Reseach area
Current Projects
Suborder Criconematina
Crico barcode tree
Criconematina are a major group of plant-parasitic nematodes found in soils from the tropics to the arctic. Their high endemicity, poor dispersal capabilities, and apparent lack of specialized survival stages make them an excellent subject for biogeographic analysis. They are potential indicators for soil disturbance
An ongoing set of studies attempting to clarify the species boundaries in the Suborder Criconematina
Discus / Rustica

Bakernema / Xenocriconemella

Possible nematode indicators of ancient environments
Discocriconemella inaratus-
an endemic Criconematid nematode of native tallgrass prairies

The 18 recorded species of Criconematidae associated with remnant prairies and woodlands in Iowa often have overlapping distributions and indistinct species boundaries. This study considers the taxonomic status and species boundaries of D. inaratus based on morphological and molecular characters.

Costa Rica diversity project

More information....

By including nematode communities above the mineral soil, our study of nematode diversity in tropical rainforests of Costa Rica demonstrates that a high level of nematode diversity exists in the humid tropics.

Connecting MOTU's with morphologically described taxa
Generating a molecular profile of an individual nematode (molecular operational taxonomic unit) is not difficult. Connecting that profile with a known living specimen is much more difficult
Molecular diagnostics
CAPS project-

Our laborotory is a designated nematode diagnostic labortory for the national Cooperative Agricultural Pest Survey program

Nacobbus project

This study attempts to clarify the taxonomic status and systematic relationships among North America isolates of the false root-knot nematode, Nacobbus aberrans.


Posters Select Images of Nematodes from Great Smoky Mountains National Park: Light and Scanning Electron Microscopy -March 2014  
  Nematodes of the George Washington Memorial Parkway -July 2013  
  Exploring Tallgrass Prairie Diversity in the Nematode Family Criconematidae -July 2013  
  The 2013 Nematode Species Count from Great Smoky Mountains National Park - March 2013  
-October 2009

Powers, Thomas; Harris, Timothy; Higgins, Rebecca; Sutton, Lisa; Powers, Kirsten. 2010.
Morphological and Molecular Characterization of Discocriconemella inarata, an Endemic Nematode from North American Native Tallgrass Prairies
Journal of Nematology

Blok,V.C. and T.O.Powers. 2009.
Biochemical and molecular identification.
In Root-knot Nematodes
, Eds Perry, Moens, and Starr. Publisher: CABI Publishing, UK.

Porazinska, Dorota; Giblin-Davis, Robin; Faller, Lina; Farmerie, William; Kanzaki, Natsumi; Morris, Krystalynne; Powers, Thomas; Sung, Way; Tucker, Abraham; Thomas, W Kelley. 2009.
Evaluating high-throughput sequencing as a method for metagenomic analysis of nematode diversity.
Molecular Ecology Resources 9(6) 1439-1450.
PDF file-format

Powers,T.O., Neher, D.A., Mullin, P., Esquivel, A., Giblin-Davis, R.M., Kanzaki, N., Stock, S.P., Mora, M.M., and L. Uribe-Lorio. 2009.
Tropical nematode diversity:Vertical stratification of nematode communities in a Costa Rican humid lowland rainforest
Molecular Ecology 18: 985-996.


Simard, L., Belair, G., Powers, T., Tremblay, N., and J. Dionne. 2008.
Incidence and population density of plant-parasitic nematodes on golf courses
in Ontario and Quebec
Canada. Journal of Nematology 40:000-000.


Mendoza , R.B., T.G. Franti, J.W. Doran, T. Powers and C.W. Zanner. 2008.
Tillage Effects on Soil Quality Indicators and Nematode Abundance in Loessial Soil Under Long-term No-till Production
Communications in Soil Science and Plant Analysis, 39:2169-2190.


Brito JA, Kaur R, Cetintas R, Stanley JD, Mendes ML, McAvoy EJ, Powers TO, and Dickson DW. 2008. Identification and isozyme characterisation of Meloidogyne spp. infecting horticultural and agronomic crops, and weed plants in Florida.
Nematology 10:757-766.


Esquivel, A., P. Guerrero., R. Pena-Santiago and T. Powers. 2007. Free-living dorylaimid nematodes from nature reserves in Costa Rica. The genus Pachydorylaimus Siddiqi, 1983. Nematropica 37:317-333

Abebe E, Baldwin JG, Adams B, Hope D, Gardner S, Huettel R, Mullin P, Powers TO, Sharma J, Ye W and Thomas WK. 2006.
A position paper on the electronic publication of nematode taxonomic manuscripts
Journal of Nematology 38:305-311.

Todd, T.C., T.O.Powers, and P.G.Mullin. 2006.
Sentinel nematodes of land-use change and restoration
Journal of Nematology 38:20-27.


Powers, T.O. P.G. Mullin, T.S. Harris,  L. A. Sutton,  and R.S. Higgins. 2005.
Incorporating molecular identification into a large-scale regional nematode survey
Journal of Nematology. 37:226-235.


Mullin, P.G., T.S. Harris, and T.O.Powers. 2005.
Phylogenetic relationships of Nygolimina and Dorylaimina (Nematoda: Dorylaimida) inferred using small subunit ribosomal DNA.
Nematology 7:59-79.


Powers, T.O. 2004. Nematode molecular diagnostics: From bands to barcodes.
Annual Review of  Phytopatology. 42:367-385


Duncan, G. A. , P.H. Adler, K.P. Pruess, and T.O.Powers. 2004.
Molecular differentiation of two sibling species of the black fly Simulium vittatum (Diptera: Simuliidae), based on randomly amplified polymorphic DNA
Genome 47(2) 373-380.


Brito,  J., T.O.Powers, P.G.Mullin, R.N. Inserra, and D. W. Dickson.  2004.
Morphological and molecular characterization of Meloidogyne mayaguensis isolates
from Florida
Journal of Nematology. 36: 232-240.

this page updated 12-2009