BIOLOGY, HOST SPECIFICITY AND IMPACT OF ISCHNODEMUS VARIEGATUS, AN HERBIVORE OF HYMENACHNE AMPLEXICAULIS By RODRIGO DIAZ A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2008 1 © 2008 Rodrigo Diaz 2 To Veronica Manrique, my best friend and companion 3 ACKNOWLEDGMENTS I extend my deepest appreciation to Dr. Bill Overholt for his support and friendship. Dr. Overholt provided a constructive scientific environment for the development of my dissertation. His role as mentor has been paramount due the constant conversations and critical discussions about different subjects such as science, politics, religion, sports, economy and foreign affairs. I cannot ask for a more nutritious intellectual environment than Dr. Overholt’s friendship. I thank Drs. Jim P. Cuda, Paul Pratt and Alison Fox for providing useful insights in biological control and weed ecology. Don Schmitz from Florida Department of Environmental Protection facilitated the funding for my research assistantship at the University of Florida. Catherine Corbet from the Charlotte Harbor Estuary program provided funding for several field experiments. I greatly appreciate their support. I am also grateful to Dr. Overholt’s lab members for their continuous support and friendship. I thank Diana Cordeau, Yordana Valenzuela, Eric Morgan, Brianne Schobert, Freddy Soza, Douglas Gonzalez, Veronica Manrique, Jackie Markle, Brittany Evans, Ana Samayoa, Fabian Diaz and Larry Markle. Paul Benshoff and Diana Donaghy from Myakka River State Park provided support and ideas during the development of this project. I thank also the members of the volunteer program from the Myakka River State Park. The realization of this project could not have been possible without the great help of the staff of the Indian River Research & Education Center at Fort Pierce, Department of Entomology and Nematology in Gainesville and the quarantine officers of the Biological Control Research and Containment Laboratory. Finally, I am gratefull to my parents, Rogelio and Maggie, for their unconditional support in my life and to my brother, Daniel, for the good conversations about happiness and family. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES...........................................................................................................................9 LIST OF FIGURES .......................................................................................................................11 ABSTRACT...................................................................................................................................14 CHAPTER 1 LITERATURE REVIEW .......................................................................................................16 Introduction.............................................................................................................................16 Why Do Exotic Plants Become Invasive?..............................................................................17 Enemy Release Hypothesis .............................................................................................17 Evolution of Increased Competitive Ability Hypothesis (EICA)....................................18 Increased Resource Availability Hypothesis...................................................................18 Resource-Enemy Release Hypothesis .............................................................................19 Biology and Ecology of Hymenachne amplexicaulis.............................................................19 Hymenachne amplexicaulis Invasion in Australia..................................................................21 Hymenachne amplexicaulis in Florida....................................................................................22 Classification of Hymenachne amplexicaulis.........................................................................23 Biology of Ischnodemus variegatus .......................................................................................24 Goals and Hypotheses.............................................................................................................25 2 TEMPERATURE-DEPENDENT DEVELOPMENT, SURVIVAL AND POTENTIAL DISTRIBUTION OF ISCHNODEMUS VARIEGATUS (HEMIPTERA: BLISSIDAE), AN HERBIVORE OF WEST INDIAN MARSH GRASS (HYMENACHNE AMPLEXICAULIS)...............................................................................................................35 Introduction.............................................................................................................................35 Materials and Methods ...........................................................................................................37 Source of Ischnodemus variegatus and Hymenachne amplexicaulis..............................37 Laboratory Studies...........................................................................................................37 Development Time and Survival.....................................................................................38 Developmental Rate and Degree Day Requirement........................................................39 Linear Model ...................................................................................................................39 Nonlinear Model..............................................................................................................39 Weather Data from Florida..............................................................................................40 Calculation of Degree-days and Number of Generations for GIS Analysis ...................40 Generation of GIS Map for Prediction of I. variegatus Generations in Florida..............40 Results.....................................................................................................................................41 Size and Behavior of Stages............................................................................................41 Immature Survival and Developmental Time .................................................................43 5 GIS Mapping of I. variegatus Generations in Florida.....................................................44 Discussion...............................................................................................................................45 3 HOST SPECIFICITY OF ISCHNODEMUS VARIEGATUS, AN HERBIVORE OF WEST INDIAN MARSH GRASS (HYMENACHNE AMPLEXICAULIS)........................57 Introduction.............................................................................................................................57 Materials and Methods ...........................................................................................................60 Origin and Maintenance of Organisms............................................................................60 Test Plants .......................................................................................................................60 No-choice Nymphal Development..................................................................................61 No-choice and Choice Oviposition .................................................................................61 Field Colonization of Potted Plants.................................................................................63 Spill-over to Co-occurring Species .................................................................................63 Statistical Analysis ..........................................................................................................64 Results.....................................................................................................................................65 No-choice Nymphal Development..................................................................................65 No-choice and Choice Oviposition .................................................................................65 Field Colonization of Potted Plants.................................................................................66 Spill-over to Co-occurring Species .................................................................................66 Discussion...............................................................................................................................67 4 LIFE HISTORY PARAMETERS OF ISCHNODEMUS VARIEGATUS (SIGNORET) (HEMITERA: BLISSIDAE) REARED ON TWO CLOSELY RELATED GRASSES........82 Introduction.............................................................................................................................82 Materials and Methods ...........................................................................................................86 Origin and Maintenance of Organisms............................................................................86 Development of First Instars on Cuttings........................................................................87 Development of Third Instars on Growing Tips and Cuttings........................................87 Adult Longevity and Oviposition Test in No-choice Conditions....................................88 Oviposition Choice Test..................................................................................................88 Population Growth