Landscape effects on insect pests of Dracaena marginata and their associated natural enemies in Costa Rica by Mildred Linkimer A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy With a Major in Ecological Agriculture Postgraduate School of CATIE Centro Agronómico Tropical de Investigación y Enseñanza Co-advised by Purdue University 2012 II DEDICATION To Heiner and Ariel, happiness and strength of my life. To my mom and dad who never stopped fighting for us. A Heiner y Ariel, la felicidad y Fortaleza de mi vida. A mi papá y mamá que nunca dejaron de luchar por nosotros. III ACKNOWLEGMENTS Many people have contributed to this research and my professional and personal development during the past six years. First, I would like to express my gratitude to my major advisor, Fernando Casanoves, for guiding and supporting me during these years. He always gave me confidence even in difficult times and taught me the passion for statistics. I would also like to thank my co-advisor Clifford Sadof who opened the doors of Purdue University for me. He has been a true mentor, guiding me with his wisdom through difficult and happy times, providing me with critical advice and knowledge. I would also like to thank Cliff´s family (Linda and Claire) for kindly having me during my time at PU. I would also like to thank my Graduate Committee (Jeffrey Holland, Kevin Gibson) for their support and advice. Specially, I would like to thank to my advisor and friend, Tamara Benjamin, for her guidance not only during the development of my research but also in my personal life. I would like to thank all CATIE and Purdue University faculty and administrative those have helped in my professional development. This work could have not been possible without the willingness of all Dracaena farmers, who allowed me to conduct my work on their farms and happily shared their knowledge with me, without expecting reward. I would also thank to the Ministry of Agriculture of Costa Rica (MAG) and especially to Magda González, Sergio Abarca, Gina Monteverde, Armando Vargas and my friends Oscar Rodríguez and Jorge Vargas, without them it would have not been possible this project. I would like to thank all the friends and colleagues of the CSP team at CATIE (Gerardo Pérez, Adriana Villalobos, Carlos Marshall, Julia Prado, Lindsay Calderón, Rebeca Novoa and Alexis) who contributed to this research. I am especially grateful to my great friend Eduardo Hidalgo, who always had time to discuss my results and findings, and always encouraged me to continue even in the most difficult times. Thank you Lalo! To Jorge, Heiner´s brother, who helped me a lot with my field experiments. My family has been my motivation during these years. My husband, Heiner, and my son, Ariel, have walked with me since the beginning and until the end of this way. My mom and dad always encouraged me to pursue a Ph.D. They worked tirelessly to give us education. Silja, Madai and Lepolt always gave me all their support and love. To Olivia, without her help I could not have finished the last years of my studies. IV Finally, to all the people of Costa Rica, who thorough their contributions make possible programs such the Programa de Reconversión Productiva of the CNP who funded this work. V CONTENTS DEDICATION ..................................................................................................................... III ACKNOWLEGMENTS ...................................................................................................... IV CONTENTS ......................................................................................................................... VI SUMMARY ......................................................................................................................... IX LIST OF TABLES ............................................................................................................... XI LIST OF FIGURES........................................................................................................... XIII LIST OF ACRONYMS..................................................................................................... XVI CHAPTER 1. INTRODUCTORY CHAPTER .............................................................. 17 1.1 Objectives ............................................................................................................. 18 General objectives ........................................................................................................ 18 Specific objectives ........................................................................................................ 18 1.2 Hypotheses ........................................................................................................... 19 1.3 Literature review .................................................................................................. 19 Generalities of Dracaena marginata ........................................................................... 19 Principal quarantine pests associated to Dracaena marginata .................................. 21 Landscape ecology ....................................................................................................... 26 Quantifying landscape patterns ................................................................................... 28 Landscape patterns and ecology of the insects ............................................................ 29 Landscape context on insects at different spatial scales.............................................. 30 Cicadellids and their relation with the macro and micro landscape ........................... 31 1.4 References ............................................................................................................ 33 CHAPTER 2. EFFECTS OF MACRO LANDSCAPE CONTEXT ON PESTS OF QUARANTINE IMPORTANCE ASSOCIATED WITH DRACAENA MARGINATA IN COSTA RICA ................................................................................................................ 39 2.1 Introduction .......................................................................................................... 39 2.2 Materials and methods ......................................................................................... 41 Study area .................................................................................................................... 41 Insect Pest Database .................................................................................................... 42 Land use mapping ........................................................................................................ 44 Quantifying landscape structure .................................................................................. 46 Statistical methods ....................................................................................................... 48 2.3 Results .................................................................................................................. 49 Landscape Characterization ........................................................................................ 49 Effect of landscape metrics on insect pest abundance at the landscape level ............. 52 Effect of landscape metrics on insect pest abundance at the class level ..................... 54 2.4 Discussion ............................................................................................................ 59 VI Effect of landscape level metrics on insect pest abundance ........................................ 60 Effect of landscape patch metrics on insect pest abundance ....................................... 62 2.5 Conclusions .......................................................................................................... 65 2.6 References ............................................................................................................ 67 2.7 Annexes ................................................................................................................ 74 CHAPTER 3. EFFECT OF FOREST AND DISTANCE FROM FIELD EDGE ON PEST POPULATIONs AND THEIR NATURAL ENEMIES IN DRACAENA MARGINATA IN COSTA RICA .......................................................................................... 80 3.1 Introduction .......................................................................................................... 80 3.2 Material and methods ........................................................................................... 82 Study area .................................................................................................................... 82 Effect of forest on insect pest population and parasitism ............................................ 82 Sampling....................................................................................................................... 83 Statistical analysis........................................................................................................ 84 Movement of leafhoppers and natural enemies in fields adjacent to forest................. 86 3.3 Results .................................................................................................................. 86 Leafhopper and parasitism level .................................................................................. 88 Katydid eggs and parasitism level ............................................................................... 90 Armored scale population ...........................................................................................