- Walter Leal, distinguished professor, Department of Molecular and Cellular Biology and former chair of the Department of Entomology (now the Department of Entomology and Nematology
- Cristina Davis, the Warren and Leta Geidt Endowed Professor and Chair, Department of Mechanical and Aerospace Engineering
NIA honors and encourages academic inventions that benefit society. Between the two UC Davis faculty members, they hold 42 patents: Davis with 12; and Leal with 28 Japanese and 2 U.S. patents.
Davis is a world leader in trace chemical sensing, while Leal is a leading global scientist in the field of insect olfaction and communication, investigating how insects detect odors, how they detect host and nonhost plant matter, and how they communicate within their species.
Leal's research, spanning three decades, focuses on insects that carry mosquito-borne diseases as well as agricultural pests, such as the Asian citrus psyllid and the orange navelworm. He and his lab drew international attention with their discovery of the mode of action of DEET, the gold standard of insect repellents.
We remember when Leal and a group of 18 students hosted a Zika Public Awareness Symposium in 2016 on the UC Davis campus. It was an amazing symposium that drew attention to Aedes aeqytpi, which transmits the disease. Soon thereafter, Brazilian-born Leal and his colleagues in Brazil, detected the Zika virus in wild-caught Culex quinquefasciatus mosquitoes in Recife, the epicenter of the Zika epidemic.
We also remember when Leal identified the sex pheromones of the navel orangeworm (Amyelois transitella), a pest of almonds, figs, pomegranates and walnuts, the major hosts. This led to practical applications of pest management techniques in the fields.
Those are just several examples of the work he does. And still, he found time to co-chair the 2016 International Congress of Entomology meeting, "Entomology Without Borders," in Orlando, Fla., that drew the largest delegation of scientists and experts in the history of the discipline: 6682 attendees from 102 countries.
We're not sure how Leal can find the time to do all this (see news story on the UC Davis Department of Entomology and Nematology). We figure he must have a clone! Make that multiple clones!
At any rate, Leal is the second faculty member affiliated with the entomology department to be selected an NIA fellow. The other scientist: Bruce Hammock, distinguished professor, who holds a joint appointment in the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center. Hammock is the co-founder and chief executive officer of EicOsis LLC, a Davis-based company that is developing a non-opiate drug to relieve inflammatory pain in companion animals and target chronic neuropathic pain in humans and horses.
As Hammock said: “When Walter Leal reached UC Davis (in 2000), he came with the reputation of being a 'one man army in research.' This reputation was well deserved. I know of no one at UC Davis who matches Walter in taking his remarkable fundamental advances in science and translating them to increase the safety and magnitude of world food production.”
Jordan, the second-highest-scoring NBA player scorer (5,987 points), "wasn't good enough" to make his high school varsity basketball team (at first). And the late Tom Eisner, the renowned Cornell University professor who went on to be known as "the father of chemical ecology," just "wasn't good enough" to be accepted at Cornell as an undergraduate student.
"Sorry, you didn't make it!" probably rang in their ears.
So when chemical ecologist and distinguished professor Walter Leal of the University of California, Davis, delivers the Founders' Memorial Award Lecture on Tom Eisner (1929-2011) at the Nov. 17-20 Entomological Society of America (ESA) meeting in America's Center in St. Louis, Mo., the Jordan-Eisner comparison will surface amid all of Eisner's incredible accomplishments, including his National Medal of Science award in 1994 from President Bill Clinton for his "seminal contributions in the fields of insect behavior and chemical ecology, and for his international efforts on biodiversity."
Leal will speak on "Tom Eisner--An Incorrigible Entomophile and Innovator Par Excellence" at the Founders' Breakfast meeting that begins at 7:30 a.m., Tuesday, Nov. 19. His presentation, at 8:15, promises to be inspirational, educational and entertaining. (And it's free to all ESA meeting registrants.)
ESA established the Founders' Memorial Award in 1958 to honor the memory of scientists providing outstanding contributions to entomology.
Eisner is known as an exemplary scientist, teacher and leader whose research discoveries focused on how insects use their chemical substances as friends or foes: to attract mates or to defend from foes. He discovered how "a bombardier beetle creates a chemical reaction within its body and then ejects a boiling hot chemical from its abdomen." As Joe Rominiecki, ESA communications manager, said: “Notable among them was deciphering how the bombardier beetle defends itself with an internal exothermic chemical reaction, explosively sprayed at attackers. That discovery topped a lengthy list of revelations about the complex and often surprising biochemicals insects produce, from the bitter, predator-deterring taste of the cochineal scale's brilliant red pigment to the sticky foot secretions that allow the palmetto beetle to cling so tightly to leaf surfaces.“
Leal, whose career spans three decades (see Bug Squad blog) built his career on Eisner's work. So we asked Leal to name 10 interesting facts about Tom Eisner. He obliged.
- Tom Eisner was born in Berlin, grew up in Uruguay, went to college and lived the rest of life in the United States.
- In 1969 Tom gave the Founders' Memorial Lecture to honor Robert Snodgrass. This year he is being honored by the same lecture.
- Tom was an excellent musician; he owned three Steinway Grands, two remains with his daughters and one he gave to the Cornell Music Department
- His application to enter Cornell University was rejected in 1947. Ten years later he was hired as an assistant professor.
- Tom got his BS and PhD from Harvard.
- Tom is considered one of the founding fathers of chemical ecology but mentioned this cannot be proven without a paternity test.
- Tom believed that he did not have good ideas, but he always got good data to support other people's idea.
- One of Tom's many covers of Science appeared on 4th of July (1969) to highlight the “firework” from bombardier beetles.
- For an unknown reason, Tom never traveled by air. He loved to drive long stretches to allow time to connect thoughts and relive experiences.
Leal, whose distinguished career includes co-chair of the 2016 International Congress of Entomology (ICE), serves as a distinguished professor in the UC Davis Department of Molecular and Cellular Biology and is a past chair of the UC Davis Department of Entomology (now the Department of Entomology and Nematology). In his research, Leal investigates the molecular basis of olfaction in insects and insect chemical communication. (See the Leal lab's work on DEET in Entomology Today.)
And another factoid: Leal is the first UC Davis scientist selected to present the Founders' Memorial Lecture. (Medical entomologist Shirley Luckhart of the University of Idaho, formerly of UC Davis, delivered the lecture in 2018.)
One other factoid: Tom Eisner, born in Berlin, was multi-lingual in German, French, Spanish and later English. Leal, born in Brazil, speaks Portuguese, Japanese and English fluently.
(Editor's Note: Listen to Walter Leal's presentation on YouTube)
The insect, a native of Asia, was first detected in the United States (Palm Beach County, Florida) in 1998, and California (San Diego County) in 2008. HLB, the bacterial disease that it transmits, was first detected in Florida in 2005, and in California (Hacienda Heights, Los Angeles County), 2012.
“The ACP has the potential to establish itself throughout California wherever citrus is grown,” according to the California Department of Food and Agriculture (CDFA).
Now an international team of scientists, led by chemical ecologist Walter Leal of the University of California, Davis, has discovered a new lure or male attractant that's more efficient and effective than the current trap surveillance system of yellow sticky traps.
“Our newly discovered lure captures an average of three times more ACP than the current trapping system, the sticky yellow traps,” said Leal, a distinguished professor in the Department of Molecular and Cell Biology and a former chair of the Department of Entomology and Nematology. “And it works in areas with low population densities. This is particularly important in California, because HLB is already established in urban areas and, therefore, trap surveillance systems are at a premium.”
The research, “Laboratory and Field Evaluation of Acetic Acid-Based Lures for Male Asian Citrus Psyllid, Diaphorina citri, is published today (Sept. 9) in Scientific Reports. It can be accessed free online at https://www.nature.com/articles/s41598-019-49469-3.
The 16-member team, which includes scientists from Brazil and Costa Rica and Benjamin Lehan of California State Polytechnic University, Pomona, wrote in their abstract: “Lures are much needed for improving ACP trapping systems for monitoring populations and surveillance. Previously, we have identified acetic acid as a putative sex pheromone and measured formic acid- and propionic acid-elicited robust electroantennographic responses. We have now thoroughly examined in indoor behavioral assays (4-way olfactometer) and field tests the feasibility of these three semiochemicals as potential lures for trapping ACP. Formic acid, acetic acid, and propionic acid at appropriate doses are male-specific attractants and suitable lures for ACP traps, but they do not act synergistically.”
“An acetic acid-based homemade lure, prepared by impregnating the attractant in a polymer, was active for a day,” they wrote. “A newly developed slow-release formulation had equal performance but lasted longer, thus leading to an important improvement in ACP trap capture at low population densities.”
“The disease has ravaged the citrus industry in China and Brazil,” said Leal, a native of Brazil. “In Brazil, about one-fourth of the citrus trees in the state of São Paulo has been eradicated since 2004 as part of an HLB control strategy. Florida has also sustained severe losses.
Now the disease threatens California's citrus growers “Of note, 1,100 findings of HLB in urban, but not in commercial orchards, suggest that the disease is already established in urban areas in California,” the scientists wrote. “Monitoring ACP populations is essential for integrated vector management and, more importantly, for surveillance. One of the challenges for abatement personnel in areas of low ACP densities is to capture the vector to determine infection status so that control strategies can be implemented before HLB is spread. Therefore, the development of trapping systems is at a premium, particularly the discovery of lures for enhancing ACP captures in areas of low populations.”
Earlier, an international team of scientists led by Leal identified the sex pheromone of the Asian citrus psyllid. Leal, a fellow of the Entomological Society of America and the Entomological Society of Brazil, announced the discovery, encompassing six years of research, at the 10th Annual Brazilian Meeting of Chemical Ecology in Sao Paulo in December 2017. (See Bug Squad blog)
Pheromones and other semiochemicals are widely used in agriculture and medical entomology. “Growers use them as lures in trapping systems for monitoring and surveillance, as well as for strategies for controlling populations, such as mating disruption and attraction-and-kill systems,” Leal noted.
In response to the ACP invasion in California, the CDFA has launched an extensive monitoring program to track the distribution of the insect and disease. They check yellow sticky traps in both residential areas and commercial citrus groves, and also test psyllids and leaf samples for the presence of the pathogen.
Survey methods for ACP include visual inspections; sweep netting, and placement of yellow sticky traps in trees in citrus nurseries, commercial citrus-producing areas and residential properties throughout the state, according to the CDFA. They also place sticky traps in California fruit packing houses, specialty markets, retail stores and airports that receive such produce from areas known to be infested with ACP.
CDFA has set up a hotline at (1-800-491-1899) for residents to report suspicious insects or disease symptoms in their citrus trees.
They manage to find us, don't they? Even when we're doing our best to try to avoid them!
It's not so well-known that mosquitoes, both male and female, frequent plants to feed on nectar for energy.
And now UC Davis chemical ecologist Walter Leal and scientists Fangfang Zen and Pingxi Xu of the Leal lab have discovered that the odorant receptors from the southern house mosquito, Culex quinquefasciatus, and the yellow fever mosquito Aedes aegypti, are sensitive to floral compounds.
The manuscript: "Odorant Receptors from Culex quinquefasciatus and Aedes aegypti Sensitive to Floral Compounds."
The team, led by Leal, a distinguished professor in the Department of Molecular and Cellular Biology and a former chair of the UC Davis Department of Entomology, cloned the genes of several odorant receptors from the mosquitoes and tested them, using egg cells of Xenopus toads. They exposed the cloned receptors to different scent chemicals.
"We are delighted to find out how mosquitoes smell plant-derived compounds and are repelled by them," Leal said. "These findings may lead to the discovery of better repellents from natural sources."
"Mosquitoes rely heavily on the olfactory system to find a host for a bloodmeal, plants for a source of energy and suitable sites for oviposition," the scientists explained in their abstract. "Here, we examined a cluster of 8 odorant receptors (ORs), which includes one OR, CquiOR1, previously identified to be sensitive to plant-derived compounds. We cloned 5 ORs from Culex quinquefasciatus and 2 ORs from Aedes aegypti, ie, CquiOR2, CquiOR4, CquiOR5, CquiOR84, CquiOR85, AaegOR14, and AaegOR15 and then deorphanized these receptors using the Xenopus oocyte recording system and a large panel of odorants. 2-Phenylethanol, phenethyl formate, and phenethyl propionate were the best ligands for CquiOR4 somewhat resembling the profile of AaegOR15, which gave the strongest responses to phenethyl propionate, phenethyl formate, and acetophenone. In contrast, the best ligands for CquiOR5 were linalool, PMD, and linalool oxide. CquiOR4 was predominantly expressed in antennae of nonblood fed female mosquitoes, with transcript levels significantly reduced after a blood meal. 2-Phenylethanol showed repellency activity comparable to that of DEET at 1%. RNAi experiments suggest that at least in part 2-phenylethanol-elicited repellency is mediated by CquiOR4 activation."
Meanwhile, Leal is gearing up for the 2019 Entomological Society of America (ESA) meeting in St. Louis, Mo., where he will deliver the Founders' Memorial Award Lecture on “Tom Eisner — An Incorrigible Entomophile and Innovator Par Excellence,” at the awards breakfast on Tuesday, Nov. 19.
ESA officials selected Leal, an ESA fellow and internationally recognized chemical ecologist, for the global honor. Leal is the first UC Davis scientist selected to present the Founders' Memorial Lecture, although medical entomologist Shirley Luckhart of the University of Idaho, formerly of UC Davis, delivered the lecture in 2018.
The 7000-member ESA is the world's largest organization serving the professional and scientific needs of entomologists and people in related disciplines. ESA, founded in 1889, is headquartered in Annapolis, Md.
What are bolas spiders? Well, they're also known as angling or fishing spiders. That's because they don't spin a web, they hunt with a sticky glob of silk on the end of a line known as "bolas."
When they swing the bolas or lines at flying moths, they snag their prey, much like an angler snags a fish on a hook. Fish on? Bug on!
And are you ready for a "Buggy Scene?"
Walter Leal, a distinguished professor with the Department of Molecular and Cellular Biology and a past chair of the UC Davis Department of Entomology, is featured on the College of Biological Sciences website in a piece titled "Discovering Curiosity: the Buggy Scene of Desire with Distinguished Professor Walter Leal."
The article, by communications specialist Greg Watry, begins with Leal watching a bolas spider snag a moth.
"The American bolas spider is no one-trick pony when it comes to its enticing chemical mimicry," Watry wrote. "As midnight approaches, bristly cutworms retreat and smoky tetanolita moths (Tetanolita mynesalis) appear, the two moth species active during different times of the night. The American bolas spider can chemically compensate for the moths' different schedules, shifting the makeup of its deadly bouquet to match the pheromones produced by a female smoky tetanolita."
"Basically, we are bolas spiders,” Leal related. Read the article here.
Leal, a native of Brazil, holds a master's degree and doctorate from Japan, where he studied insect chemical communication and olfaction, and held the position of senior research scientist in Japan's Ministry of Agriculture, the first non-Japanese scientist to do so. He joined the UC Davis faculty in 2000 and was named chair of the Department of Entomology (now the Department of Entomology and Nematology) in 2006.
Leal is internationally known for his chemical ecology research--he and his lab have identified sex pheromones of many insects, including moths, beetles, cockroaches and mites. His work is especially important in the field of agriculture, as he targets pests that eat our crops. His pheromones attract pests just as bolas spiders attract moths.
"Leal studies the molecular basis of insect olfaction, unraveling how insects detect chemicals and using that knowledge to inform pest management techniques," Watry wrote. "Most recently, he and colleagues identified a sex pheromone of the Asian citrus psyllid (Diaphorina ciri), a worldwide threat to the citrus industry that made its way to California in 2008. Identifying the pheromone could help mitigate the agricultural devastation caused by the insects."
On a side note, Leal is known for his leadership: he co-chaired the 2016 International Congress of Entomology, the largest scientific event in the history of entomology and he will deliver the Founders' Memorial Lecture at the 2019 Entomological Society of America meeting in St. Louis, Mo., on pioneer chemical ecologist Thomas Eisner, 1929-2011. Eiser is commonly regarded as the "father of chemical ecology" for his discoveries elucidating chemical defenses used by insects.
Leal is also known as an exemplary, innovative and caring teacher who seeks opportunities for their success. He was the one who brought Science without Borders (SwB) to the UC Davis campus, which resulted in many students and visitors to UC Davis laboratories.
"Really nice professor who cares about his students' future," wrote a student on Rate My Professors. "He has guest speakers from industry talk to the class and Dr. Leal always makes sure to ask them about internships and ways to get our foot in the door."
Leal recently returned from his native Brazil where UC Davis Global Affairs asked him if he would meet with the leadership of São Paulo State University to explore possible collaborations. He did, and plans are in the works. Stay tuned!