California Ag Network

Tag: UC Davis Department of Entomology and Nematology

  • UC Davis Nematologists Share International Spotlight

    UC Davis nematologists shared the international spotlight at the 64th annual meeting of the Society of Nematologists (SON), held recently in Victoria, British Columbia.

    Doctoral candidate Alison Blundell of the laboratory of associate professor Shahid Siddique, UC Davis Department of Entomology and Nematology, received the 2025 John M. Webster Outstanding Student Award from the Society of Nematologists at its recent meeting in Victoria, British Columbia. As the recipient of the $1500 prize, she presented a 30-minute talk on her research,   “Overcoming Resistance: Unraveling The Mechanisms Behind Root-knot Nematode Evasion of Tomato Mi-1 Gene.”

    Siddique delivered a keynote address, “Biotechnology and Genomics for Sustainable Nematode Management” in the international symposium series, which was sponsored by a grant received from the Organization for Economic Co-Operation and Development (OECD) and Co-Operative Research Programme: Sustainable Agricultural and Food Systems. It centered on the SON conference theme,  “Nematodes on the Move: Building Resilience and Sustainability through International Collaboration and Better Policies.”

    Siddique presented his keynote address under the realm of the symposium, “Reducing the Global Movement of Plant-Parasitic Nematodes and Rethinking Control Strategies,” Part 2.  Part 1 focused on “Understanding the Impact of Plant-Parasitic Nematodes on Global Food Security and Trade in a Changing World.”

    Siddique was one of 14 keynote speakers from 11 countries across 5 continents participating in the discussion, which consisted of three plenary sessions.

    Two doctoral candidates in the Siddique lab, Veronica Casey and Alison Blundell each won a travel award to attend the conference. Casey received the Hubbard Ag Science Award, and Blundell, the Bayer Award.

    Presenting talks were UC Davis Distinguished Professor Steve Nadler, former chair of the Department of Entomology and Nemtology; Amanda Hodson, assistant professor, and two postdoctoral researchers in the Siddique lab, Vera Putker and Bardo Castro.

    Nadler discussed “Phylogenetic Inference and the Diversity of Animal-Parasitic Nematodes”;  Hodson,  “The Relationship Between Nematode Indicators and Soil Carbon Pools across Managed and Unmanaged Landscapes in California”; Putker, “GPA2-Induced Selection Pressure Does Not Select for 187S Allele of the Effector GPRBP-1 in Virulent Globodera Pallida Populations,” and Bardo, “Biotechnology Approaches Against Root-Knot and Root Lesion Nematodes.”

    Blundell is the first UC Davis student to win the Webster award, launched in 2007 to recognize “a graduate student who has demonstrated outstanding accomplishments in his/her thesis research in nematology as well as other skills necessary to be a well-rounded scholar.”

    Blundell, who anticipates receiving her doctorate in 2026, joined the UC Davis doctoral program in 2020. She is completing her dissertation on “Trade-Offs Between Virulence and Evading Resistance in Root-Knot Nematodes.”  She investigates how root-knot nematodes overcome Mi-1 in tomatoes and is testing for susceptibility associated with resistance breaking. Mi-1 is a crucial gene in tomato plants that confers resistance against root-knot nematodes, which are parasitic nematodes that can and do severely damage crops.

    In addition to her scientific contributions, Blundell is involved in professional services with SON, including oral and poster presentations and as vice chair of the SON Graduate Student Committee. She engages in teaching, mentoring, and public outreach on the UC Davis campus. She promotes science education and agricultural awareness by volunteering at the annual UC Davis Picnic Day and the UC Davis Biodiversity Museum Day.

    Blundell, formerly Alison Coomer, holds a  bachelor of science degree in biology and a bachelor of arts in chemistry (2020) from Concordia University, Seward, Neb., where she received the Outstanding Graduate Student in Biology Award.

    The conference drew 179 attendees. The group experienced “a slightly lower attendance due to Visa concerns among foreign students attending U.S. universities,” a spokesman said. SON was formed in 1962 to advance the science of nematology in both its fundamental and economic aspects. Its membership stands at 356.

  • UC Davis Doctoral Candidate Wins International Award for Root-Knot Nematode Work in Tomato

    Doctoral candidate Alison Blundell of the laboratory of associate professor Shahid Siddique, UC Davis Department of Entomology and Nematology, is the recipient of the 2025 John M. Webster Outstanding Student Award from the Society of Nematologists.

    She is the first UC Davis student to win the award, launched in 2007 to recognize “a graduate student who has demonstrated outstanding accomplishments in his/her thesis research in nematology as well as other skills necessary to be a well-rounded scholar.”

    As the recipient of the $1500 prize, Blundell will deliver a 30-minute oral presentation of her research at SON’s 64th annual meeting, to be held July 13-17 in Victoria, British Columbia.

    “The evaluation committee was very impressed by your personal qualities and accomplishments,” the committee wrote, in praising her scientific accomplishments, leadership and commitment to the field of nematology.

    Blundell, who joined the UC Davis doctoral program in 2020, is completing her dissertation on “Trade-Offs Between Virulence and Evading Resistance in Root-Knot Nematodes.” She investigates how root-knot nematodes overcome Mi-1 in tomatoes and is testing for susceptibility associated with resistance breaking. Mi-1 is a crucial gene in tomato plants that confers resistance against root-knot nematodes, which are parasitic nematodes that can and do severely damage crops.

    Blundell has collected root-knot nematodes (RKN) isolates from affected fields across the state, developed single egg mass cultures, and is now applying whole-genome sequencing to identify genetic signatures associated with resistance and its breakdown. Simultaneously, she is investigating whether resistance-breaking RKNs suffer fitness costs when rotated with non-host crops—an approach that could directly inform nematode management strategies for growers.

    In addition to her scientific contributions, Blundell is involved in professional services with SON, including oral and poster presentations and as vice chair of the SON Graduate Student Committee. She engages in teaching, mentoring, and public outreach on the UC Davis campus. She promotes science education and agricultural awareness by volunteering at the annual UC Davis Picnic Day and the UC Davis Biodiversity Museum Day.

    Active in SON, Blundell won first place in the Three-Minute Thesis Competition at the 2022 SON meeting. At the 2024 SON meeting, judges awarded her second place in the 12-Minute Best Student Paper Award Competition.

    Blundell, formerly Alison Coomer, holds a  bachelor of science degree in biology and a bachelor of arts in chemistry (2020) from Concordia University, Seward, Neb., where she received the Outstanding Graduate Student in Biology Award.

    In the Webster Award application form, Blundell explained that “California’s processing tomato industry is responsible for one-third of all processing tomato production worldwide. The success of this industry depends on the growers’ abilities to implement management strategies such as integrated host resistance, effective pesticides, and non-host rotation crops to eliminate or control pathogens. Despite these efforts, root-knot nematodes (RKNs), Meloidogyne spp., cause an estimated 5% yield loss in processing tomatoes by suppressing the plant immune system, damaging root tissues, and creating entry points for secondary pathogens such as Fusarium species. These pathogen complexes result in a severe yield loss seen by growers each year.”

    “For decades, the resistance gene Mi-1 has retained its ability to detect and inhibit RKNs in tomatoes, but the underlying mechanisms by which it recognizes these pathogens remains largely unknown. However, resistance-breaking RKN populations have been increasingly found in both greenhouse and field settings, threatening the effectiveness of the Mi-1 gene and consequently the tomato industry.”

    “With this research we aim to improve our understanding of how RKNs evade Mi-1 resistance, increase grower and public awareness about plant parasitic nematodes, and develop management strategies to combat resistance-breaking populations, ultimately supporting California’s tomato growers.”

  • UC Davis Scientists Collaborate with Deep Look on Bindweed Turret Bees

    Microbiologist Shawn Christensen, a fifth-year doctoral candidate in the Rachel Vannette laboratory, UC Davis Department of Entomology and Nematology, and Vannette, his major professor, were among those collaborating with the producers of KQED Science’s Deep Look for its wildlife video on bindweed turret bees.

    The newly released video, titled “This Fly Torpedoes a Bindweed Bee’s Nest,” appears on YouTube at https://youtu.be/gJHCoP4WqMc.

    “Shawn has done a lot of work on this bee and with Deep Look, and he also leads our lab’s work on Anthophora bomboides, a bumble bee mimic, and studies microbial associates of pollen and solitary bees,” said community ecologist and associate professor Rachel Vannette, a Chancellor’s Fellow and vice chair of the Department of Entomology and Nematology.

    The Deep Look crew filmed the bees, Diadasia bituberculata, in a nesting area outside the UC Davis Stebbins Cold Canyon Reserve, near Winters.

    Microbiologist Shawn Christensen of the Rachel Vannette Lab, UC Davis Department of Entomology and Nematology

    The bees, also known as digger bees or chimney bees, are specialists on bindweed, commonly known as morning glory.  “The females use pollen only from one plant species and are active through the late spring and early summer,” said Vannette, an international leader in microbial ecology who studies interactions between plants, insects and microbes.

    Native to California, the bindweed turret bees build nests (turrets); provision them with pollen for their future offspring; and then lay their eggs.

    In an example of kleptoparasitism, the video shows a female bee fly (family Bombyliidae) flying over a vertical turret and dropping her eggs inside. The fly eggs hatch into larvae, which feed on the stored pollen and then eat the bee larvae. Horizontal turrets with sideway tunnels (also shown in the video) prevent the flyover egg drop.

    Gabriela Quirós, coordinating producer of Deep Look,  consulted with the UC Davis scientists, obtaining information on the location of the bee nests, as well as information on the brood cells, pollen, and turrets. The Deep Look production includes UC Davis images taken inside a bee nest.

    Quirós also consulted with seven other scientists: Stephen Buchmann, University of Arizona; Andy Calderwood,Ventura County Deputy Agricultural Commissioner;  Neal Evenhuis, Bishop Museum of Honolulu, Hawaii; Paul Havemann, UC Davis Natural Reserve System; Keng-Lou James Hung,  University of Oklahoma; Doug Yanega, UC Riverside, and James Carey, a naturalist who researches and videos bindweed turret bees in the Santa Monica Mountains National Recreational Area.

    Senior video producer Josh Cassidy, the lead producer and cinematographer, filmed all the footage except for the male bees fighting with each other (00;17;14- 00;25;22 in the video).  James Carey, who filmed that footage, “has been regularly monitoring and filming bindweed turret bees since 2016 in Rancho Sierra Vista/Satwiwa, an open space in the Santa Monica Mountains,” Quirós said. “James also filmed the shot at 04;17-04;21 showing nests in the Santa Monica Mountains covered up at the end of the nesting season.”

    Evenhuis and Calderwood, both bee fly experts, identified the bee flies as Paravilla fulvicoma.  “Neal explained the life cycle of these bee flies and advised me on the animation,” Quirós said. Deep Look editor and motion graphics expert Kia Simon created the animation of the bee fly larva eating the bee larva.

    “How I got interested in producing an episode of Deep Look about bindweed turret bees was that Rachel Vannette told me about these bees in 2021,” Quirós related. “Rachel told me that Shawn Christensen, a doctoral student in her lab, was studying their pollen. Later, I saw on the Native Bees Facebook group, the videos that James Carey had recorded of bee flies dropping their eggs into the nests of bindweed turret bees in Rancho Sierra Vista/Satwiwa, in the Santa Monica Mountains. I hadn’t known about bee flies until I saw his videos.”

    “I became interested in trying to film a video about the interactions between bee flies and bindweed turret bees. I contacted Shawn Christensen in January of this year, and Shawn and I started checking in regularly to figure out when the bindweed bees would emerge. When they finally did come out in large numbers–they were later this year than usual–we were, luckily, ready to jump into action and film an episode.”

    Quirós credited Paul Havemann, manager at the UC Davis Natural Reserve System, as instrumental in finding the filming location. “On a Sunday in early June, he clambered up the mountain at Stebbins to show me where the bees had emerged. On the way out, he told me he’d show me a parking lot where they also had emerged. The parking lot turned out to be a perfect filming location. It is very accessible and there were plenty of bees. We didn’t need to haul our gear up the mountain.”

    About 70 percent of the world’s bee species are ground-nesting.  “Females tirelessly scoop earth with their mandibles, softening it by dousing it with nectar they collected earlier,” Deep Look related. “They work side by side, but each is /queen/ of her own castle.”

    More than 4,000 species of bee flies comprise the family Bombyliidae. “How do you tell a bee fly from a bee?” Deep Look asked. “Even though bee flies have hairy bodies like bees, if you look closely, you can tell them apart. Bee flies have big eyes that cover a large area of their heads. And bee flies’ antennae are short compared to bees’ antennae.”

    Viewers are raving about the video with such online comments as:

    • “The camera work is nothing short of amazing. Great job!” (Cassidy’s photography equipment included a 100mm and 65mm macro lenses and a probe lens, a wide angle macro lens.)
    • “Love the pollen pants, and I felt so bad for the bees whose hard work was spoiled by those pesky bee flies.”
    • “This channel truly deserves much more recognition than it has, the amount of information and clear footage is marvelous.”
    • “Thanks. It’s not often I see a good short video on a native bee species or any native pollinator for that matter.”

    Christensen, a member of the UC Davis Microbiology Graduate Group and anticipating his doctorate in the spring of 2024, is an evolutionary biologist turned microbiologist. Christensen also researches other native bees,  including Melissodes and Colletes.

    Vannette focuses her research on the chemical and microbial ecology of plant-pollinator interactions and how microbes influence plant defense and resistance against insect pests.  On its website, the Vannette lab is described as “a team of entomologists, microbiologists, chemical ecologists, and community ecologists trying to understand how microbial communities affect plants and insects–sometimes other organisms, too. We often study microbial communities in flowers, on insects or in soil. We rely on natural history observations, and use techniques from chemical ecology, microbial ecology and community ecology.  In some cases, we study applied problems  with an immediate application including pathogen control or how to support pollinators.”