Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1975 Host parasite relationships and intraspecific variation in the strigeoid trematode Posthodiplostomum minimum (Trematoda: Diplostomatidae) James Robert Palmieri Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Zoology Commons Recommended Citation Palmieri, James Robert, "Host parasite relationships and intraspecific av riation in the strigeoid trematode Posthodiplostomum minimum (Trematoda: Diplostomatidae) " (1975). Retrospective Theses and Dissertations. 5392. https://lib.dr.iastate.edu/rtd/5392 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. 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Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. Xerox University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 48106 75-17,410 PAIMERI, James Robert, 1947- HOST PARASITE RELATIONSHIPS AND INTRASPECIFIC VARIATION IN THE STRIGEDID TREMATODE POSffiODIPLOSrCMUM MINIMUM (TRBIATODA: DIPLOSrCMATIDAE). Iowa State Ifciversity, Ph.D., 1975 Zoology- Xerox University Microfilms, Ann Arbor, Michigan 48106 0 1975 JAMES ROBERT PALMIERI ALL RIGHTS RESERVED THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. Host parasite relationships and intraspecific variation in the strigeoid trematode Posthodiplostomum minimum (Trematoda:Di piostomati dae) by James Robert Palmieri A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of The Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Zoology Major: Zoology (Parasitology) Approved: Signature was redacted for privacy. Signature was redacted for privacy. For the Major Department Signature was redacted for privacy. For the Gra te Collège Iowa State University Ames, Iowa 1975 Copyright©James Robert Palmieri, 1975. All rights reserved. ii TABLE OF CONTENTS Page INTRODUCTION 1 HISTORICAL REVIEW 3 Life Cycle Stages 3 MATERIALS AND METHODS 6 Intermediate Hosts 6 Definitive Hosts 8 Experimental Infections 11 Microscopy 12 SUMMARY OF LIFE CYCLE 15 ADDITIONAL LIFE CYCLE DATA 17 Natural Line of Infection 17 Experimental Line of Infection 22 Pathology 24 INTRASPECIFIC VARIATION 26 PHYSIOLOGICAL STRAINS OF POSTHODIPLOSTOMUM MINIMUM 31 RESULTS 33 Experimental Line of Infection 33 Observations 34 Body measurements 35 Oral sucker 36 Acetabulum 37 Holdfast or tribocytic organ 38 iii Page Ovary 39 Testes 40 Vitelline gland distribution 41 Egg 42 Tegumental modifications 43 Natural Line of Infection 44 DISCUSSION 49 SUMMARY AND CONCLUSIONS 55 LITERATURE CITED 58 ACKNOWLEDGMENTS 63 APPENDIX A. TABLES 65 APPENDIX B. PLATES 140 1 INTRODUCTION Posthodiplostomum minimum (MacCallum, 1921) is a strigeoid trematode of the family Diplostomatidae Poirier 1886. Adults of this species parasitize the intestine of piscivorous birds and the metacercarial stage is found in various freshwater fishes. The body of the adult consists of a distinct forebody and hindbody, the former containing a small round oral sucker, a weakly developed prepharynx, a strong muscular pharynx and a small acetabulum, posterior to which is a round tribocytic or holdfast organ. The hindbody contains two testes in tandem, the anterior being oval to elliptical and the posterior testis lobate to reniform. The ovary is located mediolaterally. Vitellaria occupy much of the hindbody and extend to various levels relative to the acetabulum. The uterus and ejaculatory duct join to form an hermaphroditic duct enclosed by a genital cone and surrounded by a prepuce. A copulatory bursa is present and the genital pore is terminal or slightly subterminal. Intrauterine eggs are generally few, rarely seen in excess of six. Two subspecies of £. minimum have been reported, based upon the ability of cercariae to penetrate and develop either in centrarchid or cyprinid fish hosts (Hoffman, 1958). Since Stunkard's report on intraspecific variation in 1957, several more recent experimental studies have shown that size, shape and position of various organs and structures in helminths may be considerably modified by the host. For many years, investigators such as Dubois (1944, 1955, 1968 and 1970) have delineated species of 2 strigeoids largely on the basis of host specificity. Recently, however, several investigators have shown that parasites can, indeed, develop within hosts that normally would be ecologically isolated from involve­ ment in normal life cycle of the parasite. The majority of the field work involved in this investigation was conducted during the spring and summers of 1971-1973 at the Iowa Lakeside Laboratory, West Lake Okoboji, Dickinson County, Iowa, where abundant naturally infected hosts were available. Most of the technical and experimental portions of this investigation were conducted at the Iowa State University of Science and Technology. Topics specifically investigated during this study include: (1) host-induced morphological variations of adult flukes, (2) a survey of naturally infected intermediate and definitive hosts, (3) ecological specificity and related considerations, (4) additional life cycle data, (5) comparative light and ultrastructural studies of organs of taxonomic importance and (6) extensive statistical analyses of morphological variations of adult P. minimum. 3 HISTORICAL REVIEW Early literature concerned with the taxonomy and development of minimum is confusing, principally because various cercariae and metacercariae have been associated with the adult stage. Two distinct subspecies or physiological strains, namely minimum minimum and 2- minimum centrarchi, are now recognized. A general historical review of cercarial, metacercarial and adult stages is presented below. Life Cycle Stages Throughout the literature, five cercarial types have been reported and described as belonging to Posthodiplostomum minimum: Cercaria multicellulata. H. Miller, 1923, 1925; C_. physaei, Cort and Brooks, 1928; £. 1oui si ana, C. Miller, 1954; C^. minimum, J. Miller, 1954; and C^. paramultieel 1ulata, Goodman, 1951. Because of the synonomy and inadequate descriptions of these cercarial types and because of reported differences in size, number and arrangement of their setae and spines, flame cell patterns, tail stem musculature and the presence or absence of caudal bodies, these reports must be viewed critically. Bedinger and Meade (1967) reported a sixth cercarial type (from Physa halei) said to be distinct from those reported above. Their study indicated that several physiological strains or subspecies of 2. minimum appear to exist. Because relationships of various cercariae and meta­ cercariae to the adult stage of £. minimum need further clarification, no subspecies designation was proposed for their specimen. 4 For additional history of cercarial types reported to be those of £. minimum and data concerning the problems of cercarial taxonomy, reference is made to papers by Ferguson (1943), Miller (1954) and Hoffman (1958). The neascus-type metacercaria of P^. minimum has been by far the most studied stage in its life cycle. It is this stage that is so often reported in fish-parasite surveys throughout the United States. Leidy (1856) reported Diplostomum cuti col a, the species presently known as Posthodiplostomum minimum, from the integument of fresh water fishes. Adult Diplostomum minimum (= P^. minimum) was