- Author: Kathy Keatley Garvey
The exciting research of Professor Takato Imaizumi of the University of Washington.
If you read Scientific Reports, you probably remember the piece he co-authored: "Circadian Clocks of Both Plants and Pollinators Influence Flower-Seeking Behavior of the Pollinator Hawkmoth Manduca sexta," published Feb. 12, 2018.
The abstract:
"Most plant-pollinator interactions occur during specific periods during the day. To facilitate these interactions, many flowers are known to display their attractive qualities, such as scent emission and petal opening, in a daily rhythmic fashion. However, less is known about how the internal timing mechanisms (the circadian clocks) of plants and animals influence their daily interactions. We examine the role of the circadian clock in modulating the interaction between Petunia and one of its pollinators, the hawk moth Manduca sexta. We find that desynchronization of the Petunia circadian clock affects moth visitation preference for Petunia flowers. Similarly, moths with circadian time aligned to plants show stronger flower-foraging activities than moths that lack this alignment."
"Moth locomotor activity is circadian clock-regulated, although it is also strongly repressed by light. Moths show a time-dependent burst increase in flight activity during subjective night. In addition, moth antennal responsiveness to the floral scent compounds exhibits a 24-hour rhythm in both continuous light and dark conditions. This study highlights the importance of the circadian clocks in both plants and animals as a crucial factor in initiating specialized plant-pollinator relationships."
And now, Takato Imaizumi will head to the University of California, Davis to present a seminar hosted by the UC Davis Department of Entomology and Nematology. His seminar, titled "Circadian Timing Mechanisms in Plant-Pollinator Interaction," is scheduled for 4:10 p.m., Wednesday, Oct. 30 in 122 Briggs Hall, off Kleiber Hall Drive.
"He will be speaking about his work on circadian clocks of plants and pollinators, and how circadian timing can shape plant-pollinator relationships," said molecular geneticist and physiologist Joanna Chiu, associate professor and vice chair of the UC Davis Department of Entomology and Nematology. Chiu, a UC Davis Chancellor Fellow, will introduce him.
- Author: Kathy Keatley Garvey
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)
- Author: Kathy Keatley Garvey
It's a tough world out there for pollinators.
Take it from UC San Diego bee scientist James Nieh, who will be on the UC Davis campus next week to speak on "Animal Information Warfare: How Sophisticated Communications May Arise from the Race to Find an Advantage in a Deadly Game Between Honey Bees and Their Predators."
His seminar, part of the fall quarter seminar series hosted by the UC Davis Department of Entomology and Nematology, will take place at 4:10 p.m., Wednesday, Sept. 25 in 122 Briggs Hall, Kleiber Hall Drive. Fellow bee scientist Brian Johnson, associate professor of entomology, is the host.
"In addition to the classical arm race that has evolved between predators and prey, information races also occur, which can lead to the evolution of sophisticated animal communication," says Nieh, a professor in the Section of Ecology, Behavior and Evolution, Division of Biological Sciences. "Such information can shape the food web and contribute to the evolution of remarkable communication strategies, including eavesdropping, referential signaling and communication within and between species, including between predators and prey."
"I focus on the world of information exchange (acoustic, olfactory and visual) that has co-evolved between Asian honey bees (Apis cerana, A. florea, and A. dorsata) and their predators, the Asian hornets (Vespa velutina and V. mandarinia)," Nieh says in his abstract. "I will explore how and why such information races occur through the remarkable examples provided by these high social insects."
He presented a TED talk on "Bees and Us: an Ancient and Future Symbiosis" in July 2019.
A native of Taiwan, Nieh grew up in Southern California and received his bachelor's degree in organismic and evolutionary biology in 1991 from Harvard University, Cambridge, and his doctorate in neurobiology and behavior from Cornell University, Ithaca, N.Y., in 1997. He subsequently received a NSF-NATO postdoctoral fellowship to study at the University of Würzburg in Germany. A Harvard junior fellowship followed.
Nieh joined the faculty of the Section of Ecology, Behavior and Evolution in 1997 as an assistant professor, advancing to associate professor in 2007 and professor in 2009. He served as vice chair of the section from 2009 to 2014, and as chair from 2014 to 2017.
His latest co-authored research, published in the journal Chemosphere in 2019, is titled Combined Nutritional Stress and a New Systemic Pesticide (flupyradifurone, Sivanto®) Reduce Bee Survival, Food Consumption, Flight Success, and Thermoregulation.
Assistant professor Rachel Vannette is coordinating the fall quarter seminars. Nieh's seminar is the first of the fall quarter. (See list of seminars.) Vannette may be reached at rlvannette@ucdavis.edu.
- Author: Kathy Keatley Garvey
Nine speakers are booked for the fall quarter seminars sponsored by the UC Davis Department of Entomology and Nematology. The seminars begin Wednesday, Sept. 25 and continue through Wednesday, Dec. 5.
Coordinated by assistant professor and community ecologist Rachel Vannette, the seminars will take place at 4:10 p.m., every Wednesday in Room 122 of Briggs Hall except on Nov. 20 (no seminar due to the Entomological Society of America meeting in St. Louis, Mo).
The schedule:
Sept. 25
James Nieh, professor, Section of Ecology, Behavior and Evolution, Department of Biological Sciences, UC San Diego
Topic: "Animal Information Warfare: How Sophisticated Communication May Arise from the Race to Find an Advantage in a Deadly Game Between Honey Bees and their Predators" (See lab website)
Host: Brian Johnson, associate professor, Department of Entomology and Nematology
Oct. 2
Nathan Schroeder, assistant professor, Department of Crop Sciences, University of Illinois, Urbana-Champaign
Topic: "Stem Cells and Neurobiology of Nematodes"
Host: Shahid Saddique, assistant professor, Department of Entomology and Nematology
Oct. 9:
John Mola, doctoral candidate, Neal Williams lab, Graduate Group in Ecology
Exit seminar: "Bumble Bee Movement Ecology and Response to Wildfire." Mola specializes in bee biology, pollinator ecology and population genetics.
Host: Neal Williams, professor, Department of Entomology and Nematology
Oct. 16:
Rebecca Irwin, professor, applied ecology, North Carolina State University, Raleigh, N.C.
Topic: (to be announced; she specializes in the ecology and evolution of multiple-species interactions, pollination biology, and species invasions)
Host: Rachel Vannette, assistant professor, Department of Entomology and Nematology
Oct. 23:
Julián Hillyer, director of the program in career development and associate professor of biological sciences, Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, Tenn.
Topic: "Not So Heartless: Functional Integration of the Immune and Circulatory Systems of Mosquitoes"
Host: Olivia Winokur, graduate student, Chris Barker lab
Oct. 30:
Takato Imaizumi, professor, Department of Biology, University of Washington, Seattle
Topic: Circadian Timing Mechanisms in Plant-Pollinator Interaction"
Host: Joanna Chiu, associate professor and vice chair of the Department of Entomology and Nematology
Nov. 6:
Brock Harpur, assistant professor, Department of Entomology, Purdue University
Topic: "Caste Differentiation in Honey Bees from the Bottom Up"
Host: Santiago Ramirez, associate professor, UC Davis Department of Evolution and Ecology, College of Biological Sciences
Nov. 13:
Allison Hansen, assistant professor, Department of Entomology, UC Riverside
Topic: Insect Herbivore-Microbe Interactions
Host: Clare Casteeel, assistant professor, UC Davis Department of Plant Pathology
Nov. 20:
No seminar (meeting of Entomological Society of America in St. Louis, Mo.)
Dec. 5:
Jackson Audley, doctoral candidate, Louie Yang lab and Steve Seybold lab
Exit seminar (topic to be announced). Audley studies the walnut twig beetle, Pityophthorus juglandis, which in association with the fungus, Geosmithia morbida, causes the insect-pathogen complex known as thousand cankers disease.)
Host: Steve Seybold, lecturer, forest entomology, UC Davis Department of Entomology and Nematology and forest entomologist and chemical ecologist with the Pacific Southwest Research Station, USDA Forest Service, Davis
The seminars are free and open to all interested persons. Some will be recorded for later viewing on YouTube. More information on the fall seminars or schedule is available from Vannette at rlvannette@ucdavis.edu.
- Author: Kathy Keatley Garvey
Pollinators aren't just bees, butterflies, beetles and bats.
They're also birds, like hummingbirds.
Ornithologists tell us that hummingbirds can easily eat their weight in a day, feasting on carbohydrates (nectar from blossoms and sugar water from feeders) and protein (insects and spiders).
The hummingbird menu includes such insects as ants, aphids, fruit flies, gnats, weevils, beetles, mites and mosquitoes. They also raid spider webs to grab a quick spider meal and any hapless insects trapped there.
We were thinking of insects and pollinators today (this blog focuses on insects and the entomologists who study them) after reading a UC Davis research paper published in the Proceedings of the Royal Society B that tested sugar water in hummingbird feeders.
Fact is, sugar water in hummingbird feeders can contain high densities of microbial cells but “very few of the bacteria or fungi identified have been reported to be associated with avian disease,” says community ecologist and co-author Rachel Vannette of the UC Davis Department of Entomology and Nematology.
The research is one of the first to explore the microbial communities that dwell in sugar water from feeders and compare them to those found in flower nectar and samples from live hummingbirds.
“The potential for sugar water from hummingbird feeders to act as a vector for avian pathogens--or even zoonotic pathogens--is unknown,” said Vannette, an assistant professor in the UC Davis Department of Entomology and Nematology. “Our study is one of the first to address this public concern. Although we found high densities of both bacteria and fungi in sugar water samples from feeders, very few of the species of bacteria or fungi found have been reported to cause disease in hummingbirds.”
“So although birds definitely vector bacteria and fungi to feeders, based on the results from this study, the majority of microbes growing in feeders do not likely pose significant health hazards to birds or humans,” Vannette said. “However, a tiny fraction of those microbes has been associated with disease, so we encourage everyone who provides feeders for hummingbirds to clean their feeders on a regular basis and to avoid areas where human food is prepared.”
The paper, “Microbial Communities in Hummingbird Feeders Are Distinct from Floral Nectar and Influenced by Bird Visitation,” is the work of first author Casie Lee, a UC Davis School of Veterinary Medicine student; Professor Lee Tell of the UC Davis School of Veterinary Medicine's Department of Medicine and Epidemiology; Tiffany Hilfer, an undergraduate student and Global Disease Biology major; and Vannette.
Lee, mentored by Vannette and Tell, led the field experiment and performed bird observations and laboratory work during a summer project funded by the Students Training in Advanced Research (STAR) and Merial Veterinary Scholars Programs.
The researchers also compared the microbes in the feeders to those in floral nectar and found they differed in microbial composition.
“Birds, feeder sugar water, and flowers hosted distinct bacterial and fungal communities,” they wrote in their abstract. “Floral nectar and feeder sugar water hosted remarkably different bacterial communities; Proteobacteria comprised over 80% of nectar bacteria, but feeder sugar water contained relatively high abundance of Firmicutes and Actinobacteria, as well as Proteobacteria. Hummingbird feces hosted both bacterial taxa commonly found in other bird taxa and novel genera including Zymobacter (Proteobacteria) and Ascomycete fungi.”
The UC Davis scientists conducted their research at a private residence in Winters, attracting two hummingbird species, Calypteanna (Anna's Hummingbird) and Archilochus alexandri (Black-chinned Hummingbird) to drop net feeder traps. They mixed bottled water with conventional white granulated sugar (one part sugar and four parts water).
See more information--and photos--on their research on the UC Davis Department of Entomology website.
But back to insects and the hummingbirds that eat them. Entomologist Doug Tallamy of the University of Delaware says that "hummingbirds like and need nectar but 80 percent of their diet is insects and spiders."
Wildbirds on Line says: "I frequently put overripe bananas of my fruit feeder to attract tiny fruit flies, which in turn attract the hummers. The hummingbirds eat every fly and return in a few hours to feast on the next batch of fruit flies that discover the overripe fruit. What an easy way to observe hummers eating insects!"
Now that's an idea! Fruit flies for the hummers!
