- Author: Kathy Keatley Garvey
Today, during the 62nd annual international conference of the Society of Nematologists, being held July 9-14 in Columbus, Ohio, The Proceedings of the National Academy of Sciences (PNAS) published a UC Davis research team's important--and exciting--research paper on root-knot nematodes.
It's online at “Root-Knot Nematodes Produce Functional Mimics of Tyrosine-Sulfated Plant Peptides."
Basically, the researchers discovered that “both a harmful plant bacterium and a parasitic worm can mimic a plant peptide hormone to enhance their ability to infect plants.”
It's a joint project of nematologist Shahid Siddique, an associate professor in the Davis Department of Entomology and Nematology, and Siddique and UC Davis distinguished professor Pamela Ronald, a plant pathologist and geneticist in the Department of Plant Pathology and the Genome Center. They are the corresponding authors. Joint first-authors are Henok Zemene Yemer, formerly of the Siddique lab and now with Gingko Bioworks, Emeryville, and Dee Dee Lu of the Ronald lab.
It's like hijacking plant development to facilitate parasitism, according to Siddique. “This finding showcases an amazing case of convergent evolution across three different types of organisms, revealing how diverse life forms can develop similar strategies for survival.”
“Root-knot nematodes are a major threat to various crops, including fruit trees and vegetables,” Siddique said. “In California, tomatoes, almonds, and walnuts are among the major hosts susceptible to root-knot nematode infection.”
Siddique and UC Davis distinguished professor Pamela Ronald, a plant pathologist and geneticist in the Department of Plant Pathology and the Genome Center, are the joint corresponding authors. Joint first-authors are Henok Zemene Yemer, formerly of the Siddique lab and now with Gingko Bioworks, Emeryville, and Dee Dee Lu of the Ronald lab.
Plant-parasitic nematodes (PPNs) are among the most destructive plant pathogens, causing an annual economic loss of $8 billion to U.S. growers and more than $100 billion worldwide, the authors said.
The team also included emerita professor Valerie Williamson of the former Department of Nematology; Maria Florencia Ercoli, postdoctoral fellow in the Ronald lab; Alison Coomer Blundell, a doctoral candidate in the Siddique lab; and Paulo Vieira of the USDA's Mycology and Nematology Genetic Diversity and Biology Laboratory, Beltsville, Md.
“Plant peptides containing sulfated tyrosine (PSY)-family peptides are peptide hormones that promote root growth via cell expansion and proliferation,” the authors explained. “A PSY-like peptide produced by a bacterial pathogen has been shown to contribute to bacterial virulence. Here, we discovered that PSY-like peptides are encoded by a group of plant-parasitic nematodes known as root-knot nematodes. These nematode-encoded PSY mimics facilitate the establishment of parasitism in the host plant. Our findings are an example of a functional plant peptide mimic encoded by a phytopathogenic bacterium (prokaryote) and a plant-parasitic nematode (an animal).”
The project drew financial support from a collaborative grant awarded to Siddique and Ronald from the National Science Foundation's Division of Integrative Organismal Systems.
Siddique, a member of the UC Davis faculty since 2019, focuses his research on basic as well as applied aspects of interaction between parasitic nematodes and their host plants. “The long-term object of our research is not only to enhance our understanding of molecular aspects of plant–nematode interaction but also to use this knowledge to provide new resources for reducing the impact of nematodes on crop plants in California.”
Ronald, noted for her innovative work in crop genetics, especially rice, is recognized for her research in infectious disease biology and environmental stress tolerance. Thomson Reuters named her one of the world's most influential scientific minds and Scientfic American recognized her as among the world's 100 most influential people in biotechnology. In 2022 Ronald received the Wolf Prize in Agriculture.
The next steps? “Currently, we are working to understand the mechanism by which these peptides contribute to the nematode infection,” Siddique said. “This entails the characterization of receptors involved and gaining insights into transcriptional changes.”
- Author: Kathy Keatley Garvey
First, they're neither tadpoles nor shrimp. Second, they're crustaceans and are pests of rice.
Tadpole shrimp will be one of the topics that Cooperative Extension specialist Ian Grettenberger, an agricultural entomologist, will cover when the Bohart Museum of Entomology hosts a family friendly open house from 1 to 4 p.m., Saturday, May 28 in Room 1124 of the Academic Surge Building, Crocker Lane, UC Davis campus.
The event, free and open to the public, is themed “Bugs in Ag: What Is Eating Our Crops and What Is Eating Them?”
Grettenberger, a member of the UC Davis Department of Entomology faculty, will discuss pests of rice and alfalfa and other agricultural crops, and also will cover such beneficial insects as lady beetles, aka lady bugs.
But back to tadpole shrimp. We asked Grettenberger 10 facts that most people may not know about these critters. Here we go!
- The common name for Triops species is tadpole shrimp because they look superficially like tadpoles (frogs), but another common name is shield shrimp, named after their shield-like carapace.
- The genus name for tadpole shrimp, "Triops" comes from Latin "tri" (three) and Greek "?ps" (eye). They have two large compound eyes and a third simple eye (ocellus) used for detecting light.
- The California crop where tadpole shrimp are relevant is rice. Triops longicaudatus is an early-season pest that can damage germinating seeds.
- While the pest species Triops longicaudatus is an abundant species because it can do well in rice fields, another species in California, Lepidurus packardi (vernal pool tadpole shrimp), is endangered and relies on limited vernal pool habitats for survival.
- Triops longicaudatus carry their eggs in egg sacs, where they are kept before being deposited.
- Eggs of Triops longicaudatus typically dry out completely as rice fields are drained or pools dry. Eggs can survive for many years (10's of years) in a desiccated state, able to hatch when they are flooded again.
- Triops longicaudatus are omnivorous, meaning they eat plant material, invertebrates, and even their siblings (cannibalism!).
- Triops longicaudatus will eat mosquito larvae.
- A possible sign of a rice field full of tadpole shrimp is very murky water; as they feed and burrow on the bottom, they stir up mud and muddy the water.
- You can actually buy dried eggs of Triops longicaudatus and keep them as a pet.
“We plan to talk broadly about the pests that eat our crops and the natural enemies that help protect them,” Grettenberger said. He and postdoctoral fellow Buddhi Achhami of the Grettenberger lab will field questions. (For more information on tadpole shrimp, be sure to access KQED's Deep Look video, Tadpole Shrimp Are Coming For Your Rice. which includes Grettenberger's expertise; and the UC Statewide Integrated Pest Management Program's information about tadpole shrimp.)
Also during the Bohart Museum open house, the family activity is to make tadpole shrimp hats or puppets. "Googly eyes" will be used to imitate the compound eyes and and the ocellus, said Tabatha Yang, the Bohart Museum education and outreach coordinator.
The Bohart Museum, directed by Lynn Kimsey, UC Davis distinguished professor of entomology, houses a global collection of eight million insect specimens; a live "petting zoo" comprised of Madagascar hissing cockroaches, walking sticks (stick insects) and tarantulas; and a year-around gift shop (also online) stocked with insect-themed gifts, such as t-shirts, hooded sweatshirts, posters, jewelry, books, puppets, candy and collecting equipment.
The Bohart Museum has been closed to the public for the last two years due to COVID-19 pandemic precautions. The Bohart observed UC Davis Picnic Day by setting up displays in the hallway of the Academic Surge Building. This spring the museum is open to the public, but groups must make reservations and everyone must follow the UC Davis visitor guidelines: https://campusready.ucdavis.edu/visitors? The museum's "visiting us" page includes more information.
- Author: Kathy Keatley Garvey
It's neither a tadpole nor a shrimp, but a crustacean pest that feasts on rice seedlings in flooded rice fields.
Rice growers currently rely heavily on pyrethroid insecticides to manage tadpole shrimp.
At the Entomological Society of America meeting this week in Denver, agricultural entomologist and Cooperative Extension specialist Ian Grettenberger of the UC Davis Department of Entomology and Nematology and his colleagues proposed alternative management.
Grettenberger's poster, “Past Pyrethroids: Alternative Management Approaches for Tadpole Shrimp in Rice,” offers non-pesticide alternatives, including the use of mosquitofish.
Collaborative research with UCCE Butte County director and Rice Farming Systems Advisor Luis Espino and UC Davis staff research associate Kevin Goding, indicates that mosquitofish proved able to suppress shrimp populations.
“Tadpole shrimp (Triops longicaudatus) are an early-season pest in California rice,” Grettenberger explained in his abstract. “Soon after flooding, eggs hatch and growing shrimp are soon large enough to damage germinating rice seedlings. Currently, pyrethroid insecticides are heavily relied upon for management, as they are in many cropping systems, because of their efficacy and low cost. However, contamination of surface waters is a concern, as is insecticide resistance.”
“In addition, we used large square metal plots to evaluate if a fish released for mosquito control, mosquitofish (Gambusia affinis), could suppress shrimp populations. We found that a number of materials could suppress shrimp populations, while unregistered materials did not provide sufficient control. Mosquitofish also proved able to suppress shrimp populations, although extremely high shrimp populations could escape predation and shrimp could outgrow risk to predators. These results could help a field crop industry move beyond pyrethroids, which will be important to address issues of environmental contamination or regulatory changes as well as changes in susceptibility.”
Deep Look Video. Tadpole shrimp recently made the national news in two ways, Grettenberger said. First, they made news with the sudden appearance of tadpole shrimp following monsoon rains this summer in an ancient ceremonial ball court at the Wupatki National Monument in northern Arizona (https://www.livescience.com/dinosaur-shrimp-emerge-arizona). In October, KQED's Deep Look released a new video, “Tadpole Shrimp Are Coming For Your Rice," the work of lead producer and cinematographer Josh Cassidy and other members of the Deep Look crew. (See https://youtu.be/T2xnXaX7r3g.) Grettenberger assisted with the project, providing tadpole shrimp and taking some of the video clips used in the five-minute video.
“Much of his shooting was in my garage,” the UC Davis entomologist said, “so I get to see just how much effort and care goes into producing these videos. They end up pretty short, but that doesn't mean it is simple to get all the pieces together.”
“This tadpole shrimp is coming for your rice,” the narrator said. “Hungry hordes of them find their way into the ice fields of California's Central Valley and go to town munching on the young seedlings. But where did they come from, with the ocean so far away? A couple of weeks ago, this was just a dry dusty field. Turns out they were here all along.”
Deep Look referred to them as “time travelers,” as the eggs of shrimp tadpoles can be viable for decades and hatch when the rice growers flood their fields. "At the very least, they have survived as eggs since last season," Grettenberger noted.
The pests are neither tadpoles or shrimp but are fresh-water crustaceans descended from the ocean. “They look like tiny horseshoe crabs,” Grettenberger told Deep Look. “It's obvious when rice fields have lots of tadpole shrimp in them, because they stir up the mud making the water look a bit like chocolate milk. There will also be shrimp zooming around, many upside down at the surface, popping up for a few seconds before disappearing back into the murkiness."
Adult tadpole shrimp cannot survive when the soil dries out. But Grettenberger said their eggs have a rugged outer layer called a “chorion” that protects the eggs from desiccation.
“They've been living this way for hundreds of millions of years-- since before the dinosaurs-- waiting out droughts, changing climates, even global catastrophes,” KQED relates in the video. “In a world where the future is unpredictable, tadpole shrimp are the ultimate survivors.”
Grettenberger, who joined the UC Davis Department of Entomology faculty in January, 2019, focuses his research on field and vegetable crops; integrated pest management; applied insect ecology; and biological control of pests.
Additional Information:
- Resource on tadpole shrimp, UC Statewide Integrated Pest Management Program (co-authors, the late Larry Godfrey, Cooperative Extension specialist, UC Davis Department of Entomology and Nematology; Luis Espino, UC Cooperative Extension; and Sharon Lawler, professor, UC Davis Department of Entomology and Nematology
- "Effect of Rice Winter Cultural Management Practices on the Size of the Hatching Population of Triops longicaudatus (Notostraca:Triopsidae) in California Rice Fields" (Co-authors Larry Godfrey,
- Author: Kathy Keatley Garvey
Don't miss the UC Davis Bohart Museum of Entomology virtual open house on alfalfa and rice from 11 a.m. to noon on Thursday, Oct. 22.
Cooperative Extension agricultural specialist Ian Grettenberger, assistant professor, UC Davis Department of Entomology and Nematology, and his second-year graduate student, Madison "Madi" Hendrick, will discuss the crops, the pests, and the natural enemies or beneficials.
The good: Think the lady beetle, aka ladybug, that can devour some 50 aphids a day.
The bad: Think the larvae of the alfalfa butterfly, a major pest of alfalfa. Other pests of alfalfa include the Western yellowstriped armyworm, beet armyworm, and alfalfa weevil. Among the pests of rice: armyworms, aster leafhoppers, crayfish, rice leafminers, rice seed midges, rice water weevils and tadpole shrimp.
The bugly: Think all the arthropods--pests and natural enemies.
The event, "The Good and the Bad: Insects and Other Arthropods in Agriculture, with a Focus on California Rice and Alfalfa," will be live-streamed on the Bohart Museum of Entomology's Facebook page. (Link to Facebook live here). Grettenberger and Hendrick will present short talks and then field questions. No personal Facebook account is required to join the session, which is free and open to the public.
As Tabatha Yang, education and outreach coordinator of the Bohart Museum, says: "This is all about the arthropods, both the pests and beneficials that they study in the rice and alfalfa fields." Most of the focus is on insects, but tadpole shrimp in rice fields also will be discussed." A virtual family craft activity on rice is also planned.
"I will be discussing some of the insect (or arthropod) problems faced by growers of rice in California and some of the challenges in managing them, Grettenberger said. "In rice, some of the key arthropod pests are tadpole shrimp, which can turn what would have been a lush stand if rice into a poor stand with a lot of floating seedlings. Meanwhile, later in the year, armyworm caterpillars, the larvae of a moth, can chew on rice leaves and destroy plants. I'll discuss some of the ongoing work to better understand and manage these pests."
Grettenberger, Yolo County Farm Advisor Rachael Freeman Long and Madi Hendrick recently wrote a piece in the UC Agricultural and Natural Resources (UC ANR) blog, Alfalfa and Forage News, "A (Virtual )Update on Worms, Weevils an Aphids in Alfalfa."
The Bohart Museum, directed by Lynn Kimsey, UC Davis professor of entomology, is located in Room 1124 of the Academic Surge Building on Crocker Lane, UC Davis campus, but is temporarily closed. The museum houses nearly eight million insect specimens; a live "petting zoo" of Madagascar hissing cockroaches, walking sticks and taranatulas; and a gift shop stocked with insect-themed T-shirts, books, posters, jewelry, candy and insect-collecting equipment. (Gift items can now be shipped during the closure.)
More information on the Bohart Museum's virtual presentation is available on its website or by contacting Yang at tabyang@ucdavis.edu.
- Author: Kathy Keatley Garvey
The Bohart Museum of Entomology at the University of California, Davis, is hosting a virtual open house dealing with alfalfa and rice.
Cooperative Extension agricultural specialist Ian Grettenberger, assistant professor, UC Davis Department of Entomology and Nematology, and his graduate student, Madison "Madi" Hendrick, will discuss the crops, the pests, and the natural enemies or beneficials at a virtual Facebook live session from 11 a.m. to noon, Thursday, Oct 22.
Yes, this applies to you. If you're a scientist or would-be scientist, you'll want to know more about these agricultural crops and the issues. If you're a consumer and like rice and ice cream (dairy cows eat alfalfa and milk comes from ice cream, you have a stake in this.
The event, "The Good and the Bad: Insects and Other Arthropods in Agriculture, with a Focus on California Rice and Alfalfa," will be live-streamed on the UC Davis Bohart Museum of Entomology's Facebook page. (Link to Facebook live here). Grettenberger and Hendrick will present short talks and then field questions. No personal Facebook account is required to join the session, which is free and open to the public.
"I will be discussing some of the insect (or arthropod) problems faced by growers of rice in California and some of the challenges in managing them, Grettenberger said. "In rice, some of the key arthropod pests are tadpole shrimp, which can turn what would have been a lush stand if rice into a poor stand with a lot of floating seedlings. Meanwhile, later in the year, armyworm caterpillars, the larvae of a moth, can chew on rice leaves and destroy plants. I'll discuss some of the ongoing work to better understand and manage these pests."
Grettenberg's fields of expertise include field and vegetable crops; integrated pest management; applied insect ecology, and biological control of pests. (See Spotlight on Ian Grettenberger.) Among his current grants:
- Protection of rice from invertebrate pests
- Insecticide resistant alfalfa weevils in the western United States: Quantifying the scope of resistance and implementing a plan to manage the threat​
- Management of key cotton arthropod pests with insecticides and acaricides, a proactive approach to prepare for the invasion of the tomato leafminer (Tuta absoluta) into California
- Detection, biology and control of the exotic Swede midge (Contarinia nasturtii) for California cole crops
- Management of the western spotted and striped cucumber beetle in melon production
- Biological control of the bagrada bug
- Insecticide resistance monitoring and evaluation of efficacy of current chemical tactics for managing aphids and thrips in lettuce
What sparked his interest in entomology? "I had biologist parents, and was drawn into entomology at a pretty young age," Grettenberger said. "I spent plenty of time looking in flowers and turning over logs looking for insects. Once I started thinking about going to graduate school for entomology, I decided to focus on the intersection of agricultural entomology and insect ecology. I wanted to work on applied issues in entomology."
Hendrick, a second-year graduate student in the Grettenberger lab, received her bachelor's degree in iInternational studies at North Carolina State University, and also spent a semester at Nagoya University in Japan (she minored in Japanese).
"I got my start in entomology completely by chance!," Hendrick related. "I needed a science credit and happened to pick a class called 'Insects and People.”' That class really helped me to reframe the way I thought about insects and appreciate what interesting little critters they are. Through that class, I was also able to get a job as an undergraduate assistant in an entomology lab. I worked in a specialty crops lab, where I developed interests in integrated pest management and invasive species. I now study insecticide resistance in the alfalfa weevil, and I'm excited to share what I've learned through this outreach event!"
Grettenberger, Yolo County Farm Advisor Rachael Freeman Long and Madi Hendrick recently wrote a piece in the UC Agricultural and Natural Resources (UC ANR) blog, Alfalfa and Forage News, "A (Virtual )Update on Worms, Weevils an Aphids in Alfalfa."
"This year, the Kearney Research and Extension Center Alfalfa and Forage Field Day went virtual," Grettenberger wrote. "Attendees did not get the chance to look out over lush fields of alfalfa or towering plantings of sorghum, but they get did an update on ongoing work in alfalfa and other forages. Our team put together a rapid-fire video to discuss what are typically the key insect pests in California alfalfa: summer worms, alfalfa weevils, and aphids."
The summer worms in alfalfa include the summer worms: Western yellowstriped armyworm, beet armyworm and alfalfa caterpillar. Another key pest is the alfalfa weevil. The trio also discussed aphids and their natural enemies, including lady beetles, aka ladybugs).
Pests of rice include armyworms, aster leafhoppers, crayfish, rice leafminers, rice seed midges, rice water weevils and tadpole shrimp.
The Bohart Museum, directed by Lynn Kimsey, UC Davis professor of entomology, is located in Room 1124 of the Academic Surge Building on Crocker Lane, UC Davis campus, but is temporarily closed. The museum houses nearly eight million insect specimens; a live "petting zoo" of Madagascar hissing cockroaches, walking sticks and taranatulas; and a gift shop stocked with insect-themed T-shirts, books, posters, jewelry, candy and insect-collecting equipment. (Gift items can now be shipped during the closure.)
More information on the Bohart Museum's virtual presentation is available on its website or by contacting Yang at tabyang@ucdavis.edu.
Resources:
- Alfalfa and Forage News: A (Virtual) Update on Worms, Weevils and Aphids in Alfalfa (By Ian Grettenberger, Rachael Freeman Long and Madi Hendrick, Sept. 20, 2020) (See video on same page)
- Alfalfa and Forage News: Natural Enemies Are Important for Control of the Aphid Complex in Alfalfa--A Case Study (By Ian Grettenberger, Rachael Freeman Long, Daniel Putnam and Rob Wilson, April 7, 2020)
- UC Statewide Integrated Pest Management Program: How to Manage Pests of Alfalfa
- UC Statewide Integrated Pest Management Program: Insects and Other Pests of Rice
