community structure, it is important to understand how host-mediated interactions influence parasite preference and success. The goal of this thesis is to examine interactions between hosts, parasitic plants and herbivores mediated by chemical traits. We first examined the effects of dodder (Cuscuta sp.) parasitism on induced defenses in cranberry, and asked how cranberry chemistry affected dodder preference and performance. We found dodder preference for some cultivars, and dodder parasitism induced many changes in cranberry chemistry, which could influence other interactions with cranberry hosts. We next examined the effects of gypsy moth herbivory on cranberry chemistry, and how plant- mediated changes affected subsequent dodder preference. Herbivory delayed and reduced the number of dodder plants that attached to cranberry hosts. Herbivory also induced vi changes in cranberry phenolic acids and phytohormones, which could mediate defenses against dodder parasitism. We also assessed the effects of previous herbivory (by tobacco hornworm or mechanical) and previous dodder parasitism on subsequent dodder preference on tomato hosts. Previous attachment followed by removal of dodder slowed subsequent dodder attachment on tomato hosts, but prior herbivory did not affect subsequent dodder attachment. Lastly, we asked whether damage to host induced changes in the host, and if attached parasites assimilated host defenses in response to host damage. Damage to host plants induces higher jasmonic acid in both hosts and attached parasites, and herbivores fed on leaves from parasites attached to damaged hosts ate more than herbivores fed on leaves attached to undamaged parasites. In summary, these studies demonstrate that parasites can induce changes in host responses that can potentially shape other interactions with the same hosts. Similarly, both herbivores and host responses can influence parasite preference, which could alter behavior of herbivores and pollinators, shaping community dynamics. vii TABLE OF CONTENTS Page ACKNOWLEDGMENTS .................................................................................................. v ABSTRACT ....................................................................................................................... vi LIST OF FIGURES ............................................................................................................ x LIST OF TABLES .............................................................................................................. x CHAPTER 1. CRANBERRY RESISTANCE TO DODDER PARASITISM: INDUCED CHEMICAL DEFENSES AND BEHAVIOR OF A PARASITIC PLANT ................. 1 1.1 Abstract ............................................................................................................. 1 1.2 Introduction ....................................................................................................... 2 1.3 Methods and materials ...................................................................................... 6 1.4 Results ............................................................................................................. 18 1.5 Discussion ....................................................................................................... 21 1.6 Acknowledgements ......................................................................................... 25 1.7 Notes ............................................................................................................... 27 2. HEBIVORY DELAYS PARASITE ATTACHMENT TO CRANBERRY HOSTS ... 43 2.1 Abstract ........................................................................................................... 43 2.2 Introduction ..................................................................................................... 44 2.3 Methods and materials .................................................................................... 47 2.4 Results ............................................................................................................. 57 2.5 Discussion ....................................................................................................... 58 2.6 Acknowledgements ......................................................................................... 62 2.7 Notes ............................................................................................................... 63 3. DODDER (CUSCUTA) REMOVAL DETERS FUTURE PARASITE ATTACHMENT ON TOMATO (SOLANUM LYCOPERSICUM) ............................. 76 3.1 Abstract ........................................................................................................... 76 3.2 Introduction ..................................................................................................... 77 3.3 Methods and materials .................................................................................... 80 viii 3.4 Results ............................................................................................................. 86 3.5 Discussion ....................................................................................................... 87 3.6 Acknowledgements
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