- Author: Kathy Keatley Garvey
They can also do something else.
Basically, if you're a plant and an insect is attacking you, you can communicate your stress to nearby plants as a way to alert them about potential danger--very similar to how animals communicate or respond to predators, according to UC Davis agricultural entomologist Christian Nansen of the Department of Entomology and Nematology.
In groundbreaking research published in the journal Plant Methods, Nansen and his team of six colleagues from Brazil discovered that plant-plant communication causes physiological changes in plants and these subtle changes can be detected via analyses of leaf reflectance or hyperspectral imaging. The article is titled “Hyperspectral Imaging to Characterize Plant-Plant Communication in Response to Insect Herbivory."
The growing knowledge about plant-plant communication and about plants' ability to assess their environment has led to concepts like “plant neuro-biology” and “plant behavior,” said Nansen, an associate professor who centers his research on host plant-stress detection, host selection by arthropods, pesticide performance, and use of reflectance-based imaging in a wide range of research applications.
“We know that plants don't have a neural system or brain,” said Nansen, “but respected scientists are studying plants as if they did, as if plants are able to assess conditions in their environments, and they can adapt/respond to those conditions.”
“In studies of plant stress signaling, a major challenge is the lack of non-invasive methods to detect physiological plant responses and to characterize plant-plant communication over time and space.” Nansen pointed out. He described the research as “initial evidence of how hyperspectral imaging may be considered a powerful non-invasive method to increase our current understanding of both direct plant responses to biotic stressors but also to the multiple ways plant communities are able to communicate.”
The UC Davis entomologist and his team used leaf reflectance data to detect and characterize plant responses to stressors, knowing that induced stress interferes with photosynthesis, chemical composition and physical structure of the plant, thus affecting the absorption of light energy and altering the reflectance spectrum of the plants.
“For several decades, it has been known that plants communicate – both among individuals of the same species and across species,” Nansen related. “That is, volatiles emitted by one plant can be received by another plant and trigger different physiological responses. It is also well-documented that plants communicate via roots, and sometimes the roots from different plants are brought together in a network of communication and exchange of nutrients through symbioses with mychorriza (soil fungi).”
Of the Nansen study, Karban said: "This study describes a technique that may provide a relatively quick and inexpensive way to evaluate levels of resistance in plants. If these results are repeatable by other workers in other systems, they will provide a very valuable tool for researchers and growers."
Both Karban and Nansen contributed chapters to the recently published book, The Language of Plants (University of Minnesota Press). The book explores "the idea that plants can think, feel, and communicate as a way of reconfiguring our relationship with the natural world," according to editors Monica Gagliano, John C. Ryan, and Patrícia Vieira.
"Within the last decade or so, extremely cutting-edge research in the field of plant-plant communication has been done by people like Dr. Monica Gagliano of the University of Western Australia," Nansen said. "She has elegantly demonstrated that plants can respond not only to aerial volatile compounds and root secretions but also to sound."
For the research project, Nansen and his team decided to conduct “a very simple experiment with corn plants and stink bugs.” They planted corn plants in separate pots or two in one pot. They subjected some plants to herbivory by stink bugs, while other plants served as control plants.
The scientists collected two types of data: phytocompounds (stress hormones and pigments) and leaf reflectance data (proximal remote sensing data).
“Our research hypothesis was that insect herbivory causes changes in leaf phytocompound levels, and these physiological defense responses are associated with detectable changes in phytocompound levels and in certain spectral bands of leaf reflectance profiles,” Nansen pointed out. As a secondary hypothesis, the researchers predicted that plant-plant communication (from plant with herbivory to an adjacent control plant without herbivory) will elicit both a change in phytocompound composition of leaves and also cause a corresponding change in leaf reflectance.
The result: The first published study, in which comprehensive phytocompound data have been shown to correlate with leaf reflectance. In addition, it is the first published study of leaf reflectance in plant-plant communication.
Nansen and co-author Leandro do Prado Ribeiro of the Research Center for Family Agriculture, Research and Rural Extension Company of Santa Catarina, Brazil, conceived and designed the experiments. The Brazilian National Counsel of Technological and Scientific Development provided partial financial support. Co-author Marilia Almeida Trapp received financial support from a Capes-Humboldt Research Fellowship.
- Author: Kathy Keatley Garvey
Congratulations to UC Davis entomology professor Diane Ullman who has just a received Fulbright to France to research plant virus-insect interactions. She will be studying plant viruses and the insects that transmit them.
Her sabbatical, to begin in November, 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.
Ullman, an international authority on orthotospoviruses, said that "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...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.
- Author: Kathy Keatley Garvey
So there they were, literally dozens of dragonflies flying around two separate Vacaville (Calif.) yards, feasting on swirling clouds of prey (gnatlike insects) and then touching down on blades of grass or fence posts.
They proved as elusive as a celebrities attempting to avoid a paparazzi.
Dragonflies, but what species?
Bohart Museum of Entomology associate Greg Kareofelas of Davis identified them as variegated meadowhawks, Sympetrum corruptum. "Notice how the pterostigma is two-toned," he said. "That is the only dragon with that, also the two black spots at the end of the tail. They kind of migrate--or maybe mass dispersal is a better name. A bunch can show up if there is something to eat, then the whole gaggle moves on."
The pterostigma cell, located in the outer wing of insects, is often thickened or colored and so it stands out from other cells, according to Wikipedia. It is particularly noticeable in dragonflies, but is also present in other insect groups, such as snakeflies, hymenopterans and megalopterans.
"The male is commonly dark brownish black with an abdomen of bright red, pink, and golden brown," Wikipedia relates. "The thorax may be marked with a pair of yellow dots on each side. The leading edges of the wings are marked with pinkish. The females are similar in color but not as brightly colored, with gray and yellow replacing the red of the male. Young variegated meadowhawks are much paler and mottled with pale green, pale yellow, golden brown, and orange."
According to Odonata Central, "this species may be seen on the ground more than other meadowhawks. It will also readily perch on the tips of grass stems and tree branches. It can be numerous flying over roads, lawns, meadows, marshes and ponds...Mating occurs while perched on twigs, stems or other vegetation. Females lay eggs accompanied by males in the open water of ponds and lakes. Mass movements of this species have been reported on several occasions."
The variegated meadowhawk, native to North America, belongs to the family, Libellulidae. They're found throughout the United States and southern Canada, according to Odonato Central. "Also, Mexico south to Belize and Honduras."
Coming soon to a yard near you?
- Author: Kathy Keatley Garvey
Thanks to the generosity of his family, his work is continuing through memorial research grants to outstanding graduate students at the University of California, Davis.
Hazeltine, a native of San Jose, was a U.S. Navy veteran who studied entomology at UC Berkeley and received his doctorate in entomology from Purdue University in 1962. He managed the Butte County Mosquito Abatement District, Oroville, from 1966 to 1992, and the Lake County Mosquito Abatement District from 1961-1964.
He was an ardent supporter of the judicious use of public health pesticides to protect public health, remembers Bruce Eldridge, emeritus professor of entomology at UC Davis and former director of the (now folded) statewide UC Mosquito Research Program. Eldridge eulogized him at the 2005 annual meeting of the American Mosquito Control Association (AMCA) as "a man who made a difference." The AMCA journal published his eulogy in its 2006 edition. (See http://entomology.ucdavis.edu/files/154217.pdf)
"Bill was a medical entomologist who had a varied career in the field of mosquito biology and control, but he will forever be remembered as a man who fought in the trenches of the pesticide controversy from 1960 until the end of his life, and who made the safe and efficient use of pesticides in public health a personal crusade," Eldridge said.
In his memory, his three sons--Craig Hazeltine of Scottsdale, Ariz., Lee Hazeltine of Lincoln, formerly of Woodland, and the late Jeff Hazeltine (1958-2013)—established the UC Davis Bill Hazeltine Graduate Student Research Awards in 1997. Each year they travel to Davis to honor the recipients at a luncheon, timed with their attendance at a scholarship and fellowship celebration, hosted by Dean Helene Dillard, UC Davis College of Agricultural and Environmental Science.
The 2017 recipients are
- Olivia Winokur of the Christopher Barker lab, Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine. Her funded project ($2425): “Identifying Aedes Mosquito Eggs Using Hyperspectral Imaging: a Rapid, Low-Cost, Non-Destructive Method to Improve Mosquito Surveillance and Control.”
- Maribel "Mimi" Portilla of the Sharon Lawler lab, UC Davis Department of Entomology and Nematology. Her funded project ($2032): “The Management of Invasive Weeds and their Effects on Larval Culex mosquitoes."
Winokur is also the newly announced 2018 recipient of $3,094 to investigate Aedes aegypti immune response to Zika virus. (Portilla expects to receive her doctorate in six to 12 months.)
Olivia Winokur
“Aedes aegypti and Aedes albopictus are mosquitoes capable of transmitting dengue, chikungunya, yellow fever, and Zika viruses,” Olivia Winokur explained in her 2017 application. “These species are invasive and present in California and continue to spread, increasing the likelihood of local transmission of these devastating viruses. Additionally, Aedes notoscriptus, an Australian mosquito whose vector competence for many viruses is unknown, has been detected in Los Angeles and is likely to spread in the state. Aedesmosquitoes are readily detected using ovitraps, a cheap and effective sampling method to detect the presence of gravid females. Ovitraps are especially useful when mosquito populations are low as traps for adult Aedes are unreliable. Once collected, the eggs cannot be differentiated using a stereomicroscope. Traditionally, identifying Aedes eggs collected in ovitraps requires hatching and rearing to adult for visual identification, which is time consuming and leads to a time lag for control, potentially allowing invasive species to spread without intervention.”
“Currently, I am developing a non-destructive, low-cost method to rapidly identify Aedes eggs,” Winokur wrote. “I have shown that species-specific surface morphologies of the exochorion can be used to differentiate species using electron microscopy. This method is expensive and therefore not a realistic surveillance technique. We can, however, exploit these species-specific surface morphologies in another way to identify Aedeseggs. Slight changes in morphological characteristics can be captured with high spatial resolution proximal sensing imaging, termed hyperspectral imaging.”
Winokur is testing “the use of hyperspectral imaging to differentiate between eggs collected from lab colonies of native and invasive Aedes mosquitoes in California. Preliminary data indicate this method shows promise for identifying species and warrants further testing. Once I have created species-specific reflectance profiles and validated my identification method using colony eggs, I will collect field eggs and validate the identification method using these field eggs.” She is working with hyperspectral imaging expert Christian Nansen, agricultural entomologist and assistant professor, UC Davis Department of Entomology and Nematology, on the project.
Winokur describes hyperspectral imaging as “a powerful tool that recognizes slight changes; therefore, we need to ensure that all samples are collected and conditioned the same way before testing. Samples must be imaged directly on the oviposition paper because exochorion cells are damaged by the ‘glue' the female uses to attach her eggs to the substrate; imaging removed eggs leads to inconsistent reflectance profiles. This method for rapidly identifying Aedes eggs will allow for quick response to the detection of invasive Aedes mosquitoes.”
After finishing her Ph.D., Winokur plans to remain in academia, but “I'm unsure exactly what that will look like! I really enjoy research, teaching, and mentoring so I'd like to have a career where I can do all of these. I also plan to have a career where I can conduct translational research with broad global health implications, engage non-scientists, create tools to help decision makers mitigate vector-borne disease burden worldwide, and encourage interest and diversity in STEM (science, technology, engineering and mathematics).”
Maribel "Mimi' Portilla
“At UC Berkeley School of Public Health, I was able to study health and disease within a larger context, and learned to consider the biological and the social determinants of disease. As I completed my degree, I realized I really missed the research experiences I had as an undergraduate. So, I looked for a way to bridge my new-found passion for public health and basic science research. This led me to UC Davis, where I learned about One Health and am now pursuing a Ph.D in medical entomology. Medical entomology is a perfect example of a One Health field, where I can seek out how interactions between humans and animals impact health. I am particularly interested in researching how disease risk may change as people manipulate the environment."
Her academic life revolves around writing her dissertation; teaching UC Davis classes (she's taught entomology, general biology and One Health classes); research; and public outreach. Since 2012, she has mentored some 30 undergraduate students on developing and executing their research experiments. She praised the “the diversity of my interns; they each brought such important and unique perspectives to the project.”
What are her career plans?
“Due to my diverse interests and skill set, I am very open about my career choices," Portilla said. "I have extensive teaching experience, and would love to be a professor with both teaching and research opportunities. However, there are many opportunities beyond academia. My research is introducing me to many other ways in which my work and research can help keep people safe and healthy. I hope to develop a strong research skill set while at UC Davis, and find a career path which takes advantage of my diverse abilities and love for One Health and Public Health."
Portilla mentioned pursuing a career as a teacher in a small liberal arts school to teach public health, general biology and global diseases classes, as well as do outreach and research. “I'm more of a scientist than an entomologist,” she said.
She may also pursue a career working in vector-control health education at the county, district or state level. “I'm open at this point,” Portilla said. Overall, she is geared toward improving public health outcomes through healthier environments. “I care about how outcomes affect the larger population,” she said.
Meanwhile, it's good to see that William Emery Hazeltine's passion for medical entomology lives on, and to see UC Davis graduate students benefit, all thanks to the generosity and thoughtfulness of the Hazeltine family. The "family" of 42 recipients since 1997 includes Christopher Barker, Winokur's major professor, who received a Hazeltine research award in 2006.
The complete list of recipients:
- 2018: Olivia Winokur (newly announced)
- 2017: Maribel "Mimi" Portilla and Olivia Winokur
- 2016: Sandy Olkowski, Maribel “Mimi” Portilla and Stephanie Kurniawan
- 2015: Sandy Olkowski, Maribel “Mimi” Portilla and Stephanie Kurniawan
- 2014: Martha Armijos, Elizabeth “Lizzy” Glennon and Rosanna Kwok
- 2013: Jenny Carlson, Elizabeth “Lizzy” Glennon and Sandy Olkowski
- 2012: Jenny Carlson, Kelly Liebman and Sandy Olkowski
- 2011: Brittany Nelms Mills, Kelly Liebman and Jenny Carlson
- 2010: Tara Thiemann and Jenny Carlson
- 2009: Kelly Liebman and Wei Xu
- 2008: Ashley Horton and Tara Thiemann
- 2007: Lisa Reimer and Jacklyn Wong
- 2006: Christopher Barker and Tania Morgan
- 2005: Nicole Mans
- 2004: Sharon Minnick
- 2003: Hannah Burrack
- 2002: Holly Ganz and Andradi Villalobos
- 2001: Laura Goddard and Linda Styer
- 2000: Laura Goddard
- 1999: Linda Boose Styer
- 1998: Larisa Vredevoe
- 1997: John Gimnig
- Author: Kathy Keatley Garvey
Irish novelist Margaret Wolfe Hungerford was right.
In Molly Bawn, published in 1878, Hungerford wrote "Beauty is in the eye of the beholder," meaning that our perception of beauty is subjective.
Beauty is also in the eye of the bee-holder, that is, a predator that "holds" bees.
We recently spotted a crabronid wasp (genus Philanthus) foraging on a pineapple sea lily (Eryngium horridum).
This solitary, digger wasp is better known by its common name, beewolf. That's because it preys on bees, including honey bees. The wasp stings the bee with its powerful venom, paralyzing it. Then it flies off with the bee (alive) to its underground nests where it provisions its cell burrows for its young.
"They are notable in stinging their prey in a membranous location on the ventral surface where the venom quickly paralyzes major voluntary muscles, yet does not kill the prey," according to Wikipedia. "The prey may attempt to sting in return, but it is always grabbed in such a way that only well-armored portions of the beewolf's body are presented. The beewolf carries the prey back to a tunnel, but usually only stores it temporarily, until it is later used to provision a cell burrow, where an egg is laid."
As we watched the beewolves (as identified by Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at the University of California Davis) we also saw other critters foraging on the pineapple sea lily: honey bees and assorted mordellid beetles.
Take a look the beewolf. Note the bold, black stripes on the abdomen; the brilliant yellow on the head and thorax; and those sea-green eyes.
It's a predator, but predators, like prey, can be strikingly beautiful. Beauty is in the eye of the bee-holder.