THRIPS COMPETITION AND SPATIOTEMPORAL DYNAMICS ON REPRODUCTIVE HOSTS By TOBIN D. NORTHFIELD 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 Tobin D. Northfield This document is dedicated to my wife, Kirsten for all of her support and understanding throughout this process. It is also dedicated to my parents for their guidance and support. ACKNOWLEDGMENTS I would like to thank my major professor, Dr. Joe Funderburk, for the guidance and assistance in designing and conducting my experiments, and for helping me develop as a scientist. I would also like to thank Dr. Dean Paini, a committee member, who also spent a great deal of time advising and assisting me whenever possible. My other committee members, Drs. Stuart Reitz and Russ Mizell, were a tremendous source of assistance and knowledge, for which I am grateful. Dr. Michelle Stuckey proofread drafts and assisted in the experimental procedure, as well as offered good advice. I would like to thank Dr. Brian Inouye for his assistance in interpreting the models, and the model-fitting process. I appreciated Dr. Ben Bolker’s patience and instruction on the modeling process and using R to fit the models. Marcus Griswold helped in providing an R code to work with. Dr. Todd Jackson also lent assistance and insight in developing my experiments. Rebecca Riddle also assisted in the experimental procedure, for which I am grateful. iv TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ........................................................................................................... ix ABSTRACT.........................................................................................................................x CHAPTER 1 LITERATURE REVIEW .............................................................................................1 Introduction...................................................................................................................1 Diversity .......................................................................................................................2 Population Attributes....................................................................................................3 Plant Defenses ..............................................................................................................4 Host Selection and Nutrition ........................................................................................5 Within Plant Distribution..............................................................................................7 Seasonal Dynamics.......................................................................................................7 Biotic Factors................................................................................................................9 North Florida Thrips...................................................................................................10 Reproductive Hosts.....................................................................................................11 Conclusion ..................................................................................................................12 2 SPATIOTEMPORAL DYNAMICS ON REPRODUCTIVE HOSTS.......................17 Introduction.................................................................................................................17 Materials and Methods ...............................................................................................18 Sampling Procedure.............................................................................................18 Data Analysis.......................................................................................................19 Results.........................................................................................................................21 Discussion...................................................................................................................25 Conclusion ..................................................................................................................30 3 INTRASPECIFIC AND INTERSPECIFIC COMPETITION IN THRIPS ON FLOWERING PEPPER PLANTS ............................................................................43 Introduction.................................................................................................................43 v Materials and Methods ...............................................................................................45 Experimental Design ...........................................................................................45 Model Fitting.......................................................................................................47 Results.........................................................................................................................48 Discussion...................................................................................................................49 Effects of Competition on F. occidentalis Population Abundance in Florida ....50 Effects of Competition on World-Wide F. occidentalis Spread .........................51 4 CONCLUSION...........................................................................................................56 LIST OF REFERENCES...................................................................................................58 BIOGRAPHICAL SKETCH .............................................................................................69 vi LIST OF TABLES Table page 1-1 F. occidentalis Reproductive Hosts. ........................................................................13 1-2 F.fusca Reproductive Hosts. ....................................................................................14 1-3 F. tritici Reproductive Hosts....................................................................................15 1-4 A list of plants F. bispinosa Reproductive Hosts.....................................................16 2-1 Mean number (SEM) of thrips per 20 Raphanus raphanistrum flowers. ................32 2-2 Mean number (SEM) of thrips per 20 Raphanus raphanistrum leaves ...................33 2-3 Mean number (SEM) of thrips per 20 Raphanus raphanistrum fruits.....................34 2-4 Mean number (SEM) of thrips per 20 Rubus trivialis flowers.................................34 2-5 Mean number (SEM) of thrips per 20 Rubus trivialis leaves...................................35 2-6 Mean number (SEM) of thrips per 20 Rubus trivialis fruits ....................................35 2-7 Mean number (SEM) of thrips per 20 Rubus cuneifolius flowers............................36 2-8 Mean number (SEM) of thrips per 20 Rubus cuneifolius leaves..............................36 2-9 Mean number (SEM) of thrips per 20 Rubus cuneifolius fruits. ..............................36 2-10 Mean number (SEM) of thrips per 20 Vicia sativa flowers .....................................37 2-11 Mean number (SEM) of thrips per20 Vicia sativa leaves ........................................37 2-12 Mean number (SEM) of thrips per 20 Vicia sativa leaves .......................................37 2-13 Mean number (SEM) of thrips per 4 Vicia sativa buds............................................38 2-14 Mean number (SEM) of thrips per 4 Trifolium repens racemes. .............................38 2-15 Mean number (SEM) of thrips per 20 Trifolium repens leaves ...............................39 2-16 Mean number (SEM) of thrips per 20 Solidago canadensis racemes. .....................40 vii 2-17 Mean number (SEM) of thrips per 20 Solidago canadensis leaves .........................40 2-18 Mean number (SEM) of thrips per 20 Chenopodium ambrosioides racemes ..........41 2-19 Mean number (SEM) of thrips per 20 Chenopodium ambrosioides leaves .............41 2-20 Mean number of thrips per plant for seven plant species on selected dates.............42 3-1 The mean number (SEM) of larvae per female of adult female F. occidentalis and F. bispinosa at various levels of densities of each species................................52 3-2 Model parameters and confidence intervals measuring effects of competition on the number of larvae produced per F. bispinosa female ..........................................53 3-3 Model parameters and confidence intervals measuring effects of competition on the number of larvae produced per F. occidentalis female ......................................53 viii LIST OF FIGURES Figure page 3-1 Example of an additive design .................................................................................53 3-2 Example of a substitutive design..............................................................................54 3-3 Treatments of varying F. bispinosa and F. occidentalis densities to measure the larvae produced per female at different levels of competition.................................55 3-4 Simulation of intraspecific competition of F. bispinosa and F. occidentalis based on the competition model.........................................................................................55 ix Abstract of Thesis Presented to the Graduate School of the University