- (Focus Area) Pest Management
And UC Davis plant nematologist Shahid Siddique, formerly with the University of Bonn, is at the heart of it.
He led a 10-member international team in discovering the role of a plant's endodermal barrier system in defending against plant-parasitic nematodes.The Plant Journal published the research, Root Endodermal Barrier System Contributes to Defence against Plant‐Parasitic Cyst and Root-Knot Nematodes, in its July 19th edition.
Fast forward to October.
Research Highlight Editor Lysa Maron chose the work as the "research highlight" in her Oct. 14th article, “Breaking or Sneaking into the Fortress: the Root Endodermis is a Defence Wall Against Nematode Infection.” The journal also showcased the team's nematode image on the cover.
What's the significance of the research?
“We discovered that the integrity of the endodermis—a specialized cell layer that surrounds the vascular system and helps regulate the flow of water, ions and minerals--is important to restrict nematode infection,” said Siddique, an assistant professor in the UC Davis Department of Nematology who joined the faculty in March after serving several years at the University of Bonn.
“We found that having defects in endodermis make it easier for parasites to reach the vascular cylinder and establish their feeding site. Although, this finding is a result of basic research, it opens new avenues to for breeding resistance against cyst nematodes in crops.”
Maron noted that “Roots are a truly amazing plant structure: they conquer the underground, form complex structures that anchor the plant, let water and nutrients in, but must not dry out. Roots store energy, send signals to the aboveground parts of the plant and to neighbors, and defend the plant against soil-borne pathogens. Within the root, the endodermis is the barrier that separates the inner vasculature from the outer cortex. If the root is a fortress, the endodermis is the gated wall. Cell wall reinforcements such as the casparian strip (CS), lignin deposition, and suberin seal the apoplast of the endodermis throughout different parts of the root. These reinforcements allow the diffusion of water and nutrients to and from the vascular tissue while blocking its penetration by pathogens such as bacteria and fungi (Enstone et al., 2002).”
“But roots also face pathogens of a different kind: root-infecting, sedentary endoparasites such as cyst nematodes (CNs) and root-knot nematodes (RKNs),” Maron wrote. “These pathogens infect a variety of important crops and cause significant yield losses (Savary et al., 2019).”
Maron quoted Siddique: “According to Siddique, investigating root traits that affect plant-nematode interactions is important for finding new strategies for plant protection. Screening for natural variation in suberin- and lignin-related traits might help identify and develop stronger fortresses, i.e., plants with enhanced resilience against pathogens, drought, and nutrient deficiency.”
Siddique collaborated with scientists from Germany, Switzerland and Poland: Julia Holbein, Rochus Franke, Lukas Schreiber and Florian M. W. Grundler of the University of Bonn; Peter Marhavy, Satosha Fujita, and Niko Geldner of the University of Lasuanne, Switzerland; and Miroslawa Górecka and Miroslaw Sobeczak of the Warsaw University of Life Sciences, Poland.
“Plant-parasitic nematodes are among the most destructive plant pathogens, causing agricultural losses amounting to $80 billion annually in the United States,” said Siddique in an earlier news story. “They invade the roots of almond, tomato, beets, potato or soybeans and migrate through different tissues to reach the central part—the vascular cylinder--of the root where they induce permanent feeding sites.”
“These feeding sites are full of sugars and amino acids and provide the parasite all the nutrients they need,” Siddique explained. “A specialized cell layer called the endodermis surrounds the vascular system and helps regulates the flow of water, ions and minerals into and out of it. However, the role of endodermis in protecting the vascular system against invaders such as nematodes had remained unknown.
The German Research Foundation funded the research.
So here are all these milkweed bugs clustered on a showy milkweed leaf, Asclepias speciosa. It's early morning and the red bugs are a real eye opener.
They're seed eaters, but as Hugh Dingle, emeritus professor of entomology, UC Davis Department of Entomology and Nematology says: "They are opportunistic and generalists." They not only eat seeds, but monarch eggs and larvae, as well as the oleander aphids that infest the milkweed.
But wait, one of these is not like the other.
A lady beetle, aka ladybug, photobombs the scene. It sleeps with them and eats (aphids) with them. They are sharing the same food source: oleander aphids.
Wait, there's more! "Not So Heartless: Functional Integration of the Immune and Circulatory Systems of Mosquitoes."
This may not be the proverbial heart-stopping seminar, but it promises to be an eye opener by a medical entomologist and captivating speaker.
Julián Hillyer, associate professor of biological sciences, Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, Tenn., will deliver that seminar at 4:10 p.m., Wednesday, Oct. 23, in 122 Briggs Hall, as part of the weekly UC Davis Department of Entomology and Nematology seminars.
"Mosquitoes--like all other animals--live under constant threat of infection," Hillyer says in his abstract. "Viral, bacterial, fungal, protozoan and metazoan pathogens infect mosquitoes through breaches in their exoskeleton and following ingestion. Because these pathogens pose a threat to their survival, mosquitoes have evolved a powerful immune system."
In his seminar, Hillyer will present his laboratory's work characterizing the circulatory and immune systems of the African malaria mosquito, Anopheles gambiae. "Specifically," he says. "the talk will describe the structural mechanism of hemolymph (insect blood), circulation in different mosquito life stages, and the role that immune cells, called hemocytes play in the killing of pathogens by phagocytosis, melanization and lysis. Then I will describe the functional integration of the circulatory and immune systems a process that is manifested differently in larvae and adults. Specifically, the infection of an adult mosquito induces the aggregation of hemocytes at the abdominal ostia (valves) of the heart--where they sequester and kill pathogens in areas of high hemolymph flow--whereas the hemocytes of larvae aggregate instead on respiratory structures that flank the posterior in current openings of the heart."
"This research," Hillyer explains, "informs on the physiological interaction between two major organ systems and uncovers parallels between how the organ systems of invertebrate and vertebrate animals interact during the course of an infection."
What does the mosquito heart look like? Check out former Vanderbilt graduate student Jonas King's prize-winning image--a fluorescent image of the heart of a mosquito. It won first place in Nikon's "Small World'" photomicrography competition in 2010. King's image shows a section of the tube-like mosquito heart magnified 100 times. At the time he was a member of Hillyer's research group and is now an assistant professor at Mississippi State University.
In a piece by David Salisbury of Vanderbilt News, Hillyer related that "Surprisingly little is known about the mosquito's circulatory system despite the key role that it plays in spreading the malaria parasite. Because of the importance of this system, we expect better understanding of its biology will contribute to the development of novel pest- and disease-control strategies.”
"The mosquito's heart and circulatory system is dramatically different from that of mammals and humans," wrote Salisbury in the Oct. 15, 2010 piece. "A long tube extends from the insect's head to tail and is hung just under the cuticle shell that forms the mosquito's back. The heart makes up the rear two-thirds of the tube and consists of a series of valves within the tube and helical coils of muscle that surround the tube. These muscles cause the tube to expand and contract, producing a worm-like peristaltic pumping action. Most of the time, the heart pumps the mosquito's blood—a clear liquid called hemolymph—toward the mosquito's head, but occasionally it reverses direction. The mosquito doesn't have arteries and veins like mammals. Instead, the blood flows from the heart into the abdominal cavity and eventually cycles back through the heart."
“The mosquito's heart works something like the pump in a garden fountain,” Hillyer told Salisbury.
Hillyer was a Vanderbilt Chancellor Faculty Fellow (2016-2018) and was awarded the 2015 Henry Baldwin Ward Medal by the America Society of Parasitologists. He was elected to the Council of the American Society of Parasitologists, serving from 2012-2016. Other recent awards: the 2011 Jeffrey Nordhous Award for Excellence in Undergraduate Teaching and the 2012 Recognition Award in Insect Physiology, Biochemistry and Toxicology from the Southeastern Branch of the Entomological Society of America.
Hillyer received his master's degree and doctorate from the University of Wisconsin-Madison under the mentorship of Ralph Albrecht and Bruce Christensen, respectively. He completed a postdoctoral fellowship under the mentorship of Kenneth Vernick at the University of Minnesota, now with Institut Pasteur. In 2007, Hillyer moved to Nashville, Tenn. to establish Vanderbilt University's mosquito immunology and physiology laboratory. (See more.)
The Hillyer Lab is interested in basic aspects of mosquito immunology and physiology, focusing on the mechanical and molecular bases of hemolymph (blood) propulsion, and the immunological interaction between mosquitoes and pathogens in the hemocoel (body cavity)," according to his website. "Given that chemical and biological insecticides function in the mosquito hemocoel, and that disease-causing pathogens traverse this compartment prior to being transmitted, we expect that our research will contribute to the development of novel pest and disease control strategies."
Host is Olivia Winokur, doctoral student in the Chris Barker lab. Community ecologist Rachel Vannette, assistant professor, Department of Entomology and Nematology, coordinates the weekly seminars. (See list of seminars)
The highly respected California Academy of Sciences greeted its 2019 Class of Fellows on Oct. 15, and one of them is a pollination ecologist from the University of California, Davis.
Professor Neal Williams of the UC Davis Department of Entomology and Nematology was inducted into the scientific organization at the annual Bay Area gathering of the Fellows. The group includes more than 450 distinguished scientists who have made notable contributions to science.
Fellows nominate others for the high honor, and then the California Academy of Sciences' Board of Trustees votes on the nominees. James R. Carey, distinguished professor of entomology, nominated Williams, with Claire Kremen of the University of British Columbia, formerly of UC Berkeley, seconding the nomination. Maverakis was nominated by Walter Leal, distinguished professor, UC Davis Department of Molecular and Cellular Biology, and a former chair of the entomology department.
In his letter of nomination, Carey wrote that Williams is “widely known and respected for his excellence in research, extension, outreach, teaching and leadership” and “is not only one of the stars of our campus, and the UC system, but is an internationally recognized leader in pollination and bee biology and strong voice in the development of collaborative research on insect ecology. He has organized national and international conferences, leads scores of working groups, and guides reviews of impacts of land use and other global change drivers on insects and the ecosystem services they provide.”
The UC Davis professor served as co-chair (with Extension apiclturist Elina Lastro Niño) of the seventh annual International Pollinator Conference, a four-day conference held July 17-20 on the UC Davis campus. The global conference focused on pollinator biology health and policy.
In his work--a labor of love--Williams seeks and finds found common solutions for sustaining both wild and managed bees and communicates that information to the public and stakeholder groups. Said Carey: “This is a critical perspective in natural and agricultural lands, but also in urban landscapes in northern and southern California.”
Each year the UC Davis professor speaks to multiple beekeeper, farmer and gardener groups, and provides guidance to governing bodies, including the state legislature, and environmental groups. He and his lab are involved in a newly initiated California Bombus assessment project, which is using both museum and citizen scientist records to understand past, current and future distributions and habitat use by bumble bees. This program will host a series of workshops this spring and summer open to practitioners and the public.
Williams received his doctorate in ecology and evolution in 1999 from the State University of New York, Stony Brook and served as an assistant professor in the Department of Biology at Bryn Mawr (Penn.) College from 2004 to 2009. He joined the UC Davis faculty in 2009, advancing to full professor in 2017.
His honors and awards are numerous. Williams was part of the UC Davis Bee Team that won the Team Research Award from the Pacific Branch, Entomological Society of America (PBESA) in 2013. In 2015, he was named a five-year Chancellor's Fellow, receiving $25,000 to support his research, teaching and public service activities. And then earlier this year, Williams received PBESA's Plant-Insect Ecosystems Award, presented annually for outstanding accomplishments in the study of insect interrelationships with plants.
In addition to Carey, five others affiliated with UC Davis Department of Entomology and Nematology are Fellows of the California Academy of Sciences:
- Professor Phil Ward, ant specialist
- Frank Zalom, integrated pest management specialist and distinguished professor of entomology. He is a past president of the Entomological Society of America
- Robert E. Page Jr., bee scientist and UC Davis distinguished emeritus professor. He is a former chair of the UC Davis Department of Entomology and provost emeritus of Arizona State University
- Walter Leal, distinguished professor, UC Davis Department of Molecular and Cellular Biology, and a former chair of the entomology department; and
- Visiting scientist Catherine Tauber, formerly of Cornell University.
Former Fellows from the UC Davis entomology department include Robbin Thorp (1933-2019), distinguished emeritus professor of entomology, and visiting scientist Maurice Tauber (1931-2014), formerly of Cornell University.
But the Bohart Museum of Entomology open house on "Parasitoid Palooza" on Saturday, Oct. 19 from 1 to 4 p.m. promises to provide a touch of Halloween, what with all the Halloween decorations and the pests that eat pumpkins and the parasitoids that eat their hosts.
The open house, free and family friendly, takes place in Room 1125 of the Academic Surge Building on Crocker Lane, UC Davis campus.
"We will celebrate all things parasitoid with (senior museum scientist) Steve Heydon and with some parasite input from (graduate student) Socrates Letana," said Tabatha Yang, education and outreach coordinator. Heydon, who researches Pteromalids or jewel wasps, will display his work and answer questions.
There are some 3,450 described species of Pteromalids, found throughout the world and in virtually all habitats. Many are important as biological control agents.
"An insect parasitoid is a species whose immatures live off of an insect host, often eating it from the inside out," Yang said. "It is part of their life cycle and the host generally dies."
- Display of pumpkin-eating pests orange from Jasmin Ramirez Bonilla of the Ian Grettenberger lab, UC Davis Department of Entomology and Nematology. These include the orange and black Harlequin bugs and cucumber beetles (See UC Statewide Integrated Pest Management Program website)
- Family craft activity: no sew, sock caterpillars with parasitoid eggs on the outside.
- Sampling of Chirp Chips, from the Bohart Museum's recent entomophagy open house
The Bohart Museum, directed by Lynn Kimsey, professor of entomology at UC Davis, houses a global collection of nearly eight million specimens. It is also the home of the seventh largest insect collection in North America, and the California Insect Survey, a storehouse of the insect biodiversity.
Special attractions include a “live” petting zoo, featuring Madagascar hissing cockroaches, walking sticks, praying mantids and tarantulas. Visitors are invited to hold some of the insects and photograph them. The museum's gift shop, open year around, includes T-shirts, sweatshirts, books, jewelry, posters, insect-collecting equipment and insect-themed candy.
The Bohart Museum holds special open houses throughout the academic year. Its regular hours are from 9 a.m. to noon and 1 to 5 p.m. Mondays through Thursdays. The museum is closed to the public on Fridays, Saturdays and Sundays and on major holidays. Admission is free.
More information on the Bohart Museum is available by contacting (530) 752-0493 or emailing firstname.lastname@example.org or Tabatha Yang at email@example.com.