EFFECT OF DIAPREPES ROOT WEEVIL ON LEAF GAS EXCHANGE AND GROWTH OF SELECT ORNAMENTAL TREE SPECIES By ALEXANDER P. DIAZ A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2005 Copyright 2005 by Alexander P. Diaz ACKNOWLEDGMENTS I would like to thank Catharine Mannion and Bruce Schaffer for granting me this opportunity to pursue graduate studies and providing funding for this research project. I would also like to thank them along with Susan Webb for their guidance and support throughout this experience. I would like to thank all those who helped me in many different ways while working on my research, especially Holly Glenn, Julio Almanza, Karen Griffin, Mike Gutierrez and Dalia Stubblefield. Finally, I would like to thank my family for their continual encouragement and support. iii TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iii LIST OF TABLES............................................................................................................. vi LIST OF FIGURES .......................................................................................................... vii ABSTRACT....................................................................................................................... ix CHAPTER 1 LITERATURE REVIEW .............................................................................................1 Introduction...................................................................................................................1 Weevils..................................................................................................................2 Root Weevils .........................................................................................................3 Citrus Root Weevils ..............................................................................................5 Diaprepes Root Weevil..........................................................................................7 Damage..................................................................................................................9 Arthropod feeding and whole-plant physiology...........................................11 Flooding stress and plant physiology...........................................................16 The ornamental plant industry......................................................................18 Current and potential impact of Diaprepes root weevil on the ornamental plant industry ............................................................................................19 Buttonwood, Live Oak and Pygmy Date Palm ...................................................20 Research Objectives....................................................................................................22 2 EFFECT OF LARVAL ROOT FEEDING BY DIAPREPES ROOT WEEVIL ON LEAF GAS EXCHANGE AND GROWTH OF SELECT ORNAMENTAL TREE SPECIES.....................................................................................................................23 Introduction.................................................................................................................23 Materials and Methods ...............................................................................................25 Plant and Insect Material.....................................................................................26 Experiment 1 ................................................................................................26 Experiment 2 ................................................................................................26 Treatments ...........................................................................................................27 Experiment 1 ................................................................................................27 Experiment 2 ................................................................................................28 iv Temperature Measurements ................................................................................29 Statistical Analysis ..............................................................................................30 Results.........................................................................................................................30 Experiment 1 .......................................................................................................30 Experiment 2 .......................................................................................................32 Discussion...................................................................................................................35 3 EFFECT OF FLOODING AND DIAPREPES ROOT WEEVIL LARVAL FEEDING ON LEAF GAS EXCHANGE AND GROWTH OF BUTTONWOOD AND LIVE OAK........................................................................................................54 Introduction.................................................................................................................54 Materials and Methods ...............................................................................................56 Plant and Insect Material.....................................................................................56 Treatments ...........................................................................................................56 Soil Redox Potential............................................................................................57 Leaf Gas Exchange..............................................................................................58 Plant Growth and Larval Recovery .....................................................................58 Statistical Analysis ..............................................................................................58 Results.........................................................................................................................59 Soil Redox Potential (Eh)....................................................................................59 Leaf Gas Exchange..............................................................................................59 Plant Growth and Larval Recovery .....................................................................60 Discussion...................................................................................................................61 4 EFFECT OF ADULT DIAPREPES ROOT WEEVIL ON LEAF GAS EXCHANGE AND GROWTH OF BUTTONWOOD AND LIVE OAK.................72 Introduction.................................................................................................................72 Materials and Methods ...............................................................................................74 Plant and Insect Material.....................................................................................74 Leaf Gas Exchange..............................................................................................75 Plant biomass.......................................................................................................76 Statistical Analysis ..............................................................................................76 Results.........................................................................................................................76 Visible Signs of Herbivory..................................................................................76 Leaf Gas Exchange..............................................................................................77 Plant Biomass ......................................................................................................77 Discussion...................................................................................................................78 5 SUMMARY AND CONCLUSIONS.........................................................................86 LIST OF REFERENCES...................................................................................................89 BIOGRAPHICAL SKETCH .............................................................................................97 v LIST OF TABLES Table page 2-1 The effect of Diaprepes root weevil larvae on height and trunk diameter of buttonwood and live oak trees..................................................................................51 2-2 The effect of Diaprepes root weevil larvae on buttonwood leaf, stem and root fresh and dry weights at each harvest date...............................................................52 2-3 The effect of Diaprepes root weevil larvae on leaf stem and root fresh and dry weights of live oak and pygmy date palm................................................................53 2-4 Number of Diaprepes root weevil larvae recovered from plants harvested 2, 3, 4 & 5 months after infestation.....................................................................................53 3-1 The effect of flooding (FLD) and insect infestation (INFST) on leaf gas exchange of buttonwood and live oak trees. ............................................................70 3-2 The effect of Diaprepes root weevil larvae on leaf, stem, root and total biomass of infested or non-infested buttonwood and live oak trees. .....................................71 4-1 The effect of adult Diaprepes root weevil