# Walter S. Leal
Walter S. Leal is a Brazilian-born chemical ecologist and Distinguished Professor of Biochemistry in the Department of Molecular and Cellular Biology at the [University of California, Davis](https://www.edgepedia.org/university-of-california-davis), who chaired the UC Davis Department of Entomology and studies insect chemical ecology, olfaction, and chemical communication.[1](https://www.nasonline.org/directory-entry/walter-s-leal-jya6rs/) He is known for elucidating the mode of action of the insect repellent DEET and for research on odorant receptors, odorant binding proteins, and odorant degrading enzymes.[1](https://www.nasonline.org/directory-entry/walter-s-leal-jya6rs/) He was elected to the National Academy of Sciences in April 2024.[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects)
| Fact | Detail |
|---|---|
| Position | Distinguished Professor of Biochemistry, Department of Molecular and Cellular Biology, UC Davis[1](https://www.nasonline.org/directory-entry/walter-s-leal-jya6rs/) |
| Field | Insect chemical ecology and olfaction[1](https://www.nasonline.org/directory-entry/walter-s-leal-jya6rs/) |
| NAS election | April 2024[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects) |
| Training | B.Eng. chemical engineering, UFPE (1982); M.Sc. agricultural chemistry, Mie University (1987); Ph.D. applied biochemistry, University of Tsukuba (1990)[3](https://www.abc.org.br/membro/walter-soares-leal/) |
| Career in Japan | First non-Japanese to earn tenure with Japan's Ministry of Agriculture, Forestry, and Fisheries; headed the Laboratory of Chemical Prospecting at NISES[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award) |
| UC Davis career | Entomology faculty 2000; department chair 2006–2008; professor of biochemistry 2013[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award) |
| Signature work | 2026 Annual Review of Entomology synthesis of odorant reception; 2018 PNAS identification of a Culex oviposition attractant by reverse chemical ecology[5](https://www.annualreviews.org/content/journals/10.1146/annurev-ento-121423-013351) |
| Patents | More than 20[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award) |
## Early life and training
Leal graduated in chemical engineering from the Federal University of Pernambuco (UFPE) in Recife, Brazil, in 1982.[3](https://www.abc.org.br/membro/walter-soares-leal/) He then moved to Japan for graduate education; according to Bug Squad (UC ANR), he was required to become proficient in Japanese and English within six months of arrival, learning Japanese in a six-month crash course.[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects) He earned a master's degree in agricultural chemistry from Mie University in Tsu in 1987 and a doctorate in applied biochemistry from the University of Tsukuba in 1990.[3](https://www.abc.org.br/membro/walter-soares-leal/)
After his Ph.D. he took postdoctoral training in entomology and chemical ecology, first at the National Institute of Sericultural and Entomological Science (NISES) in Japan and then at Cornell University.[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award)
## Career
Leal spent the middle of his career in the Japanese public research system. He became head of the Laboratory of Chemical Prospecting at NISES in Tsukuba, a post he held for six years, and was the first foreigner granted tenure at that institution; the National Academy of Sciences describes him as the first non-Japanese to earn tenure with Japan's Ministry of Agriculture, Forestry, and Fisheries.[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects)
He joined the UC Davis entomology faculty in 2000.[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award) According to UC Davis's Academic Senate Faculty Research Award profile, he chaired the Department of Entomology from 2006 to 2008, a period in which the department was ranked first in the country, and in 2013 accepted a position as professor of biochemistry in the Department of Molecular and Cellular Biology.[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award) The Brazilian Academy of Sciences records him as a former head of the Department of Entomology and currently a full professor at UC Davis.[3](https://www.abc.org.br/membro/walter-soares-leal/)
## Representative work
His laboratory identified the first adult mosquito receptor for the insect repellent DEET, resolving a mode of action that had remained unexplained for six decades after DEET's development in 1946.[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award) His team identified specific neurons in the antennae of Southern house mosquitoes that respond to DEET, work suggesting the insect can smell the chemical and will avoid it.[6](https://www.aaas.org/membership/member-spotlight/walter-leal-has-nose-insects-sense-smell) The same laboratory isolated, cloned, and expressed the first moth's pheromone-degrading enzymes.[7](https://caes.ucdavis.edu/news/plant-researchers-and-molecular-biologist-elected-national-academy-sciences)
Two papers stand for the laboratory's method and reach. In 2018, *PNAS* published the laboratory's identification of an oviposition attractant for the Southern house mosquito (*Culex quinquefasciatus*) using a reverse chemical ecology approach, which starts from molecular knowledge of the insect's sensory proteins rather than from behavior-guided purification; the paper appeared in volume 115, issue 4, pages 714 to 719 ([doi:10.1073/pnas.1718284115](https://www.pnas.org/doi/10.1073/pnas.1718284115)).[8](https://www.pnas.org/doi/10.1073/pnas.1718284115) Earlier, in 2009, *PNAS* carried the laboratory's finding that *Culex quinquefasciatus* can smell nonanal, an attractant derived from humans and birds, and that nonanal and carbon dioxide synergize, leading to significantly higher catches of Culex mosquitoes in traps ([doi:10.1073/pnas.0906932106](https://www.pnas.org/doi/abs/10.1073/pnas.0906932106)).[9](https://www.pnas.org/doi/abs/10.1073/pnas.0906932106)
His pheromone work spans species including scarab beetles, true bugs, longhorned beetles, the citrus leaf miner, the navel orangeworm, and the citrus fruit borer.[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects) The Royal Entomological Society describes his current research as the molecular mechanisms of odorant binding, release, and transport, including pH-dependent conformational changes in moths and mosquitoes.[10](https://www.royensoc.co.uk/about-us/people/professor-walter-leal/) In 2026 he synthesized the field in the *Annual Review of Entomology* article "Odorant Reception in Insects: Functional and Evolutionary Perspectives" (volume 71, pages 275 to 297; [doi:10.1146/annurev-ento-121423-013351](https://www.annualreviews.org/content/journals/10.1146/annurev-ento-121423-013351)), which reports that structural biologists have resolved three-dimensional structures of pheromone-binding proteins and odorant receptors, and that odorant receptors evolved from gustatory receptors as insects adapted to terrestrial life.[5](https://www.annualreviews.org/content/journals/10.1146/annurev-ento-121423-013351)
## Honors and recognition
Leal is a member of the National Academy of Sciences, a Corresponding Member of the Brazilian Academy of Sciences, an Honorary Member of the [Entomological Society of America](https://www.edgepedia.org/entomological-society-of-america), and a Trustee and Honorary Fellow of the [Royal Entomological Society](https://www.edgepedia.org/royal-entomological-society).[1](https://www.nasonline.org/directory-entry/walter-s-leal-jya6rs/) He was elected to the Brazilian Academy of Sciences in 2012 and, according to an interview in *Antenna*, became an Honorary Fellow of the Royal Entomological Society in 2015, as the first UC Davis scientist elected a trustee of that society.[10](https://www.royensoc.co.uk/about-us/people/professor-walter-leal/) • [11](https://www.royensoc.co.uk/antenna-50-1-interview-walter-leal/) • [4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award)
Society fellowships and awards include Fellowship of the Entomological Society of America (2009), which cited his pioneering work in [insect olfaction](https://www.edgepedia.org/insect-olfaction) including identifying and synthesizing complex pheromones; according to the Academia Brasileira de Ciências, his honors also include Fellowship of AAAS (2005), the Silverstein-Simeone Award (2007), the C. W. Woodworth Award (2010), the Nan Yao Su Award (2011), and Fellowship of the National Academy of Inventors (2019).[12](https://entsoc.org/fellows/walter-s-leal-esa-fellow-2009) • [3](https://www.abc.org.br/membro/walter-soares-leal/) • [4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award) He also received the Silver Medal of the International Society of Chemical Ecology, for which he served as [Councillor](https://www.edgepedia.org/councillor) and President; the Royal Entomological Society dates it to 2012, while the Brazilian Academy of Sciences lists 2013.[11](https://www.royensoc.co.uk/antenna-50-1-interview-walter-leal/) • [3](https://www.abc.org.br/membro/walter-soares-leal/) Other honors recorded by the NAS directory include a Medal of Achievement from the Entomological Society of Brazil, the Gijistusho technology prize from the Japan Society for Bioscience, Biotechnology, and Agrochemistry, the Gakkai-sho award from the Japanese Society of Applied Entomology and Zoology, and Fellowship of the California Academy of Sciences.[1](https://www.nasonline.org/directory-entry/walter-s-leal-jya6rs/)
He is one of few UC Davis faculty members to have won all three major Academic Senate honors: the Distinguished Teaching Award for Undergraduate Teaching in 2020, the Distinguished Scholarly Public Service Award in 2022, and the 2024 Faculty Distinguished Research Award.[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects)
## Patents and practical applications
His research has produced more than 20 patents.[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award) AAAS reports more than 30 in the United States and Japan,[6](https://www.aaas.org/membership/member-spotlight/walter-leal-has-nose-insects-sense-smell) and Bug Squad reports about 20.[13](https://www.ucanr.edu/blog/bug-squad/article/well-deserved-honor-0) He serves as principal investigator for the Pacific Southwest Regional Center of Excellence for Vector-Borne Diseases, affiliated with the CDC.[4](https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award)
The applied record is in agriculture. Synthetic sex pheromones for pests he identified are deployed through [mating disruption](https://www.edgepedia.org/mating-disruption) in projects that have saved producers in Brazil and California hundreds of millions of dollars,[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects) and UC Davis credits his pheromone identifications across dozens of insect species with helping save agricultural industries millions of dollars.[7](https://caes.ucdavis.edu/news/plant-researchers-and-molecular-biologist-elected-national-academy-sciences) As of 2026 his laboratory is working on the Asian citrus psyllid (*Diaphorina citri*), aimed at reducing populations and transmission of the bacterium that causes citrus disease.[11](https://www.royensoc.co.uk/antenna-50-1-interview-walter-leal/)
## Record through 2026
Since 2023 his record includes the NAS election in April 2024,[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects) the 2024 Faculty Distinguished Research Award,[2](https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects) and the 2026 Applied Chemical Ecology Award from the International Society of Chemical Ecology for applied research targeting insect pests, presented at the ISCE conference hosted by Cornell University.[13](https://www.ucanr.edu/blog/bug-squad/article/well-deserved-honor-0) According to the article itself, his 2026 *Annual Review of Entomology* piece, *Odorant Reception in Insects: Functional and Evolutionary Perspectives*, is his most recent major synthesis,[5](https://www.annualreviews.org/content/journals/10.1146/annurev-ento-121423-013351) and his UC Davis faculty page points to the NAS member profile and the 2024 award lecture as the record of his current standing.[14](https://biology.ucdavis.edu/people/walter-leal)
## References
1. Walter S. Leal – National Academy of Sciences member directory. https://www.nasonline.org/directory-entry/walter-s-leal-jya6rs/
2. UC Davis Distinguished Professor Walter Leal Elected to NAS – Bug Squad, UC ANR. https://ucanr.edu/blog/bug-squad/article/uc-davis-distinguished-professor-walter-leal-used-dislike-insects
3. Walter Soares Leal – Academia Brasileira de Ciências. https://www.abc.org.br/membro/walter-soares-leal/
4. UC Davis Distinguished Professor Walter Leal: Academic Senate's Faculty Research Award – UC Davis Entomology. https://entomology.ucdavis.edu/news/uc-davis-distinguished-professor-walter-leal-academic-senates-faculty-research-award
5. Leal, W.S. (2026). Odorant Reception in Insects: Functional and Evolutionary Perspectives. Annual Review of Entomology 71:275–297. https://www.annualreviews.org/content/journals/10.1146/annurev-ento-121423-013351
6. Walter Leal has a nose for insects' sense of smell – AAAS Member Spotlight. https://www.aaas.org/membership/member-spotlight/walter-leal-has-nose-insects-sense-smell
7. Plant Researchers and Molecular Biologist Elected National Academy of Sciences – UC Davis CAES. https://caes.ucdavis.edu/news/plant-researchers-and-molecular-biologist-elected-national-academy-sciences
8. Reverse chemical ecology approach for the identification of an oviposition attractant for Culex quinquefasciatus. PNAS 115(4):714–719 (2018). https://www.pnas.org/doi/10.1073/pnas.1718284115
9. Acute olfactory response of Culex mosquitoes to a human- and bird-derived attractant. PNAS (2009). https://www.pnas.org/doi/abs/10.1073/pnas.0906932106
10. Professor Walter Leal Hon.FRES – Royal Entomological Society. https://www.royensoc.co.uk/about-us/people/professor-walter-leal/
11. Honorary Fellow Interview: Walter Leal – Antenna 50(1), 2026, Royal Entomological Society. https://www.royensoc.co.uk/antenna-50-1-interview-walter-leal/
12. Walter S. Leal, ESA Fellow (2009) – Entomological Society of America. https://entsoc.org/fellows/walter-s-leal-esa-fellow-2009
13. Well-Deserved Honor – Bug Squad, UC ANR. https://www.ucanr.edu/blog/bug-squad/article/well-deserved-honor-0
14. Walter S. Leal – UC Davis College of Biological Sciences faculty page. https://biology.ucdavis.edu/people/walter-leal
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*Topic: Encyclopedia › Life and health › Life and health scientists › Life scientists › Researchers in entomology*
*Initially written Sep 21, 2026 · Reviewed: Sep 25, 2026; Sep 30, 2026 · Edited: Sep 25, 2026 · Last review: Sep 30, 2026*
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