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United States Department of Agriculture

Agricultural Research Service

2011 Annual Report

1a.Objectives (from AD-416)
Objective 1: Define higher-level genealogical relationships among strongylate nematodes through analyses of morphological and molecular data as a basis for identification of species and populations of trichostrongyloids and metastrongyloids. Objective 2: Define faunal diversity, exploring history, geography (biogeography), host associations (coevolution) and population genetics (phylogeography) for parasitic nematodes and other helminths in ungulates across North America, Eurasia and globally. Objective 3: Build specimen collections and informatics resources of the U.S. National Parasite Collection.

1b.Approach (from AD-416)
Generality of Phylogenetic Approaches: Comparative phylogenetics is inherently long-term, hierarchical and complex and resides at the core of all approaches outlined in this project (9). Research is largely empirical and hypothesis driven, involving articulation, integration and analyses of comparative morphological and molecular databases. The revolution of phylogenetic systematics has transformed systematic parasitiology and its linkage to animal health, medicine and biodiversity research. Development of phylogenetically informative databases is cumulative, typically involving extensive and detailed description and revision as a first-level process to provide a comparable array of structural, meristic and other characters, and phylogenetically informative sequences from nuclear and mitochondrial loci, across both higher-level and species-level taxa. Hierarchical approaches- e.g., sequential top-down research programs, have proven to be particularly effective beginning with resolution of relationships for higher taxa that form the foundations for eventual elucidation of species-level phylogeny. Robust phylogenies for parasitic groups (the focus of Objective.
1)provide the basis for analyses of cospeciation, historical biogeography and phylogeography (the focus of Objective.
2)applied to elucidating patterns of host-parasite association, geographic distribution and disease.

Phylogenetic studies will address crown clades of nematodes among Strongylida represented by the superfamilies Metastrongyloidea, and Trichostrongyloidea. Investigations will emphasize resolution of relationships at levels extending from putative monophyletic taxa within each major taxon to the level of species and populations as outlined in detail in subsequent sections. Systematic analyses will follow established methodology as exemplified in recent studies.

Represented is an integrated program linking research (Objectives 1 &.
2)and the U.S. National Parasite Collection (Objective 3). Integration is defined by the following model: (Obj..
1)Specimens with definitive identifications based on morphology from field-based research, including vouchers and type materials, are linked to frozen tissue collections and DNA products as a basis for comprehensive taxonomic revision, description (diagnostic characters), and phylogenetic analyses of specific parasite groups; (Obj..
2)Results of phylogenetic analyses are used as a foundation for historical explorations of biogeography and coevolution and definition of faunal structure over time; and (Obj..
3)Primary specimens, host information, and spatial and temporal data are archived and databased in the USNPC, with results of analyses, diagnostic capacity, images, etc., being integrated in synoptic summaries for parasite and host associations. These archives further summarize the results of phylogenetic, phylogeographic and historical studies.

3.Progress Report
Research activities were focused on the biodiversity of complex parasite systems, the abiotic and biotic factors influencing geographic and host distribution, and the conceptual work addressing invasive species and invasion biology under accelerating climate change. Studies in ruminant nematodes systematics applied integrated approaches from comparative morphology and molecular analyses of nuclear and mitochondrial genes. Specimens of medium stomach worms (Marshallagia spp., and the putative species complex represented by Teladorsagia spp.) from diverse ruminant hosts and geographic sources were examined. (2) Morphological and molecular assessment of numerous populations of Haemonchus contortus and H. placei in cattle and free-ranging pronghorn from Texas revealed considerable mixed species infections, the occurrence of hybrids and problems with current criteria that are applied to identification of these species. These issues are confounded by the possibility of a previously unrecognized cryptic species of Hameonchus in North America. (3) Protostrongylid lungworms (Protostrongylus and Varestrongylus) and muscleworms (Parelaphostrongylus) in ruminants were evaluated and initial comparative phylogeographic studies were completed for Parelaphostrongylus odocoilei and P. andersoni among free-ranging ungulates. The first morphologically based phylogeny for species of Varestrongylus in the global fauna was developed. These studies led to the discovery of 2 new species of nematodes, and identified serious challenges to currently applied criteria used for identification of the pathogenic large stomach worms.

Collections activities for the U.S. National Parasite Collection (USNPC) focused on continuing acquisition of specimens and loans in the national and international community: approximately 1,500 new lots accessioned; 500 lots loaned; and 500 slides rehabilitated. Series of photomicrographs were provided to researchers in lieu of international loans of irreplaceable type specimens. The USNPC continues as one of the largest specimens-based collections in the world and as an active and vital cornerstone for parasitological research globally and nationally. Other activities included training and mentoring graduate students at the University New Mexico and the University of Calgary, Canada.

1. Discovery and characterization of a new species of Varestrongylus lungworm in North American ungulates. Integrated molecular and morphological studies revealed a previously unknown lungworm parasite in free-ranging ungulates from North America, contributing to a better understanding of species occurrence and host associations.

Review Publications
Hoberg, E.P. 2010. Invasive Processes, Mosaics and the Structure of Helminth Parasite Faunas. Office of International Epizootics Scientific and Technical Review. 29:255-272.

Ezenwa, V.O., Hines, A.M., Archie, E.A., Hoberg, E.P., Asmundsson, I.M., Hogg, J.T. 2010. Muellerius capillaris dominates the lungworm community of Bighorn Sheep at the National Bison Range, Montana. Journal of Wildlife Diseases. 46:988-993.

Durette-Desset, M.C., Galbreath, K.E., Hoberg, E.P. 2010. Discovery of new Ohbayashinema spp. (nematoda: heligomosomoidea) in Ochotona princeps and O. cansus (lagomorpha: ochotonidae) from western North America and central Asia, with considerations of historical biogeography. Journal of Parasitology. 96:569-579.

Weaver, H.J., Hawdon, J., Hoberg, E.P. 2010. Soil transmitted helminthiases: implications of climate change and human behaviour. Trends in Parasitology. 26:574-581.

Rossin, M.A., Timi, J.T., Hoberg, E.P. 2010. An endemic Taenia from South America: validation of T. Talicei Dollfus, 1960 (Cestoda: Taeniidae) with characterization of metacestodes and adults. Zootaxa. 2636:49-58.

Kuchboev, A., Hoberg, E.P. 2010. Morphological and Ultrastructural Changes in Tissues of Intermediate and Definitive Hosts Infected by Protostrongylid Lungworms (Nematoda: Metastrongyloidea). Turkish Journal of Zoology. 35:1-7.

Reinstein, S.L., Lucio-Forster, A., Bowman, D.D., Eberhard, M.L., Hoberg, E.P., Pot, S., Miller, P.E. 2010. Surgical extraction of intraocular Parelaphostrongylus tenuis (Nematoda: Metastrongyloidea) in a horse. Journal of the American Veterinary Medical Association. 237:196-199.

Last Modified: 7/24/2016
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