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Thesis (Ph. D.)--University of Michigan, 1940. / Caption title. Thesis note on slip mounted on p. 171. "Contribution from the Department of Zoology, University of Michigan." "Reprinted from Transactions of the American Microscopical Society, vol. LX, no. 2, April, 1941." Bibliography: p. 208-210.

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2009. / Submitted in partial fulfillment of the requirements of the degree Master of Science in Natural Resources (Wildlife), College of Natural Resources. Includes bibliographical references (leaves 167-174).

Apophallus donicus is examined, its life cycle is described, and certain additions are made to its biology. It is thought, but not proven, that eggs are eaten by the first.intermediate host, the local stream snail FluI menicola virens, and the miracidia escape internally. Mother and daughter rediae stages result, the later producing cercariae which are shed into the water. After burrowing just beneath the skin in suckers (Catostomus macrocheilus Girard), rainbow trout (Salmo 9airdneri Richardson), coho salmon (Oncorhynchus kisutch (Walbaum) squawfish (Ptychocheilus oregonensis Richardson), blackside dace (Rhinichthys osculus nubilus (Girard), redside shiners (Richardsonius balteatus balteatus (Richardson),and possibly other fish, the cercariae encyst and the resulting metacercariae cause black-spot disease in the host. Natural definitive hosts were not found, but laboratory infections included gerbils, white rats, golden hamsters, chickens, catfish (Ictalurus punctatus (Rafinesque), cats, and the author. A rainbow trout was found which had 33 immature Apophallus in its small intestine. All were alive and active, but their entire posterior ends, including all the sex organs, were degenerate and poorly formed compared to the anterior halves of their bodies, and there was no evidence that adults with eggs would have resulted. This trematode is very hardy and adaptable in all stages of its life cycle, e.g., cercariae lived and were active up until eight days after being shed, metacercariae remained infective in fish which had been dead and out of water for 60 hours, and adults lived in tap water at room temperature for 72 hours.

The present paper deals with the digenetic trematodes collected by the author from fishes of Tomales Bay (including Dillon Beach) during the summers of 1967 and 1968. Also included in this study are several trematodes collected by the late Alden E. Noble (hereinafter referred to as the “Noble Collection”) at Hopkins Marine Station, Monterey Bay in 1936 and 1937. Unfortunately the majority of the slides in the “Noble Collection” have been lost with the exception of specimens of the Family Meniuridae and a few representatives of other digenea that were in the personal collection of Dr. F.M. Nahhas. A few vials containing unprocessed material were also still available but their contents were in poor condition as evidenced by the stained material prepared from them. The records for the “Noble Collection” were intact and various notations were included in the descriptions of these species. These records show an original collection consisting of 170 individuals representing 69 species of fishes. Twenty species represented by 27 fishes were negative for digenetic trematodes, and of the remaining 49, slides of trematodes were found that were obtained from but 25 species. The Tomales Bay material consisted of 495 individual fishes representing 33 species. Of these, 11 species represented by 35 individuals were negative for digenea. Four species of fish that barbored trematodes were common to both localities.

Trematodes belonging to the blood-inhabiting group have long attracted the attention of parasitologists and medical men, especially those trematodos belonging to the family Schistosomidae because throw widely distributed species, Schistosoma Japonicum, S. haematobium, and S. mansoni, are parasitic in man, and in endemic regions are the cause of important human diseases. These schistosomes, with a few exception, have undergone more detailed research than any other trematodes. Since the discovery of the first digenetic trematode exhibiting sexual dimorphism by Rudolphi (1819), which was named Distoma canaliculatum, and the descriptions of the other blood flukes up until the present time, a vast amount of material has been put forth in publications having a more or less limited circulation. The writer has, therefore, attempted to assemble descriptions of all the genera and species, hoping that this will be an aid in the identification of these trematodes. Unfortunately many of the descriptions are inadequate as they are based in many instances upon a limited number of specimens. In compiling these data the writer was struck by the possibility of further using them to investigate the genetic and evolutionary relationships of the blood-inhabiting trematodes. Looss (1899) noticed a similarity in the structure, the dermo-muscular sac of the suckers, and in the details of the digestive tract in those blood flukes that had been found. He concluded that their adaptations to existence were similar, as both had a constant environment and a common food supply. Odhner, (1912) through a long study, concluded that the blood flukes were genetically related. The discovery of the life cycles of Sanguinicola and Schistosoma japonicum added further evidence in support of this hypothesis.

Most, if not all, animals will at some stage in their lives encounter parasites. Some of the most widespread and abundant parasites belong to the Class Trematoda. Trematodes often have a substantial negative impact on individual intermediate host ecology. In this thesis, I investigate ecological and evolutionary consequences of the interaction between the microphallid trematode, Maritrema novaezealandensis, and its intermediate snail and crustacean hosts. Parasites often show a heterogeneous spatial distribution pattern in natural animal host populations. In this study, factors determining the spatial distribution of larval trematodes in Zeacumantus subcarinatus were investigated at two spatial scales (within and among bays). The distribution of shorebird definitive hosts explained a significant amount of the variation in the distribution of trematodes among bays. However, within a bay, other factors override the effect of bird distribution. The influence of larval trematodes on reproduction, survival and population density of Z. subcarinatus was investigated using laboratory and field studies. In the laboratory, it was found that larval trematodes induce castration and mortality of Z. subcarinatus. The field study revealed that the local prevalence of trematodes had a significant negative effect on population density of Z. subcarinatus. Through castration, trematodes act as strong selective agents on snail host life history. The effect of trematodes on life history characteristics (reproductive effort, juvenile growth, size at maturity and susceptibility to trematode infections) were investigated among natural populations of Z subcarinatus. Reproductive effort was not higher for uninfected females from populations where the risk of becoming infected was high. However, offspring from those populations were significantly larger, and laboratory-reared juveniles grew significantly faster than conspecifics from other populations. In addition, size at maturity was negatively correlated with trematode prevalence across snail populations. Z. subcarinatus thus adapts to a high local risk of trematode infection by reaching maturity early, thereby increasing the chance of reproducing. The influence of M. novaezealandensis on the survial of the amphipod host, Paracalliope novizealandiae was examined using experimental infections and field observations. The experimental infections demonstrated that parasite-induced mortality was intensity-dependent. The number of M. novaezealandensis per amphipod was too low to significantly induce host mortality in the field. However, the transmission strategy of this parasite allows it to affect host populations during weather conditions ideal for trematode transmission. Trematode strategies in the second intermediate host are important to the understanding of host-parasite co-evolution and the evolution of parasite life cycles. In this study, potential density-dependent effects at the metacercarial stage on size and fecundity of in vitro adult M. novaezealandensis was examined in both experimentally infected P. novizealandiae and naturally infected Macrophthalmus hirtipes. For this purpose, a method to excyst and cultivate M. novaezealandensis metacercariae to an egg producing stage, was developed. Naturally infected M. hirtipes also harboured larval stages of three other helminths. Crowding effects in the two crustacean hosts were expressed as a decreased volume and smaller egg production of in vitro adult M. novaezealandensis. In addition, interspecific interactions among parasite species were observed in crab hosts. The work in this thesis provides evidence that M. novaezealandensis significantly and negatively affect intermediate host ecology. The heterogeneous distribution of trematodes causes differential effects among host populations with subsequent effects on the life history of snail hosts. In addition, this study demonstrates that parasites interact within their second intermediate host with possible implications for the way parasites exploit their hosts.

Determining the extent to which parasites influence natural populaions of hosts is a major focus of studies in parasitology. Addressing this issue requires host-parasite systems that can be monitored under natural conditions and can be manipulated in the laboratory. I study a model system involving the larval trematode Ornithodiplostomum ptychocheilus that encysts in the brains of its intermediate host, the fathead minnow (Pimephales promelas). This parasite was the most common and abundant of 13 other parasites found in minnows in four boreal lakes in Alberta, Canada. In two of these lakes, prevalence of infection reached 100% in most years and mean intensity ranged from 4 to 40 parasites/host. Field and laboratory experiments showed that the size, the rate of parasite development, and time to encystment were intensity-dependent. However, parasite intensity had no effect on host or parasite survival after a simulated winter in the laboratory. One effect of infection was that infected fish and significantly greater cranial heights and widths than controls. The expression of this parasite-induced alteration in host phenotype was dependent on the size of the fish at infection and on parasite intensity. The cranial distortion led to significantly higher mortality of fish maintained on poor diets and altered the host's phototactic response. / ix, 131 leaves : ill. (some col.), map ; 29 cm.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 115-119).