Posts Tagged: Walter Leal
It's a killer, pure and simple.
But the issue is as complex as it comes.
The malaria mosquito, from the genus Anopheles, infects some 350 to 500 million people a year, killing more than a million. Most are young children in sub-Saharan Africa.
Female mosquitoes “bite” because they require a blood meal to develop their eggs. They detect their prey via olfactory receptor neurons found on their antennae, the insect equivalent to the human “nose.”
When Anopheline mosquitoes are infected with a parasite that causes malaria, the insect-host transmission occurs. The result: a deadly killer.
Identifying exactly how malaria mosquitoes detect their human prey is crucial to developing strategies for mosquito control, says chemical ecologist Walter Leal, professor of entomology at the University of California, Davis.
Leal, recently asked to write a "News-and-Views" piece on a Yale-Vanderbilt study for the international science journal, Nature, did so eloquently in its March 4th edition. He praised the scientific report as a “milestone discovery in our understanding of the malaria mosquito’s sense of smell.”In the article, headlined "The Treacherous Scent of a Human," Leal zeroes in the widespread threat of malaria, a disease that threatens half of the world’s population. It's "an accessory to the deaths of about one million humans every year,” Leal wrote. “Globally, the number of people who get malaria each year is greater than the population of the United States.”
That's putting a number on the numbers.
The Yale-Vanderbilt team, headed by John Carlson of the Yale Department of Molecular, Cellular and Developmental Biology, examined 79 of the malaria mosquito’s odorant receptors, finding that some are well-tuned to detect specific human odors and others aren’t. Certain odorants activate some receptors but inhibit others, according to their comprehensive study published March 4 in Nature.
Indeed. The Leal lab back in 2008 published groundbreaking research that revealed the secret mode of the insect repellent, DEET. The scent doesn't jam the insect senses and it doesn't mask the smell of the host, as scientists previously thought. Mosquitoes avoid it because it smells bad to them.
Leal advocates more molecular studies in the war against malaria and other mosquito-borne diseases. But that research can't stand alone. As he succinctly points out: “The development of effective malaria control will require a multidisciplinary approach that includes, but is not limited to, improvements to social infrastructure in countries affected by disease, vaccination programs and vector management.”New mosquito attractants or repellents, he says, could be developed through reverse chemical ecology, determining which odorant attracts and which repels.
Mosquitoes don't like the scent of DEET. What else do they NOT like?
The study, as Leal correctly observes, "offers a fresh strategy for controlling the unwitting accessories to one of the world’s most prolific killers.”
Walter Leal in lab
Human blood--it drives mosquitoes wild.
Today Marlene Cimmons of the National Science Foundation (NSF) spotlights chemical ecologist Walter Leal, professor of entomology, University of California, Davis, on the LiveScience Web site.
This interesting feature takes a behind-the-scenes look at Leal, a Brazilian-born scientist trained in three countries: Brazil, Japan and the United States.
His research, partly funded by a NSF grant, has received international acclaim. Last year he was elected a Fellow of the 6000-member Entomological Society of America, a prestigious honor reserved for only 10 or fewer scientists a year.
Leal, who focuses his research on how insects detect smells, is not shy about being a human subject.
Or human pincushion.
Cimmons wrote about how Leal "rolled up his sleeves" when he and his colleagues were looking for the substance that would lure mosquitoes into a blood meal. "And they found it--nonanal, a substance made by humans and birds that creates a powerful scent that Culex mosquitoes find irresistible."
Leal also recalls the time when he was searching for beetles in Mexico and mosquitoes went after him with a vengeance.
"They'll go through anything, even jeans, as long as they know there is a blood vessel on the other side," Leal told Cimmons. "They can sense the heat."
Indeed, some folks just seem to attract more than their share of mosquitoes.
Only the female mosquitoes bite--they need a blood meal to develop their eggs.Related links:
UC Davis Researchers Identify Dominant Chemical That Attracts Mosquitoes to Humans
Groundbreaking Research on DEET
It's a career high.
Three University of California professors were among the 10 inducted as Fellows at the Entomological Society of America's annual meeting held Dec. 13-16 in Indianapolis.
When you consider that the ESA selects only 10 members--or not more than 10--each year from its 6000-member roster to become Fellows, that's indeed a high honor.ESA spokesperson Richard Levine says that Fellows are selected for their outstanding contributions in one or more of the following areas: research, teaching, extension, or administration.
The accomplishments of Leal, Federici and Raikhel could fill several books.
An insect-net salute to the UC trio!
The Mafia has its Good Fellas.
The Entomological Society of America (ESA) has its Fellows, too.
And they're not just "good"--they're excellent.
Every year ESA singles out up to 10 members from the 6000-member organization for the Fellow Award, paying tribute to their outstanding contributions in research, teaching, extension or administration.
This year one of the 10 selected is chemical ecologist Walter Leal, professor and former chair of the UC Davis Department of Entomology. He is internationally recognized for his pioneering and innovative work in insect olfaction, or how insects detect smells.
He'll receive the Fellow award on Sunday at the ESA's meeting in Indianapolis, Indiana.Leal is one of 11 UC Davis Department of Entomology faculty to receive the award since 1947:
1947: Richard M. Bohart (for whom the Bohart Museum of Entomology is named)
1990: Donald McLean
1991: Harry H. Laidlaw Jr. (for whom the Harry H. Laidlaw Jr. Honey Bee Research Facility is named)
1994: John Edman
1996: Robert Washino
2001: Bruce Eldridge
2004: William Reisen
2007: Harry Kaya
2008: Michael Parella and Frank Zalom
This year's list of ESA Fellows not only includes Leal from UC Davis, but Brian Federici and Alexander Raikhel of UC Riverside.
Three from the UC system--that's a three insect-net salute!
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