- Author: Kathy Keatley Garvey
Two UC Davis nematology doctoral students were invited to give research presentations at the international Society of Nematologists' conference in Park City, Utah and they excelled.
Meet the two young women: Alison Blundell, a doctoral candidate who was invited to compete in a 12-minute student oral competition to discuss her research on root-knot nematodes, and doctoral student Veronica Casey, invited to share her research on "Pathogenic Hitchhikers."
Their major professor, Shahid Siddique, encourages his students to participate in the Society of Nematologists (SON), an international organization that advances the science of nematology in both its fundamental and economic aspects.
Blundell, who anticipates receiving her doctorate in 2026, won second place in the international competition with her presentation, “Overcoming Resistance: Unraveling the Mechanisms Behind Root-Knot Nematode Evasion of Tomato Mi-Gene.” She received a $250 prize.
Blundell researches plant-parasitic nematodes specifically root-knot nematodes, and their molecular mechanism to defend against plant immune systems. In her abstract, she wrote: "Root-knot nematodes (RKNs) are among the most devastating pathogens of crops, causing substantial yield and economic losses worldwide. These parasitic organisms can infect over a hundred different plant species and can evade plant defense mechanisms by secreting a concoction of effectors. For decades, the Mi-1 resistance gene has been effective in detecting and inhibiting RKNs in tomatoes. However, the underlying mechanisms by which Mi-1 detects these pathogens remain largely unknown. In recent years, resistance-breaking populations have emerged in both greenhouse and field settings, posing a threat to the potency and effectiveness of the Mi-1 gene and, consequently, the tomato industry. "
"We used two strains of M. javanica, one strain VW4, which is recognized by Mi-1, and another strain, VW5, which was selected from VW4 and can overcome resistance mediated by Mi-1," Blundell explained. "Utilizing the newly constructed reference genome for M. javanica (VW4), we compared genomes of VW4 and VW5 and identified an approximately 50 kb region that is present in VW4 but missing in VW5. This missing region contains seven protein-coding genes, three of which encode putative effectors and are currently being tested as potential avirulence genes for Mi-1."
"In addition, we have conducted a series of infection assays on different host plants lacking Mi-1, and the results revealed a significantly lower egg count in VW5 when compared to VW4. We plan to expand these assays by testing additional M. javanica resistance-breaking strains collected from fields all over California to determine if this trade-off is consistent across other strains. Overall, our results suggest that although VW5 can overcome Mi-1, there is a trade-off in the form of compromised reproduction. This research helps to better understand the mechanism and components of Mi-1 and develop strategies for addressing resistance-breaking populations."
Pathogenic Hitchhikers
Doctoral student Veronica Casey delivered her invited presentation on “Pathogenic Hitchhikers: Investigating the Synergy of Bacteria and Nematodes on Plant Health.”
a"In the vast scope of soil ecology, plant-parasitic nematodes can forge alliances with other microbial adversaries, such as the disease complex formed between nematodes and bacterial wilt-causing Ralstonia spp.," Casey wrote in her abstract. "These disease complexes exacerbate disease symptoms and yield losses. Plant-parasitic nematodes are microscopic roundworms that cause approximately $100 billion in yield loss a year, and most of the damage is attributed to root-knot nematodes (RKNs; Meloidogyne spp.). Bacterial wilt is caused by multiple Ralstonia species, namely Ralstonia pseudosolanacearum, R. solanacearum, and R. sygzii that enter the plant's roots to colonize its vascular system. Prior to Ralstonia infection, RKN infection may facilitate bacterial disease by increasing access to the vascular tissue."
"However, little research has been conducted to elucidate the molecular details of this interaction," Casey pointed out. "Previous reports of RKN and Ralstonia spp. in the field hypothesized that the infection was due to root wounding and physiological changes. In this study, I will determine the nature of the interaction between Ralstonia and nematodes at both ecological and molecular levels. This research project will explore the hypotheses that 1) Ralstonia adheres to the cuticle of nematodes using specialized appendages called pili and 2) de novo xylem formation in the galls increases Ralstonia transport into the plant. A common strategy for preventing nematode infection is by using resistant plant cultivars."
"However, resistance-breaking nematode populations have arisen and we plan to utilize resistance-breaking nematodes, which are most likely to interact with bacterial wilt in the field," Casey noted. "This presentation will report on the attachment and greenhouse experimental results of the RKN-Ralstonia complex. The escalation of climate change is leading to increased instances of pathogenicity; therefore, it is crucial to uncover disease complexes which can have monumental consequences on food security. A meticulous study into the nematode and Ralstonia disease complex will support the management of these damaging pathogens across the world."
Blundell and Siddique also delivered invited presentations in the illustration workshop. Blundell gave her presentation on "Become an Illustrator Mender Simply by Using BioRender," and Siddique, "Doodle Your Data: Adobe Illustrator for Nematodes."
Other lab mates from the Siddique lab also participated in the SON meeting. (See news story). In the ecology session, doctoral candidate Chris Pagan participated from the UC Davis lab of distinguished professor Steve Nadler, former chair of the Department of Entomology and Nematology. Pagan's presentation: "Nematode Community Structure in the Rhizopsheres of Southern California Creosote (Larrea trientata).”
Of note, Blundell and Casey were among the four graduate students from the Siddique lab who received travel awards. Blundell won a Corteva award and Casey, a Certis award. Also receiving travel awards wer Ching-Jung Lin, a Bayer CropScience award and Romnick Latina, a N. A. Cobb Foundation award.
Honorary Member. At the 2024 conference, UC Davis distinguished professor emeritus Howard Ferris was selected a Honorary Member, the highest award that SON offers. (Feature story pending; wait 'til you hear his exciting life story!)
UC Davis nematologists are already looking forward to the next annual meeting: July 13-17 in Victoria, British Columbia, Canada. Meanwhile, you can chat one-on-one with them at the annual UC Davis Biodiversity Museum Day, usually held in February on the UC Davis campus. It traditionally featuring a dozen or so UC Davis museums. Student nematologists are spotlighted on the current website.
- Author: Kathy Keatley Garvey
Its population is declining and he feared it might become extinct. B. occidentalis, sometimes called the "white-bottomed bee" due to its distinctive white markings on its abdomen, is known for pollinating blackberries, cherries, apples and blueberries.
Fast forward to today and the UC Davis research on how climate change is "rapidly restructuring North American bumble bee communities."
Newly published research from the laboratory of Professor Neal Williams, a pollination ecologist in the UC Davis Department of Entomology and Nematology (and close friend and colleague of Thorp), indicates a substantial shift in bumble bee communities.
The analytical paper, “Warming Summer Temperatures Are Rapidly Restructuring North American Bumble Bee Communities” --authored by ecologist Jeremy Hemberger, a former postdoctoral fellow in the Williams lab, and Professor Williams--appears in Ecology Letters.
“This is one of the first papers to show really substantial shifts in community composition in bumble bees due to climate, but also in insects more broadly,” said Hemberger, now a postdoctoral researcher at his alma mater, the University of Wisconsin, Madison. “We're also able to partition the effect we found to being driven by a loss of cold-adapted species, and a rapid rise in warm-adapted species across North America, but alarmingly we see that, above 50° parallel north, even warm-adapted species are declining.”
The 50th parallel north is a circle of latitude that is 50 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America and the Atlantic Ocean. At this latitude, the sun is visible for 16 hours and 22 minutes during the summer solstice, and 8 hours, 4 minutes during the winter solstice, according to Wikipedia.
“Though additional confirmation is needed, our results suggest that northern bumble bee communities may be in crisis, with significant species turnover and declines in abundance that may threaten the persistence of populations in the coming decades,” they wrote.
“Overall, our work provides strong evidence of the pervasive impacts a warming planet has for insect biodiversity, particularly for historically cool-adapted species,” they related. “It also identifies regions of concern where anthropogenic climate warming is rapidly restructuring the communities of an ecologically important group of insects.”
They used along-term dataset of North American bumble bee species occurrences to determine whether the community temperature index (CTI), a measure of the balance of warm- and cool-adapted species in a community, has increased given warming temperatures. The database of 781,280 records from 1805 to 2020 was derived from a variety of sources, including natural history collections, research studies, and citizen science programs. To match the temporal range of available climate data, they used bumble bee records collected between 1960 and 2018.
“Over the last 29 years across the continent, bumble bee communities increasingly consist of fewer cool-adapted and more warm-adapted species with resultant increases in the community temperature index, a measure of the balance of warm- and cool-adapted species,” they wrote. “Changes are most pronounced at mid- to high latitudes and high elevations in the American Rockies, Intermountain West and central Mexico.”
Their project, launched in 2020 and completed in 2023, focused on 59 species. All California bumble bees were included in the analysis. The authors noted that the long-term, rising summer temperatures are “particularly alarming” to the Western bumble bee, Bombus occidentalis; the two-formed bumble bee, B. bifarius of Western North America; and the forest bumble bee, B. sylvicola, a high-altitude specialist native to North America and widely distributed in Canada.
B. occidentalis is one of the cool-adapted species that is declining. The yellow-faced bumble bee, B. vosnesenskii, native to the West Coast, is one of the "biggest winners” per the analysis.
Read the paper at https://onlinelibrary.wiley.com/doi/full/10.1111/ele.14492.
- Author: Kathy Keatley Garvey
So there you are, admiring your Coreopsis and suddenly you notice spots and holes--spots on the backs of two western spotted cucumber beetles, and holes cut in the petals.
Ah, there's two of them.
The beetles, about a fourth of an inch long, are fun to photograph, but they're not your buddies. Nor would they want to be!
"Cucumber beetles are very common pests in vegetable gardens and may also attack ripening stone fruit," says the UC Statewide Integrated Pest Management Program. "The most abundant species in California is the western spotted cucumber beetle, Diabrotica undecimpunctata...The western spotted cucumber beetle is greenish yellow and has twelve black spots on its back."
Ever counted the spots? Yes, 12.
We've seen the beetles feeding on the leaves of flowers and many vegetables. "Cucumber beetles may also spread cucumber mosaic virus or wilts in cucurbits," UC IPM says. "Larvae feed exclusively on roots, but do not generally damage garden plants, although corn may occasionally be damaged."
Spotted cucumber beetles don't move very fast early in the morning, so they're fairly easy to photograph.
And sometimes you get a "two-fer," two in the same image. 24 spots.
- Author: Kathy Keatley Garvey
Nine members of the UC Davis Animal Behavior Graduate Group (ABGG) who are active in The Ethogram will present a special outreach program, "Animal Behavior for Young Explorers," from 2:30 to 4 p.m., Monday, Aug. 19 in the Blanchard Room of the Mary L. Stephens branch of the Davis Library, 315 E. 14th Street, Davis.
It's a free, hands-on, science-communication event intended for the age group of kindergarten through eighth grade. As young explorers, they will learn why animals behave the way they do.
“There will be living and pinned animal specimens (including insects), trivia games with winners receiving small prizes, arts and crafts, and books to peruse on animal behavior," said Nicole Keough (formerly Korzeniecki), a PhD candidate in the Brian Johnson lab, UC Davis Department of Entomology and Nematology. She is a member of ABGG and an editor of The Ethogram, which is ABGG's official blog. Graduate students founded The Ethogram in 2014.
Attendees at the Aug. 19th event can ask scientists questions about animal behavior research. A scientist-led bird walk around the Community Park is planned, weather permitting. Keough said the displays will range from her live termites to kittens. As a doctoral candidate in the Johnson bee lab, she is interested in eusociality, host-microbe symbiosis, and social behavior. Her research focuses on "exploring the relationship between termites and their gut microbiome in the context of termite social hygienic behaviors such as allogrooming and cannibalism." Using genetic sequencing, she investigates this symbiotic relationship and identify endosymbionts with overlapping roles in termite nutrition.
The group also will show insect specimens from the Bohart Museum of Entomology, as well as live insects, including Madagascar hissing cockroaches and walking sticks, from the Bohart petting zoo.
Hosts at the Aug. 19th event will include:
- Isabelle McDonald-Gilmartin, PhD candidate and editor-in-chief of The Ethogram
- Nicole Keough, PhD candidate and editor for The Ethogram
- Siobhan Calhoun, PhD student and editor for The Ethogram
- Nicole Rodrigues, PhD candidate and editor for The Ethogram
- Sabrina Mederos, PhD candidate and editor for The Ethogram
- Jessica Schaefer, PhD candidate and editor for The Ethogram
- Kirsten Sheehy, PhD candidate and editor emeritus of The Ethogram
- Dr. Josephine Hubbard, editor emeritus of The Ethogram
- Hee Jin Chung, PhD candidate and co-chair of the Animal Behavior Graduate Group's Diversity, Equity, and Inclusion Committee
This is a one-time event but plans may call for more outreach programs, depending on the interest, Keough said.
What is an ethogram? "Ethogram is a list or catalogue of behaviors that are being studied in animal behavior research (also known as ethology)," according to The Ethogram website. "The aim is to make scientific topics and findings more accessible to non-scientists through articles, videos, and other multimedia communication."
"The Ethogram encourages interaction between scientists and non-scientists in order to spark curiosity and passion for the study of animal behavior and general scientific research," the message continues. "Our mission is to create a platform that allows scientists to disseminate their research in approachable and exciting ways. In doing so, we also aim to train the next generation of science communicators. Using diverse narratives of animals and those who study them, we provide accessible scientific information through a variety of media types, from text to sketch to video."
Meanwhile, explore the writings and illustrations on The Ethogram blog.
Here are two of the insect sketches:
- The Honey Bee, by Nicole Rodrigues, a PhD candidate in the Biochemistry, Molecular, Cellular, and Developmental Biology program.
- The Bumble Bee, by Danielle Rutkowski of the Rachel Vannette and Rick Karban labs, UC Davis Department of Entomology and Nematology. She received her doctorate in June.
Also, Ethogram maintains an Instagram account.
- Author: Kathy Keatley Garvey
Photographers call the first hour after dawn and the last hour before dusk "The Golden Hour."
That's when the sunlight is softer and warmer.
It's also called "The Magic Hour."
Compare that to high noon, when the sun casts such strong highlights and shadows on the subject that even images of Miss Universe and Miss America look harsh.
Now if you photograph a golden honey bee during The Golden Hour, the world looks even warmer and softer.
But use the term, Golden Hour, figuratively. As Wikipedia explains: "The term hour is used figuratively; the effect has no clearly defined duration and varies according to season and latitude. The character of the lighting is determined by the sun's altitude, and the time for the sun to move from the horizon to a specified altitude depends on a location's latitude and the time of year. In Los Angeles, California, at an hour after sunrise or an hour before sunset, the sun has an altitude of about 10–12°. For a location closer to the Equator, the same altitude is reached in less than an hour, and for a location farther from the equator, the altitude is reached in more than one hour. For a location sufficiently far from the equator, the sun may not reach an altitude of 10°, and the golden hour lasts for the entire day in certain seasons."
The honey bee (below), foraging on a blanket flower, Gaillardia, couldn't discuss Golden Hours, seasons, latitude and longitude with you. But she knows how to return to her colony (which could be five miles away) and how to communicate with the other bees. And that, too, is Golden.