Chemical ecologist Anjel Helms of Texas A&M University will share information on that topic from 4:10 to 5 p.m., Wednesday, Oct. 28, in a virtual seminar hosted by the UC Davis Department of Entomology and Nematology. Access this site for the Zoom link.
Host and the fall seminar coordinator is Cooperative Extension specialist and agricultural entomologist Ian Grettenberger, assistant professor, UC Davis Department of Entomology and Nematology.
"The research in our lab focuses on understanding how chemical compounds mediate interactions among microbes, plants, herbivores, and herbivore natural enemies," Helms says. "We combine analytical chemistry and behavioral ecology in laboratory and field-based research to investigate how organisms use chemistry to navigate, communicate, and defend themselves. This seminar will discuss some of our ongoing projects examining how plants and insect herbivores use chemical information from their environment to assess their risk of attack and how herbivore natural enemies use such information to find potential prey."
The insects Helms researches include the striped cucumber beetle (Acalymma vittatum) and squash bug (Anasa tristis).
Helms, an assistant professor, holds two degrees from Pepperdine University, Malibu, Calif., both awarded in 2009: a bachelor of science degree in biology and a bachelor of arts degree in biochemistry. She received her doctorate in ecology in 2015 from The Pennsylvania State University, State College, Penn. While in the John Tooker lab, Helms studied the chemical ecology of plant-insect interactions, especially how plants defend themselves against insect herbivores. She investigated how plants use olfactory cues to predict impeding herbivore attacks and the molecular mechanisms involved.
In addition to the general field of chemical ecology, Helms' research interests include plant-insect interactions, tritrophic interactions, belowground chemical ecology, chemical communication, and plant defense.
Her most recent publications:
Helms, A.M., Ray, S., Matulis, N.L.*, Kuzemchak, M.C.*, Grisales, W.*, Tooker, J.F., Ali, J.G. Chemical cues linked to risk: Cues from belowground natural enemies enhance plant defences and influence herbivore behaviour and performance. Functional Ecology. 33, 798-808 (2019). DOI: 10.1111/1365-2435.13297
Acevedo, F.E., Smith, P., Peiffer, M., Helms, A.M., Tooker, J.T., Felton, G.W. Phytohormones in fall armyworm saliva modulate defense responses in plants. Journal of Chemical Ecology. (2019). https://doi.org/10.1007/s10886-019-01079-z
Yip, E.C., Sowers, R.P.*, Helms, A.M., Mescher, M.C., De Moraes, C.M., Tooker, J.F. Tradeoffs between defenses against herbivores in goldenrod (Solidago altissima). Arthropod-Plant Interactions. 13, 279-287 (2019). DOI: 10.1007/s11829-019-09674-3
For any technical issues regarding the seminar, contact Grettenberger at firstname.lastname@example.org.
So says noted chemical ecologist Walter Leal, newly selected recipient of the 2020 Distinguished Teaching Award for Undergraduate Teaching from the UC Davis Academic Senate.
The award recognizes outstanding teaching and dedication to student success. Leal will be honored with other Academic Senate and Academic Federation award recipients at a ceremony in the spring.
"When I started teaching chemistry in high school--while I was a sophomore in college--students were only one to two years older than me," said Leal, a distinguished professor in the UC Davis Department of Molecular and Cellular Biology and former chair of the UC Davis Department of Entomology (now Department of Entomology and Nematology). "Now they are younger than my sons and daughter! My goal remains the same--not only to excite students about the content of my lectures, be it high school chemistry, insect physiology, or biochemistry, but also to trigger their curiosity.
"I don't teach because I have to; I teach because it is a joy to light the way and to spark the fire of knowledge," Leal said. "Teaching is, and out to be, the raison d'etre of a university professor. It is really an honor to receive the Academic Senate Distinguished Teaching Award. Many thanks to my peers, all students, and teaching assistants, particularly Fran Keller and Silvia Hilt who teamed up for insect physiology and biochemistry, respectively, for more than three years."
Nominator J. Clark Lagarias, distinguished professor of biochemistry in the Department of Molecular and Cellular Biology described Leal as an exemplary, innovative and highly respected teacher. “Walter excels in developing new courses, programs and teaching methods. He is a trendsetter whose passion, innovation, dedication and outstanding contributions to teaching inspire us all.”
Distinguished professor James R. Carey of the UC Davis Department of Entomology and Nematology--and the recipient of four teaching awards including the Academic Senate's top teaching award--praised Leal's innovative and dedicated teaching.
"I consider Professor Leal as an exceptional instructor," Carey wrote in the nomination packet. "His exceptionalism is derived from his dedication to student learning, his innovation in content delivery, his engagement with students (including his always-clever touches of humor), and his ability to both motivate them and incentivize their investment in studies. All of these efforts rest on the deep foundation of the disciplinary authority that he brings to the classroom as an eminent basic and applied biochemist, a stature that his students clearly recognize...Walter is a natural teacher who not only speaks with a voice of great authority in the classroom, but with the voice of a person who cares deeply about student learning."
Stanford graduate student Garrison Buss, who studied with Leal ("my research mentor at UC Davis"), said the professor "consistently encouraged active learning at a high level through a variety of modalies. Among these, the most novel and beneficial included having students solve equations by writing them out on an iPad and projecting what they wrote in real time—similar to having a portable overhead projector that any student in the lecture hall could use. This way, the whole class could see and provide feedback by critiquing the problem and solutions together with Dr. Leal. The lecture material itself was also innovative. Dr. Leal would show videos of real life experiments and interviews that he had made with prominent scientists who were subject matter experts in the topic that we were discussing."
"The lecture material itself was also innovative," Buss related. "Dr. Leal would show videos of real life experiments and interviews that he had made with prominent scientists who were subject matter experts in the topic that we were discussing. As an instructor, he challenged the way that I understood my academic performance and through his extra effort showed me that I could achieve much more than I had previously believed. As a mentor, he gave me opportunities and responsibilities that were out of reach for many of my fellow researchers."
A native of Brazil, Leal was educated in Brazil, Japan and the United States in the fields of chemical ecology, biochemistry, insect physiology and olfaction. He joined the UC Davis faculty in 2000, and chaired the Department of Entomology from 2006 to 2008.
The veteran teacher, a member of the Department of Molecular and Cellular Biology faculty since 2013, has taught insect physiology for 13 years and biochemistry for six years. In his classrooms, he employs the strategic use of digital technology, which has led to such unsolicited comments on the “Rate My Professors” website as “best professor at UC Davis.” His tools include Camtasia, PowerPoints, podcasts, e-reviews and Skype for ease of learning and knowledge retention. He generates animated e-reviews by recording a narrative summary of each of his lectures with Camtasia software. In place of a verbal narrative, his students watch videos--featuring animations and illustrations--to review major concepts.
The e-reviews can be time-consuming to produce but he considers them—and rightfully so—valuable for increased student engagement and comprehension. With Skype, Leal also brings noted guests into his classroom: researchers, textbook authors and colleagues who have made landmark discoveries in the field.
Known as a leader and inventor as well as a noted scientist and teacher, Leal co-chaired the 2016 International Congress of Entomology and also served as president of the International Society of Chemical Ecology. He is a fellow of the 7000-member Entomological Society of America, which selected him to deliver the Founders' Memorial Lecture at its recent meeting in St. Louis, Mo. His topic chronicled the life of Tom Eisner, the father of chemical ecology and a role model: “Tom Eisner: an Incorrigible Entomophile and Innovator Par Excellence.” Leal also is a newly selected fellow of the National Academy of Inventors, which honors and encourages academic inventions that benefit society.
Teaching, however is the raison d'etre.
"I don't teach because I have to; I teach because it is a joy to light the way and to spark the fire of knowledge."
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 Nazi Germany, moved to Spain, grew up in Uruguay, moved to the United States, and lived the rest of life here.
- In 1969 Tom delivered the Founders' Memorial Lecture to honor Robert Snodgrass. This year he is being honored by the same memorial lecture.
- Tom was an excellent musician; he owned three Steinway Grands (two remain with his daughters and the other he gave to the Cornell Music Department
- Cornell University rejected his undergraduate application in 1947.
- After being rejected by Cornell, Tom attended community college and received both his bachelor's degree and doctorate from Harvard.
- Ten years after Cornell rejected his undergraduate application, Cornell hired him as an assistant professor. Tom kept a framed copy of his rejection letter from Cornell on his office wall, all during his career.
- Tom is considered one of the founding fathers of chemical ecology but he joked that this cannot be proved "without a paternity test."
- Tom humbly said he had no good ideas, but that he "got good data to support other people's ideas."
- One of Tom's many covers of Science appeared on 4th of July (1969) to highlight the “fireworks” 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)
In a ground-breaking discovery encompassing six years of research, an international team of scientists led by UC Davis chemical ecologist Walter Leal announced they've identified the sex pheromone of the pest, which feeds on citrus and transmits the bacteria that causes the deadly citrus greening disease known as Huanglongbing (HLB).
Leal, a native of Brazil and a fellow of both the Entomological Society of America and the Entomological Society of Brazil, revealed the discovery during his presentation Dec. 5 at the 10th Annual Brazilian Meeting of Chemical Ecology in Sao Paulo. His team included scientists from UC Davis, University of Sao Paulo, and the Fund for Citrus Protection (FUNDECITRUS) from the state of Sao Paulo.
“Dr. Leal's discovery of the Asian citrus psyllid pheromone is a significant breakthrough in preventing the spread of this serious citrus insect, and may offer a less toxic method for its control,” said integrated pest management specialist Frank Zalom, distinguished professor with the UC Davis Department of Entomology and Nematology and a past president of the Entomological Society of America. He was not involved in the study.
“Having a lure to dramatically improve captures of this psyllid with the conventional sticky traps is a major progress toward integrated pest management,” said Professor Jose Robert Parra of the University of Sao Paulo.
Identifying the sex pheromone proved “complicated and quite a challenge” because of the insect's complex behavior and biology, said Leal, a UC Davis distinguished professor who has discovered the sex pheromones of moths, beetles, bugs, cockroaches, mites and other arthropods. A patent was filed Friday, Dec. 1, and journal publication is pending.
Citrus trees infected with HLB usually die within five years, according to the UC Statewide Integrated Pest Management Program. There is no known cure. “The only way to protect trees is to prevent spread of the HLB pathogen in the first place, by controlling psyllid populations and removing and destroying any infected trees,” UC IPM says on its website.
Native to Asia, the Asian citrus psyllid, Diaphorina ciri, was first detected in the United States in June 1998 in Palm Beach County, Florida, and in California in August 2008 in San Diego County. Scientists discovered HLB in Florida in August 2005, and in Los Angeles in March 2012. The mottled brown insect, about 3 to 4 millimeters long, or about the size of an aphid, is now widespread throughout Southern California and is now found in 26 of the state's 58 counties.
The Asian citrus psyllid, or ACP, feeds on new leaf growth of oranges, lemons, mandarins, grapefruit and other citrus, as well as some related plants. Infected psyllids can transmit the bacterium Candidatus Liberibacter asiaticus, which causes the fatal citrus disease. An early symptom of HLB in citrus is the yellowing of leaves on an individual limb or in a sector of a tree's canopy.
Currently growers are using yellow sticky traps to detect the insect and to monitor the population. “Efficient lures,” Leal said, “are sorely needed for sticky traps, particularly for early ACP detection. Otherwise, growers have to resort to regular sprays to avoid infection given that infected insects from gardens and noncommercial areas migrate to citrus farms.”
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.
Although ACP is present in Arizona and California, the disease itself has not been established, Leal said. “The emphasis is on detection, eradication and limiting the spread of the disease. In Florida, where HLB is widespread, monitoring ACP populations is essential to avoid reinfection after eradication of infected plants.”
The detection of the pest has led to widespread eradication of citrus trees in China, Brazil and the United States. “In Brazil as many as 46.2 million citrus trees, representing 26 percent of the currently planted trees, have been eradicated since the detection of HLB in 2004,” Leal said. “In Florida, HLB has caused severe losses to the citrus industry. This year's production loss is estimated to be about 28 million fewer boxes of oranges than in 2014-2015.”
The announcement of the discovery coincides with the 40th anniversary celebration of FUNDECITRUS in Araraquara, Sao Paolo. “I am delighted that Walter Leal accepted our challenge to work on this project as the lead investigator,” said Juliano Ayres, FUNDECITRUS director. “The combination of his work ethics and qualifications are unparalleled. And, he loves challenges.”
In response to the ACP invasion in California, the California Department of Food and Agriculture (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.
Since August 2008, ACP has now been detected in 26 of California's 58 counties: Alameda, Contra Costa, Fresno, Imperial, Kern, Kings, Los Angeles, Madera, Merced, Monterey, Orange, Placer, Riverside, San Benito, San Bernardino, San Diego, San Joaquin, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Solano, Stanislaus, Tulare, Ventura, and Yolo. “The ACP has the potential to establish itself throughout California wherever citrus is grown,” the CDFA says on its website.
CDFA has set up a hotline at 1-800-491-1899 for residents to report suspicious insects or disease symptoms in their citrus trees.
California Department of Food and Agriculture (CDFA)
Save Our Citrus: Hotline Information
UC Agriculture and Natural Resources (UC ANR)
(Update: The research was published in the Jan. 11 edition of the journal Scientific Reports.)
In a groundbreaking discovery, a scientific team of Brazilians and Brazilian-born chemical ecologist Walter Leal of the University of California, Davis, has announced that the Zika virus has been detected in wild-caught Culex quinquefasciatus mosquitoes in Recife, the epicenter of the Zika epidemic.
Scientists from the Fiocruz Institute, Pernambuco, confirmed the discovery July 21. The detection could have widespread repercussions, as the Culex mosquitoes are more common and widespread than the yellow fever mosquito, Aedes aegypti, known as the primary carrier of the Zika virus.
Leal, who collaborates with Fiocruz Institute researcher Constancia Ayres in a National Institutes of Health-sponsored project on the investigation of Zika in the C. quinquefasciatus, said that the Brazilian lab earlier discovered that Culex had the capability of transmitting the virus. Although the scientists were able to infect the lab mosquitoes with the virus, they had not found the virus in wild-caught mosquitoes—until now.
“This could have major repercussions here in the United States and in other parts of the world,” said Leal, a distinguished professor in the UC Davis Department of Molecular and Cellular Biology who is co-chairing the International Congress of Entomology meeting Sept. 25-30 in Orlando, Fla. The conference is expected to draw some 7000 entomologists throughout the world.
Leal said more work needs to be done to see if Culex mosquitoes are playing a role in the current epidemic. In an interview July 21 with health reporter Jennifer Yang of the Toronto Star, Canada's largest daily, he commented: “It looks like there were more vectors than we thought, and this is one of them. We don't have to panic, but we have to know. And now that we know, we have to take care of the Culex.”
A. aegypti is already established in California; it has spread to at least seven counties since its discovery in Clovis, Fresno County, in June 2013, according to medical entomologist Anthony Cornel of the UC Davis Department of Entomology and Nematology and the UC Kearney Agricultural Research and Extension Center, Parlier.
The Zika virus, which can result in birth defects in pregnancy, can be transmitted through exposure to infected blood or sexual contact. The Centers for Disease Control estimates that between 400,000 and 1.3 million cases have been discovered across South, Central, and North America, where the disease was previously unknown.
Leal and a group of 18 students just hosted a Zika Public Awareness Symposium on May 26 at Giedt Hall, UC Davis campus. The podcast can be accessed at https://video.ucdavis.edu/media/Zika+Virus+Public+Awareness+Symposium/0_n3aupf5c