Molecular Basis of Insect Olfaction
& Chemical Ecology
Mosquito Attractants

Welcome to the research page of the Leal Lab in the Department of Molecular and Cellular Biology, College of Biological Sciences, at the University of California-Davis.

Walter Leal
Principal Investigator
Walter S. Leal, Ph.D, Honorary FRES
(wsleal at ucdavis.edu)


Fundamental research in the Leal lab is aimed at unraveling the molecular mechanisms that make the insectís olfactory system so sensitive and selective. Insect prominence among other animals is due in large part to a key physiological element for their survival and reproduction - a refined olfactory system. Olfaction is orchestrated at various levels starting with reception of odorants at the periphery, processing and integration of olfactory and other sensory modalities in the brain, and ultimately translation of olfactory signal into behavior. Thus, the cornerstone of a sophisticated olfactory system is the ability of the insectís peripheral system to selectively detect and rapidly inactivate minute amounts of odorants. Reception of odorants is mainly mediated by three olfactory proteins, namely, odorant-binding proteins (OBPs or PBPs when the odorant is a pheromone), odorant receptors (ORs), and odorant-degrading enzymes (ODEs). OBPs are involved in the uptake, transport and delivery of odorants to ORs. In collaboration with structural biologists, including Drs. Kurt Wuthrich (Scripps), Jon Clardy (Harvard), David Wilson (UC Davis), Glaucius Oliva (University of Sao Paulo), and James Ames (UC Davis), we determined the 3D structures of various PBPs and OBPs from moths and mosquitoes, and unraveled their mode of action. Using stopped-flow fluorescence, our laboratory determined the kinetics of odorant binding and release by PBPs. With recombinant and native enzymes (i.e., isolated from insect antennae), we demonstrated that ODEs are involved in the rapid inactivation of chemical signals in insect antennae. By using bioinformatics, molecular approaches, RNAi, transgenic flies, and sensory physiology techniques (e.g., the Xenopus oocyte recording system; single sensillum recordings), we have identified ORs from moths, mosquitoes, and other insects, and investigated how they contribute to the selectivity of the insectís olfactory system. One of these receptors, CquiOR136, was isolated from the southern house mosquito, Culex quinquefasciatus , and is involved in the reception of DEET as a spatial repellent. We use odorant receptors in our translational research, which combined with conventional chemical ecology approaches, allows us to identify oviposition attractants, repellents and other semiochemicals of potential application in agriculture and medical entomology.


Recent Publications (Last Five Years)

Current Laboratory Members & Students who Authored these Publications

Dr. Pingxi Xu

Dr. Young-Moo Choo

Thiago A. Franco

Xiaolan Wen

Fangfang Zeng

Daniele S. Oliveira

Kaiming Tan

WeiYu (James) Lu

Justin K. Hwang

Helena M. Leal

Choo YM, Xu P, Hwang JK, Zeng F, Tan K, Bhagavathy G, Chauhan K, Leal WS. Reverse chemical ecology approach for the identification of an oviposition attractant for Culex quinquefasciatus. Proc Natl Acad Sci U S A., doi: 10.1073/pnas.1718284115

Xu P, Choo YM, Chen Z, Zeng F, Tan K, Chen, TY, Cornel AJ,Liu N, Leal WS. Peripheral, intrareceptor inhibition in mosquito olfaction. bioRxiv 243162; doi:https://doi.org/10.1101/243162

Zanardi OZ, Volpe HXL, Favaris AP, Silva WD, Luvizotto RAG, Magnani RF, Esperanca V, Delfino JY, de Freitas R, Miranda MP, Parra JRP, Bento JMS, Leal WS. Putative sex pheromone of the Asian citrus psyllid, Diaphorina citri, breaks down into an attractant. Sci Rep. 2018;8(1):455. Epub 2018/01/13. doi: 10.1038/s41598-017-18986-4. PubMed PMID: 29323263

Leal HM, Hwang JK, Tan K, Leal WS. Attraction of Culex mosquitoes to aldehydes from human emanations. Scientific Reports. 2017;7(1):17965. doi: 10.1038/s41598-017-18406-7

Paiva MHS, Guedes DRD, Leal WS, Ayres CFJ. Sensitivity of RT-PCR method in samples shown to be positive for Zika virus by RT-qPCR in vector competence studies. Genet Mol Biol. 2017;40(3):597-9. Epub 2017/05/24. doi: 10.1590/1678-4685-GMB-2016-0312. PubMed PMID: 28534930; PMCID: PMC5596374.

Oliveira DS, Brito NF, Nogueira FCS, Moreira MF, Leal WS, Soares MR, Melo ACA. Proteomic analysis of the kissing bug Rhodnius prolixus antenna. J Insect Physiol. 2017;100:108-18. Epub 2017/06/14. doi: 10.1016/j.jinsphys.2017.06.004. PubMed PMID: 28606853.

Lu W, Hwang JK, Zeng F, Leal WS. DEET as a feeding deterrent. PLoS One. 2017;12(12):e0189243. Epub 2017/12/15. doi: 10.1371/journal.pone.0189243. PubMed PMID: 29240785.

Leal WS, Barbosa RM, Zeng F, Faierstein GB, Tan K, Paiva MH, Guedes DR, Crespo MM, Ayres CF. Does Zika virus infection affect mosquito response to repellents? Sci Rep. 2017;7:42826. Epub 2017/02/17. doi: 10.1038/srep42826. PubMed PMID: 28205633; PMCID: PMC5311973.

PNAS Commentary
Leal WS. Reverse chemical ecology at the service of conservation biology. Proc Natl Acad Sci U S A. 2017;114(46):12094-6. Epub 2017/11/03. doi: 10.1073/pnas.1717375114. PubMed PMID: 29093161.

Hughes DT, Pelletier J, Rahman S, Chen S, Leal WS, Luetje CW. Functional and Nonfunctional Forms of CquiOR91, an Odorant Selectivity Subunit of Culex quinquefasciatus. Chem Senses. 2017;42(4):333-41. Epub 2017/03/24. doi: 10.1093/chemse/bjx011. PubMed PMID: 28334229.

Guedes DR, Paiva MH, Donato MM, Barbosa PP, Krokovsky L, Rocha S, Saraiva K, Crespo MM, Rezende TM, Wallau GL, Barbosa RM, Oliveira CM, Melo-Santos MA, Pena L, Cordeiro MT, Franca RFO, Oliveira AL, Peixoto CA, Leal WS, Ayres CF. Zika virus replication in the mosquito Culex quinquefasciatus in Brazil. Emerg Microbes Infect. 2017;6(8):e69. Epub 2017/08/10. doi: 10.1038/emi.2017.59. PubMed PMID: 28790458; PMCID: PMC5583667.

Carvalho WJ, Fujimura PT, Bonetti AM, Goulart LR, Cloonan K, da Silva NM, Araujo ECB, Ueira-Vieira C, Leal WS. Characterization of antennal sensilla, larvae morphology and olfactory genes of Melipona scutellaris stingless bee. PLoS One. 2017;12(4):e0174857. Epub 2017/04/20. doi: 10.1371/journal.pone.0174857. PubMed PMID: 28423045; PMCID: PMC5396885.

Nikbakhtzadeh MR, Buss GK, Leal WS. Toxic Effect of Blood Feeding in Male Mosquitoes. Front Physiol. 2016;7:4. Epub 2016/02/10. doi: 10.3389/fphys.2016.00004. PubMed PMID: 26858651; PMCID: PMC4726748.

Leal WS. Zika mosquito vectors: the jury is still out. F1000Res. 2016;5:2546. Epub 2016/11/18. doi: 10.12688/f1000research.9839.1. PubMed PMID: 27853521; PMCID: PMC5105876.

Franco TA, Oliveira DS, Moreira MF, Leal WS, Melo AC. Silencing the odorant receptor co-receptor RproOrco affects the physiology and behavior of the Chagas disease vector Rhodnius prolixus. Insect Biochem Mol Biol. 2016;69:82-90. Epub 2015/03/10. doi: 10.1016/j.ibmb.2015.02.012. PubMed PMID: 25747010.

Bento JM, Parra JR, de Miranda SH, Adami AC, Vilela EF, Leal WS. How much is a pheromone worth? F1000Res. 2016;5:1763. Epub 2016/09/02. doi: 10.12688/f1000research.9195.1. PubMed PMID: 27583133; PMCID: PMC4972084.

Yin J, Choo YM, Duan H, Leal WS. Selectivity of odorant-binding proteins from the southern house mosquito tested against physiologically relevant ligands. Front Physiol. 2015;6:56. Epub 2015/03/17. doi: 10.3389/fphys.2015.00056. PubMed PMID: 25774136; PMCID: PMC4343023.

Xu P, Zhu F, Buss GK, Leal WS. 1-Octen-3-ol - the attractant that repels. F1000Res. 2015;4:156. Epub 2015/11/07. doi: 10.12688/f1000research.6646.1. PubMed PMID: 26543554; PMCID: PMC4623779.

Pelletier J, Xu P, Yoon KS, Clark JM, Leal WS. Odorant receptor-based discovery of natural repellents of human lice. Insect Biochem Mol Biol. 2015;66:103-9. Epub 2015/10/24. doi: 10.1016/j.ibmb.2015.10.009. PubMed PMID: 26494014; PMCID: PMC4663167.

PNAS Commentary
Leal WS. Snapshot of insect-fungus arms race. Proc Natl Acad Sci U S A. 2015;112(28):8519-20. Epub 2015/07/01. doi: 10.1073/pnas.1510615112. PubMed PMID: 26124139; PMCID: PMC4507252.

Choo YM, Buss GK, Tan K, Leal WS. Multitasking roles of mosquito labrum in oviposition and blood feeding. Front Physiol. 2015;6:306. Epub 2015/11/19. doi: 10.3389/fphys.2015.00306. PubMed PMID: 26578978; PMCID: PMC4625056.

Xu P, Choo YM, De La Rosa A, Leal WS. Mosquito odorant receptor for DEET and methyl jasmonate. Proc Natl Acad Sci U S A. 2014;111(46):16592-7. Epub 2014/10/29. doi: 10.1073/pnas.1417244111. PubMed PMID: 25349401; PMCID: PMC4246313.

Ueira-Vieira C, Kimbrell DA, de Carvalho WJ, Leal WS. Facile functional analysis of insect odorant receptors expressed in the fruit fly: validation with receptors from taxonomically distant and closely related species. Cell Mol Life Sci. 2014;71(23):4675-80. Epub 2014/05/13. doi: 10.1007/s00018-014-1639-7. PubMed PMID: 24816944; PMCID: PMC4231014.

Leal WS. The enigmatic reception of DEET - the gold standard of insect repellents. Curr Opin Insect Sci. 2014;6:93-8. Epub 2014/12/23. doi: 10.1016/j.cois.2014.10.007. PubMed PMID: 25530943; PMCID:

Leal GM, Leal WS. Binding of a fluorescence reporter and a ligand to an odorant-binding protein of the yellow fever mosquito, Aedes aegypti. F1000Res. 2014;3:305. Epub 2015/02/12. doi: 10.12688/f1000research.5879.2. PubMed PMID: 25671088; PMCID: PMC4309172.

Zhu F, Xu P, Barbosa RM, Choo YM, Leal WS. RNAi-based demonstration of direct link between specific odorant receptors and mosquito oviposition behavior. Insect Biochem Mol Biol. 2013;43(10):916-23. Epub 2013/08/06. doi: 10.1016/j.ibmb.2013.07.008. PubMed PMID: 23911547; PMCID: PMC3800558.

Xu P, Leal WS. Probing insect odorant receptors with their cognate ligands: insights into structural features. Biochem Biophys Res Commun. 2013;435(3):477-82. Epub 2013/05/16. doi: 10.1016/j.bbrc.2013.05.015. PubMed PMID: 23673297; PMCID: PMC3836372.

Xu P, Choo YM, Pelletier J, Sujimoto FR, Hughes DT, Zhu F, Atungulu E, Cornel AJ, Luetje CW, Leal WS. Silent, generic and plant kairomone sensitive odorant receptors from the Southern house mosquito. J Insect Physiol. 2013;59(9):961-6. Epub 2013/07/24. doi: 10.1016/j.jinsphys.2013.07.004. PubMed PMID: 23876610; PMCID: PMC3800014.

Vasquez GM, Syed Z, Estes PA, Leal WS, Gould F. Specificity of the receptor for the major sex pheromone component in Heliothis virescens. J Insect Sci. 2013;13:160. Epub 2014/04/30. doi: 10.1673/031.013.16001. PubMed PMID: 24773407; PMCID: PMC4015405.

Leal WS, Choo YM, Xu P, da Silva CS, Ueira-Vieira C. Differential expression of olfactory genes in the southern house mosquito and insights into unique odorant receptor gene isoforms. Proc Natl Acad Sci U S A. 2013;110(46):18704-9. Epub 2013/10/30. doi: 10.1073/pnas.1316059110. PubMed PMID: 24167245; PMCID: PMC3831946.

Leal WS. Odorant reception in insects: roles of receptors, binding proteins, and degrading enzymes. Annu Rev Entomol. 2013;58:373-91. Epub 2012/10/02. doi: 10.1146/annurev-ento-120811-153635. PubMed PMID: 23020622.

PNAS Commentary
Leal WS. Healing power of honey. Proc Natl Acad Sci U S A. 2013;110(22):8763-4. Epub 2013/05/07. doi: 10.1073/pnas.1306617110. PubMed PMID: 23645636; PMCID: PMC3670395.

Ishida Y, Ishibashi J, Leal WS. Fatty acid solubilizer from the oral disk of the blowfly. PLoS One. 2013;8(1):e51779. Epub 2013/01/18. doi: 10.1371/journal.pone.0051779. PubMed PMID: 23326317; PMCID: PMC3543412.

Figueira-Mansur J, Ferreira-Pereira A, Mansur JF, Franco TA, Alvarenga ES, Sorgine MH, Neves BC, Melo AC, Leal WS, Masuda H, Moreira MF. Silencing of P-glycoprotein increases mortality in temephos-treated Aedes aegypti larvae. Insect Mol Biol. 2013;22(6):648-58. Epub 2013/08/29. doi: 10.1111/imb.12052. PubMed PMID: 23980723.

di Luccio E, Ishida Y, Leal WS, Wilson DK. Crystallographic observation of pH-induced conformational changes in the Amyelois transitella pheromone-binding protein AtraPBP1. PLoS One. 2013;8(2):e53840. Epub 2013/02/19. doi: 10.1371/journal.pone.0053840. PubMed PMID: 23418423; PMCID: PMC3572114.

Damberger FF, Michel E, Ishida Y, Leal WS, Wuthrich K. Pheromone discrimination by a pH-tuned polymorphism of the Bombyx mori pheromone-binding protein. Proc Natl Acad Sci U S A. 2013;110(46):18680-5. Epub 2013/10/26. doi: 10.1073/pnas.1317706110. PubMed PMID: 24158483; PMCID: PMC3832013.

Choo YM, Pelletier J, Atungulu E, Leal WS. Identification and characterization of an antennae-specific aldehyde oxidase from the navel orangeworm. PLoS One. 2013;8(6):e67794. Epub 2013/07/05. doi: 10.1371/journal.pone.0067794. PubMed PMID: 23826341; PMCID: PMC3691121.

Xu P, Hooper AM, Pickett JA, Leal WS. Specificity determinants of the silkworm moth sex pheromone. PLoS One. 2012;7(9):e44190. Epub 2012/09/08. doi: 10.1371/journal.pone.0044190. PubMed PMID: 22957053; PMCID: PMC3434217.

Xu P, Garczynski SF, Atungulu E, Syed Z, Choo YM, Vidal DM, Zitelli CH, Leal WS. Moth sex pheromone receptors and deceitful parapheromones. PLoS One. 2012;7(7):e41653. Epub 2012/08/23. doi: 10.1371/journal.pone.0041653. PubMed PMID: 22911835; PMCID: PMC3401280.

Eliyahu D, Nojima S, Santangelo RG, Carpenter S, Webster FX, Kiemle DJ, Gemeno C, Leal WS, Schal C. Unusual macrocyclic lactone sex pheromone of Parcoblatta lata, a primary food source of the endangered red-cockaded woodpecker. Proc Natl Acad Sci U S A. 2012;109(8):E490-6. Epub 2011/12/21. doi: 10.1073/pnas.1111748109. PubMed PMID: 22184232; PMCID: PMC3286908.

See Complete Bibliography
in Google Scholar

Research Activities in our Lab are Sponsored by:

National Institutes of Health-NIH
Research Agreement with FUNDECITRUS
Gifts from Various Donors, including
Bedoukian Research Incorporation

Walter S. Leal
1107 Surge I
UC Davis/MCB
Phone: +1-530-752-7755
Email: wsleal at ucdavis.edu


Site maintained by Walter S. Leal
Design was adapted from http://entomology.ucdavis.edu/
Last Updated: 1/5/18