PREDACEOUS ARTHROPODS OF THE SWEETPOTATO WHITEFLY, BEMISIA TABACI (GENNADIUS) , ON TOMATOES IN FLORIDA BY DAVID ED DEAN 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 1994 ACKNOWLEDGMENT S Much of the time and effort that went into this program was contributed by someone other than myself. Unfortunately, space will not permit an exhaustive list. Certainly a large commitment has come from my major advisor. Dr. D. J. Schuster. Among other things, he has been a generous and patient mentor, a constant encouragement, a good example, a great fishing guide, and a trusted friend. I am fortunate to have had the opportunity to know him. My time spent on coursework in Gainesville was directed by Dr. C. S. Bar field who has served as cochairman on the advisory committee. Like Dr. Schuster, he also has taken an interest in my personal welfare, as well as my academic preparation. Along with good academic counsel, he gave me full access to his laboratory and office space while on campus. I benefited from his instruction in the classroom and had the opportunity to assist him with two international IPM courses. I am grateful for the opportunity to know him as an instructor and friend. Dr. F. D. Bennett served on my committee until his retirement in 1993. He was a great encouragement and source of valuable information on biological control. It was a privilege to have had the opportunity to know him and draw ii from his experience in the field. Dr. J. B. Jones generously gave me bench space and access to equipment in his laboratory. Upon Dr. Bennett's retirement. Dr. Jones agreed to fill his place on the committee. I am very grateful for his generosity and for his counsel concerning antibody techniques. Dr. L. S. Osborne has been a source of information concerning biological control of whiteflies and was a major influence in the decision to investigate the predation of whiteflies. Dr. J. A. Bartz has always encouraged me and given a good balance to all the entomologists on the committee. I want to thank each of these individuals for the time invested in committee meetings and reading of manuscripts. Dr. J. E. Polston has also donated laboratory space and Dr. G. M. Danyluck gave direction for electrophoresis and protein work. Dr. J. H. Frank gave many hours to personally tutor me through his course in biological control. Dr. J. R. McLaughlin loaned a 'D vac' for insect sampling. Dr. R. D. Getting sent greenhouse whiteflies. Dr. P. J. Walgenbach sent potato aphids. Dr. D. G. Boucias assisted in the concentration and quantification of whitefly protein. Identification of insects important to this study was provided by Drs. T. J. Henry (Hemiptera) , R. D. Gordon (Coccinellidae) , R. J. Gagne and N. E. Woodley (Diptera) of the Systematic Entomology Laboratory, Agriculture Research Service, USDA and by Drs. M. C. Thomas (Coleoptera) and L. A. Stange of the Entomology Section of the Division of Plant iii . Industries, Florida Department of Agriculture. Dr. J. H. Frank, University of Florida, identified the staphylinids Mr. M. Maedgen of Biofac insectary in Mathis, TX has generously supplied the green lacewings for this research. Mr. Fred Adams of the USDA insectaries in Gainesville gave me noctuid larvae and eggs for rearing lacewings. Mr. C. Liewald gave 30 hibiscus plants for rearing whiteflies. B. Mr. S. Wood assisted me faithfully as a part-time technician for two years. Mrs. L. Green was a tremendous help at the hybridoma lab. Mrs. M. Litchfield helped with long distance registration and department records each semester. To each of these individuals mentioned, I would like to express my sincere gratitude for their selfless generosity. Lastly, my family has sacrificed time and finances during the time I have spent in graduate school. They have endured two moves, spent countless hours waiting for me while I checked on experiments at night and weekends, helped me find articles in the library, moved insect traps, and brought me 'neat bugs'. My wife has had to keep me going many times, proof papers, remind me of deadlines and important dates, and pay most of the bills. Words alone are inadequate to express what their support has meant to me. So, I will just have to make some time to demonstrate my gratefulness. iv TABLE OF CONTENTS page ACKNOWLEDGMENTS ii TABLE OF CONTENTS V LIST OF TABLES viii LIST OF FIGURES x ABSTRACT xiv CHAPTER I. INTRODUCTION AND LITERATURE REVIEW 1 Introduction 1 Literature Review 3 History of The Sweetpotato Whitefly 3 Whiteflies 5 Biological Control of Whiteflies 6 Natural enemies 6 Predators of whiteflies 9 Predation and Prey Populations 10 Models of predation 13 Population regulation and predators 15 Sampling Predators 18 Evaluation of Predation 19 Prey preference 20 Prey suitability for development 22 Detecting Predation in the Field 24 Augmentation of Predators 25 The Use of Chemicals to Manipulate Predators .... 26 Attractants and predators 27 Screening Predators for Pesticide Tolerance 28 CHAPTER II. PREDATION OF THE SWEETPOTATO WHITEFLY ON FIELD TOMATOES 54 Introduction 54 Methods and Procedures 56 Statistical Treatment 63 Results and Discussion 64 Predator Survey 64 Archnida 68 Insecta 70 V Population Dynamics 83 Conclusions 129 CHAPTER III. PREY PREFERENCE AND SUITABILITY OF PREY FOR GREEN LACEWINGS 132 Introduction 132 Materials and Methods 134 Preference 134 Preference models 135 Prey Suitability 137 Development and Mortality 137 Fecundity 137 Maximum consumption 138 Statistical analysis 138 Preference 138 Prey suitability 139 Results 140 Preference 140 Prey Handling 145 Prey Suitability 148 Development 148 Mortality 150 Fecundity 151 Maximum consumption 151 Conclusion and Discussion 151 CHAPTER IV. ATTRACTION AND ARRESTMENT OF ADULT LACEWINGS 158 Introduction 158 Materials and Methods 160 Olfactometer 160 Attract ant Bioassays 162 Statistical Analysis for Olfactometer 163 Field trials 164 Sampling method 165 Statistical analysis of Field Data 168 Results 169 Olfactometer assays 169 Field Trials 172 Lacewing attraction and oviposition 172 Effects of Attractant on Other Arthropods 177 Conclusion and Discussion 182 vi CPIAPTER V. SUMMARY AND CONCLUSIONS 184 Introduction 184 General Discussion 185 Predator Survey 185 Predator Manipulation 187 Attractants 196 Introduced Predators 199 REFERENCES 201 BIOGRAPHICAL SKETCH 230 vii LIST OF TABLES Table page 1.1. Predators of Whiteflies 30 2.1. Predaceous arthropods observed feeding on Bemisia tabaci in the laboratory or field 65 2.2. Seasonal incidence of orders of arthropods and related prey collected with the whitefly, Bemisia tabaci , on unsprayed tomatoes in Bradenton, FL 89 2.3. Seasonal abundance of selected predator taxa collected during the survey of the fauna associated with Bemisia tabaci on unsprayed tomatoes in Bradenton, FL 96 2.4. Correlation coefficients (r^) for combinations of prevalent whitefly (WF) predators and the whitefly predator complex with alternative prey present on insecticide free tomatoes at Bradenton, FL 125 2.5. Association coefficients for various whitefly (WF) predators and common prey found on unsprayed tomatoes in Bradenton, FL 127 3.1. Means (±SE) of prey consumption by larvae of two lacewing species at a standard density of 30 prey and a standard time of 30 minutes 141 3.2. Relative preference of each larval instar of £. CUbana (Cc) and £. rufilabris (Cr) larvae for M. euphorbiae and nymphs of E. tabaci 143 3.3. Development of Q. rufilabris and Q. cubana ,, on three different prey diets consisting of M. euphorbiae f and B. tabaci alone and combined (A/W) 149 viii 4.1. Responses of the lacewings, £. rufilabris (Cr) and cubana (Cc) to various compounds and products in an olfactometer in the laboratory 170 4.2. Mean number of arthropods collected in vacuum samples taken from tomato plots sprayed with an artificial honeydew and unsprayed control plots, spring 1992 178 4.3. Mean number of arthropods collected in vacuum samples taken from tomato plots sprayed with an artificial honeydew and unsprayed control plots, fall 1992 179 4.4 Mean number of arthropods collected in vacuum samples taken from squash plots sprayed with an artificial honeydew and from unsprayed control plots, summer 1993 180 ix LIST OF FIGURES Figure P^ge 2.1. Cylindrical drop trap 59 2.2. Collection of arthropods 60 2.3. Mechanical timer 61 2.4. Mean number of whitefly adults per plant and immature lifestages per leaf sample, on unsprayed tomatoes at Bradenton, FL, fall 1991 84 2.5. Mean number of whitefly adults per plant and immature lifestages per cm^ leaf sample, on unsprayed tomatoes at Bradenton, FL, spring 1992 85 2.6. Mean number of whitefly adults per tomato plant and immature lifestages per cm^ leaf sample, on unsprayed tomatoes at Bradenton, FL, fall 1992 86 2.7. Mean number of whitefly adults per plant and immature lifestages per cm^ leaf sample, on unsprayed tomatoes at Bradenton, FL, spring 1993 87 2.8. Mean plant height, mean number of predators of the immature lifestages of the whitefly, mean number of B. t abaci nymphs and eggs per cm^ of leaf, and mean number of spiders on unsprayed tomatoes at Bradenton, Fl, spring 1992 92 2.9. Mean plant height, mean number of predators of the immature lifestages of the whitefly, mean number of B. tabaci nymphs and eggs per cm^ of leaf, and mean number of spiders on unsprayed tomatoes at Bradenton, Fl, fall 1992 93 2.10. Mean plant height, mean number of predators of the immature lifestages of the whitefly, mean number of B. tabaci nymphs and eggs per cm^ of X leaf, and mean number of spiders on unsprayed tomatoes at Bradenton, Fl, spring 1993 94 2.11.