Thomas Powers

  • PH.D., University of California - Riverside, 1983

Dr. Powers is interested in the evolutionary biology of nematodes. His research interests include the development of molecular diagnostics for plant parasitic nematodes, nematodes as invasive species, and nematode biogeography. NSF funded research projects have involved determining nematode diversity in remnant prairies of the Great Plains, humid lowland tropical rainforests, and agricultural fields in Nebraska.

Recent Research:

Several Pratylenchus species have been obtained from corn and are currently being tested for reproductive capabilities on various cover crops in Nebraska, including cereal rye. Preliminary results from two Pratylenchus lineages are shown below, where higher numbers equate to increased reproduction on that cover crop.

Pratylenchus from corn on cereal rye


  1. Powers, T.O. ,Baldwin, J. G.; and Bell, A. H. 1983. Taxonomic Limits of the Genus Nagelus (Thorne and Malek, ]968) Siddiqi,1979 with a Description of Nagelus borealis n.sp. from Alaska. Journal of Nematology. 15. 582-93.
  2. Powers, T.O., Platzer, E.G. & Hyman, B.C. 1986. Large mitochondrial genome and mitochondrial DNA size polymorphism in the mosquito parasite, Romanomermis culicivorax Current Genetics 11:71–77.
  3. Powers, T.O., Platzer, E.G., and B. C. Hyman. 1986. Species-Specific Restriction Site Polymorphism in Root-knot Nematode Mitochondrial DNA. J Nematol. 1986 Jul; 18(3): 288–293.
  4. Radice, A. D., Powers, T. O., Sandall, L. J., & Riggs, R. D. 1988. Comparisons of Mitochondrial DNA from the Sibling Species Heterodera glycines and H. schachtii. Journal of Nematology, 20: 443–450.
  5. Powers, T. O., & Sandall, L. J. (1988). Estimation of Genetic Divergence in Meloidogyne Mitochondrial DNA. Journal of Nematology, 20(4), 505–511.
  6. Besal, E. A., Powers, T. O., Radice, A. D., and Sandall, L. J. 1988. A DNA hybridization probe for detection of soybean cyst nematode. Phytopathology 78: 1136-1139.
  7. Powers, T.O., Sandall, L. J., and Wysong, D. S. 1989. Distribution of Soybean Cyst Nematode in Nebraska. Journal of Nematology  21:(4S)612-614.
  8. Harris, T. S., Sandall, L. J., & Powers, T. O. 1990. Identification of Single Meloidogyne Juveniles by Polymerase Chain Reaction Amplification of Mitochondrial DNA. Journal of Nematology, 22(4), 518–524.
  9.  Hyman B.C., Powers. T.O. 1991. Integration of molecular data with systematics of plant parasitic nematodes. Annual Review Phytopathology.29:89-107.
  10. Powers, T.O. and T.S. Harris. 1993.  A polymerase chain reaction method for identification of five major Meloidogyne species.  J. Nematol. 25:1-6.
  11. Powers, T.O., T.S. Harris, and B.C. Hyman. 1993.  Mitochondrial DNA sequence divergence among Meloidogyne incognita,  Romanomermis culicivorax, Ascaris suum, and Caenorhabditis elegans.  J.  Nematology 25:563-571.
  12. Joyce, S.A., A.M. Burnell, and T.O.Powers. 1994.  Characterization of Heterorhabditis isolates       by PCR amplification of segments of mtDNA and RDNA genes.  J. Nematology 26:260-270.
  13. Powers, T.O. and B.J. Adams. 1994.  Nucleotide sequences in nematode systematics.  In: Advances in Molecular Plant Nematology pp. 99-108 ads.  F. Lamberti et al., Plenum Press, New York (book chapter)
  14. Tomaszewski, E.K., M.A.M. Khalil, A.A. El-Deeb, T.O.Powers, and J.L.Starr. 1994. Meloidogyne javanica on peanut. Journal of Nematology 26:436-441.
  15. Powers, T.O. 1996. Molecular diagnostics of plant and insect nematodes. (in)Diagnostics in Crop Production, BCPC Symposium Proceedings NO. 65. Pp 121-126. (review)
  16. Szalanski, A.L. and T.O. Powers. 1996. Molecular diagnostics of three Diabrotica (Coleoptera: Chrysomelidae) pest species. J. Kans. Entomol. Soc. 69:260-266.
  17. Erney, S.J., K.P. Pruess, S. D. Danielson, and T. O. Powers. 1996. Molecular differentiation of alfalfa weevil strains (Coleoptera: Curculionidae). Ann. Entomol. Soc. Amer. 89: 804-811.
  18. Szalanski, A.L., D.D. Sui, T. S. Harris, and T.O. Powers. 1997. Identification of cyst nematodes of agronomic and regulatory concern by PCR-RFLP of ITS1. Journal of Nematology 29: 253-264.
  19. Cherry, T., A. L. Szalanski, T. C. Todd, and T. O. Powers. 1997. The internal transcribed spacer region of Belonolaimus (Nemata: Belonolaimidae). Journal of Nematology 29: 23-29.
  20.  Powers, T.O., T. C. Todd, A. M. Burnell, P.C.B. Murray, C.C. Fleming, A. L. Szalanski, B. J. Adams, and T. S. Harris. 1997. The internal transcribed spacer region as a taxonomic marker for nematodes. Journal of Nematology 29:(4) 441-450.
  21. Zhu, X., K.P. Pruess, and T.O.Powers. 1998. Mitochondrial DNA polymorphism in a black fly, Simulium vittatum (Diptera: Simuliidae). Canadian Journal of Zoology.  76:440 – 447.
  22. Adams, B.J., A.M.Burnell, and T.O.Powers. 1998. A phylogenetic analysis of the genus Heterorhabditis (Nemata: Rhabditidae) based on internal transcribed spacer 1 DNA sequence data. Journal of Nematology 30: 22-39.
  23. Koch, D.A., G.A.Duncan, T.J.Parsons, K.P. Pruess, and T.O.Powers. 1998. Effects of preservation methods, parasites and gut contents of black flies (Diptera: Simuliidae) on polymerase chain reaction products. Journal of Medical Entomology. 35:314-318.
  24. Powers, T.O. ,and C. C. Fleming. 1998. Biochemical and molecular characterization. Pp. 355-370. In The Physiology and Biochemistry of Free-Living and Plant–Parasitic Nematodes. (ed. R.N.Perry) CAB International. (book chapter).
  25. Fleming, C.C. and T.O.Powers. 1998. Potato cyst nematodes: species, pathotypes, and virulence concepts. Pp. 51-59. In Potato Cyst Nematodes. Biology, Distribution, and Control. (ed. R.J.Marks and B.B. Brodie) CAB International. (book chapter).
  26. Fleming, C.C., S.J.Turner, T.O.Powers, and A.L.Szalanski, 1998. Diagnostics of cyst nematodes: use of the polymerase chain reaction to determine species and estimate population levels. Aspects of applied biology. 52:375-382.
  27. Adams, B. J., A.M. Burnell, and T.O. Powers. 1998. Phylogenetic inference and taxonomic resolution among heterorhabdid species: limitations and delimitations. Pp. 75- 86. In Genetic and Molecular biology of Entomopathogenic nematodes. (ed. Abad et al.) European Commission COST 819 (book chapter)
  28. Powers, T.O. 1999. Biological invaders. (letter to Science) published October 29, 1999.
  29. Pruess, K. P., B. J. Adams, T. J. Parsons, X. Zhu, and T.O. Powers. 2000. Utility of the mitochondrial Cytochrome Oxidase II gene for resolving relationships among black flies(Diptera:Simuliidae). Molecular Phylogenetics and Evolution 16: (2) 286-295.
  30. Szalanski, A. L., K. Church, D. Oates, R. Bischof, and T. O. Powers. 2000. Mitochondrial DNA variation within and among wild turkey (Meleagris gallopavo) subspecies. Transactions of the Nebraska Academy of Sciences. 26: 47-53.
  31. Powers, T. O., Szalanski, A. L., Mullin, P. G., Harris, T. S., Bertozzi, T. and Griesbach, J. A. 2001. Identification of seed gall nematodes of agronomic and regulatory concern with PCR-RFLP of ITS1. Journal of Nematology. 33(4) 191-194.
  32. Szalanski, A.L., P. G. Mullin, T. S. Harris, and T. O. Powers. 2001. First report of Columbia Root Knot Nematode (Meloidogyne chitwoodi) in potato in Texas. Plant Disease 85:422.
  33. Powers, T. O. 2001. Seed Gall Nematodes. (in)  The Encyclopedia of Plant Pathology. John Wiley and Sons. 
  34. Powers, T. O. 2001. Earcockle. (in)  The Encyclopedia of Plant Pathology. John Wiley and Sons.
  35. Mullin, P.G., T.S. Harris, and T.O.Powers. 2003. Systematic status of Campydora (Nematoda: Camphydorina). Nematology 5(5) 699-711 .
  36. Neher, D.A. and Powers, T.O. 2004. Nematodes. In: Hillel, D., Rosenzweig, C., Powlson, D., Scow, K., Singer, M. and Sparks, D. (editors) Encyclopedia of Soils in the Environment, Academic Press, New York.
  37. 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.
  38. 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.
  39. Powers, T.O. 2004. Nematode molecular diagnostics: From bands to barcodes. Annual Review of Phytopatology. 42:367-385.
  40. 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.
  41. 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.
  42. 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.
  43.  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.
  44. 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.
  45. Brito JA, Kaur R, Cetintas R, Stanley JD, Mendes ML, McAvoy EJ, Powers TO, and Dickson DW. 2008. Identification and isozyme characterization of Meloidogyne spp. infecting horticultural and agronomic crops, and weed plants in Florida. Nematology 10:757-766.
  46. 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.
  47. 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 40:241-251.
  48. 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.
  49.  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.
  50. 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.
  51. Powers, T.O., Harris, T.S., Higgins, R.S., Sutton, L.A., and K. S. Powers. 2010. Morphological and molecular characterization of Discocriconemella inarata, an endemic nematode from North American native tallgrass prairies. Journal of Nematology 42:35-45.
  52. Bernard, E.C., Handoo, Z.A., Powers, T.O., Donald, P.A., and Heinz, R.D. 2010. Vittatidera zeaphila (Nematoda:Heteroderidae), a new genus and species of cyst nematode parasitic on corn (Zea mays). Journal of Nematology 42:139-150.
  53. Porazinska, D.L., Giblin-davis, R.M., Esquivel, A., Powers, T.O., Sung, W. and Thomas, W.K. 2010. Ecometagenetics confirms high tropical rainforest nematode diversity. Molecular Ecology 19: 5521-5530.
  54. Bliss, T., T. O. Powers, and C. E. Brassil. 2010. The spatial influence of aboveground diversity on belowground communities. Ecosphere 1(2/3):art7. doi:10.1890/ES10-00040.1.
  55. Brito, J. A., R. Kaur, R. Cetintas, J. D. Stanley, M. L. Mendes, T. O. Powers, and D. W. Dickson. 2010. Meloidogyne spp. infecting ornamental plants in Florida. Nematropica 40:87-103.
  56. Subbotin, S.A., Inserra, R. N., Marais, M., Mullin, P., Powers, T.O., Roberts, P.A., Van Den Berg, E., Yeates, G., and Baldwin, J.G. 2011. Diversity and phylogenetic relationships within the spiral nematodes of Helicotylenchus Steiner, 1945 (Tylenchida: Hoplolaimidae) as inferred from analysis of the D2-D3 expansion segments of 28S rRNA gene sequences. Nematology 13:333-345.
  57. Powers T., Harris T., Higgins R., Mullin P., Sutton L., Powers, K. 2011. MOTUs, morphology and biodiversity estimation: A case study using nematodes of the suborder Criconematina and a conserved 18S DNA barcode. Journal of Nematology 43:35-48.
  58. Porazinska D.L., Giblin-Davis R.M., Powers, T.O., Thomas W.K. 2012. Nematode spatial and ecological patterns from tropical and temperate rainforests. PLoS ONE 7(9):e44641. Doi:10.1371/journal.pone.0044641
  59. Ferris, H., Griffiths, B.S., Porazinska, D.L., Powers, T.O., Wang, K-H, Tenuta, M. 2012. Reflections on plant and soil nematode ecology: past present and future. Journal of Nematology 44:115-126.
  60. Powers, T.O. and Ramirez-Suarez, A. 2012. Molecular diagnostics of nematodes: some practical considerations. in Practical Plant Nematology. Eds Manzanilla-López and Marbán-Mendoza. Biblioteca Básica de Agricultura, Estado de México, México.
  61. Narain, R.B., Kamble, S.T., Powers, T.O., Harris, T.S. 2013. DNA barcode of thief ant complex (Hymenoptera:Formicidae) J. Entomol.Sci. 48(3):234-242.
  62. Conflitti, I.M., Pruess, K.P., Cywinska, A., Powers, T.O., Currie, D.C. 2013. DNA barcoding distinguishes pest species of the black fly genus Cnephia (Diptera:Simuliidae). Journal of Medical Entomology. 50(6):000-000.
  63. Ramirez-Suarez, A., Rosas-Hernandez, L., Alcasio-Rangel, S., Powers, T. O. 2014. First Report of the Root-Knot Nematode Meloidogyne enterolobii Parasitizing Watermelon from Veracruz, Mexico. Plant Disease 98:428.
  64. Giblin-Davis, R. M., Kanzaki, N., Davies, K. A., Ye, W., Zeng, Y., Center, B. J., Esquivel, A., Powers, T. O. 2014. Ficotylus laselvae n. sp. (Tylenchomorpha: Anguinidae) associated with Ficus colubrinae in Costa Rica. Nematology 16:1139-1151.
  65. Proença, D. N., Fonseca, L., Powers, T. O., Abrantes, I. M. O., Morais, P. V. 2014. Diversity of Bacteria Carried by Pinewood Nematode in USA and Phylogenetic Comparison with Isolates from Other Countries. PLoS ONE 9(e105190), 1-8.
  66. Powers, T. O., Bernard, E. C., Harris, T., Higgins, R., Olson, M., Lodema, M., Mullin, P., Sutton, L., Powers. K. S. 2014. COI haplotype groups in Mesocriconema (Nematoda: Criconematidae) and their morphospecies associations. Zootaxa 3827(2), 101-146.
  67. Powers, T. O., Bernard, E. C., Harris, T., Higgins, R., Olson, M., Olson, S., Lodema, M.,   Matczyszyn, J., Mullin, P., Sutton, L., Powers. K. S. 2016. Species discovery and diversity in Lobocriconema (Criconematidae: Nematoda) and related plant-parasitic nematodes from North American ecoregions. Zootaxa 4085 (3): 301–344.
  68. Powers, T.O., Mullin, P., Higgins, R., Harris, T. and Powers, K.S., 2016. Description of Mesocriconema ericaceum n. sp.(Nematoda: Criconematidae) and notes on other nematode species discovered in an ericaceous heath bald community in Great Smoky Mountains National Park, USA. Nematology, 18(8), pp.879-903. Accepted for publication: 31 May 2016
  69.  Yu, Q., Ye, W. & Powers, T. 2016. Morphological and Molecular Characterization of Gracilacus wuae n. sp. (Nematoda: Criconematoidea) Associated with Cow Parsnip (Heracleum maximum) in Ontario, Canada. Journal of Nematology 48(3), 203- 213. (Accepted for Publication 3 August 2016)
  70. Olson, M., Harris, T., Higgins, R., Mullin, P., Powers, K., Olson, S. and Powers, T.O., 2017. Species Delimitation and Description of Mesocriconema nebraskense n. sp.(Nematoda: Criconematidae), a Morphologically Cryptic, Parthenogenetic Species from North American Grasslands. Journal of nematology, 49(1) 42-68.
  71. Powers, T. O., Harris, T., Higgins, R., Mullin, P., and Powers, K. 2017. An 18S rDNA Perspective on the Classification of Criconematoidea. Journal of Nematology 49(3):236–244. 2017.