Location: Animal Parasitic Diseases Laboratory2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Determine parasite distribution based on climate change based on the geographic information systems, comprehensive data, and specimens contained in the U.S. National Parasite Collection. Sub-Objective 1.1: Determine and summarize contemporary parasite distribution based on comprehensive georeferenced data and specimens contained in the U.S. National Parasite Collection and resources in the literature. Sub-Objective 1.2: Apply GIS-based methods to develop baselines for parasite distribution linked to point occurrence data for helminths in domestic and free-ranging ruminants. Sub-Objective 1.3: Use protocols from Species Distribution Models (SDMs) to explore outcomes of climate change for distributions of complex host-parasite assemblages, emphasizing ruminants. Objective 2: Determine the helminth faunal diversity among domestic and free ranging ungulates and other vertebrates to understand and predict responses to environmental changes at the host-parasite interface in managed and natural environments. Sub Objective 2.1: Develop synoptic and annotated checklists. Sub-Objective 2.2: Develop synoptic keys for identification of ruminant parasites including digital imaging for parasite species occurring in North America. Sub-Objective 2.3: Summarize current knowledge for biodiversity of ruminant helminth systems (species occurrences, distribution, phylogeny and historical processes).
1b. Approach (from AD-416):
The USNPC will initiate a long-term transition from a specimens-based repository to an integrated facility for biodiversity informatics. Emphasis will be on development/validation of the collections database (www.anri.barc.usda.gov) with a focus on records for parasites from ruminants. Digitized databases provide immediate accessibility for detailed biodiversity information to both ARS and a broader global research community on parasites that threaten animal health, food security, and food safety. Evolution of the USNPC will require new methods and approaches driving a transformation to a primary informatics facility. - Develop model archives (museum records and specimen-based collections) linking comprehensive and annotated lists for host-parasite-pathogen systems and spatial information linked to GIS to explore biotic and abiotic determinants of selected host-parasite systems. Archival information and resources are then integrated with historical information contributing directly to completion of Objective 2. - Build collections through continued strategic survey and inventory (geographically extensive and site intensive sampling) to support integrated morphological and molecular research. - Frozen tissue collections for molecular-based research with definitively identified and validated voucher specimens. - Specimen collections, with definitively identified and validated voucher specimens, linked directly to frozen tissues. - Build collections through continued deposition of types and vouchers from a dispersed and global research community. - Curate holdings of orphaned collections/accession in USNPC. The primary focus will be on continued development and expansion of the Collection and the array of services available to the research community. The United States National Parasite Collection will remain the primary repository for North America and much of the global community.
3. Progress Report:
Biodiversity data (host and geographic distribution) for parasites of ruminants derived from the U.S. National Parasite Collection (USNPC) continue to be summarized and processed in a spreadsheet format in preparation of mapping analyses linked to geographic information systems (GIS). Emphasis was placed on summarizing records for gastrointestinal nematodes in domestic (cattle, sheep) and free-ranging (deer, elk, caribou, muskoxen, wild sheep) ungulates, and in developing fully geo-referenced data (with geographic coordinates) from the USNPC database and the available literature. Spreadsheets are being augmented by assessment of validated records in the peer-reviewed literature in order to provide a clear picture of distribution for these nematode parasites (a similar summary has not been completed since 1964). A key focus is on the large stomach worms in the genus Haemonchus which remain of particular significance as pathogens in ruminants, and which populations have been shown to be resistant to many of the commonly used anti-parasitic drugs. As an extension of this databasing, we continue to examine populations of Haemonchus in the southwestern U.S. based on morphology and molecular data, revealing mixed species infections (in cattle and pronghorn) and potential hybrids of two species (H. placei and H. contortus) circulating at some geographic localities. These results in progress have considerable implications for evaluating the current methods used for identification of different species in this genus, and in understanding how genes for drug resistance may be circulated among parasites in domestic and free-ranging hosts. Additional research was conducted on the species diversity of filarial nematode parasites in ungulates, which are transmitted by biting fly vectors. Geographic distribution of genera and species of filarial nematodes remains poorly defined, yet these parasites may be particularly sensitive to perturbations linked to accelerating climate warming in North America. We further explored the species diversity within Varestrongylus, a group of pulmonary parasites of ungulates across Eurasia and North America. Studies led to the characterization of a new species in North America and resurrection of a species in Eurasian moose, allowing further refinement of our understanding of the role of historical climate change as a driver of geographic expansion and colonization. Theoretical insights about the nature of geographic and host colonization were explored in the context of understanding patterns of emerging infectious diseases linked to ecological change in evolutionary and ecological time. Activities of the USNPC involved continuing acquisition of specimens (approximately 1,000 new lots) from North America and globally; loans to the national and international community involved about 600 lots. In a number of cases, detailed photomicrographs were provided to researchers in lieu of international loans of irreplaceable type specimens. The USNPC continues as one of the largest single repositories for parasitological specimens globally, and remains a vital foundation for research by both national and international scientists.
1. Resolution of global species diversity in the genus Varestrongylus, a group of lungworms characteristic of ungulates at temperate to high latitudes of the Northern Hemipshere. ARS researchers and Canadian collaborators evaluated the global fauna for the 7-8 species of Varestrongylus in ruminants, including a description of a new species from North America and resolved the status for all named species in the genus. A robust understanding of diversity, host association and geographic range in this group of parasites serves as a foundation for defining shifts in faunal structure in response to climate change and environmental perturbation.
2. Definition of historical factors that determine the diversity, assembly and structure of parasite faunas. ARS researchers, in collaboration with academic scientists, completed a synthesis of biological, climatological and physical data to reveal the primary factors involved historically (over the past 3 million years) in determining the structure and diversity of parasite faunas in mammals linking Eurasia and North America. Over this time period, climate and geographic invasion emerge as primary factors that have been important in the evolution and distribution of complex host-parasite systems. Insights about geographic expansion and switching by parasites among hosts provide a comparative foundation to understand and predict the potential impacts of contemporary accelerated climate change on patterns of parasite distribution and emerging disease in free-ranging and domestic animals.
Hoberg, E.P., Brooks, D. 2013. Episodic processes, invasion and faunal mosaics in evolutionary and ecological time. In: Rohde, K., editor. The Balance of Nature and Human Impact. Cambridge, UK: Cambridge University Press. p. 199-214.