Progress 10/01/00 to 09/30/05
Outputs
Nematodes typically are the most abundant invertebrates in agricultural ecosystems. Diverse plant parasitic taxa, order Tylenchida, cause substantial crop loss through feeding and interactions with additional disease agents. Non-parasitic nematodes, including Cephalobina, are also significant components of agricultural ecosystems, feeding on bacteria, regulating nutrient cycling and thus affecting soil fertility; specific diversity and taxonomic structure of nematode communities may be indicative of environmental changes linked to agricultural practices. Efficient characterization and management of agricultural ecosystems, and of plant parasitic pest nematodes, is dependent on reliable taxonomy and specifically a classification system that is predictive because it reflects phylogeny. Our goal on this Hatch project has been to advance a new phylogenetic classification of Tylenchida while addressing: 1) the phylogenetic context of Tylenchida (=the origin of plant
parasitism) 2) the internal phylogenetic resolution of diverse and often convergent-pathogenesis in Tylenchida. 3) resolution of taxonomic problems of particular plant pests within Tylenchida. These challenges have tackled in collaboration with molecular systematists and through a range of morphological tools (SEM, TEM, confocal, 4D microscopy) directed at unraveling questions of morphological evolution and character homology. The phylogenetic context of Tylenchida (plant parasites) began, in this project, with the premise (after Blaxter et al.) that this order shares a unique common ancestry with Cephalobina (bacterial-feeders). In collaboration with Nadler and De Ley, this relationship has been specifically articulated through a detailed phylogeny based on nearly complete sequences of LSU RNA that provide a new basis for revised classification (Nadler, Baldwin et al., in preparation). The relationship has also been morphologically defined, with new characters for phylogenetic
analysis and particularly with respect to feeding structures in both Cephalobina and Tylenchida in Baldwin et al., 2001,2004ab; Dolinski, Baldwin et al. 2001; Dolinski & Baldwin, 2003, Zhang & Baldwin, 2000a, 2000b, 2001. Molecular work on the broader context of Tylenchida is the basis for new questions on the monophyly of Tylenchida and Aphelenchina (classically considered sister taxa), with important implications for classification and the independent evolution of plant parasitism in these two groups (Baldwin et al., 2004). Within the broader phylogenetic context we have continued to address more focused taxonomic questions including the cyst nematodes, Heteroderoidea (Ferris, Baldwin et al. 2004), Pratylenchidae (Souza & Baldwin, 2000), Paratylenchus (Chau, Baldwin et al., 2004) and a molecular phylogeny of Criconematidae (Subbotin, Baldwin et al, submitted), while supporting outreach to the agricultural community (Baldwin, 2003). From these efforts we are now participating as part
of a consortium (Baldwin, Nadler, De Ley, Thomas, Fitch; http://nematol.unh.edu/tree/tyl3.php) leading a subgroup with the immediate goal of developing molecular-morphologically based phylogeny within the Tylenchida.
Impacts
Improved taxonomy of plant parasitic nematodes, supports applied management including regulation of exotic pests, implementation of crop rotation, and development/use of resistant cultivars; these are dependent on accurate, predictive identification. Molecular sequences, while primarily for phylogenetic classifications, include regions that are diagnostic for efficient species identification. Detailed morphology, developed for phylogenetic classification, clarifies misunderstood or misinterpreted features, thus supporting efficient species identification. Through-focus video vouchers, museum collections and online databases support research, training tools and outreach for agriculture. These investigations support promising novel approaches to management that are dependent on understanding/confounding particular gene pathways of pathogenesis. This work has demonstrated that certain non-parasitic Cephalobina are a rational focus of comparison to discover genes specific
to Tylenchida parasitism. This project points to patterns that provide new rationale to select model systems for the most efficient and predictive approach to genomics related to pathogenesis. Contrary to classical views, pathways understood for Tylenchida are not likely to be applicable to convergent pathogenesis is Aphelenchida, and pathways of pathogenesis in Meloidogyne are not likely conserved with cyst nematodes. Rather the emerging phylogenetic framework directs research to alternative more reliable extrapolations from models designed for novel environmentally sound approaches to pest management.
Publications
- Taylor, Timothy M., J. G. Baldwin and M. Mundo-Ocampo. 2004. Paracrobeles mojavicus n. sp. (Cephalobidae) from the Mojave Desert, California. Journal of Nematode Morphology and Systematics 6:151-160.
- Nguyen, Chau, J. G. Baldwin, and Y. E. Choi, 2004. New records of Paratylenchus Micoletzky, 1922 (Nematoda: Paratylenchinae) from Viet Nam with description of Paratylenchus laocaiensis sp. n. Journal of Morphology and Systematics. 7:51-75.
- Baldwin, J. G., E. J. Ragsdale and D. Bumbarger. 2004. Revised hypotheses for phylogenetic homology of the stomatostylet. Nematology.6:623-632
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Progress 01/01/03 to 12/31/03
Outputs
We are developing an evolution-based classification of agricultural nematodes (viz. Tylenchida) in the context of their non-parasitic relatives, with results primarily applicable to sophisticated management of nematodes in agricultural ecosystems. Within Tylenchida morphological characters informative for phylogenetics are poorly understood and new research indicates they often are misinterpreted in classical classifications. Surprisingly overall comprehensive molecular phylogenies of Tylenchida have never been produced. Although analysis of the 18S rRNA gene sequences revealed that tylenchids share a common ancestor with bacteriovore Cephalobina, the relationships within tylenchids remain largely unresolved. Our approach is to use a combination of molecular and carefully-resolved morphological data, the later including fine structure, tomography, confocal, florescence and video microscopy (Dolinski and Baldwin, 2003; Nadler et al., 2003). Based on this ongoing
research, during 2004 we published an overview of the evolution of plant parasitism, including relevant new molecular data (Baldwin et al., 2004). Although Tylenchida rRNA phylogenies are not fully resolved, the most significant finding is that they strongly support convergent evolution of sedentary endoparasitism (includes the most economically important genera) and convergence of the capacity to induce plant nurse cells in cyst and root-knot nematodes (Baldwin et al., 2004). We address how this has important implications for morphological evolution and for current work by other PIs on model systems designed to understand (and ultimately confound) pathogenesis. During 2004, we further engaged molecular tools to explore phylogenetic relationships within Heteroderoidea including plant parasites that form cysts and some that do not (Ferris et al., 2004). Developing a fuller understanding of plant parasitism will require integrating more comprehensive and resolved phylogenies with
appropriate choices of model organisms and comparative evolutionary methods. Current work on this project is designed to resolve phylogeny based on analyses of sequences of the nuclear ribosomal RNA (D2-D3 expansion fragments of the 28S gene), mitochondrial DNA (16S ribosomal RNA and cytochrome b) and nuclear protein-coding (actin and beta-tubulin) genes. The fragments of these genes will be amplified using PCR from a wide range of representative species belonging to different families of the Tylenchida in the context of outgroups (viz closely related nematode orders). Since the tylenchid stylet is a key adaptation for parasitism we are using molecular trees to target key models for detailed morphological investigations that will elucidate the evolution of this and related structures and how they adapt and function in mechanisms of plant parasitism.
Impacts
Our research is making important progress toward developing a phylogenetic classification of the most important group of agricultural nematode parasites, Tylenchida. This classification is essential to developing a framework for sophisticated management of plant parasitic nematodes. Specifically, a classification system based on evolution supports all other nematology research because, for example, it is the basis of predictability and repeatability of experimentation. An important example is that much current research designed to understand and confound complex host parasitic relationships use Meloidogyne (root knot) species as models. From these models there is often ill-advised extrapolation of results to interpret host-parasite relationships in similar Heterodera/Globodera (cyst) nematodes because classical classifications errantly imply a close relationship between root-knot and cyst nematodes. Conversely new molecular and morphological data, including this
project (Baldwin et al. 2004), strongly supports that endoparasitism evolved independently in root-knot and cyst nematodes and thus predicts that the similarities in structure and mechanisms are only superficial. This result has critical implications for using model systems and genomics to identify and characterize parasitism genes for representatives of this clade; and ultimately to confound processes of pathogenesis for management in agriculture.
Publications
- Dolinski, C. and Baldwin, J. G.. 2003. Fine structure of the stoma of Bunonema sp. and Teratorhabditis palmarum (Nematoda) and its phylogenetic significance. Journal of Nematology. 35:244-251.
- Nadler, S. A. Carreno, R. A., Adams, B. J., Kinde, H.. Baldwin, J. G. and Mundo Ocampo. M. 2003. Molecular phylogenetics and diagnosis of soil and clinical isolates of Halicephalobus gingivalis (Nematoda: Cephalobina: Panagrolaimoidea), an opportunistic pathogen of horses. International Journal of Parasitology 33:1115-1125..
- Ferris, V. R., Sabo, A., Baldwin, J. G., Mundo-Ocampo, M., Inserra, R. N., Sharma, S. 2004. Phylogenetic relationships among selected Heteroderoidea based on 18S and ITS ribosomal DNA. Journal of Nematology. In Press.
- Baldwin, J. G., Nadler, S. A. Adams, B. J.. 2004. Evolution of Plant Parasitism. Annual Review of Phytopathology. 42: In Press.
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Progress 01/01/02 to 12/31/02
Outputs
My goal is to develop an evolution-based classification system of agricultural nematodes in the context of non-parasitic relatives, with results applicable to both management of agricultural and natural (non-agricultural) ecosystems. During 2002 we moved forward with clearer phylogenetic resolution of Cephalobina (the closest relatives of agricultural plant-parasitic Tylenchida) with publications including new species of Nothacrobeles and Acrobeles (Poiras et al, 2002 and Mundo-Ocampo et al. 2002). Both of these papers involve redefinition of the genus involving fine structure, including features previously unknown. In addition, we have submitted a manuscript clarifying the intraspecific pathogenic variability, including new diagnostic tests of a cephalob nematode parasite of horses, Halicephalobus. We are moving forward with a collaborative molecular/morphological phylogeny of Cephalobina that we expect to submit for publication during 2003-2004. Currently underway
is an SEM and TEM resolution (focusing on the feeding system) of the bacterial feeding nematode, Bunonema, including discovery of new characters that bring resolution to previous apparent discrepancies between molecular and morphological evolution. Outreach including new insight into nematode taxonomy is addressed in broader publications including Baldwin, 2003; Baldwin and Perry, 2003)
Impacts
Results during 2002 move us closer to our goal, with collaborators, of developing a sound phylogenetic classification of Tylenchida. A classification system based on evolution supports all other nematology research because, for example, it is the basis of predictability and repeatability of experimentation. These taxonomic systems are critical to natural ecosystems for surveys in developing a base-line and monitoring for ecological and invasive species. Fine structural characterization of feeding systems in parasitic nematodes, within an evolutionary context provides a starting point to manipulate these systems to favor agricultural production.
Publications
- Baldwin, J. G. and Perry, R. N. 2003. Nematode morphology, sensory structure and function in Chen, Z. X., S. Y. Chen and D. W. Dickson eds. Nematology, Advances and Perspectives. ACSE-TUP Book Series: "Frontiers of Science and Technology for the 21st Century" Springer Verlag New York. In press
- Baldwin, J. G. 2003. Classification and Identification (nematodes). in Encyclopedia of Plant & Crop Science Marcel Dekker, Inc. New York. In press
- Poiras, Larisa, James G. Baldwin, Manuel Mundo-Ocampo and Daniel J. Bumbarger, 2002. Nothacrobeles borregi sp.n. (Nematoda: Cephalobidae) from Anza Borrego, California and N. laticollaris n. comb. (De Ley & Vandebroek, 1992) n. comb. Nematology 865-874
- Mundo-Ocampo, M., J. G. Baldwin, O. Dorado Ramirez, and M. Del Carmen Morales Ruiz, 2003. Acrobeles zapatai n. sp. (Cephalobina) from the Biosphere Reserve "Sierra de Huautla", Mexico with a discussion of the taxonomic limits of the genus. Journal of Nematode Morphology and Systematics. In press.
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Progress 01/01/01 to 12/31/01
Outputs
My research priority is resolution of features that can be used to understand character evolution in both plant parasitic nematodes and their non-parasitic relatives. One result of understanding evolutionary relationships is a basis for a stable predictable classification system of agricultural parasites within the context of their non-parasitic relatives. Using a combination of light, scanning and, transmission electron microscopy we have demonstrated homologies of cuticular layers and esophageal characters between bacterial feeders Cephalobina), and and Tylenchida (plant parasites) (Mounport et al., 2000; Zhang et al., 1999, 2000a,b, 2001, Souza and Baldwin, 2000; see last years APR). Most recently we published convincing fine structural evidence that the glandular basal bulb characterisitic of plant parasitic Tylenchida evolved independently from that of Diplogasterida (Baldwin et al, 2001). This work has important implications in rejecting classical views of
homology and evolution of the esophagus and putative lack of a valve and musculature in the basal bulb of plant parasites in Tylenchida. Ongoing work includes a number of taxonomic descriptions of cephalobs, heteroderids, and pratylenchids (Baldwin et al., 2001, Chiu et al., 2001, De Ley et al., 2000, Stock et al., 2002; Stanton et al., 2001).
Impacts
Results of this project, analyzed in conjunction with molecular data from collaborators, will lead to a sound taxonomic revision and classification of Tylenchida in the context of other Secernentea and consistent with evolution. We will also gain new insight into the feeding mechanisms and biology and ecosystems of plant parasites with potential to manipulate these systems to favor agriculture.
Publications
- STANTON, M. MUNDO-OCAMPO , J. G. BALDWIN * AND D. T. KAPLAN, 2001. Radopholus musicola n. sp., a new pathogenic species from Australia (Nematoda: Pratylenchidae). Nematology. 3:689-698.
- STOCK, S. P. P. DE LEY I. DE LEY M. MUNDO, J. G. BALDWIN AND S. A. NADLER. 2002 Plectonchus hunti n. sp. and Panagrobelus stammeri (Ruhm, 1956): Implications of new morphlogical observations for charcterization of these closely related genera (Nematoda: Panagrolaimoidea). Nematology (In press).
- BALDWIN, J. G. R. M. SOUZA, AND C. M. DOLINSKI, 2001. Fine structure and phylogenetic significance of a muscular basal bulb in Basiria gracilis (Tylenchidae). Nematology. Nematology 3:681-688.
- CHIU, CHISTOPHER T., JAMES G. BALDWIN, MANUEL-OCAMPO, 2002. Metacrobeles bradyurus n. sp. (Nematoda: Cephaloboidea) from Death Valley, California. Nematology (In press).
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Progress 01/02/00 to 12/31/00
Outputs
The goal of my research is to resolve taxonomic characters and elucidate character evolution in both plant parasitic nematodes and their non-parasitic relatives. We also strive to understand the role all types of nematodes play in agricultural ecosystems and to understand evolution of plant parasitism. Insight into evolutionary relationships is essential to developing a stable predictable classification system of parasites within the context of their non-parasitic relatives. During the past year we have used a combination of light, scanning and, transmission electron microscopy to demonstrate homologies of cuticular layers and esophageal characters between bacterial feeders Cephalobina), and and Tylenchida (plant parasites) (Mounport et al., 2000; Zhang et al., 1999, 2000a,b, 2001, Souza and Baldwin, 2000). This work has important implications in rejecting classical views of homology and evolution of the esophagus and putative lack of a valve and musculature in the
basal bulb of plant parasites in Tylenchida (Baldwin et al. submitted). We have also investigated the evolution of plant parasitic nematodes in the context of other Secernentea using characters of embryonic development (Dolinski et al. 2001). Ongoing work includes a number of taxonomic descriptions of cephalobs, heteroderids, and pratylenchids (Baldwin et al., 2001, De Ley et al., 2000, Stanton et al., submitted). We have also worked to increase public awareness of plant parasitic nematodes in the context of biodiversity and the implications for quarantine (Baldwin et al., 2000).
Impacts
One impact of this project is that it will lead to a sound taxonomic revision and classification of Tylenchida in the context of other Secernentea and consistent with evolution. We will also gain new insight into the feeding mechansims and biology and ecosystems of plant parasites with potential to manipulate these systems to favor agriculture.
Publications
- Baldwin, J. G., I. T. De Ley, M. Mundo Ocampo, P. De Ley and S. A. Nadler and M. Gebre. 2001. Acromoldavicus mojavicus n. sp. (Nematoda: Cephalobidae) from the Mojave Desert, California. Nematology In press.
- Baldwin, J.G., S.A. Nadler and D.W. Freckman. 2000. Nematodes - pervading the earth and linking all life. 176-191 In: Nature and Human Society, the Quest for a Sustainable World, P. Raven and Williams, T. (ed.), National Academy Press.
- De Ley, I. T., P. De Ley, J. G. Baldwin, M. Mundo Ocampo and S. A. Nadler. 2000. Three new species of Nothacrobeles (Nemata: Cephalobidae) from the Mojave Desert, California. Journal of Nematology 31:482-497.
- Dolinski, C., J. G. Baldwin and W. K. Thomas. 2001. Comparative survey of early embryogenesis of Secernentea (Nematoda) with phylogenetic implications. Canadian Journal of Zoology. 79:82-94.
- Mounport, D., P. Baujard, P. De Ley, M.C. Van De Velde, A. Coomans, and J. G. Baldwin. 2000. Interspecific ultrastructural variation of cuticular layers in Cephalobinae (Nematoda: Rhabditida). Journal of Nematology 32:13-19.
- Zhang and J. G. Baldwin. 2001. Ultrastructure of the postcorpus of the esophagus of Teratocephalus lirellus (Teratocephalida) for interpreting character evolution in Secernentea (Nematoda). Canadian Journal of Zoology 79:16-25.
- Souza, R.M. and Baldwin, J.G. 2000. Differential behaviour of the survival stages of Nacobbus aberrans (Nemata:Pratylenchidae) under sub-optimal environments. Nematology: 211-215.
- Zhang, Y. and J. G. Baldwin, 1999. Ultrastructure of the esophagus of Diplenteron sp. (Diplogasterida) To test hypotheses of homology with Tylenchida and Rhabditida. Journal of Nematology. 31:1-19.
- Zhang, Y. and J. G. Baldwin. 2000a. Phylogenetic implications of ultrastructure of the postcorpus of Zeldia punctata (Cephalobina) with comparisons to Caenorhabditis elegans (Rhabditina) and Diplenteron sp. (Diplogasterina) Philosophical Transactions of the Royal Society of London Series B 267:1229-1238.
- Zhang, Y. and J. G. Baldwin. 2000b. Phylogenetic implications of ultrastructure of the postcorpus of Zeldia punctata (Cephalobina) with comparisons to Caenorhabditis elegans (Rhabditina) and Diplenteron sp. (Diplogasterina) Philosophical Transactions of the Royal Society of London Series B 267:1229-1238.
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Progress 01/01/99 to 12/31/99
Outputs
Our work is designed to resolve taxonomic characters in both plant parasitic nematodes and their non-parasitic relatives. The goal is understand the role all types of nematodes play in agricultural ecosystems and to understand evolution of plant parasitism. Insight into evolutionary relationships is essential to developing a stable predictable classification system of parasites within the context of their non-parasitic relatives. During 1999 we have used a combination of light, scanning and, transmission electron microscopy to demonstrate homologies of cuticular layers and esophageal characters between bacterial feeders (Rhabditida and Cephalobina), and predators (Diplogasterina) and well as Tylenchida (plant parasites) (Mounport et al., in press; Zhang et al., in press, Souza and Baldwin, unpublished). This work has important implications in rejecting classical views of homology and evolution of the esophagus and putative lack of a valve and musculature in the basal
bulb of plant parasites in Tylenchida. The work complements our previous work on this project related to the stoma and evolution of the tylenchid stylet. An extension of this project has been a study of esophageal glands in the economically important plant parasite, NACOBBUS ABERRANS, and we have identified the particular life stages at which specific glands are active and the relationship between postembryonic development and pathogenesis; we have also clarified survival stages in this nematode creating new strategies for management (Souza and Baldwin, in press). Ongoing work includes a number of taxonomic descriptions of cephalobs, heteroderids, and pratylenchids (De Ley et al. in press). We have also worked to increase public awareness of plant parasitic nematodes in the context of biodiversity and the implications for quarantine (Baldwin et al., 2000)
Impacts
One impact of this project is that it will lead to a sound taxonomic revision and classification of Tylenchida in the context of other Secernentea and consistent with evolution. We will also gain new insight into the feeding mechansims and biology and ecosystems of plant parasites with potential to manipulate these systems to favor agriculture.
Publications
- No publications reported this period
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Progress 01/01/98 to 12/01/98
Outputs
This project seeks character resolution in both plant parasitic nematodes and their nonparasitic relatives to understand the role all types of nematodes play in agricultural ecosystems to under-stand evolution of plant parasitism. Understanding evolutionary relationships is essential to a stable predictable classification system. During the past year we have used a combination of 4-D microscopy, transmission electron microscopy, and specific florescent staining to demonstrate homologies of feeding apparatus parts between bacterial feeders, Rhabditina and Cephalobina (Dolinski et al, 1998). This work has important implications in rejecting classical views of homology and evolution of the stylet of plant parasites in Tylenchida. The work is being expanded to consider additional taxa and to similarly consider homologies in the esophageal gland region (Zhang and Baldwin, 1998, In Press). An extension of this project has been a study of esophageal glands in the
economically important plant parasite, NACOBBUS ABERRANS, and we have identified the particular life stages at which specific glands are active and the relationship between postembryonic development and pathogenesis (Souza and Baldwin, 1999). Additional research focuses on nematode pests (including NACOBBUS ABERRANS) of critical importance to international trade. In this regard we have extended investigations of the biology of N. ABERRANS using UCR quarantine facilities (Souza and Baldwin in preparation) and have published a book chapter on quarantine regulation of plant parasites (Baldwin et al. 1998).
Impacts
(N/A)
Publications
- SOUZA, R. M. and J. G. BALDWIN, 1998. Ultrastructural changes in the esophageal glands of NACOBBUS ABERRANS (Nematoda Pratylenchidae) throughout its life cycle. J. Nematol. 30:275-290.
- DOLINSKI, C. J. BALDWIN, G. BORGONIE and R. SCHNABEL. 1998. Buccal capsule development as a consideration for phylogenetic analysis of Rhabditida (Nemata). Developmental Genes and Evolution: 208:495-503.
- BALDWIN, J.G., M. MONSON and E. PAINE. 1998. University of California, Riverside quarantine and isolation facility for soil and water nematodes. In: Exclusion of Exotic Plant Pests and Pathogens: Containment Facilities and Safeguards. R.P.
- ZHANG, Y. and J. G. BALDWIN. 1998. Ultrastructure of the esophagus of DIPLENTERON sp. (Diplogasterida) To test hypotheses of homology with Tylenchida and Rhabditida. J. Nematol. In Press.
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Progress 01/01/97 to 12/01/97
Outputs
As previously noted, character resolution of non-parasites is crucial to the objectives of this project because these nematodes play a role in agricultural ecosystems and in testing hypotheses of evolution of plant parasitism. Insight into evolutionary relationships is essential to a stable predictable classification system. We continue to use transmission electron microscopy to redefine taxonomic characters in outgroups of Tylenchida, including CAENORHABDITIS ELEGANS; during the past year we have developed a morphological/molecular evolutionary framework for extending this nematode model (Baldwin et al. 1997). We have also developed a new tool for linking morphological and molecular approaches to identification of nematodes, with a technique for PCR and sequencing specimens, where the same individuals also have been processed by classical methods suitable for morphological vouchers (Thomas et al. 1997). We continue work on taxonomic description of new species of
Heteroderinae (Baldwin et al, 1998a); including a new review with keys to all cyst nematodes (Wouts and Baldwin, 1998). New work on nematology as it relates to biodiversity and sustaining the world's resources is presented in Baldwin et al. (1998b). Ongoing projects include work on comparative developmental biology and pathogenicity of the plant parasite NACOBBUS ABERRANS (DeSouza and Baldwin, unpublished) and comparative development of the feeding mechanism in the microbivorous nematode, ZELDIA PUNCTATAi (Dolinski and Baldwin, unpublished; Zhang and Baldwin, unpublished).
Impacts
(N/A)
Publications
- BALDWIN, J.G., FRISSE, L.M., VIDA, J.T., EDDLEMAN, C.D. and THOMAS, W.K. 1997. An evolutionary framework for the study of developmental evolution in a set of nematodes related to CAENORHABDITIS ELEGANS.
- BALDWIN, J.G., MUNDO-OCAMPO, M., and McCLURE, M.A. 1998a. CACTODERA SALINA n. sp. from the estuary plant, SALICORNIA BIGELOVII Torr. in Sonora, Mexico. Journal of Nematology. In Press.
- BALDWIN, J.G., NADLER, S.A. and FRECKMAN, D.WALL. 1999b. Nematodes - pervading the earth and linking all life. IN: Nature and Human Society: The quest for a sustainable world (P.H. Raven, ed.).
- THOMAS, W.K., VIDA, J.T., FRISSE, L., MUNDO, M. and BALDWIN, J.G. 1997. DNA sequences from formalin fixed nematodes: integrating molecular and morphological approaches to taxonomy. Journal of
- WOUTS, W. and BALDWIN, J.G. 1998. Taxonomy and identification of cyst-forming nematodes. IN: Cyst Nematodes (S.B. Sharma, ed.). Chapman and Hall. In Press. (56 manuscript pages).
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Progress 01/01/96 to 12/30/96
Outputs
Character resolution of non-parasites is crucial to the objectives of this project because these nematodes play a role in agricultural ecosystems and in testing hypotheses of evolution of plant parasitism. We have used electron microscopy to redefine the characters of the buccal region in the non-parasitic outgroups CAENORHABDITIS ELEGANS and additional Rhabditida, ZELDIA PUNCTATA, and ADUNCOSPICULUM HALICTI; these characters were then mapped over a molecular (18S, 28S) tree. Results reject extant hypotheses of evolution of plant parasitism. Strong morphological and molecular evidence is building that plant parasitic Tylenchida evolved from Cephalobina including ZELDIA PUNCTATA (Baldwin and Eddleman, 1995; Baldwin et al, 1997). Collaborative research on detailed characters of plant parasites continues and has led to publications clarifying the taxonomic status of CRICONEMA PARADOXIGER and confirmed the presence of MELOIDOGYNE PARTITYLA on pecan in Texas. Although the
latter nematode is present in South Africa, the evidence is that it was introduced from the United States (Decraemer et al, 1996; Starr et al., 1997). An additional plant parasite of quarantine significance to California is NACOBBUS ABERRANS. New molecular data has proved a basis for addressing questions of speciation in this nematode (Ibrahim et al, 1997). Work on NACOBBUS ABERRANS is continuing to clarify how developmental changes in the female relate to pathogenesis.
Impacts
(N/A)
Publications
- DECRAEMER, W., BALDWIN, J. G., EDDLEMAN, C. D. and GERAERT, E. 1996. CRICONEMA PARADOXIGER (Orton Williams, 1982) Raski and Luc, 1985: cuticle ultrastructure and reflection on its taxonomic status. Nematologica 42:408-416.
- STARR, J. L., TOMASZEWSKI, E. K., MUNDO OCAMPO, M. and BALDWIN, J. G. 1997. MELOIDOGYNE PARTITYLA on pecan: isozyme phenotypes and other hosts. J. Nematol. In Press.
- BALDWIN, J. G., GIBLIN-DAVIS, R. M., EDDLEMAN, C. D., WILLIAMS, D. S., VIDA, J. T. and THOMAS, W. K. 1997. Buccal capsule of ADUNCOSPICULUM HALICTI (Nemata: Diplogasterina): an ultrastructural and molecular phylogenetic study. Can. J. Zool.
- BALDWIN, J. G., MONSON, M., PAINE, E. 1997. University of California Riverside quarantine and isolation facility for soil and water nematodes In: Khan, R. P. and S. B. Mathur, (eds.) Exclusion of Exotic Plant Pests and Pathogens:.
- IBRAHIM, S. K., BALDWIN, J. G., ROBERTS, P. A. and HYMAN, B. C. 1997. Genetic variation in NACOBBUS ABERRANS. An approach towards taxonomic resolution. J. Nematol. In Press.
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Progress 01/01/95 to 12/30/95
Outputs
The phylogenetic bases for classification of Heteroderinae as reviewed in Baldwin (1992) and Baldwin and Mundo (1991) has been strengthened by new insight (based on LM, SEM, and TEM) into characters including cuticular layering of females (Cordero and Baldwin, 1991; Baldwin and Eddleman, 1992); host parasite relationships (Mundo and Baldwin, 1992); and genera-specific polymorphism of spermatozoa (Cares and Baldwin,1994 a, b;1995). New reports include introduction of the HETERODERA GOETTINGIANA in western Washington (Handoo, et al. 1995), HETERODERA MANI in southern California, and H. CRUCIFEREA in Hawaii. Character insight based on fine structure for phylogenetic classification of Heteroderidae has provided a model for classification of additional agriculturally important nematodes, such as Pratylenchidae (Baldwin and Cap, 1992; Navas, et al., 1995). Work has begun to clarify the taxonomic status of physiologically diverse isolates of NACOBBUS spp. using a combination
of fine structure, biochemistry and molecular biology (Ibrahim, et al., 1995). Classical taxonomic descriptions, new distributions, and phylogenetic analyses on taxa with agricultural pests have been expanded to include TYLENCHORHYNCHUS (Golden, et al, 1995), BURSAPHELENCHUS (Giblin Davis, et al.), BELONOLAIMUS (Mundo, et al, 1994) and LONGIDORUS (Navas, et al, 1995 a,b).
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Publication on fine structure (SEM and TEM) of spermatozoa in Heteroderinae has nearly been completed including discussion of genus-specific characters suitable for testing previous phylogenetic analyses of the group (Cares and Baldwin, 1994). Collaborative research with Dr. McClure at the University of Arizona has begun on the taxonomic description of a new CACTODERA (Heteroderinae) from an estuary region in Baja California. This salt-tolerant nematode has already been shown to have damaging potential on new commercial desert crops, and also to play a positive role in the balance of a healthy estuary ecosystem. We have also begun work on the agriculturally important group of nematodes TYLENCHORHYNCUS, including description of a new desert species from California (Golden, et al, In press); this work will continue with additional new species. Ongoing taxonomic research includes BELONOLAIMUS LONGICAUDATUS, HETERODERA MANI (newly introduced to southern California),
NACOBBUS ABERRANS, and several exotic species of PRATYLENCHUS; our objective is to confirm taxonomic status and to better predict potential for damage to California agriculture.
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
GRADUATE STUDENTS=1. Heteroderinae taxonomy is being advanced by spermatozoa fine structure (SEM and TEM), and demonstrating specific characters in five genera suitable for testing phylogenetic analyses (Cares and Baldwin, In Press; Unpublished). Morphology of feeding sites of Heteroderinae was elucidated by computer reconstruction of micrographs for 3-dimensional visualization (Mundo et al., In Press). SEM was also incorporated into a new species description of a nematode associated with insects (Giblan-Davis et al., 1993). We are investigating morphology, biology, and host range of BELONOLAIMUS LONGICAUDATUS and HETERODERA MANI (newly introduced to Southern California) for confirmation of their taxonomic status and to better predict their potential for damage to California agriculture (Mundo et al, In Press); we have also contributed to addressing taxonomic questions concerning the introduction of HETERODERA GOETTINGIANA to the Northwestern United States (Handoo et
al, In Press). A new project tests previous hypotheses about evolution of plant parasitic nematodes from a common ancestor with Diplogasterida and Rhabditida. DNA sequence data is utilized to develop an evolutionary tree and fine structure-based characters of the stoma/stylet are superimposed on this tree to infer evolution of plant parasitism.
Impacts
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Progress 01/01/92 to 12/30/92
Outputs
Taxonomy of Heteroderinae is being further developed with electron and light microscope investigation (Baldwin, J. G. 1992; Baldwin and Eddleman, 1992; Baldwin and Mundo-Ocampo, 1992). Recent work demonstrates spermatozoa in VERUTUS, MELOIDODERA, EKPHYMATODERA, HETERODERA AND PUNCTODERA have genus-specific characters which are being used to test previous phylogenetic analyses of the group (cares and Baldwin, unpublished). Additional preliminary electron microscope investigations suggest that Heteroderinae taxa vary in the morphology of the perineal musculature and that these differences may be useful in diagnosis of closely related species of GLOBODERA. Presently, we are developing new techniques for staining this musculature so differences can be used in routine light microscope identification. We completed a project on taxonomy and biogeography of LONGIDORUS (Navas et al, 1993ab). We are using quarantine facilities to compare morphology, biology, and host range of
BELONOLAIMUS LONGICAUDATUS and HETERODERA MANI (newly introduced to Southern California) for confirmation of their taxonomic status and to better predict their potential for damage to California agriculture. An additional new project tests previous hypotheses about evolution of plant parasitic nematodes from a common ancestor with Diplogasterida and Rhabditida.
Impacts
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Progress 01/01/91 to 12/30/91
Outputs
New characters for phylogenetic analysis of Heteroderinae have been expanded to include the body wall cuticle of BELLODERA and EKPHYMATODERA and this work has been accepted for publication (Baldwin and Eddleman). The host response of EKPHYMATODERA was demonstrated to be unique among Heteroderinae (Baldwin and Mundo). In addition, two taxonomic reviews of Heteroderinae were completed and published (Baldwin and Mundo, 1991; Baldwin). Recently completed work on the fine structure of the terminal region of cyst nematodes HETERODERA SCHACHTII and CACTODERA CACTI (Cordero and Baldwin, 1991; Cordero et al, 1991) is being expanded to other cyst nematodes GLOBODERA TABACUM and PUNCTODERA CHALCOENSIS as well as noncyst-forming species VERUTUS VOLVINGENETIS and EKPHYMATODERA THOMASONI. We have also begun collaborative work which examines characters of DNA in Heteroderinae. Work on characters of spermatozoa is continuing. We are also conducting surveys in Mexico and are
describing new cyst species which have the potential to be introduced to California agriculture.
Impacts
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Progress 01/01/90 to 12/30/90
Outputs
During the past year new characters for phylogenetic analysis of Heteroderinae have been discovered from TEM of the body wall cuticle of two genera previously discovered and taxonomically described by our laboratory: BELLODERA UTAHENSIS and EKPHYMATODERA THOMASONI. In addition, detailed examination of the host response of EKPHYMATODERA THOMASONI included the discovery of new characters which will be useful to the taxonomy. We recently obtained material of the agriculturally important cyst nematodes GLOBODERA TABACUM and PUNCTODERA CHALCOENSIS and succeeded in culturing this material in compliance with quarantine regulations. Currently we are developing techniques for TEM investigation of the terminal region including bullae, denticles, bridge, underbridge, vaginal musculature, fenestrae, and surface patterns. Findings will be used to develop a meaningful taxonomy. We are also beginning collaborative studies to consider characters from molecular biology in our taxonomy
of Heteroderinae. In addition, we have recently begun exploring taxonomic characters in spermatozoa of Heteroderinae.
Impacts
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Progress 01/01/89 to 12/30/89
Outputs
I use transmission (TEM), scanning (SEM) and light microscopy to discover new characters and gain a more complete understanding of classical characters of plant parasitic nematodes. Findings are used to develop a matrix for computer assisted phylogenetic analysis because taxonomic systems based on such analysis are more stable and useful. The focus of my work is one of the most economically important groups of nematodes, Heteroderinae. Work on development of the cone of Heteroderinae was expanded this year. Tissue culture methods combined with video recording and electron microscopy provided the basis for characterizing differences between the cone in Heterodera and Cactodera and insight into bullae, denticles, bridge, underbridge, vaginal musculature, fenestrae, and surface patterns. Bullae are extensions of an E layer which forms in aging females. A D-layer, previously considered absent, was found in some portions of the body in Heterodera. This layer
strengthens arguments that the cyst evolved only once in Heteroderinae. The investigations will be extended to additional species and will include characters of spermatozoa and the uterus.
Impacts
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Progress 01/01/88 to 12/30/88
Outputs
My objective is to develop taxonomic systems for plant parasitic nematodes whichare stable because they reflect phylogeny. My approach is to use transmission (TEM), scanning (SEM) and light microscopy to discover new characters and gain a more complete understanding of classical characters. A matrix of these characters is used in computer assisted analysis to obtain the most parsimonious evolutionary explanation for the patterns of distribution of characters. This pattern is used as a basis for developing a system of classification. We have used Heteroderinae, one of the most economically important groups of plant parasitic nematodes, as a model for phylogenetic analysis, and results of our work have been compiled and presented with a new classification in Baldwin and Schouest, 1989. This study has incorporated new phylogenetically important findings on the heteroderid phasmid, based on TEM, and completed during the past year (Carta and Baldwin, 1989 a,b). Work on the
comparative development of the cyst, begun last year, is ongoing and will be completed for publication this year (Cordero and Baldwin, in preparation). During the past year we begun a project on comparative morphology of some economically important tropical aphelenchs; results have important taxonomic implications. One paper has been published from this project (Giblin et al., 1989) and during the next year we expect to complete work on additional closely related genera for publication.
Impacts
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Progress 01/01/87 to 12/30/87
Outputs
I have proposed to develop stable taxonomic systems which reflect phylogeny of plant parasitic nematodes. My approach is to discover new characters, and elucidate classical characters through the use of transmission (TEM), scanning (SEM) and light microscopy. These characters are entered into a matrix for computer analysis using a variety of algorithms, and competing hypotheses of phylogeny are tested with additional biological parameters. The focus of my work continues to be Heteroderidae. We have completed SEM investigations of lip patterns and identified several features as reliable for phylogenetic analysis while rejecting others due to high variability at the population level. We have nearly completed comparative development of the phasmid at the fine structural (TEM) level. Several new species and a new genus of Heteroderidae has been described, and the cyst has been more clearly defined as a taxonomic character. These characters and new taxa are included
in computer generated analyses. Results and a tentative classification are being prepared for publication. We are also investigating physiologic variation of the burrowing nematode (Radopholus similis) and Punctodera chalcoensis. New work is being planned for detailed comparisons of cyst development among heteroderid taxa, and for congruency tests between morphologic and biochemical characters.
Impacts
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Progress 01/01/86 to 12/30/86
Outputs
Our objective is to develop stable taxonomic systems which reflect phylogeny of plant parasitic nematodes, and to interpret their functional morphology. Our approach is to discover new characters, and elucidate classical characters through the use of transmission (TEM), scanning (SEM), & light microscopy. During the past year we have continued to focus on Heteroderidae. SEM of lip patterns and other surface structures have been expanded to include Globodera, Cactodera and Punctodera, as well as preliminary investigations of Heterodera. In addition, we have investigated the phasmid as a taxonomic character using developmental TEM observations to access variability and test hypotheses of polarity and function. These and additional fine structural characters are being incorporated in descriptions of number of new heteroderid species and genera. Additional projects include a revision of Scutellonema incorporating SEM characters; taxonomic and biological evaluation
of Punctodera chalcoensis for regulatory decisions, and characterization of burrowing nematode (Radopholus similis andR. citrophilus) for regulatory decisions.
Impacts
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Progress 01/01/85 to 12/30/85
Outputs
Previously we proposed to develop stable taxonomic systems which reflects phylogeny of plant parasitic nematodes as well as to elucidate functional morphology of nematodes. During the past year our approach has been to discover new characters primarily through use of transmission (TEM) and scanning (SEM) electron microscopy; much of this work has been on one of the most economically important groups, Heteroderidae. Findings reflected in publications include new characters of females, males, and second-stage juveniles: lip patterns, cuticular patterns, lateral lines, perineal and tail regions. Although many observations support existing taxonomic schemes others indicate paraphyletic groups. Results are being compiled for incorporation in a new phylogenetic analysis and taxonomic revision of Heteroderidae. Ongoing SEM and TEM observations of phasmids have also revealed new insights into phylogeny through identification of parallel evolution in the pore-like opening
of certain Meloidodera and Heterodera spp. These studies are being expanded to include additional genera. We have also begun developmental studies on heteroderid phasmids to associate morphological changes with changes in biological requirements of the nematode; we anticipate that these studies will give a basis for hypotheses of phasmid function. Additional taxonomic studies on the plant parasitic genera Scutylenchus and Pratylenchus have been completed.
Impacts
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Progress 01/01/84 to 12/30/84
Outputs
Our objective is to discover new characters which can be used in phylogenetic analyses and taxonomic revisions of Heteroderidae. We have compared surface structures of members of the family using SEM. New characters which will be incorporated in an analysis include features of en face patterns, lateral lines, plasmid openings, and female perineal regions (Othman and Baldwin, 1985, and additional papers in preparation). Results have, in part, been basic to a revision of Sarisodera including a redescription of Afenestrata africana (= Sarisodera africana) (Baldwin and Bell, 1985). In addition, we have found useful patterns for testing phylogeny in layering of the body wall cuticle in females of 10 genera of Heteroderidae using TEM (Cliff and Baldwin, 1985). In some cases patterns suggest inconsistencies with proposed phylogenies for the family, and may, in part, indicate justification for further revision. TEM has also been employed to elucidate comparative
structures of phasmids (caudal sensory organs) within the genus (Baldwin, 1985; additional papers in preparation). Phasmids appeared with light microscopy, to be incongruent with other characters in indicating phylogenetic patterns, but TEM investigations support the hypothesis that the distribution of types of phasmids is the result of parallel or convergent evolution.
Impacts
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Progress 01/01/83 to 12/30/83
Outputs
Our objective is to discover new characters which can be used in phylogenetic analyses and taxonomic revisions of plant parasitic nematodes, with particular emphasis on Heteroderidae. Work on comparative histopathology of Heteroderidae has indicated such characters and has been completed. Ongoing projects on comparative morphology (SEM) of en face patterns continues to reveal new characters. In addition, we have begun a project on the comparative fine structure (TEM) of phasmids among Heteroderidae. Results indicate several character states among juveniles; in addition, the phasmid appears to be diminutive in second-stage cyst nematodes, and absent in males of some species. Previous TEM studies on layering of the body wall cuticle of females of Heteroderidae are being expanded to include additional species and genera. A taxonomic revision of Merliniinae has been completed, and several publications from this study are in preparation.
Impacts
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Progress 01/01/82 to 12/30/82
Outputs
Research on comparative morphology and systematics of plant parasitic nematodes is continuing with emphasis on Heteroderidae, and Tylenchorhynchidae. Completed studies on the comparative morphology of cuticle of females of Heteroderidae have indicated this to be a valuable source of new characters for incorporation in a phylogenetic analysis of the group. New characters have also been discovered through completed work on the comparative histopathology among Heteroderidae. Work has begun on comparative morphology of en face patterns and TEM of phasmids of Heteroderidae. Several new species and new genera have been described or are being described. Work has begun on a revision of Tylenchorhynchidae, and within this group a revision of Nagelus has been completed for publication. We expect to complete a revision of Merliniinae (within Tylenchorhynchidae) during 1983.
Impacts
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Progress 01/01/81 to 12/30/81
Outputs
Research on comparative morphology and systematics of plant parasitic nematodes is continuing with efforts being concentrated on the Heteroderoidea, Pratylenchoides, Nacobbus and Merlininae. Work comparing the esophagus of Sarisodera with Heterodera and Meloidogyne, using the transmission electron microscope (TEM) has been completed for publication. Additional light microscope (LM), scanning electron microscope (SEM), and TEM studies have been initiated for comparative studies of the cutile, to be used in testing current hypotheses of phylogeny of this group. We expect to complete comparative histopathology studies on the same group within the next year. A reavision of the genus Pratylenchoides has recently been completed and is being prepared for publication. A similar revision of Nacobbus has been initiated, but studies will be limited until the nematology quarantine greenhouse is available for host range tests. We expect to complete publications on a revision
of Merlininae during 1982.
Impacts
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Progress 01/01/80 to 12/30/80
Outputs
Research is continuing on the comparative morphology of Heteroderoidea using light, scanning (SEM) and transmission electron microscopy. The fine structure of the esophagus of males of Sarisodera is distingive from Heterodera and Meloidogyne; these results are significant in interpreting phylogeny and improving taxonomy of the superfamily. Histopathological studies involving heteroderoidea, have also indicated important genus-specific characteristics within the group, which may also be useful in interpreting phylogeny. Two new taxonomic projects have been started: revision of Nacobbus and revision of Merlinihae. Both studies are employing newly discovered characters obtained with SEM.
Impacts
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Progress 01/01/79 to 12/30/79
Outputs
Research has been completed on description of a new subfamily, Pararotylenchinae(Hoplolaimidae), with six new species and two new combinations. This work, based on light and scanning electron microscope (SEM) observations, indicates that the new subfamily is most similar to Hoplolaimidae, regardless of the presence of a basal esophageal gland bulb, as occurs in Tylenchorhynchidae. Additional studies have begun on comparative morphology of various Heteroderoidea, using the light, scanning and transmission electron microscope. The research is designed to discover morphological relationship that will lead to a useful stable taxonomic system of this group. Work on comparative morphology is being complimented by our investigations on the comparative histopathology among species of relatively rare genera of Heteroderoidea.
Impacts
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Progress 01/01/78 to 12/30/78
Outputs
Research was continued on Hoplalaimidae including the proposal of a new subfamily based on new species collected plus a study of some previously described species presently in other families which will be transferred to the new subfamily. This research is based on light and scanning electron microscopy (SEM). Additional SEM work was provided for Dr. Raski in his study of the Criconematidae and for Dr. Luc for a survey of the Heteroderidae. During the year, 2280 nematode specimens were processed to permanent slides and added to the collection. Assistance was provided in mounting and identifying nematodes from California and Alaska.
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Progress 01/01/77 to 12/30/77
Outputs
Pratylenchoides. Three papers on Trichodoridae were submitted for publication and are presently in press. The monodelphic species of Trichoridae were studied and the relationship to the Mominal taxa shown, along with the description of a new genus and four new species. Trichodoridae spicule morphology was compared by means of light microscopy and scanning electron microscopy in order to clarify structures not previously understood. Two new species in the genus Trichodorus and one specie in Paratrichodorus were described. A key to the subgenera of Paratrichodorus was constructed based upon the female. Survey samples of nematodes of Alaska were examined and 4490 specimens representing 44 genera were processed to permanent slides, a portion of which will be used for a reference collection at the University of Alaska and the remainder deposited in the Riverside slide collection.
Impacts
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Progress 01/01/76 to 12/30/76
Outputs
The permanent Riverside slide collection was increased by 5165 specimens in 1976. A major revision of the Trichodoridae was completed and prepared for publication. A collaborative project was initiated with the Nematology Branch of the California State Department of Food and Agriculture to supply them with sets of permanent slides of nematodes for their reference collection. Nematode samples from various parts of the world have been studied and added to our mass collections.
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Progress 01/01/75 to 12/30/75
Outputs
The permanent Riverside slide collection was increased by 7,015 specimens in 1975. The largest additions being in Trichodorus, Paratrichodorus and the subfamily Tylenchinae. The distribution and identification of nematode specimens from over 100 soil and root samples from South Korea was completed andtype specimens of Tylenchoidea described from this area added to the collection.Taxonomic studies on the Tylenchoidea are continuing and a taxonomic study of Trichodorus and Paratrichodorus has been started; the scanning electron microscope is being used in these studies.
Impacts
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Progress 01/01/74 to 12/30/74
Outputs
2674 permanent slide specimens of soil and plant parasitic nematodes were added to the Riverside collection during 1974. A survey of the anterior region of Tylenchoidea, as seen with the scanning electron microscope, has been completed and accepted for publication. Studies on the face view and extended spicules ofthe Tylenchoidea are being continued with the scanning electron microscope. Taxonomic publications on the genera of Merlininae and Tylenchorhynchinae are being prepared. The scanning electron microscope and numerical taxonomy methodsare being used to provide additional input for the systematics of these groups. A survey of the plant parasitic nematodes in the U.C.R. Botanical Garden has been initiated and 96 soil samples from 92 hosts have been examined for nematodes.
Impacts
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Progress 01/01/73 to 12/30/73
Outputs
5,470 permanent specimens of soil and plant parasitic nematodes were added to the Riverside collection during 1972. Most of the specimens were in the superfamily Tylenchoidea and collected in California. Other areas from which large numbers of nematodes were obtained were the midwestern part of the U.S.A. and Canada and Bahia, Brazil. Over 400 scanning electron micrographs of the face views and over 30 scanning electron micrographs of the extended spicules in75 species of Tylenchoidea have been studied. These nematodes have a much greater diversity than previously known and the studies are being continued. Taxonomic studies on a new species of Pratylenchus from California, the genus Dolicodorus, the family Tylenchorhynchinae and the classification of the Tylenchoidea are being continued.
Impacts
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Progress 01/01/72 to 12/30/72
Outputs
3,936 permanent specimens of soil and plant parasitic nematodes were added to the Riverside collection during 1972. Most of these specimens were in the subfamilies Tylenchorhynchinae, Merliniinae, Tylenchinae and Psilenchinae. Three taxonomic papers have been completed. Leipotylenchus abulbosus (Thorne, 1949) n. comb. in the Leipotylenchinae n. subf. and Triversus annulatus (Merny, 1964) n. comb. have been proposed for species previously in the genus Tetylenchus Filipjev, 1936. Tetylenchus tenuis (Micoletzky, 1921) has been proposed as genus and species dubia after an examination of type material. Two new genera, Apratylenchoides in the Radopholinae and Antarctylus in the Hoplolaiminae have been proposed. Electron scanning microscope studies have been started on the face view of Tylenchorhynchinae. Work on a revision of the Tylenchoidea is being continued.
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Progress 01/01/71 to 12/30/71
Outputs
Permanent specimens (5,558) of soil and plant parasitic nematodes were added to the Riverside collection during 1971. Most of these specimens were in the subfamily Tylenchorhyninae and the genus Xiphinema. A review of the genus Xiphinema has been completed and accepted for publication. Eight subgenera and two new species are proposed. The significance of the female gonad structure isdiscussed and the morphology of the three types of gonads in this genus is illustrated and defined. The identification, distribution and plant associationsof Xiphinema and Longidorus spp. in California has been completed. Work on a revision of the Tylenchorhynchinae and related taxa is being continued.
Impacts
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Progress 01/01/70 to 12/30/70
Outputs
5,583 permanent specimens of soil and plant parasitic nematodes were added to the collection during 1970. Over half of these specimens were in the subfamily Tylenchorhynchinae which is now being revised. The genera of Heteroderinae review has been completed and two new genera are being described. Work has started on the identification, distribution and plant associations of Xiphinema spp. in California.
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