Research entomologist Daniel Hasegawa of the Crop Improvement and Protection Research Unit, Agricultural Research Service, U. S. Department of Agriculture, will speak on "Landscape and Molecular Approaches for Managing Thrips and Thrips-Transmitted Viruses in the Salinas Valley" at the UC Davis Department of Entomology and Nematology's first seminar of the winter quarter on Wednesday, Jan. 20.
"In 2019-2020, lettuce production in the Salinas Valley of California was devastated by thrips-transmitted impatiens necrotic spot virus (INSV)," Hasegawa says in his abstract. "Due to the inherent challenges in managing thrips using conventional chemical tactics, and no direct means for managing the virus, there is a strong need for new management strategies. This seminar will provide an overview of (1) the challenges in managing thrips and INSV in lettuce production, (2) what we've learned about the epidemiology of thrips and INSV, and (3) opportunities to improve cultural practices and develop biotechnology tools, such as RNAi for managing thrips and INSV in the Salinas Valley."
Hasegawa joined the Salinas USDA-ARS team in May 2019 after serving as a postdoctoral research associate (molecular biology) for three years with USDA-ARS in Charleston, S. C. He specializes in vector entomology, molecular biology and biotechnlogy. "My lab uses a variety of techniques to understand insect vector-virus relationships that impact plant health and agriculture," he says on Linked In. "We use molecular, genetic, and epidemiological concepts to understand drivers of vector-borne transmission of pathogens and utilize genetic technologies (e.g. RNAi and CRISPR), to improve agriculture productivity and sustainability."
Hasegawa received his bachelor of science degree in biochemistry in 2007 from UC Riverside and his doctorate in biology from Clemson University in 2013.
The mission of the Crop Improvement and Protection Research Unit is to improve germplasm of lettuce, spinach and melon, determine basic biology of viral, fungal and bacterial diseases affecting these crops, develop alternatives to methyl bromide as a soil fumigant for control of soilborne pests in strawberry and vegetables, reduce postharvest losses of lettuce, develop scientifically based organic crop production practices, and develop methods for control of weeds. See more on the Pacific West Area website./span>
The article, “Genome-Enabled Insights into the Biology of Thrips as Crop Pests,” is published in the journal BMC Biology. It is the work of 57 scientists on five continents.
“This project represents over eight years of work by at least 17 laboratories across the globe,” said Professor Ullman, a former chair of the entomology department and a fellow of the Entomological Society of America and the American Association for the Advancement of Science. Her laboratory worked closely with project leader and first author Dorith Rotenberg of North Carolina State University. Project scientist Sulley Ben-Mahmoud of the Ullman lab is the paper's third author.
The western flower thrips, Frankliniella occidentalis, causes billions of dollars a year in damage worldwide. Native to Western North America and about the size of a pinhead, the insect feeds on a wide array of food, fiber, and ornamental crops and transmits plant viruses that cause significant economic damage.
“The western flower thrips and the viruses it transmits, including tomato spotted wilt virus, is important to California agriculture, causing serious problems for tomato growers, pepper growers and growers of leafy greens,” Ullman said. The tomato spotted wilt virus infects more than 1000 plant species, ranging from tomatoes, tobacco and peanuts to pansies and chrysanthemums.
“This system has been a central element of my research program for over 30 years," Ullman said, "and I am extremely excited to see this important resource made available as a tool to help us understand and control these important pests.”
In their abstract, the authors wrote that the publication should lead to “understanding the underlying genetic mechanisms of the processes governing thrips pest and vector biology, feeding behaviors, ecology, and insecticide resistance.”
“Attaining a tool to unlock the mysteries of western flower thrips biology and interactions with plant viruses in the family Tospoviridae has been a dream of mine through over 30 years of working on this system,” Ullman commented. “The genome project enabled the discovery of salivary gland-enriched genes in this tiny insect that is now guiding work that Sulley Ben-Mahmoud and I are doing with collaborators Dorith Rotenberg, Joshua Benoit, Samuel Bailey and Priya Rajarapu to identify salivary proteins acting as effectors.”
Rotenberg launched the project in 2011 after delivering a lecture at the 5th Annual Arthropod Genomics Symposium in Kansas City, Mo. “At the time, I was very naïve about what it would take to steward a thrips genome project, but was excited about what a genome sequence could mean for those of us interested in the molecular basis of thrips vector competence and thrips pest biology.”
The team worked with the i5k initiative, an international effort to sequence and analyze 5,000 arthropod genomes. This includes insects, crustaceans, spiders and other creatures with exoskeletons, segmented bodies and pairs of jointed legs.
The Rotenberg-led thrips genome project team first developed an inbred line of thrips. Baylor College of Medicine's Human Genome Sequencing Center sequenced and assembled the genome. The Rotenberg team then verified the location of 10 percent of the nearly 17,000 genes and annotated them to better understand what they do.
The authors report that some genes are associated with the thrips' ability to develop and reproduce, to find plant hosts through taste and smell, to protect against pathogens, and to detoxify plant-produced chemicals and insecticides. The latter is of special interest because thrips are known for rapidly building up resistance to chemicals.
Said Rotenberg: “I discovered over the course of eight years that the thrips genome consortium created something much greater than the sum of its parts. I was fortunate to recruit 17 international groups with expertise in arthropod genomics, evolution and development, thrips vector biology and microbe (and virus)-insect interactions to volunteer their time not only to manually correcting and annotating gene models, but to use expression evidence to explore with me new frontiers in thrips innate immunity, lateral gene transfers of bacterial origin, thrips-plant interactions, thrips development and reproduction. These world-renowned experts helped shape the landscape for contemporary molecular and evolutionary studies of Thysanoptera and in my opinion, as important, helped shape the careers of several undergraduates, grad students and postdoctoral scholars involved in the process. I am excited and proud of what we accomplished together.”
Ben-Mahmoud described the research as “a monumental feat, and I am proud of my contributions to it. I have no doubt that the paper will inform and benefit the studies of many other international insect-vector research groups, not only those who work directly with the western flower thrips.”
UC Davis entomology professor Diane Ullman is off to France in November but it's not a dream vacation. It's a dream opportunity: a Fulbright-funded scholarship to research plant virus-insect interactions. She will be studying plant viruses and the insects that transmit them.
Her sabbatical will take her to Montpellier, France, to work with renowned vector biologists Stéphane Blanc and Marilyne Uzest at the National Institute of Agronomic Research (INRA) on the Campus International de Baillarguet near Montpellier. The Biologie et Génetique des Interactions Plante-Parasite (UMR-BGPI, CIRAD-INRA-SupAgro) focuses on plant pathogens and their interactions with arthropod vector in agroecosystems. She will be studying plant viruses in the genus Orthotospovirus (family Tospoviridae). This family holds the only plant infecting members in the order Bunyaviriales. The other viruses in this order infect animals and humans and are transmitted primarily by mosquitoes and ticks.
"New evidence suggests the bunyavirus, Rift valley fever virus (an animal infecting member of the Bunyavirales), uses a multicomponent system in which individual virions do not co-package all segments and infection requires virion populations, a possibility with profound implications for virus evolution and antiviral target discovery,” said Ullman, an international authority on orthotospoviruses. “I will test the hypothesis that orthotospoviruses use multicomponent genome organization and segment copy regulation occurs in their hosts.”
The UC Davis professor has researched insect-transmitted plant pathogens for 37 years, targeting numerous insect vector species--from thrips, whiteflies, and leafhoppers to mealybugs--and the plant pathogens they transmit, including viruses, phytoplasma and bacteria.
“Sustainable management of insect-transmitted pathogens is a key concern for food production in France and the United States,” Ullman wrote in her Fulbright application. “Both countries grow many of the same crops and growers face similar challenges from insect-transmitted plant viruses. Current management strategies rely heavily on pesticides that may cause significant health and environmental concerns, including damage to bees and other pollinators, as shown with neonicotinoid pesticides. Clearly, better knowledge about these insect-transmitted viral systems…has potential to reduce pesticide use by providing novel and innovative technologies to manage tospoviruses and thrips in France and the United States.”
Ullman, former chair of the Department of Entomology and Nematology and a former associate dean with the UC Davis College of Agricultural and Environmental Sciences, expects the project will build strong research relationships between UC Davis and Montpellier that will lead to grant applications for international research and scholarly exchange opportunities for scientists, students and post-doctoral scholars.
You could, but you wouldn't.
O'Donnell, a noted USDA thrips expert and educator with three degrees from the University of California, Davis, knows well those tiny insects that cause billions worth of damage annually to U.S. agricultural crops. She's studied thrips for 18 years and worked on thrips programs with the U.S. Department of Agriculture (USDA) for the last seven years.
Today O'Donnell continues to target thrips in her new position with the USDA. As of April 6, she is the National Thysanoptera Taxonomist with the National Identification Services (NIS) at the Systematic Entomology Laboratory (SEL) in Beltsville, MD.
Specifically, her position is with the National Identification Services (NIS) of the Plant Protection and Quarantine (PPQ) program of USDA's Animal and Plant Health Inspection Service (APHIS) or what USDA officials refer to as "APHIS PPQ NIS." The Thysanoptera collection of the Systematic Entomology Laboratory (SEL) is housed with USDA's Agricultural Research Service (ARS).
“I love my work,” she said, “and I love my favorite insect, thrips.”
"Cheryle is a tremendously talented biologist and she holds a real fascination for thrips, their classification, host relationships and biology," said former major professor Diane Ullman, professor in the UC Davis Department of Entomology and Nematology. "She will do a fantastic job in this position, which will be important to the global community studying thrips and trying to develop management strategies."
The Beltsville position, last held in 1999 by mentor Sueo Nakahara, will involve working for National Identification Services in the Agricultural Research Station and with the National Museum of Natural History Thysanoptera collection.
Thrips, barely visible to the naked eye, heavily damage fruits, vegetable and horticultural crops, so much so that they can—and do--pose a biosecurity threat. In 1996, Cuba's Fidel Castro accused the United States of aerially releasing Thrips palmi over potato fields.
“Of the more than 5000 species of thrips known in the world, some are serious pests, and some are beneficial as pollinators and predators,” O'Donnell said. “Some thrips transmit plant diseases, such as the tomato spotted wilt virus and the Impatients necrotic spot viruses.”
“To monitor agricultural crops effectively, it's important to be able to identify them, but it's difficult to do so without understanding thrips taxonomy and identification,” O'Donnell said. “Thrips are so small—one millimeter long or less--that they're like a speck. Inspectors see larvae, eggs and adults on plant material coming in. It's difficult to separate species at the life stage of eggs, larvae and adult males.”
O'Donnell recalled that her first position with USDA was as an area identifier of thrips. “It encompassed the identification of pests intercepted in cargo and baggage from origins around the world,” she said. “ My first assignment was at the Plant Inspection Station in Nogales, Ariz., one of the largest Mexican produce importing ports. I then transferred to Florida to the Miami Plant Inspection Station where the majority of cut flowers enter into the U.S. from Central and South America.“ She also saw temporary duty in Blaine, Wash., as an identifier and then transferred to the Plant Inspection Station in San Diego.
"In Miami, thrips larvae are intercepted regularly on cut flowers coming into the U.S. from south and Central America," O'Donnell said. "We did not have the tools to separate the quarantine significant thrips from those that are not of concern at the larval stage. My suspicion has been that there were a handful of thrips species of concern whereas the majority were not. The PPQ agency developed a pilot program to conduct molecular pilot program in Miami which may lead to a policy change in how we make quarantine decisions regarding the larvae intercepted. I have been the coordinator of this pilot program."
"There were several thrips species coming in from Mexico listed as quarantine significant that I knew to be found within the U.S. and those species have been removed from the quarantine status."
O'Donnell published “job aids” on the USDA website that include multilevel and gender identification, plus digital imaging. Over the last decade, she has organized and conducted thrips workshops, produced videos, and published research. She edited a monthly Pest Interception Report and co-edited the Looking Glass quarterly journal on activities at plant inspection stations. She also conducted outreach sessions at schools, universities and trade shows.
Learning about thrips came naturally. "I follow in the footsteps of my great uncles and my father," O'Donnell related. "My uncle, Richard Clemens, worked for CDFA at the port of Los Angeles and at the ferry building in San Francisco. My uncle, Michael Clemens, worked with CDFA in Smith River and Winterhaven, CA. Both were looking for agricultural pests of quarantine significance. Last year in San Diego when I was cleaning out some older documents at the plant inspection station, I found a request and a few letters (1940s) from my uncle Richard Clemens asking the area identifier in San Diego at the time for information on new pests he found in California. It's a small world!"
O'Donnell arrived at UC Davis in the mid-1990s as a single mom raising a young daughter. A former employee of an electronic manufacturing business, she enrolled at UC Davis to study ornamental horticulture. At the same time she managed a landscaping business.
“There were many times I was doubtful that I could continue to meet the demands of my chosen field,” O'Donnell said, crediting her family, friends and UC Davis scientists with offering her the support she needed to complete her education.
“When I began my education at UC Davis I chose Agricultural Systems and the Environment as my major. However, while working on my bachelor's degree I became infatuated with insects and their interaction with plants,” she said, which led to her endearing nickname, “The Bug Lady.”
“I continued my academic career in entomology and have never regretted that decision. I was privileged to study under the guidance of Professors Michael Parrella and Diane Ullman.” They, along with Professors Jay Rosenheim, Lynn Kimsey and Penny Gullan “became not only my instructors, guidance counselors, but also my mentors throughout my years at UC Davis.”
Parrella and O'Donnell collaborated with Moritz, (University of Halle-Wittenberg in Germany) on a grant to produce a molecular and morphological identification key, now available online.
An avid entomologist with a passion for soft spot for thrips—“my favorite insect!”--O'Donnell takes every opportunity to discuss the insect order, Thysanoptera, and train others to identify them. She provides training tools and workshops to assist with identification and curation of thrips.
In addition to her doctorate, O'Donnell holds two other degrees from UC Davis: a bachelor's in agricultural systems and the environment (1997) and a master's degree in plant protection and pest management (2000). Her master's thesis: “The Biology and Identification of Selected North American Thysanoptera Associated with Ornamental Plants.” Her dissertation covered “Color Morphology of the Western flower thrips in California and virus-vector relationships of members in the Terebrantia: Thysanoptera (a molecular and morphological analysis).” She praised her advisors, Penny Gullan, insect systematics; Diane Ullman, virus vectors; Steve Nadler, molecular phylogeny; and Parrella, integrated pest management.
While at UC Davis, O'Donnell organized and conducted a three-day thrips workshop funded by a biosecurity grant from USDA. It drew a capacity crowd.
The UC Davis-product encourages students to follow their dreams. “Focus on your goals, never deviate from those goals, and never allow obstacles to get in the way,” she advises. It is a difficult and challenging path you have chosen but it will be worth all the hard work. The UC Davis community, the ‘village' which supports you, is an experience you will never forget and the payoff will be great throughout your life.”
He will be hosted by colleague and collaborator Diane Ullman, professor of entomology at UC Davis.
"Thrips-transmitted, tomato spotted wilt virus (TSWV), which has an extremely broad host range and is transmitted exclusively by thrips, ranks among the most economically important plant viruses affecting crops worldwide," Kennedy says in his abstract.
"Effective management of this virus in commercial crop production systems requires an understanding of the factors that determine the timing and magnitude of virus spread. This seminar will discuss the ways in which seasonal weather events influence the dispersal dynamics of vector thrips populations, the abundance of virus inoculum sources in the landscape, and ultimately the timing and magnitude of TSWV spread into susceptible crops. It will further provide an illustration of how efforts to model these relationships improved understanding of the epidemiology of TSWV and led to the development of a TSWV risk prediction tool that is now being used in pest management decision making."
Kennedy, past president of the Entomological Society of America (ESA), is an ESA fellow, recipient of the ESA's Award for Excellence in Entomology and chaired the Entomological Foundation, a non-profit educational foundation whose mission is “to excite and educate young people about science through insects.”
He also served as program manager for the National Research Initiative, affiliated with the U.S. Department of Agriculture (USDA), and on numerous advisory panels for the USDA, U.S. Environmental Protection Agency and the National Research Council, addressing issues relating to pesticides, pest resistance, integrated pest management, and biotechnology.
Kennedy holds a bachelor's degree in entomology from Oregon State University and a doctorate in entomology from Cornel University. He served as assistant professor of entomology at UC Riverside from 1974-1976, before joining the faculty at North Carolina State University.
Kennedy writes on his website: "Research in my program focuses on understanding the ecology and life systems of arthropods affecting agricultural crops and applying that understanding to improve the effectiveness and sustainability of arthropod management in vegetable crops. We study fundamental interactions and processes that influence pest status, population dynamics and the insect/crop interactions that result in damage. We apply the resulting information in combination with new technologies to enhance IPM. Areas of emphasis include insect-plant interactions, resistance management, landscape scale population dynamics, and epidemiology and management of insect transmitted plant viruses. Current research projects focus on understanding the determinants of tospovirus transmission by thrips in relation to epidemiology and management of tomato spotted wilt virus and on the development of reduced risk arthropod management systems for fruiting vegetables. These efforts include both field and laboratory research and collaborations with faculty in Entomology, Horticulture and Plant Pathology at NCSU and colleagues at other institutions. We also work closely with extension colleagues, growers and the agribusiness community to facilitate implementation of new pest management practices."
The seminar will be recorded for later viewing on UCTV Seminars.