Cestoda: Cyclophyllidea) Hugo Alvin James Iowa State University
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1968 Studies on the genus Mesocestoides (Cestoda: Cyclophyllidea) Hugo Alvin James Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Zoology Commons Recommended Citation James, Hugo Alvin, "Studies on the genus Mesocestoides (Cestoda: Cyclophyllidea) " (1968). Retrospective Theses and Dissertations. 3478. https://lib.dr.iastate.edu/rtd/3478 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. This dissertation has been microfilmed exactly as received 69-4245 JAMES, Hugo Alvin, 1930- STUDIES ON THE GENUS MESOCESTOIDES (CESTODA: CYCLOPHYLLIDEA). Iowa State University, Ph.D., 1968 Zoology University Microfilms, Inc., Ann Arbor, Michigan STUDIES ON THE GENUS MESOCESTOIDES (CESTODA: CYCLOPHYLLIDEA) by Hugo Alvln James A Dissertation Submitted to the Graduate Faculty In Partial Fulfillment of The Requirements for the Degree of DOCTOR OP PHILOSOPHY Major Subject: Zoology (Parasitology) Approved : Signature was redacted for privacy. Signature was redacted for privacy. Head of Major Department Signature was redacted for privacy. Iowa State University Ame^, Iowa 1968 il TABLE OF CONTENTS Page INTRODUCTION 1 PART I. SYSTEMATIC CONSIDERATIONS 4 MATERIALS AND METHODS 5 LITERATURE REVIEW 9 NATURAL INFECTIONS 13 Adults 13 Species and species criteria 13 Geographic distribution 24 Hosts 25 Tetrathyridia 33 Relationship to adult 33 Geographic distribution 37 Hosts 38 EXPERIMENTAL STUDIES 46 Eggs and Oncospheres 46 Feeding experiments 46 Invertebrate hosts 46 Vertebrate hosts 53 Injection experiments 59 Tetrathyridia 60 Feeding experiments 60 • Injection experiments ' 77 PART II. THE MESOCESTOIDID PARAUTERINE ORGAN 80 MATERIALS AND METHODS Bl GENERAL CONSIDERATIONS 84 ill Page MORPHOLOGY AND HISTOCHEMISTRY 88 Origin of the Parauterine Organ 91 Structure 93 Incidental Observations on Eggs and Developing Oncospheres 97 Metabolic Activities 99 Calcareous Corpuscles 101 Proteins 104 Carbohydrates 10? Lipids 113 Nucleic Acids 117 Inorganic Constituents 119 DISCUSSION 121 SUMMARY AND CONCLUSIONS 129 LITERATURE CITED 132 ACKNOWLEDGEMENTS 144 APPENDIX A. TABLES 146 APPENDIX B. ILLUSTRATIONS 190 Abbreviations 191 1 INTRODUCTION This Investigation was initiated during the early summer of 1961 when particularly heavy Infections of the cestode genus, Mesocestoldes, were found in raccoons In the environs of Lakeside Laboratory in northwestern Iowa. According to published reports, no substantiated life cycle of these cestodes had been published, nor was the position of the tetrathyrldlum, in the mesocestoidld life cycle, clear. The availability of gravid Mesocestoides provided an ample supply of eggs for feeding experiments with selected Invertebrate and vertebrate hosts. Finding of tetrathyridla in local toads and frogs provided the materials for a developmental study of this larval stage. The genus Mesocestoides Vaillant, I863 has been an enigma since the description of its type species by Goeze in I782. Exclusive of generic synonyms, 35 species, varieties and/or forms of species have appeared In the literature. In the absence of an experimentally proven life cycle for any member of this group, the systematic position of the genus or even family is not clearly understood. During the course of this investigation, attempts to elucidate the life cycle of Mesocestoides have proven unsuccessful. However, data ob tained from natural and experimental infections of host animals coupled with those data available in the literature have resulted in a clearer understanding of the taxonomic 2 position of the genus and, to a lesser degree, of the family. Witenberg (1934) and Voge (1955) have suggested that morphological features used in determining mesocestoidld species are unsuitable or at least unreliable. Witenberg has pointed out that the anatomy of the members of this genus is so unstable that even apparently distinctive character istics overlap to such a degree that species identification is quite difficult. This study supports the contention that present criteria for defining species of Mesocestoldes are useless and strongly suggests that if more than one species does exist, criteria for separation will probably be phys iological and not morphological. Numerous early investigations, well reviewed in Witenberg (1934), have shown conclusively that tetrathyrldla are larvae of Mesocestoldes. However, whether a tetrathyrldium is re- * quired in the cycle, or is merely paratenlc, or is the terminal stage of oncospheral development in a cycle requiring only a single intermediate host, as suggested by Spasskil (1951), are all a matter of conjecture. Most previous Investigators have felt that Mesocestoldes required tv;o intermediate hosts. This study casts doubt on the validity of the currently proposed life cycles of mesocestoidids and suggests a need for an experimentally proven cycle before any categorical statements are made. However, the primitive *As defined in Baer (1951). 3 phylogenetlc position of this genus, suggested by its broad host spectrum for both adult and larval stages, points clearly to the potentiality of the tetrathyridium to exist paratenlcally. Experimental transfers of tetratbyridJa from one class of vertebrate hosts to another conclusively support the paratenic capabilities of this larval stage. Because the taxonomic position and productivity of parasitic worms is so closely associated with their morphol ogy, an interest in the anatomy of the Mesocestoididae could hardly be avoided. Morphologically, the family is an ex ception to the general pattern of cyclophyllideans. Obser vations of Byrd and Ward (1943) on the segmental anatomy of a gravid mesocestoidid from an opossum have been corroborated during the course of this study but have not been incorporated in it. However, the parauterine (= paruterine) organ, be cause of its especial role as a taxonomic criterion and its function as a possible mechanism of egg dispersal and/or protection, has been carefully studied in detail. Ultra- structural and histochemical observations of the mesoces toidid parauterine organ are reported in Part II of this dissertation. The dual nature of this investigation has necessitated a physical dichotomy of the work: Part I is comprised of systematic problems and their possible solutions; Part II, of morphology and histochemistry of th^i parauterine organ. 4 PART I. SYSTEMATIC CONSIDERATIONS 5 MATERIALS AND METHODS Post-tetrathyrldial stages of Mesocestoldes used in this study, were obtained from both naturally and experimentally infected hosts. Wild hosts were taken by shooting and trap ping or as road kills. In many cases during the trapping season, only viscera of host animals were examined and data from these animals are hence incomplete. Experimental hosts were taken either as nursing young and were reared to infec tive age, or were obtained at an already infective age from the Iowa State Conservation Commission at Boone, Iowa. In fective age is used in this study to mean the age at which hosts could take solid food, since no experimental work was done to determine at what chronological age infectivity could occur. All hosts received from the Iowa Conservation Commis sion had been held in captivity for a minimum of 33 days, during which time they were fed on commercially prepared food. During the course of this investigation, animals in the laboratory were fed Purina Dog Chow unless an otherwise specified diet v/as required. Preceding all experimental exposures to parasites, animals were quarantined for several days during which time they were wormed and their faeces periodically checked for proglottids. Animals to be infected were fed tetrathyridia obtained from frogs (Rana pipiens Schreber) and/or toads (Bufo americanus Holbrook and B. cognatus Say). Progs harboring tetrathyridia were caught 5 wild in northwestern Iowa or came from E. G. Steinhilber & Company, Inc. in Oskosh, Wisconsin but, according to Mr. Steinhidber,* were not necessarily collected in Wisconsin. Toads were collected from central and northwestern Iowa (B. amerlcanus) and southeastern South Dakota (B. cognatus). Larvae obtained from the body cavities of the amphibian hosts were transferred to mice of moderately inbred Marker stock, maintained by the Iowa State University Genetics Department. The technique of Specht and Voge (1965) was followed but modified by omission of antibiotics. A few & laboratory-reared Peromyscus, Rattus and Cltellus as well as frogs (R. pipiens), toads (B. amerlcanus) and salamanders (Ambystoma tigrinum Green) were also Injected. Following injection, tetrathyridla were successfully maintained in mice for several months. Tetrathyridla obtained from natu rally Infected amphibian hosts or experimentally Infected transfer hosts were fed to a variety of animals including amphibians, birds, and several species of mammals. These are listed specifically in the text under experimental feedings. In addition to the vertebrate hosts, numerous inverte brate hosts, some taken from the wild and some laboratory reared, were fed whole proglottiJs, parauterine organs *Steinhilber, E. G. Steinhilber