Posts Tagged: Walter Leal
Chemical ecologist Walter Leal, professor and former chair of the UC Davis Department of Entomology, and his postdoctoral researcher Zain Syed have done it again.
In August of 2008, they discovered the secret mode of the insect repellent, DEET. In groundbreaking research published in the Proceedings of the National Academy of Sciences (PNAS), they found that DEET doesn't mask the smell of the host (that would be you and me), nor does DEET jam the insect's senses.
Mosquitoes CAN indeed smell DEET. They avoid it because they don't like the odor.
Then on Monday, Leal and Syed published more groundbreaking research, also in PNAS. They identified the dominant compound that attracts Culex mosquitoes to both birds and humans.
It's a compound called nonanal, naturally produced in birds and humans. This not only explains the host shift from birds to humans, but paves the way for key developments in mosquito and disease control.
Infected Culex mosquitoes transmit life-threatening diseases, including West Nile virus. Since 1999, the Centers for Disease Control and Prevention has recorded 29,397 human cases and 1,147 fatalities in the United States alone.
“Nonanal is how they find us,” Leal said. “The antennae of the Culex quinquefasciatus are highly developed to detect even extremely low concentrations of nonanal.”
Researchers from throughout the country this week praised their work.
Yale University professor John Carlson, a leading scientist in insect olfaction, described the study as “exciting with important implications for the intriguing question of how mosquitoes find the humans they bite.”
“Leal and Syed have identified a human odor that is detected with great sensitivity by the antennae of mosquitoes that transmit West Nile virus,” Carlson said. “In addition to its scientific interest, the study may have important practical applications in the control of these mosquitoes and the diseases they carry.”
Chemical ecologist Coby Schal, a professor at North Carolina State University, described the research as representing “some of the best research on insect olfaction that I have ever read. By combining trapping experiments in the field with careful characterization of the response profiles of antennal and maxillary sensilla of Culex mosquitoes, Syed and Leal show not only that the combination of carbon dioxide and nonanal is an important beacon for blood-seeking mosquitoes, but also that a large fraction of the sensilla on the mosquito’s nose (antennae) is dedicated to the detection of nonanal at incredibly low concentration.
“Such high sensitivity of olfactory receptor neurons to nonanal – rivaling the response characteristics of pheromone responsive neurons – suggests that nonanal has played an important role in the evolution of host-finding and host-preferences in Culex mosquitoes,” Schal said. “This is a truly exceptional achievement by the outstanding Syed/Leal team, but in step with their previous outstanding contributions on a wide range of arthropods.”
More information on the Leal lab research is on the Department of Entomology Web page.
Leal, a newly elected Fellow of the Entomological Society of America (he's one of 10 entomologists to be so honored this year) and Syed, named one of the top post-doctoral researchers at UC Davis this year, have indeed done it again.
When you think of all the havoc that mosquito-borne diseases have wreaked, this is the kind of research that definitely deserves a round of applause.
Dr. Leal and Dr. Syed are a highly efficient and effective SWAT team.
Walter Leal and Zain Syed
Like to know more about the biocontrol of tea pests? Aging of insects? What honey bee research is under way?
If you can't physically attend the UC Davis Department of Entomology's fall seminars, starting Wednesday noon, Oct. 7 in 122 Briggs Hall, you can participate via Webinars or listen to the archived Webcasts. Most will be Webcast.
UC Davis entomology professor James Carey, former chair of the UC Systemwide Academic Senate University Committee on Research Policy, launched a pilot program in February to inform and educate the scientific community and the public on research findings.
Carey's lab researchers and graduate students began taping the series of Webinars on Feb. 18. Then came the summer break. Now that we're into the fall season, the Webinars will continue Oct. 7.
Here's the link to access the Webinar.
The UC Davis Webinars drew international attention on March 4 when chemical ecologist Tom Baker of Pennsylvania State University spoke on “But Do We Shoot the Driver? Meeting New Challenges in Detecting Agents of Harm by Using Old Entomological Knowledge.” Joining in were listeners from 10 countries: Argentina, Uruguay, Brazil, Mexico, France, Spain, Netherlands, Germany and Japan as well as the United States.
“We were hooked up to Pennsylvania State, too, so my colleagues knew where I was at, what I was doing and what I was saying,” Baker quipped.
Fellow chemical ecologist Walter Leal, UC Davis professor of entomology, who hosted Baker, later marveled at the technology.
“Just think, someone was sitting at a computer in Japan at 4 in the morning listening to Tom,” Leal said.
Both the virtual and physical audience can ask questions.
Webinars not only save time, but money, Leal pointed out. “The average round trip cost for airfare only for the 10 countries that participated in Baker’s seminar is $1,480, with Mexico being the cheapest ($700) and Montivideo, Uruguay the most expensive ($3,600).”
“It means that we saved in average $59,200 considering one participant per computer,” Leal said. “Note that in a couple of cases the presentation was displayed for multiple participants. If all participants would be accounted for, the cost would be astronomical.”
“As for travel time, only for each way, the average for the 10 countries would be 20 hours and 30 minutes, with the shortest trip being from Mexico (six-hour flight plus six hours of layover and check-in) and the longest from Montivideo (19-hour flight, plus six hours for layover and check-in),” Leal said.
The archived Webinars, from Feb. 18 through May 27, are online.
Here's the fall line-up:
Oct. 7: Biological control scientist Madoka Nakai, associate professor, Tokyo University of Agriculture and Technology, will discuss biocontrol of tea pests in her talk, “A Novel Protein from Lepidopteran Virus Killing Endoparasitoid and Viral Control for Tea Pests in Japan” (Webcast)
Oct. 14: Plant taxonomist Dean Kelch, assistant researcher, University and Jepson Herbaria, UC Berkeley, “Mimicking Science Interpretation: A Visit to the Creation Museum” (this one won't be Webcast)
Oct. 21: Entomologist James R. Carey, professor, UC Davis Department of Entomology, “Demography of the Finitude: Insights into Lifespan, Aging and Death from Insect Studies" (Webcast)
Oct. 28: Insect virus researcher Michelle Flenniken, Haagen-Dazs Postdoctoral Fellow, “Microarray-Based Pathogen Detection and the Antiviral Role of RNA Interference in Honey Bees” (not Webcast)
Nov. 4: Chemical ecologist Jonathan Gershenzon, professor, Max Planck Institute for Chemical Ecology, Jena, Germany, "Plant Volatiles: Versatile Agents of Defense"
Nov. 18: Community ecologist and population biologist Matt Forister, assistant professor, University of Nevada-Reno, on the “Agricultural” Melissa Blue butterfly: “Anatomy of a Niche Shift: Lycaeides melissa and the Colonization of Alfalfa”
Dec. 2: Entomologist Michael Parrella, professor and chair, UC Davis Department of Entomology, “An International Perspective on Sustainable Production in Greenhouses”
Two highly talented and enthusiastic university students from Brazil have joined the Walter Leal lab in the Department of Entomology, University of California, Davis, as part of a unique and growing international agricultural exchange program.
The program is known as SUSPROT.
SUSPROT? That's the Sustainable Crop Protection in Agriculture Program, a federally funded program designed to promote scientific cooperation and collaborative education between academic and professional communities in Europe (Belgium, France, Germany and the Netherlands) and the United States.
And now Brazil.
Aline Guidolin (top right) and Diogo Vidal (bottom left) arrived Sept. 14 to work three months with Leal, a noted chemical ecologist and professor of entomology, and with several other researchers in the lab.
Vidal is working with pheromone binding proteins and isolation and identification of pheromones, and Guidolin, gene silencing of pheromone-binding proteins.
“This year we’ve been able to extend SUSPROT into Brazil,” said Brazilian-born Leal, who serves as the UC Davis coordinator of SUSPROT. The organization is headquartered at Pennsylvania State University.
All universities participating in SUSPROT were selected for their strong agricultural programs. “It’s a global agricultural industry now, and we need to know how to research the problems and how to solve them,” Leal said. “We need to learn from one another.”The Brazilian students, both pursuing their bachelor of science degrees, will receive university credit for their work here. Vidal, 22, is majoring in chemistry at the Universidade Federal do Paraná, Curitiba, and Guidolin, 23, is majoring in biological sciences at the University of Sao Paulo, Piracicaba. “They are very enthusiastic,” said Leal. “In fact, the same day they arrived, Aline wanted to start the experiments. And when I left the lab Wednesday night (Sept. 16), I thought I was the last one to leave the lab. I was wrong. They were both still here.”
The two young scientists will join the Leal family for Thanksgiving dinner. You can bet that the turkey will be just one of the main attractions. Expect lively conversations on pheromone-binding proteins and gene silencing.
In multiple languages.
Leal and his wife Beatrix were both born in Brazil and lived in Japan before relocating to Davis. They speak Portuguese, English and Japanese. Their children are also multilingual. Sons Augusto, 18 (now studying at Princeton) and Gabriel, 12, were both in Japan, and daughter Helena, 9, in the United States.
Meanwhile, Walter Leal is gearing up for the SUSPROT exchange trip to Brazil next July. He will accompany a group of UC Davis and Penn State students.
The team “will be exposed to the agricultural or entomology side, the industrial side and the production side,” said Leal. “We can learn a lot from Brazil. Brazil is known for its ethanol production and is the world’s biofuel industry leader, while the U.S. is still in its infancy. Brazil is the leading soybean producer."
As Leal said, it's "a global agricultural industry now, and we need to know how to research the problems and how to solve them.”
Cooperation, collaboration and commitment.
In the Leal Lab
Congratulations are in order.
Chemical ecologist Walter Leal, professor and former chair of the UC Davis Department of Entomology, has just been selected a Fellow of the Entomological Society of America, a prestigious honor granted to only 10 or few members of the 6000-member organization each year.
Leal is internationally known for his pioneering and innovative work on insect communication.
“This is a highly prestigious honor and richly deserved,” said Michael Parrella, professor and chair of the UC Davis Department of Entomology and one of 10 other UC Davis entomologists named ESA Fellows since 1947.
May Berenbaum, professor and head of the Department of Entomology, University of Illinois, Urbana-Champaign, one of the scientists who supported his nomination, praised him as a "trail blazer" and lauded his leadership.
Leal and his lab discovered the secret mode of DEET, the insect repellent. For some 50 years, scientists figured it worked by either jamming the insect's senses or masking the smell of the host. Not so. In groundbreaking research, the Leal lab showed that mosquitoes can indeed smell DEET, but they avoid it because they don't like the smell.
In other words, it smells bad. That's why they avoid it.
The groundbreaking research, published Aug. 18, 2008 in the Proceedings of the National Academy of Sciences, is among the most widely downloaded and cited PNAS documents.
Leal's pheromone work has graced the cover of several journals, including Structure, and has been showcased in the popular press, including the BBC, New York Times, and National Public Radio.
Leal has identified and synthesized complex pheromones from such insects as scarab beetles, true bugs, longhorn beetles, moths, and the naval orangeworm.
Entomologist Bruce Hammock, UC Davis distinguished professor of entomology, said Leal’s research has “practical implications in explaining how insects communicate within species, how they detect host and non-host plants, and how insect parasites detect their prey.”
Leal's navel orangeworm work alone is certain to result in a multi-million dollar beneficial impact on crops ranging from almonds to citrus, Hammock said. Leal's research on mosquito behavior is crucial to controlling vectorborne diseases like West Nile virus and malaria.
And now, an honor to match.
Chemical ecologist Zain Syed of the Walter Leal lab, University of California, Davis, knows just where to find mosquitoes for his research.
He's been collecting up to 3000 mosquitoes a night along the Yolo Causeway, located on Interstate 80 between Davis and West Sacramento. The Yolo basin is home to the Vic Fazio Yolo Wildlife Area.It's easy to catch mosquitoes.
Syed is using carbon-dioxide traps to capture host-seeking mosquitoes. The female skeeters are seeking a blood meal (you, if you're around there). His traps entice them to "come on in."
"Once mosquitoes are lured to the vicinity," Syed says, "a suction fan traps them and sends them to the sleeve, a mesh bag that holds mosquitoes."
The mesh bag below holds 2000 mosquitoes. They are mostly Culex tarsalis, but also some Culex pipiens.
Culex mosquitoes are known for transmitting West Nile virus.
Syed and Leal are known for uncovering the mode of action for DEET, the chemical insect repellent used by more than 200 million people worldwide. Their groundbreaking research last year found that DEET doesn't jam a mosquito's senses or mask the smell of the host, as scientists previously thought for some 50 years. Mosquitoes avoid DEET because it smells bad to them.
Syed recently won one of two coveted campuswide awards for excellence in postdoctoral research from a field of 800 postdocs.
But other fields--rice fields--have always drawn his attention.
That's where the skeeters are.