In the spotlight: the newly discovered beech leaf disease caused by the nematode, Litylenchus crenatae mccannii. First found in Ohio in 2012 and now spreading to at least 10 other states, plus Canada, the lethal disease kills the native American beech as well as the commonly planted European beech, scientists say. There is no known cure. 

Enter researcher Paulo Vieira, a plant pathologist, molecular biologist and nematologist with USDA's Agricultural Research Service (USDA-ARS), Beltsville, MD.

He will speak on "Beech Leaf Disease: An Emergent Threat to Beech Forest Ecosystems in North America" at a virtual seminar hosted by the UC Davis Department of Entomology and Nematology, announced host and nematologist Shahid Siddique. It is set for 4:10 p.m., Wednesday, May 17. The Zoom link: 
https://ucdavis.zoom.us/j/95882849672.

"The beech leaf disease nematode, Litylenchus crenatae mccannii, is recognized as a newly emergent nematode species that causes beech leaf disease (BLD) in beech trees (Fagus spp.) in North America," Vieira says in his abstract. "Since the first report of BLD on Fagus grandifolia in Ohio in 2012, the disease has rapidly spread to other states and Canada. This nematode has been so far reported in Pennsylvania, New York, Connecticut, Massachusetts, Maine, Michigan, Rhode Island, New Jersey, West Virginia, and Virginia, as well as Ontario. Leaf symptoms include swelling and darkening of interveinal tissues as well as chlorosis, while tissue necrosis and leaf curling occur at later stages of the disease. As a result, mortality of nematode infected understory beech trees has been reported after several years of infection in the United States. The fast dissemination of this nematode can impose a dramatic effect on beech forest ecosystems and natural diversity in North America."

Vieira says that "Little information on the molecular and cellular interaction between this nematode and its hosts is available. To advance our understanding into this unknown host- nematode system, we investigated the cytological aspects of this interaction using bright-field and scanning electron microscopy. Our data reveal that these nematodes can induce morphological changes in both bud and leaf tissues, which so far seem unique in the Nematoda phylum. These cellular changes ultimately provide the necessary nutrients for completion of the nematode life cycle, while dramatically affecting bud and leaf morphology. In addition, we used Illumina mRNA sequence analysis of a mixed stage population to obtain insight into the transcriptome of this nematode. Gene comparative analyses were combined to select a list of candidate effector/parasitism genes. Spatial expression of transcripts within the esophageal glands of L. crenatae mccannii by in situ hybridization validated a list of pioneer effectors novel to this species and across the Nematoda phylum. These analyses provide additional data for understanding the mode of parasitism of this newly emergent plant-parasitic nematode."

Vieira, who joined USDA-ARS in November 2021, holds a master's degree (2007) in plant pathology, phytopathoogy from the University of Évora, Portugal, and a doctorate (2012 in plant pathology, plant-nematode interaction from the  University of Nice Sophia-Antipolis and Institute Sophia Agrobiotech, France. His resume includes postdoctoral researcher at the University of Évora (2012-2013) and USDA (2013-2015). Vieira served as a researcher in molecular biology at Virginia Tech for eight years before joining USDA-ARS in Beltsville.

Vieira's current research interests:

• Identification and functional analyses of effectors of plant-parasitic nematodes
• Genomics and transcriptomics of plant-parasitic nematodes, with a particular focus on migratory nematodes
• Plant-nematode interaction studies using cell and molecular biology approaches

Department seminar coordinator is urban landscape entomologist Emily Meineke,  assistant professor.   For technical issues regarding Zoom connections, she may be reached at ekmeineke@ucdavis.edu. (See complete list of spring seminars.)

Related Resources:

First report of the beech leaf disease nematode Litylenchus crenatae mccannii (Nematoda: Anguinidae) in Michigan (Plant Disease journal, Nov. 22, 2022)
Paulo Vieria: Google scholar and Twitter accounts

Paulo Vieira, a plant pathologist, molecular biologist and nematologist with USDA's Agricultural Research Service (USDA-ARS), Beltsville, MD., will speak on "Beech Leaf Disease: An Emergent Threat to Beech Forest Ecosystems in North America" at the next UC Davis Department of Entomology and Nematology seminar.

The seminar is set for 4:10 p.m., Wednesday, May 17 and will only be virtual, announced host Shahid Siddique, nematologist. The Zoom link:
https://ucdavis.zoom.us/j/95882849672.

"The beech leaf disease nematode, Litylenchus crenatae mccannii, is recognized as a newly emergent nematode species that causes beech leaf disease (BLD) in beech trees (Fagus spp.) in North America," Vieira says in his abstract. "Since the first report of BLD on Fagus grandifolia in Ohio in 2012, the disease has rapidly spread to other states and Canada. This nematode has been so far reported in Pennsylvania, New York, Connecticut, Massachusetts, Maine, Michigan, Rhode Island, New Jersey, West Virginia, and Virginia, as well as Ontario. Leaf symptoms include swelling and darkening of interveinal tissues as well as chlorosis, while tissue necrosis and leaf curling occur at later stages of the disease. As a result, mortality of nematode infected understory beech trees has been reported after several years of infection in the United States. The fast dissemination of this nematode can impose a dramatic effect on beech forest ecosystems and natural diversity in North America."

Vieira says that "Little information on the molecular and cellular interaction between this nematode and its hosts is available. To advance our understanding into this unknown host- nematode system, we investigated the cytological aspects of this interaction using bright-field and scanning electron microscopy. Our data reveal that these nematodes can induce morphological changes in both bud and leaf tissues, which so far seem unique in the Nematoda phylum. These cellular changes ultimately provide the necessary nutrients for completion of the nematode life cycle, while dramatically affecting bud and leaf morphology. In addition, we used Illumina mRNA sequence analysis of a mixed stage population to obtain insight into the transcriptome of this nematode. Gene comparative analyses were combined to select a list of candidate effector/parasitism genes. Spatial expression of transcripts within the esophageal glands of L. crenatae mccannii by in situ hybridization validated a list of pioneer effectors novel to this species and across the Nematoda phylum. These analyses provide additional data for understanding the mode of parasitism of this newly emergent plant-parasitic nematode."

Vieira, who joined USDA-ARS in November 2021, holds a master's degree (2007) in plant pathology, phytopathoogy from the University of Évora, Portugal, and a doctorate (2012 in plant pathology, plant-nematode interaction from the  University of Nice Sophia-Antipolis and Institute Sophia Agrobiotech, France. His resume includes postdoctoral researcher at the University of Évora (2012-2013) and USDA (2013-2015). Vieira served as a researcher in molecular biology at Virginia Tech for eight years before joining USDA-ARS in Beltsville.

Vieira's current research interests:

• Identification and functional analyses of effectors of plant-parasitic nematodes
• Genomics and transcriptomics of plant-parasitic nematodes, with a particular focus on migratory nematodes
• Plant-nematode interaction studies using cell and molecular biology approaches

Department seminar coordinator is urban landscape entomologist Emily Meineke,  assistant professor.   For technical issues regarding Zoom connections, she may be reached at ekmeineke@ucdavis.edu. (See complete list of spring seminars.)

Related Resources:

First report of the beech leaf disease nematode Litylenchus crenatae mccannii (Nematoda: Anguinidae) in Michigan (Plant Disease journal, Nov. 22, 2022)
Paulo Vieira: Google scholar, Twitter accounts

Professor Irene Garcia Newton of the Indiana University Department of Biology, Bloomington, will present a UC Davis Department of Entomology and Nematology Seminar on "Friends with Benefits: Protective Microbial Symbiosis in the Honey Bee" on Wednesday, May 10.

Her talk will be in 122 Briggs Hall and also will be virtual. The Zoom link:
https://ucdavis.zoom.us/j/95882849672.

"The most important agricultural insect, the honey bee, houses multiple bacterial symbionts that provide distinct benefits under environmental stress," Newton says in her abstract. "Our lab has been at the forefront of identification and characterization of the honey bee microbiome, using a polyphasic approach combining in vivo, in vitro, microbiological, and 'omics assays. I will present our most recent results on the microbe Bombella apis - who it is, what it's doing in association with the bee, and its evolution in symbiosis."

A pre-seminar coffee will take place from 3:30 to 4:10 p.m. in 158 Briggs. 

Irene, a first-generation, Latina scientist, received her doctorate from Harvard University in 2008 and served as a postdoctoral fellow at Tufts University from  2008 to 2010. She grew up in south Florida, the daughter of immigrant parents from Cuba and the Dominican Republic. She began her research experience as an undergraduate student at Swarthmore College under Rachel Merz.

She continued her training as a Howard Hughes predoctoral fellow with Colleen Cavanaugh at Harvard University, where she completed her dissertation, focused on functional genomics in deep sea hydrothermal vent symbionts. She joined the faculty of Indiana University in 2011.

"The Newton Laboratory is broadly interested in host-associated microbes," she writes on her website. "We study who those microbes are, what those microbes are doing , how they persist and infect and what the consequences are to their genomic evolution. Projects in the laboratory range from highly mechanistic and cell biological to ecological and bioinformatic."

For her work with IU students, she won the Outstanding Mentor Award (2022) and the Trustees Teaching Award (2017). Her other honors include American Academy of Microbiology Fellow, 2023; American Society for Microbiology Honorary Diversity Lecturer Award, 2023; American Association for the Advancement of Science Fellow, and 2022 Woodrow Wilson Foundation Fellow, 2013.

Department seminar coordinator is urban landscape entomologist Emily Meineke,  assistant professor.   For technical issues regarding Zoom connections, she may be reached at ekmeineke@ucdavis.edu. (See complete list of spring seminars.)

John Hargrove, director emeritus of the South African Centre for Epidemiological Modelling and Analysis, will present a UC Davis Entomology and Nematology seminar on "Tsetse, Trypanosomiasis, and Climate Change: What Can We Learn from Field Data Collected in the Zambezi Valley of Zimbabwe?" on Wednesday, May 3 in 122 Briggs Hall.

His seminar begins at 4:10 p.m. and also will be on Zoom:
https://ucdavis.zoom.us/j/95882849672.

Host is UC Davis distinguished professor James R. Carey, UC Davis Department of Entomology and Nematology.

"African Trypanosomiasis, also known as 'sleeping sickness,' is caused by microscopic parasites of the species Trypanosoma brucei," according to the Centers for Disease Control and Prevention. "It is transmitted by the tsetse fly (Glossina species), which is found only in sub-Saharan Africa."

"Insect vectors attract small fractions of the funding spent on studying and controlling the diseases they transmit," Hargrove says in his abstract. "Emphasis on vector studies for tsetse (Glossina spp) have, however, resulted in several novel vector and disease control options. Experiments carried out over the past 60 years at Rekomitjie Research Station in the Zambezi Valley of Zimbabwe, together with daily meteorological readings, provide a platform for studying the effects of climate change on the population dynamics of tsetse species occurring around Rekomitjie. Rates of pupal production and development, of abortion rates and of mortality among immature and adult stages of the flies are all highly correlated with temperature. Methods used to estimate such relationships in the field will be discussed and the relationships are used in explaining the sudden collapse in tsetse populations during the past decade, consequent on significant increases in temperature, particularly in the hot dry season."

Hargrove, associated with the International Clinics on Infectious Disease Dynamics and Data Program (ICI3D), is a faculty member with the Clinic on Meaningful Modeling of Epidemiological Data (MMED) and the Clinic on Dynamical Approaches to Infectious Disease Data (DAIDD). He is a senior research fellow for the South African Centre for Epidemiological Modelling and Analysis, Stellenbosch University, Stellenbosch, South Africa, and a professor emeritus of mathematical sciences at Stellenbosch University.

Hargrove served as the inaugural director of the South African Centre for Epidemiological Modelling and Analysis (SACEMA). The precursors for MMED and DAIDD were launched in 2006 at the beginning of his directorship; he has been involved continuously as an instructor in the program since, according to his biography on ICI3D. Over the past nearly 50 years, Hargrove has combined fieldwork and mathematical epidemiology to understand the population dynamics and control of tsetse flies, the vectors of human African Trypanosomiasis.

He focuses his current research on the modelling population dynamics, with a particular focus on how increasing temperatures in Africa will affect tsetse distribution. This work involves improving estimation of mortality in adult and immature stages of the fly. Since 1999, he has also focused on the analysis and modelling of data in the world of HIV. Current interest are in improving the use of biomarkers for the accurate estimation of HIV incidence.

He holds a bachelor's degree in zoology (1968) from the University of Oxford; a master's degree in biomathematics  (1981) from UCLA, and a doctorate in insect physiology (1973) from the University of London.

Department seminar coordinator is urban landscape entomologist Emily Meineke,  assistant professor.   For technical issues regarding Zoom connections, she may be reached at ekmeineke@ucdavis.edu. (See complete list of spring seminars.)

Resource: 
SERVIR--From Space to Tsetse Fly 
World Health Organization: Trypanosomiasis (Human African Sleeping Sickness)