Effects of the Trematode Bolbophorus Damnificus on Channel and Hybrid Catfish
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Template Effects of the trematode Bolbophorus damnificus on channel and hybrid catfish By TITLE PAGE Mackenzie Ann Gunn A Thesis Submitted to the Faculty of Mississippi State University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Wildlife, Fisheries and Aquaculture in the Department of Wildlife, Fisheries and Aquaculture Mississippi State, Mississippi May 2020 Copyright by COPYRIGHT PAGE Mackenzie Ann Gunn 2020 Effects of the trematode Bolbophorus damnificus on channel and hybrid catfish By APPROVAL PAGE Mackenzie Ann Gunn Approved: ____________________________________ Peter J. Allen (Co-Major Professor) ____________________________________ Matthew J. Griffin (Co-Major Professor) ____________________________________ Thomas Graham Rosser (Committee Member) ____________________________________ David Wise (Committee Member) ____________________________________ Kevin M. Hunt (Graduate Coordinator) ____________________________________ George M. Hopper Dean College of Forest Resources Name: Mackenzie Ann Gunn ABSTRACT Date of Degree: May 1, 2020 Institution: Mississippi State University Major Field: Wildlife, Fisheries and Aquaculture Major Professors: Peter J. Allen & Matthew J. Griffin Title of Study: Effects of the trematode Bolbophorus damnificus on channel and hybrid catfish Pages in Study: 87 Candidate for Degree of Master of Science The trematode Bolbophorus damnificus (Digenea: Bolbophoridae) has deleterious effects on production efficiency of farm-raised catfish. The effects of B. damnificus on channel and hybrid catfish, as well as the prevalence and longevity of the trematode stages impacting production, are not well understood. This study aimed to understand the prevalence of infected snails, determine the longevity and site specificity of B. damnificus cercaria in catfish, and compare mortality and physiological response between channel and hybrid catfish during infection. The infectivity and survival of B. damnificus cercariae declined significantly at 12h intervals from 12-36h, and subsequent trials were standardized using cercariae <12h old. Metacercariae persisted in both fish types for 13 months and were found commonly in the posterior midsection. Hybrid catfish exhibited lower mortality than channel catfish. Exposed catfish exhibited anemia corresponding to parasite encapsulation, however no difference was found between fish types in physiological response during infection and subsequent recovery. DEDICATION I would like to dedicate this thesis to my grandmother, Barbara “Graham Cracker” Cozzens, whose words of encouragement, attention to detail, and sense of humor continue to inspire me. ii ACKNOWLEDGEMENTS I would like to thank Dr. Peter Allen for all of his help, guidance, and support throughout the last few years; Dr. Matt Griffin for his steadfast dedication to snail collecting, endless support and encouragement, and patience over the course of this project; Dr. Graham Rosser for his words of wisdom and spreading a contagious love of parasites; Dr. David Wise for all of his time, assistance, and great humor. A special thank you to Brian Ott for contributing countless hours of his time to this project. Additional thanks to Adrián López-Porras, Brad Richardson, Brittany Chesser, Conner Almond, Ethan Woodyard, Heaven Martin, Allison Wise, Cynthia Ware, Monroe Walker, James Steadman, Marsha Lewis, and Brandon Gerhart for providing assistance. This project took a village and I could not have done it without all of you. I would also like to thank my family for all of their support and encouragement, and my dogs, Tessa and Voodoo, for keeping me sane. Funding for this research was provided by the US Department of Agriculture (USDA) Agricultural Research Service (Grant Number 58-6066-5-042), the USDA National Institute of Food and Agriculture (Grant Number 1006942; Project Number 58-6402-2729), the USDA Catfish Health Research Initiative (CRIS 6402-31320-002-02), the Mississippi Agricultural and Forestry Experiment Station (MAFES), the Mississippi State University College of Forest Resources and the Mississippi State University College of Veterinary Medicine. iii TABLE OF CONTENTS DEDICATION ................................................................................................................................ ii ACKNOWLEDGEMENTS ........................................................................................................... iii LIST OF TABLES ......................................................................................................................... vi LIST OF FIGURES ......................................................................................................................viii CHAPTER I. INTRODUCTION .............................................................................................................1 1.1 Commercial catfish industry ..................................................................................1 1.2 Bolbophorus damnificus ........................................................................................2 1.3 Impact on channel and hybrid catfish ....................................................................5 1.4 Objectives ..............................................................................................................7 II. ASSESSMENT OF BOLBOPHORUS DAMNIFICUS PREVALENCE AND CERCARIAE SHEDDING IN PLANORBELLA TRIVOLVIS POPULATIONS IN CATFISH AQUACULTURE PONDS ...........................................................................10 2.1 Introduction .........................................................................................................10 2.2 Methods ...............................................................................................................13 2.2.1 Bolbophorus damnificus active shedding prevalence ....................................13 2.2.2 Molecular analysis .........................................................................................14 2.2.3 Statistical Analysis ........................................................................................15 2.3 Results .................................................................................................................16 2.4 Discussion ............................................................................................................17 2.5 Tables ..................................................................................................................23 III. LONGEVITY AND INFECTIVITY OF CERCARIAE AND PERSISTANCE AND SITE SPECIFICITY OF METACERCARIAE OF BOLBOPHORUS DAMNIFICUS IN CATFISH ........................................................................................................................25 3.1 Introduction .........................................................................................................25 3.2 Methods ...............................................................................................................28 3.2.1 Experiment 1: Bolbophorus damnificus cercariae longevity and infectivity 31 3.2.2 Experiment 2: Metacercariae site specificity ................................................32 3.2.3 Experiment 3: Bolbophorus damnificus metacercariae longevity .................33 iv 3.2.4 Statistical analysis .........................................................................................33 3.3 Results .................................................................................................................35 3.3.1 Experiment 1: Cercariae longevity and infectivity ........................................35 3.3.2 Experiment 2: Metacercariae site specificity ................................................35 3.3.3 Experiment 3: Metacercariae longevity .........................................................36 3.4 Discussion ............................................................................................................37 3.4.1 Experiment 1: Cercariae longevity and infectivity ........................................37 3.4.2 Experiment 2: Metacercariae site specificity ................................................38 3.4.3 Experiment 3: Metacercariae longevity .........................................................40 3.4.4 Summary ........................................................................................................42 3.5 Tables ..................................................................................................................44 3.6 Figures .................................................................................................................46 IV. COMPARATIVE MORTALITY OF JUVENILE CHANNEL AND HYBRID CATFISH EXPOSED TO BOLBOPHORUS DAMNFICUS CERCARIAE ..................47 4.1 Introduction .........................................................................................................47 4.2 Methods ...............................................................................................................49 4.2.1 Challenge 1 ....................................................................................................51 4.2.2 Challenge 2 ....................................................................................................51 4.2.3 Statistical Analysis ........................................................................................52 4.3 Results and Discussion ........................................................................................52 4.4 Tables ..................................................................................................................57