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United States Department of Agriculture

Agricultural Research Service

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2010 Annual Report

1a. Objectives (from AD-416)
1) Discover, refine, and implement improved microscopic, molecular, and software tools to modernize classification and improve predictive features for plant-parasitic and other agriculturally important nematodes; and 2) Discover new nematode species, new host associations, and new geographic occurrences among the many nematodes sent to the Nematology Laboratory for identification by various customers.

1b. Approach (from AD-416)
1) Adapt and test recently discovered and potentially promising light and scanning electron microscopic methods to determine if visualization of diagnostically important critical features can be improved in resolution and consistency. Characterize new agriculturally important nematodes with expanded or novel morphological and molecular diagnostic characters for the development of improved diagnostic keys and phylogenetic trees. Identify and prioritize, using phylogenetic methods, potential molecular control targets based on physiologically important peptides within diverse nematodes having analogous phenotypes; and 2) Characterize unknown or important nematodes by morphology, molecular biology and host range; and continue to computerize and curate the USDA Nematode Collection.

3. Progress Report
New nematode identification methods and phylogenies. The identification of new species of nematodes and the development of new methods to rapidly and accurately identify plant-parasitic nematodes are urgently needed by researchers, regulators, diagnosticians and growers to deliver the safest, most effective possible plant disease controls. To this end ARS researchers are describing new species of root-knot, cyst, lesion and insect-associated nematodes. Progress on locating new geographic locations for known species of cyst nematodes and related genera has been made because of intense interest in potato cyst nematode in the western U.S. An isolate of a nematode previously known only from soil was found within a regulated insect, the emerald ash borer. Nematode DNA sequences from standard and newly introduced molecular markers are being generated for use in building family trees, and DNA sequences from new genes are being evaluated for possible use in family trees. These methods and tools will be used by diagnosticians and extension personnel throughout the world to accurately diagnose and select appropriate controls for a wide variety of crops. Building the USDA Nematode Collection. The researchers and extension personnel that identify nematodes need a source of nematode reference specimens to assure that identifications are accurate. The USDA Nematode Collection at Beltsville, Maryland, is the most important repository of nematode reference specimens in the world. Curatorial services and maintenance are constantly needed to improve the quality and breadth of the Collection. Therefore, scientists at the Nematology Laboratory in Beltsville added 385 slides and vials from worldwide sources to create a total collection of 43,711 slides and vials, loaned 54 slides and vials containing valuable nematode specimens to scientists around the world to enable them to perform accurate nematode identifications, and entered 1,350 records of specimens into the computerized database, bringing it to a total of 37,841 records. Nematologists throughout the world are using the specimens and related information in the Collection as essential aids in nematode identification and research.

4. Accomplishments
1. New cyst nematode species discovered in corn fields. New, comprehensive information to rapidly and accurately identify plant-parasitic nematodes is urgently needed by researchers, diagnosticians and growers to deliver the safest, most effective possible plant disease controls. To this end, ARS researchers at Beltsville, Maryland and Jackson, Tennessee in collaboration with scientists at the University of Tennessee, University of Nebraska, and University of Missouri, described a new cyst nematode reproducing on corn and goosegrass. The team also discovered the anatomic features diagnostic for this species, and described the relationships of the new species with other cyst nematode species. The results are significant because they provide valuable details that allow this species to be more readily extracted from soil and distinguished from other cyst nematodes that commonly are found in corn cropping systems, such as the soybean cyst nematode. This research will be of great use to growers, nematode diagnosticians and crop advisers seeking to minimize nematode-inflicted losses to corn and other crops.

Review Publications
Hunt, D.J., Handoo, Z.A. 2009. Taxonomy, identification and principal species. In: Perry, R.N., Moens, M. and Starr, J., editors. Root-knot Nematodes. Wallingford, Oxfordshire, UK: CABI. p.55-97.

Handoo, Z.A., Iqbal E.Y., Kazi, N., Shahina, F. 2010. Two new species of Paurodontella Husain and Khan, 1968 (Nematoda: Sphaerulariidae) associated with wheat and a diagnostic compendium to the genus. Nematology. 12(2):181-192.

Mennan, S., Handoo, Z.A., Ecevit, O. 2009. Distribution and infestation rate of cyst nematodes (Tylenchida: Heteroderidae) in cabbage growing areas in Samsun. Turkish Journal of Entomology. 33(4):289-303.

Handoo, Z.A., Skantar, A.M., Mulrooney, R. 2010. First report of the sting nematode Belonolaimus longicaudatus on soybean in Delaware. Plant Disease. 94(1):133.

Carta, L.K., Handoo, Z.A., Hoberg, E.P., Erbe, E.F., Wergin, W.P. 2009. Evaluation of some vulval appendages in nematode taxonomy. Comparative Parasitology. 76(2):191-209.

Last Modified: 2/23/2016
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