Progress 10/01/03 to 09/30/08
Outputs
OUTPUTS: The southern root-knot nematode, Meloidogyne incognita, is a major cause of plant disease on numerous horticultural and field crops causing an estimated global loss in the billions of dollars. Unfortunately it occurs as two cytological forms (A and B) with each form having 4 distinct host races. Because each host race reproduces on different hosts, this project includes a search for morphologic and morphometric characters that will enable a more precise identification of populations of southern root-knot nematode. Fourteen populations from both cytological host races and all four host races have been examined with the light and scanning electron microscope. The characters that are useful for identification of this species have been disseminated at the Multistate Project Annual Meeting, the Annual Meetings of the Society of Nematologists, and at the Potomac Division of the American Phytopathological Society. In addition, the suitable characters for species identification have been presented at grower meetings and county agents. Populations from Virginia, Texas, Indiana, Pennsylvania, Maryland, South Carolina, Brazil, and Iran have been identified for colleagues, consultants, county extension agents, and the Plant Disease Clinic at Virginia Tech. Finally, collaborations with several county agents have been initiated and fostered through ongoing surveys, field trials, and on-farm tests. PARTICIPANTS: Joao M. Charchar, Maria Jose Charchar and Maria Esther N.F. Boiteux, researchers at EMBRAPA/CNPH - BR 060 Km 09 Caixa Postal 0218, Brasilia, DF. 70359, Brazil and EMBRAPA/CPAC - BR 020 Km 18 Caixa Postal 08223, Planaltina, DF. 70301-970. Patrick Lummus, Agricultural Consultant, Devine, Texas. David Holshouser, Keith Balderson, David Moore, Pat Phipps, Katy Rainey, Charles Johnson, and Wade Thomason, County Agents and Extension Specialists, Virginia Tech. TARGET AUDIENCES: Nematologists, Extension Specialists, Plant Pathologists, Plant Breeders, Count Agents, Agricultural Consultants, Plant Disease Diagnosticians, and Growers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Characters that are useful for the identification of the southern root-knot nematode have been found that will enable nematologists to make quick and precise recognition of this species. These characters include shape of the female stylet, perineal pattern, shape of the male head and stylet, and shape and head of the second-stage juvenile head and stylet. Even though this species is composed of two different cytological forms and four host races they are morphologically identical. Therefore, identification to species is possible using morphological features alone; however, identification at the subspecific level is only possible by the use of a host range test. Additional taxonomic techniques including the examination of the banding patterns formed by the isozymes of esterases have confirmed the similarity of these fourteen populations. Molecular tools including the sequences of the ITS regions of the 18s mitochondrial DNA are currently needed to to find out if these markers can identify the host race. Thus far attempts to do so have failed. Development of a quick and easy procedure to identify the host races of this nematode will enhance the grower's ability to manage this important agricultural pest. Currently reducing the economic harm caused by this pest is limited to the application of agricultural chemicals and crop rotation. In order for rotations to be effective, the host race of this species must be determined by more expensive methods.
Publications
- Charchar, J.M., Eisenback, J.D., Charchar, M.J. & M.E. Boiteux. 2008. Meloidogyne pisi n. sp. (Nematoda: Meloidogynidae), a root-knot nematode parasitizing pea in Brazil. Nematology 10, 479-493.
- Charchar, J.M., Eisenback, J.D., Charchar, M.J. & M.E. Boiteux. 2008. Meloidogyne phaseoli n. sp. (Nematoda: Meloidogynidae), a root-knot nematode parasitizing bean in Brazil. Nematology 10, 525-538.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: The southern root-knot nematode, Meloidogyne incognita, causes major economic injury to numerous field and horticultural crops. This species is comprised of two cytological races that are made up of four host races. Precise identification of the various forms is necessary to properly manage field populations. Fourteens populations from all of the forms have been examined with the light and scanning electron microscope. Other than numerous morphometric differences, all morphological characters are similar. Characters that are useful for the identification of this species have been disseminated at the Annual Meeting of the Society of Nematologists and at the Multistate Region Project Meeting. In addition populations of M. incognita from Texas, Indiana, Maryland, South Carolina, Brazil, and Iran have been identified for either crop consultants or the state Plant Disease and Diagnostic Lab. Likewise numerous populations of this nematode were identified for researchers and
growers within the commonwealth of Virginia. Collaborations with two county agents have been fostered by this research and ongoing investigations of the effect of these nematodes on corn and soybean.
PARTICIPANTS: Joao M. Charchar, Maria Jose Charchar and Maria Esther N.F. Boiteux, researchers at EMBRAPA/CNPH - BR 060 Km 09 Caixa Postal 0218, Brasilia, DF. 70359, Brazil and EMBRAPA/CPAC - BR 020 Km 18 Caixa Postal 08223, Planaltina, DF. 70301-970. Patrick Lummus, Agricultural Consultant, Devine, Texas David Holshouser, Keith Balderson, David Moore, Pat Phipps, Katy Rainey, Charles Johnson, and Wade Thomason, County Agents and Extension Specialists, Virginia Tech.
TARGET AUDIENCES: Nematologists, Extension Specialists, Plant Pathologists, Count Agents, Agricultural Consultants, Plant Disease Diagnosticians, and Growers.
Impacts
Characters that are useful for the identification of the southern root-knot nematode have been found that will enable nematologists to make quick and precise recognition of this species. These characters include shape of the female stylet, perineal pattern, shape of the male head and stylet, and shape and head of the second-stage juvenile head and stylet. Even though this species is composed of two different cytological forms and four host races they are morphologically identical. Therefore identification to species is possible using morphological features alone; however, identification at the subspecific level is only possible by the use of a host range test. Additional taxonomic techniques, perhaps molecular tools, are needed to eliminate the costly and time-consuming host range tests. Development of a quick and easy procedure to identify the host races of this nematode will enchance the grower's ability to manage this important agricultural pest.
Publications
- Joao M. Charchar, Jonathan D. Eisenback, Maria Jose Charchar and Maria Esther N.F. Boiteux (2007). Meloidogyne pisi n. sp. (Nematoda: Meloidogynidae), a root-knot nematode parasitising pea in Brazil. Nematology 9:912-921.
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Progress 10/01/05 to 09/30/06
Outputs
Males of populations of the southern root-knot nematode (Meloidogyne incognita) were examined by light (LM) and scanning electron microscopy (SEM). They included representatives from all four host races of cytological races A and B. Host races vary in their ability to reproduce on cotton and root-knot resistant tobacco. Race 1 cannot reproduce on cotton or tobacco; race 2 reproduces on tobacco, but not cotton; race 3 reproduces on cotton, but not tobacco; and race 4 reproduces on both. Race A populations had chromosome numbers from 40 to 46, whereas race B populations had chromosome numbers between 32 to 38. In the SEM, males were characterized with numerous head annules (4-5), the labial disc was concave and fused with the medial lips, and the lateral lips were indistinct. In the LM, the head-cap was distinct and covered the head region, the stylet knobs were large, broad and slanted backwards. All fourteen populations were quite similar in overall head and tail
morphology. Morphometrics of all populations are currently in progress. The overall trend for the measurements is for the measurements in populations belonging to cytological race A are statistically significantly larger than in the populations from race B.
Impacts
This reseach will determine morphological characters that are useful in the identification of the southern root-knot nematode, Meloidogyne incognita. Light and scanning electron microscopy will reveal the similarities and differences amoung 14 populations from many parts of the world. Those characters that are stable and useful will be noted so that an accurate identification of this species can be made with confidence so that useful tactics for minimizing their economic impact can be minimized. For males, the shape of the head and the morphology of the stylet are useful for identifying members of this species even though they vary greatly in chromosome number and host range.
Publications
- P. M. Phipps, and J. D. Eisenback. 2006. Comparative performance of Avicta and Temik in control of southern root-knot nematode on cotton in Virginia. Proceedings of the Cotton Beltwide Conference.
- Eisenback, JD, P. Vieira, A. Ryss & M. Mota. 2006. Taxonomic databases for Bursaphelenchus and other aphelenchoid nematodes. In Vieira, P. & M. Mota, eds. 2006. Pine wilt disease: a worldwide threat to forest ecosystems (http://www.nemalab.uevora.pt/). Fundacao Calouste Gulbenkian, July 10-14, 2006. Lisboa, Portugal. Kluwer-Springer.
- Eisenback, JD. 2006. Megapixel Mosaic Micrographs of Nematodes. In Vieira, P. & M. Mota, eds. 2006. Pine wilt disease: a worldwide threat to forest ecosystems (http://www.nemalab.uevora.pt/). Fundacao Calouste Gulbenkian, July 10-14, 2006. Lisboa, Portugal. Kluwer-Springer.
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Progress 10/01/04 to 09/30/05
Outputs
Second-stage juveniles of populations of the southern root-knot nematode (Meloidogyne incognita) were examined by light (LM) and scanning electron microscopy (SEM). They included representatives from all four host races of cytological races A and B. Host races vary in their ability to reproduce on cotton and root-knot resistant tobacco. Race 1 cannot reproduce on cotton or tobacco; race 2 reproduces on tobacco, but not cotton; race 3 reproduces on cotton, but not tobacco; and race 4 reproduces on both. Race A populations had chromosome numbers from 40 to 46, whereas race B populations had chromosome numbers between 32 to 38. In the SEM, juveniles were characterized with numerous head annules (4-5), the labial disc was fused with the medial lips forming a barbell-shaped head cap, and the lateral lips were distinct and cigar-shaped. In the LM, the head-cap was distinct and covered the head region, the stylet knobs were large, broad and slanted backwards. The tail
terminus was not definite in most specimens, although some had a distinct terminal knob. All fourteen populations were quite similar in overall head and tail morphology. Morphometrics of all populations are currently in progress. The overall trend for the measurements is for the measurements in populations belonging to cytological race A are statistically significantly larger than in the populations from race B.
Impacts
This reseach will determine morphological characters that are useful in the identification of the southern root-knot nematode, Meloidogyne incognita. Light and scanning electron microscopy will reveal the similarities and differences amoung 14 populations from many parts of the world. Those characters that are stable and useful will be noted so that an accurate identification of this species can be made with confidence so that useful tactics for minimizing their economic impact can be minimized. For second-stages juveniles, the shape of the head and tail, and the morphology of the stylet are useful for identifying members of this species even though they vary greatly in chromosome number.
Publications
- Vieira. P. C. R., M. M. Mota, and J. D. Eisenback. 2005. Pine wood nematode taxonomic database, 2nd ed. Mactode Publications: Hamburg, Germany. ISBN: 1-893961-36-2.
- A. J. Syracuse, C. S. Johnson, J. D. Eisenback, C. L. Nessler, and E. P. Smith. 2004. Intraspecific variability within Globodera tabacum solanacearum using Random Amplified Polymorphic DNA. Journal of Nematology 36:433-439.
- Eisenback, J.D., J. G. Baldwin and K. R. Barker. 2006. Hedwig HirschmannTriantaphyllou. Pp. xxx-xxx, in, Ristaino, Jean, ed., Pioneering Women in Plant Pathology. APS Press: St. Paul, MN. (in press)
- Eisenback, J. D. and P. C. R. Vieira. 2006. Trichodoridae (Thorne, 1935) Siddiqi, 1961 taxonomic database. Mactode Publications: Hamburg, Germany. ISBN: 1-893961-37-4.
- Charchar, J. M., and J. D. Eisenback . 2006. Meloidogyne phaseoli n. sp. (Nematoda: Meloidogynidae), a root-knot nematode parasitizing bean in Brazil. Nematology 4: (in press).
- Tiwari, Siddharth, J. D. Eisenback, and Roger Youngman. 2005. Root-knot nematode in field corn. Virginia Cooperative Extension Publication 444-107. Blacksburg, VA.
- Vieira, P. C. R., A. Ryss, M. M. Mota, and J. D. Eisenback. 2005. Laimaphelenchus Fuchs, 1937 taxonomic database. Mactode Publications: Hamburg, Germany. ISBN: 1-893961-32-X.
- Vieira, P. C. R., M. M. Mota, and J. D. Eisenback. 2005. Dolichodoridae, 1950 taxonomic database. Mactode Publications: Hamburg, Germany. ISBN: 1-893961-33-8.
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Progress 10/01/03 to 09/30/04
Outputs
Populations of southern root-knot nematode, Meloidogyne incognita, from four host races of each of the two cytological races have been established in greenhouse cultures on tomato. Preliminary examinations have been made with the light and scanning electron microscopes. Second-stage juveniles of this species have many head annulations that are very distinct. The stylet knobs are quite large and broad and slanted backwards; especially the dorsal knob. The head is smoothly rounded. The tail has a distinct terminal knob present in many specimens, but the terminus is not definite in the majority of specimens. The rectum is usually inflated. Males of the populations examined thus far contain several distinct head annulations. The labial disk is concave and distintly set-off from the medial lip pairs. Stylet knobs are rounded and slanted backward; and the dorsal gland orifice is 2-4 micrometers from the stylet base.
Impacts
This research will attempt to find characters that will enble a more accurate identification of populations of the southern root-knot nematode, Meloiodgyne incognita. Because different populations can attacked different host plants, it is necessary to identify unknown populations in order to make economically important recommendations such as use of resistant cultivars, crop rotations, and application of nematicides.
Publications
- Vieira, P., J. D. Eisenback, and M. Mota. 2004. PWN-Cd: a taxonomic database for the pine wood nematode, Bursaphelenchus xylophilus, and other Bursaphelenchus species. P. 165, in, Mota, M., and P. Vieira. (eds.) The Pinewood Nematode, Bursaphelenchus xylophilus. Brill: Leiden.
- Vieira, P. C., M. Mota, and J. D. Eisenback. 2003. Pinewood Nematode Taxonomic Database. Mactode Publications: Blacksburg, Va. and Hamburg, Germany. ISBN: 1-893961-30-3.
- A. J. Syracuse, C. S. Johnson, J. D. Eisenback, C. L. Nessler, and E. P. Smith. 2004. Intraspecific variability within Globodera tabacum solanacearum using Random Amplified Polymorphic DNA. Journal of Nematology (accepted for publication).
- Eisenback, J. D., E. C. Bernard, J. L. Starr, T. A. Lee, Jr., and E. K. Tomaszewski. 2003. Meloidogne haplanaria n. sp., a root-knot nematode parasitizing peanut in Texas. Journal of Nematology 35:395-403.
- Eisenback, J. D., Nina Hopkins, and P. M. Phipps. 2004. First report of reniform nematode, Rotylenchus reniformis in Virginia on cotton. Plant Disease 88: 367.
- Eisenback, J. D. 2003. Nematology Laboratory Investigations: Morpholgy and Taxonomy. Mactode Publications: Blacksburg, Va. and Hamburg, Germany. ISBN: 1-893961-13-3.
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