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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)


Biology and Microbiology

First Advisor

R. Neil Reese


Haemonchus contortus is a common, global, ruminant parasite. The major strategies for controlling this parasite involve the utilization of conventional anthelminthics. The appearance of anthelmintic resistance with the overuse of anthelmintics has created a greater need to look for the alternative source for anthelmintics. Therefore, this thesis focuses on evaluating medicinal plants from the USA Northern Great Plains for anthelmintic activity against H. contortus. Initially, 40 plant extracts were screened with an egg hatch assay, and the 8 plants with the highest activity in this assay were further screened with a larval migration assay. Ericameria nauseosa and Rhus aromatica exhibited the highest activity in both assays, and were, therefore, further evaluated in a larval development assay. For both plants, inhibition of egg hatching, development of first and second stage larvae, and migration of third stage larvae were all dose dependent at the concentrations tested. Phytochemical analysis indicated the presence of phenolics, flavonoids, essential oils, and hydrolysable tannins in both plants, however, condensed tannins were only detected in R. aromatica. Cytotoxicity of the methanolic extracts from both plants was examined using normal swine intestinal epithelial cells (IPEC-J2) with an alamarBlue assay and a BrdU assay. Both assays showed that the methanolic extracts from both plants were toxic to the IPECJ2 cells at high concentrations, with ED50 value 4.93 mg/ml for E. nauseosa and 9.63 mg/ml for R. aromatica in the alamarBlue assay, and 4.34 mg/ml for E. nauseosa and 5.17 mg/ml for R. aromatica in the BrdU assay. Because of availability, it was possible to evaluate the in vivo effect of R. aromatica on egg output in sheep naturally infected with H. contortus. Feeding R. aromatica leaves to sheep for 9 days did not cause any obvious health problems for sheeps used in the in vivo study, but it also did not cause a statistically significant decrease in Haemonchus egg output. The results from this study suggests the need for future studies on the in vivo activity of E. nauseosa, and also additional studies to further identify the compounds present in E. nauseosa and R. aromatica that possess nematocidal activity.

Library of Congress Subject Headings

Endemic plants -- Great Plains
Endemic plants -- Therapeutic use -- Great Plains
Haemonchus contortus
Medicinal plants -- Great Plains


Includes bibliographical references



Number of Pages



South Dakota State University


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