Term of Award

Spring 1997

Degree Name

Master of Science

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

Oscar J. Pung

Committee Member 1

Ann E. Pratt

Committee Member 2

C. Ray Chandler

Abstract

Intestinal helminths occupy specific sites within the digestive tract of the host. The helminth fauna of the Virginia opossum (Didelphis virginiana) was examined for site specificity within the digestive tract by live-trapping 30 opossums from an inland location (Bulloch Co.) and a coastal location (Mclntosh Co.) in southeast Georgia. Opossums were euthanized and their digestive tracts removed and divided into the following sections; esophagus, stomach, small intestine (20 equal sections), cecum, and large intestine (five equal sections). The helminths present in each section were identified and counted. Four trematode, one cestode, two acanthalocephala, and six nematode species were found. Two parasites (Centrorynchus sp. and Viannaia bamata) were new state records for Georgia. Only the helminths occurring in the small intestine (Brachylaima virginiana, Viannaia hamata, Didelphodiplostomum variabiie, Rhopaiias macracanthus, Mesocestoides variabilis, Oligacanthorhynchus tortuosa, and Longistriata didelphis) were examined for site specificity and interspecific relationships. The location of each helminth species in the small intestine was unaffected by the sex of the host or trapping site (Student's t-test, P>0.05). There was a significant difference (ANOVA, P<0.05) between the average median locations for the majority of species. The median location of two parasite species (D. variabiie and V. hamata) was influenced by the presence or absence of other parasite species (ANOVA, P<0.05). This suggests that interaction between certain species occurred. Also, the intensity (numbers of) R. macracanthus increased when present in intestinal sections with D. variabile. These species may have been competing for attachment or feeding sites. Finally, the intensity of L. didelphis was positively correlated with the intensity of V. hamata. This may have occurred because the intermediate hosts for the parasites were in equal abundance within the environment of the opossum.

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