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1.  Assessing Heterodera glycines-Resistant and Susceptible Cultivar Yield Response 
Journal of nematology  2006;38(1):76-82.
The soybean cyst nematode Heterodera glycines (SCN) is of major economic importance and widely distributed throughout soybean production regions of the United States where different maturity groups with the same sources of SCN resistance are grown. The objective of this study was to assess SCN-resistant and -susceptible soybean yield responses in infested soils across the north-central region. In 1994 and 1995, eight SCN-resistant and eight SCN-susceptible public soybean cultivars representing maturity groups (MG) I to IV were planted in 63 fields, either infested or noninfested, in 10 states in the north-central United States. Soil samples were taken to determine initial SCN population density and race, and soil classification. Data were grouped for analysis by adaptation based on MG zones. Soybean yields were 658 to 3,840 kg/ha across the sites. Soybean cyst nematode-resistant cultivars yielded better at SCN-infested sites but lost this superiority to susceptible soybean cultivars at noninfested sites. Interactions were observed among initial SCN population density, cultivar, and location. This study showed that no region-wide predictive equations could be developed for yield loss based on initial nematode populations in the soil and that yield loss due to SCN in our region was greatly confounded by other stress factors, which included temperature and moisture extremes.
PMCID: PMC2586441  PMID: 19259433
crop loss; crop rotation; Glycine max; Heterodera glycines; management; resistance; soybean; soybean cyst nematode; yield; soil type
2.  ß-tubulin Paralogs Provide a Qualitative Test for a Phylogeny of Cyst Nematodes 
Journal of Nematology  2004;36(4):440-448.
Evolutionary relationships among cyst nematodes based on predicted ß-tubulin amino acid and DNA sequence data were compared with phylogenies inferred from ribosomal DNA (ITS1, 5.8S gene, ITS2). The ß-tubulin amino acid data were highly conserved and not useful for phylogenetic inference at the taxonomic level of genus and species. Phylogenetic trees based on ß-tubulin DNA sequence data were better resolved, but the relationships at lower taxonomic levels could not be inferred with confidence. Sequences from single species often appeared in more than one monophyletic clade, indicating the presence of ß-tubulin paralogs (confirmed by Southern blot analysis). For a subset of taxa, good congruence between the two data sets was revealed by the presence of the same putative ß-tubulin gene paralogs in monophyletic groups on the rDNA tree, corroborating the taxon relationships inferred from ribosomal DNA data.
PMCID: PMC2620793  PMID: 19262824
ß-tubulin; cyst nematodes; paralogous genes; ribosomal DNA
3.  Phylogenetic Relationships Among Selected Heteroderoidea Based on 18S and ITS Ribosomal DNA 
Journal of Nematology  2004;36(3):202-206.
In a study of relationships among selected cyst-forming and noncyst-forming species of Heteroderoidea, combined sequences comprised of DNA from part of the conserved 18S ribosomal RNA gene (rDNA) plus the complete ITS rDNA segment were more similar to analyses based on the ITS data alone than to analyses based on the 18S data alone. One of the two noncyst-forming species, Ekphymatodera thomasoni, grouped with cyst-forming species of Heteroderoidea. Bilobodera flexa, also a noncyst-forming species, was separated from all the other taxa by a long branch. Afenestrata koreana, with a weakly sclerotized cyst, grouped closely with H. bifenestra. These observations suggest that phylogenetic analyses using molecular data may aid in our understanding of the evolution of cyst formation in nematodes, including the possibility of secondary loss. The usefulness of molecular phylogenetic analyses in nematodes may depend more on the particular selection of taxa than on mere addition of data from additional genes.
PMCID: PMC2620772  PMID: 19262808
Afenestrata koreana; Bilobodera flexa; Cactodera betulae; Ekphymatodera thomasoni; Globodera; Heterodera bifenestra; ITS1; ITS2; nematode; phylogenetic analysis; ribosomal DNA; 5.8S gene; 18S gene
4.  Phylogenetic Relationships of a Distinct Species of Globodera from Portugal and Two Punctodera Species 
Journal of Nematology  2002;34(3):263-266.
Evolutionary relationships based on ribosomal DNA (rDNA) sequence data for a previously unknown species of Globodera from Portugal, Punctodera chalcoensis from Mexico, and P. punctata from Estonia, plus previously published sequences, support the following relationships: (((Cactodera weissi, G. artemisiae, C. milleri), ((G. sp. Bouro, G. sp. Canha, G. sp. Ladoeiro), ((G. pallida, G. rostochiensis), (P. chalcoensis, P. punctata)))), Heterodera avenae). Globodera sp. from Portugal, which can be confused with potato cyst nematodes by phytosanitary services when the identification is based only on morphological characters, is clearly different based on our molecular data. In addition, the rDNA data show the Globodera sp. to be only distantly related to other European Globodera species that parasitize Asteraceae. Punctodera chalcoensis and P. punctata form a sister clade to the G. pallida + G. rostochiensis clade.
PMCID: PMC2620565  PMID: 19265942
5.8S gene; Globodera; ITS1; ITS2; nematode; phylogenetic analysis; Punctodera; Punctodera chalcoensis; Punctodera punctata; ribosomal DNA
5.  Phylogenetic Relationships Based on Ribosomal DNA Data for Four Species of Cyst Nematodes from Italy and One from Syria 
Journal of Nematology  2001;33(4):183-190.
Phylogenetic analysis of new ribosomal DNA (rDNA) data for Heterodera mediterranea, H. hordecalis, H. carotae, and H. fici from Italy and H. ciceri from Syria, along with published data for other species, showed high bootstrap support for the following relationships: (((((H. carotae H. cruciferae) H. goettingiana) (((H. trifolii H. ciceri) H. mediterranea) ((H. avenae H. latipons) H. fici))) (Cactodera betulae H. hordecalis)) (Globodera rostochiensis G. pallida)). The rDNA sequence data were for the two internal transcribed spacers (ITS1 and ITS2) plus the 5.8S gene between them. These inferred relationships support the classic ''Goettingiana Group'' of H. carotae, H. cruciferae, and H. goettingiana. A clade comprised of Cactodera betulae and H. hordecalis is only distantly related to the other species in the analysis.
PMCID: PMC2620511  PMID: 19265879
Heterodera; Heterodera carotae; Heterodera ciceri; Heterodera fici; Heterodera hordecalis; Heterodera mediterranea; ITS1; ITS2; phylogenetic analysis; ribosomal DNA; 5.8S gene
6.  Phylogenetic Relationships of Globodera millefolii, G. artemisiae, and Cactodera salina Based on ITS Region of Ribosomal DNA 
Journal of Nematology  1999;31(4):498-507.
Globodera millefolii and G. artemisiae are interesting because their type localities (Estonia and Russia, respectively) are geographically distant from those of the potato cyst nematodes and other Globodera species that seem to have originated in the Western world, and because the type host for each is a member of Compositae rather than Solanaceae. Sequence data for ITS1, ITS2, and 5.8S ribosomal DNA (ITS rDNA) for G. millefolii and G. artemisiae were nearly identical to sequence data for Cactodera salina from the rhizosphere of the estuary plant Salicornia bigelovii in Sonora, Mexico. The ITS rDNA sequences of these three species were all about 94% similar to those of two other Cactodera species for which ITS rDNA data were obtained. Phylogenetic analysis indicated that, based on the ITS rDNA data, G. millefolii and G. artemisiae are more closely related phylogenetically to the Cactodera species than to other nominal Globodera species. The molecular data further suggest that the genus Cactodera may comprise two or more morphologically similar but separate groups.
PMCID: PMC2620398  PMID: 19270922
Cactodera; Cactodera salina; Globodera; Globodera artemisiae; Globodera millefolii; ITS1; ITS2; nematode; phylogenetic analysis; ribosomal DNA; rDNA; 5.8S gene
7.  Species Concepts Do Matter in Nematology 
Journal of Nematology  1999;31(2):93-94.
Nematology is a taxon-based science, and a correct understanding of species and their relationships is basic to all nematological research. Modern methods of systematic analysis have reshaped issues concerning species recognition.
PMCID: PMC2620365  PMID: 19270880
nematode; species concepts; systematics
8.  Resistance Genes in a 'Williams 82' x 'Hartwig' Soybean Cross to an Inbred Line of Heterodera glycines 
Journal of Nematology  1995;27(3):418-422.
The number of resistance genes in soybean to soybean cyst nematode (SCN) Heterodera glycines was estimated using progeny from a cross of 'Williams 82' x 'Hartwig' (derived from 'Forrest'³ x PI 437.654) screened with a fourth-generation inbred nematode line derived from a race 3 field population of SCN. Numbers of females developing on roots of inoculated seedlings were assigned to phenotype cells (resistant, susceptible, or segregating) using Ward's minimum variance cluster analysis. The ratio obtained from screening 220 F₃ soybean families was not significantly different from a 1:8:7 (resistant:segregating:susceptible) ratio, suggesting a two-gene system for resistance. The ratio obtained from screening 183 F₂ plants was not significantly different from a 3:13 (resistant:susceptible) ratio, indicating both a dominant (Rhg) and a recessive (rhg) resistance gene.
PMCID: PMC2619625  PMID: 19277307
Glycine max; Hartwig; Heterodera glycines; PI 437.654; resistance soybean; soybean cyst nematode; soybean resistance gene
9.  Ribosomal DNA Comparisons of Globodera from Two Continents 
Journal of Nematology  1995;27(3):273-283.
Ribosomal DNA (rDNA) sequence data were compared for five species of Globodera, including G. rostochiensis, G. pallida, G. virginiae, and two undescribed Globodera isolates from Mexico collected from weed species and maintained on Solanum dulcamara. The rDNA comparisons included both internal transcribed spacers (ITS1 and ITS2), the 5.8S rRNA gene, and small portions of the 3' end of the 18S gene and the 5' end of the 28S gene. Phylogenetic analysis of the rDNA sequence data indicated that the two potato cyst nematodes, G. pallida and especially G. rostochiensis, are closely related to the Mexican isolates, whereas G. virginiae is relatively dissimilar to the others and more distantly related. The data are consistent with the thesis that Mexico is the center of origin for the potato cyst nematodes.
PMCID: PMC2619624  PMID: 19277290
Globodera; G. rostochiensis; G. pallida; G. virginiae; G. tabacum; nematode; ribosomal DNA; rDNA ITS1 and ITS2; 5.8S rRNA gene
10.  Comparisons of Isolates of Heterodera avenae using 2-D PAGE Protein Patterns and Ribosomal DNA 
Journal of Nematology  1994;26(2):144-151.
Six geographic isolates of Heterodera avenae, including two isolates each from Sweden, Australia, and the United States, were compared on the basis of 2-D PAGE protein patterns and the complete DNA sequence for the two internal transcribed ribosomal DNA spacers (rDNA ITS1 and ITS2) and the 5.8S rRNA gene. The protein pattern data and rDNA ITS sequence data both indicated that the Swedish Gotland strain of H. avenae differed markedly from the rest of the isolates. Protein patterns for the Australia isolates differed more from a Swedish strict H. avenae isolate and isolates from Oregon and Idaho, than the two U.S. isolates and the Swedish strict H. avenae isolate differed from each other. Except for the Gotland strain isolate, the rDNA ITS sequences were highly conserved among all of the H. avenae isolates, just as we earlier found them to be conserved among species of the schachtii group of Heterodera.
PMCID: PMC2619483  PMID: 19279877
Heterodera avenae; nematode; 2-D PAGE; protein pattern; ribosomal DNA; rDNA ITS1 and ITS2; 5.8S rRNA gene
11.  Plant and Soil Nematodes: Societal Impact and Focus for the Future. 
Journal of Nematology  1994;26(2):127-137.
Plant and soil nematodes significandy impact our lives. Therefore, we must understand and manage these complex organisms so that we may continue to develop and sustain our food production systems, our natural resources, our environment, and our quality of life. This publication looks specifically at soil and plant nematology. First, the societal impact of nematodes and benefits of nematology research are briefly presented. Next, the opportunities facing nematology in the next decade are outlined, as well as the resources needed to address these priorities. The safety and sustainability of U.S. food and fiber production depends on public and administrative understanding of the importance of nematodes, the drastic effects of nematodes on many agricultural and horticultural crops, and the current research priorities of nematology.
PMCID: PMC2619488  PMID: 19279875
alternative management tactics; behavior; benefit to society; beneficial nematodes; biochemistry; biological control; constraints in nematology; control; crop rotation; cultural practice; ecology; education; environment; extension; diagnostics; funding; genetics; host-parasite interaction; information transfer; molecular genetics; nematicide; nematode; nematology; nematode management; nutrient cycling; pesticide; plant parasites; research goals; research priorities; resistance; resource; science of nematology; society; spread; sustainable agriculture; systematics
12.  Why Ecologists Need Systematics: Importance of Systematics to Ecological Research 
Journal of Nematology  1989;21(3):308-314.
Ecologists are concerned with population dynamics of organisms and with the spatial patterns of single or multiple populations. The goal of the ecologist is usually to explain the observed patterns in terms of processes. Field samples of nematodes from different habitats may contain similar but not identical specimens of a nominal taxon, and the systematist can help the ecologist decide whether the specimens are ecophenotypes of a single taxon or represent distinct species. A correct decision may be important or trivial, depending on the parameters and goals of the ecological study. When a precise identification is crucial to the success of the study, new biochemical methodologies of systematists may provide rapid and accurate diagnoses. Systematists can provide additional help in the assignment of taxa to trophic groups. For clarifying host-parasite associations, often a goal in ecological investigations, modern analytical methods of systematists can facilitate the ordering of systematic relationships.
PMCID: PMC2618945  PMID: 19287614
coevolution; nematode species; taxa; trophic group
13.  Phylogenetic Analyses in Dorylaimida Using Data from 2-D Protein Patterns 
Journal of Nematology  1988;20(1):102-108.
Data from two-dimensional protein patterns for nine dorylaimid isolates were analyzed using PAUP, a computer program for inferring phylogenies under the principle of maximum parsimony. With a variety of available options, including branch swapping and rooting, essentially the same tree was obtained. When isolates of the genus Labronema were analyzed alone, all trees obtained had the same topology, although tree length varied considerably, depending on whether a hypothetical ancestral taxon was included.
PMCID: PMC2618779  PMID: 19290191
Labronema; Eudorylaimus; Aporcelaimellus; 2-D PAGE; phylogenetic analysis; PAUP; Dorylaimida
14.  Two-dimensional Protein Patterns in Labronema, Aporcelaimellus, and Eudorylaimus (Nematoda: Dorylaimida) 
Journal of Nematology  1987;19(4):431-440.
Two-dimensional polyacrylamide gel electrophoretic patterns of proteins for two isolates of Labronema from Indiana were nearly identical to the pattern for L. vulvapapillatum from Europe. The pattern for a nominal isolate of L. pacificum from Florida was very different from the patterns of nominal L. pacificum isolates from Hawaii and Fiji (which had patterns very similar to each other). Patterns for four other isolates (in Eudorylaimus and Aporcelaimellus) were different from the Labronema patterns and from each other, although some constellations of protein spots were shared among all the isolates. The study demonstrates the utility of 2-D PAGE for clarifying taxonomic problems that cannot be resolved using classical morphological data alone.
PMCID: PMC2618664  PMID: 19290167
two-dimensional gel electrophoresis; 2-D PAGE protein patterns; Labronema; Aporcelaimellus; Eudorylaimus; Nematoda: Dorylaimida; systematics; Jaccard analysis; similarity coefficient
15.  Heterodera glycines in Indiana: I. Reproduction of Geographical Isolates on Soybean Differentials 
Journal of Nematology  1986;18(2):169-172.
Four of five geographical isolates of Heterodera glycines from Indiana classified as Race 3 using standard differentials showed many differences when classified using another group of differentials comprised of five soybean breeding lines and cultivars. Two isolates from northern Indiana produced cysts on more of the differentials tested than did three isolates from southern Indiana, suggesting that potential resistant lines should be tested on a range of H. glycines populations originating from the areas for which cultivars are being developed.
PMCID: PMC2618541  PMID: 19294160
soybean cyst nematode; Glycine max; pathogenicity; Heterodera glycines; soybean
16.  Heterodera glycines in Indiana: III. 2-D Protein Patterns of Geographical Isolates 
Journal of Nematology  1986;18(2):177-182.
Protein patterns obtained by two-dimensional polyacrylamide gel electrophoresis for three isolates of Heterodera glycines from southern Indiana appear qualitatively similar and have higher pairwise Jaccard similarity coefficients with each other than with isolates from northern Indiana. Three isolates from three northern counties share proteins not present in the southern isolates, but as a group the northern isolates are less similar to each other than are the southern Indiana isolates.
PMCID: PMC2618529  PMID: 19294162
soybean cyst nematode; polyacrylamide gel electrophoresis
17.  Heterodera glycines in Indiana: II. Morphology of Geographical Isolates 
Journal of Nematology  1986;18(2):173-177.
Although much morphometric overlap occurs among five geographical isolates of Heterodera glycines in Indiana, significant differences in means exist among the isolates for various comparisons of second-stage juveniles. By using combinations of means, most of the isolates can be distinguished from the rest: e.g., the Vanderburgh County isolate (southern Indiana) has the longest esophagus, tail, and tail terminus; the Vigo County isolate (also from the south) has the shortest esophagus; the White County isolate (northern Indiana) has the shortest tail and tail terminus and the greatest total length; the Benton County isolate (north) is the shortest. Morphological similarities and differences do not appear to be coordinated with reproductive behavioral patterns we observed in the northern versus the southern isolates.
PMCID: PMC2618528  PMID: 19294161
soybean cyst nematode; Glycine max; soybean; Heterodera glycines; Indiana; morphology; races; geographical isolate
18.  Two-Dimensional Protein Patterns in Heterodera glycines 
Journal of Nematology  1985;17(4):422-427.
Two-dimensional polyacrylamide gel electrophoretic protein patterns of H. glycines from southern Indiana (Posey County) and northern Indiana (Pulaski County) were largely similar, but many differences existed. The pattern of the Posey isolate was similar to patterns from isolates collected in other areas of the United States. Unique dense protein spots in the pattern of an isolate from Hokkaido, Japan, distinguished it from patterns of six U.S. isolates.
PMCID: PMC2618475  PMID: 19294120
soybean cyst nematode; two-dimensional gel electrophoresis; soybean
19.  Dispersion and Distribution of Pratylenchus scribneri and Hoplolaimus galeatus in Soybean Fields 
Journal of Nematology  1983;15(3):418-426.
Examination of dispersional characteristics of Pratylenchus scribneri and Hoplolaimus galeatus indicated that there were patches within soybean fields in which both survival and reproduction wexe enhanced in spite of apparent homogeneity of soil type and topography. Treatment with carbofuran reduced the patchiness (or increased the dispersion) for H. galeatus while it had the opposite effect for P. scribneri. P. scribneri was less highly dispersed in conventional tillage plots than in the zero tillage plots. Populations from quadrats contained entirely within the patches could be described by the normal distribution (in the case of P. scribneri) or by the Poisson distribution (in the case of H. galeatus), while populations from quadrats contained entirely outside the patches could be described by the Poisson distribution for both nematodes. None of the distributions tested (Poisson, normal, negative binomial, Neyman's) gave an adequate fit when populations from both inside and outside the patches were considered together. In all instances, log₁₀ and ln transformations reduced the goodness of fit of the data to all of the distributions tested. Even with logarithmic transformations, parametric statistics were not appropriate for analysis of data in most instances.
PMCID: PMC2618294  PMID: 19295827
nematode frequency; population ecology; index of dispersion; plot size selection; data transformation
20.  Population Development of Pratylenchus hexincisus in Eight Corn Inbreds 
Journal of Nematology  1983;15(2):243-252.
Of eight corn inbreds tested in the greenhouse and field, three (H60, H95, and H84) supported lower populations of Pratylenchus hexincisus than other inbreds included in this study. No apparent differences existed among inbreds in nematode invasion or development in the roots, or in population structure. Differences in population were therefore attributed to differential reproduction.
PMCID: PMC2618280  PMID: 19295798
lesion nematode; corn nematode; screening
21.  Sclerostylus n. gen. from Panama and Other Neotropical Species of LeptonIchoidea (Dorylaimida) 
Journal of Nematology  1981;13(1):79-86.
Leptonchoid species found in soil samples taken in lowland and mid-elevation seasonal forests at four locations in Panama were as follows: Sclerostylus karri n. gen., n. sp., Basirotyleptus saccatus n. sp., B. nemoralis, B. acus, B. penetrans, Doryllium neotropicum n. sp., D. minor, Tyleptus gymnochilus, Gerthus jamesi, Dorylaimoides micoletzkyi, and Tylencholaimellus macrophallus. The discoveries corroborate our earlier suggestion of a Gondwanian origin for Tyleptus and Basirotyleptus and provide data for additional biogeographical study.
PMCID: PMC2618054  PMID: 19300726
Basirotyleptus; Doryllium; Tyleptus; Gerthus; Dorylaimoides; Tylencholaimellus; nematode taxonomy; Gondwanaland
22.  Proleptonchoides southindiae n. gen., n. sp., a New Leptonchoid from South India 
Journal of Nematology  1979;11(1):70-72.
Proleptonchoides southindiae n. gen., n. sp. (Dorylaimida: Leptonchidae), is described from soil around false tobacco (Lobelia excelsa) and cardamom (Elettaria cardamomurn) in South India. P. southindiae is prodelphic, has a short constricted esophageal bulb and flanged odontophore, and is phylogenetically close to Proleptonchus.
PMCID: PMC2617934  PMID: 19305531
taxonomy; Nematoda; Dorylaimida; Leptonchidae; Proleptonchus
24.  Funaria maryanneae n. sp. and Proleptonchus weischeri n. sp. (Nematoda: Dorylaimida) from Europe and New Synonyms in Leptonchoidea 
Journal of Nematology  1976;8(3):213-217.
Funaria maryanneae n. sp., distinguished by its large size and long prerectum, is described from specimens collected in Bad Sooden, Germany, D. B. R. This nematode was collected also from Fräkmüntegg (Mt. Pilatus), Switzerland. Proleptonchus weischeri n. sp., with short hemispheroid female tail and relatively anterior vulva, is described from specimens collected in Kaufunger Wald near Kassel, Germany, D. B. R. This is the first report of either genus from the continent of Europe. Leptonchus parisii Zullini, 1973, from Chiapas, Mexico, becomes a junior synonym of Funaria obtusa (Thorne, 1939) Goseco, Ferris and Ferris, 1974. Leptonchus acutus Zulliui, 1973 becomes Funaria acuta n. comb., and Funaria rothi Goseco, Ferris and Ferris, 1974 becomes a junior synonym of Funaria acuta.
PMCID: PMC2620180  PMID: 19308225
Taxonomy; Leptonchus
25.  Nematode Community Structure of Forest Woodlots: III. Ordinations of Taxonomic Groups and Biomass 
Journal of Nematology  1974;6(3):118-126.
Nematode communities of 18 Indiana mixed hardwood stands were comprised of an average of 23% tylenchid species, 31% dorylaimid species, and 46% species of six other orders. Based on total numbers of individuals present the stands averaged 42% tylenchids, 20% dorylaimids, and 38% individuals of other orders. Ordination of the sites using data only for tylenchid species gave an even distribution of sites, indicating little effect of site disturbances on tylenchid populations. By contrast an ordination using data for dorylaimid species showed a high degree ofd issimilarity between reference sites indicating that disturbances at some sites had drastically affected the dorylaimid fauna. An ordination utilizing biomass of all species present was very similar to the ordination based on data for dorylaimid species only.
PMCID: PMC2620054  PMID: 19308112
Indiana hardwood stands; Tylenchida; Dorylaimida; Rhabditida; Teratocephalida; Araeolaimida; Monhysterida; Chromadorida; Enoplida

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