Walter S Leal

Walter S Leal
University of California, Davis | UCD · Department of Molecular and Cellular Biology

Ph.D.

About

419
Publications
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Publications

Publications (419)
Article
The insect repellent methyl salicylate elicits excitatory responses upon interaction with CquiOR32, an odorant receptor (OR) from the southern house mosquito, Culex quinquefasciatus. By contrast, eucalyptol binds to CquiOR32 to generate electrophysiological and behavioral inhibitory responses. In an attempt to identify CquiOR32 variants displaying...
Article
Full-text available
Some pathogens can manipulate their host plants and insects to optimize their fitness, increasing the attraction of insects to the infected plant in ways that facilitate pathogen acquisition. In tropical American sugarcane crops, the fungus Colletotrichum falcatum, the red rot causal agent, usually occurs in association with the sugarcane borer Dia...
Article
Previously, we have identified an odorant receptor (OR) from the southern house mosquito Culex quinquefasciatus, CquiOR32, which responded to both odorants (agonists) and inhibitory compounds (antagonists). CquiOR32/CquiOrco-expressing oocytes responded to methyl salicylate and other odorants with inward (regular) currents but gave currents in the...
Preprint
Previously, we have identified an odorant receptor (OR) from the southern house mosquito Culex quinquefasciatus, CquiOR32, which responded to both odorants (agonists) and inhibitory compounds (antagonists). CquiOR32/CquiOrco-expressing oocytes responded to methyl salicylate and other odorants with inward (regular) currents but gave currents in the...
Article
Full-text available
Vector-borne plant pathogens often change host traits to manipulate vector behavior in a way that favors their spread. By contrast, infection by opportunistic fungi does not depend on vectors, although damage caused by an herbivore may facilitate infection. Manipulation of hosts and vectors, such as insect herbivores, has not been demonstrated in i...
Article
Full-text available
Cyclocephalini beetles of the genus Cyclocephala (Coleoptera: Melolonthidae: Dynastinae) use flowers of some plants as food, shelter, and mating sites. However, little is known about floral scent chemistry involved in this interaction. Here we show that a sesquiterpene alcohol mediates attraction of Cyclocephala paraguayensis Arrow, on bottle gourd...
Chapter
Besouros do gênero Migdolus (Coleoptera: Vesperidae) são polífagos e nativos da região centro-sul da América do Sul. Os danos são provocados pelas larvas, que durante sua alimentação, destroem o sistema radicular de diversas famílias de plantas. Os adultos não se alimentam, são escavadores e sobem à superfície do solo para acasalar, entre outubro a...
Preprint
Full-text available
Cyclocephalini beetles of genus Cyclocephala (Coleoptera: Melolonthidae: Dynastinae) use flowers of some plants as food, shelter, and mating stands. However, little is known about floral scent chemistry involved in this interaction. Here we show that a sesquiterpene alcohol mediates attraction of Cyclocephala paraguayensis Arrow on bottle gourd flo...
Article
Full-text available
Background: Zika virus (ZIKV) has been isolated from many mosquito species in nature, but it is believed that the main vectors in urban environments are species of the genus Aedes. Here, we detected and isolated ZIKV in samples from Aedes aegypti, Aedes taeniorhynchus and Culex quinquefasciatus, collected during the Zika epidemic in Vitória, south...
Article
Full-text available
Insect repellents are widely used as the first line of defense against mosquito bites and transmission of disease-causing agents. However, the cost of daily applications of even the most affordable and the gold standard of insect repellents, DEET, is still high for low-income populations where repellents are needed the most. An Indian clove-based h...
Article
Full-text available
Carbon dioxide has been used in traps for more than six decades to monitor mosquito populations and help make informed vector management decisions. CO2 is sensed by gustatory receptors (GRs) housed in neurons in the maxillary palps. CO2-sensitive GRs have been identified from the vinegar fly and mosquitoes, but it remains to be resolved whether the...
Preprint
Full-text available
Carbon dioxide has been used in traps for more than six decades to monitor mosquito populations and help make informed vector management decisions. CO 2 is sensed by gustatory receptors (GRs) housed in neurons in the maxillary palps. CO 2 -sensitive GRs have been identified from the vinegar fly and mosquitoes, but it remains to be resolved whether...
Article
Full-text available
One of the strategies of integrated vector management is to lure gravid mosquitoes for surveillance purposes or to entice them to lay eggs in water containing toxins that kill the offspring (attract-and-kill or trap-and-kill). Typically, the major challenge of this approach is the development of a lure that stimulates oviposition plus a toxin with...
Article
Full-text available
The Asian citrus psyllid (ACP) is a vector of a pathogen associated with greening and thus a major problem in citriculture worldwide. 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...
Preprint
Full-text available
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. 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...
Article
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. Here, we examined a cluster of eight odorant receptors (ORs), which includes one OR, CquiOR1, previously identified to be sensitive to plant-derived compounds. We cloned 5 ORs from Culex quinquefasciatus...
Article
Full-text available
In addition to its primary function as an insect repellent, DEET has many "off-label" properties, including a deterrent effect on the attraction of gravid female mosquitoes. DEET negatively affects oviposition sites. While deorphanizing odorant receptors (ORs) using the Xenopus oocyte recording system, we have previously observed that DEET generate...
Preprint
Full-text available
In addition to its primary function as an insect repellent, DEET has many "off-label" properties, including a deterrent effect on attraction of gravid female mosquitoes. DEET negatively affects oviposition sites. While deorphanizing odorant receptors (ORs) using the Xenopus oocyte recording system, we have previously observed that DEET generated ou...
Preprint
Full-text available
Insect repellents are important prophylactic tools for travelers to and populations living in endemic areas of malaria, dengue, encephalitis, and other vector-borne diseases, and the first line of defense against emerging arboviruses. However, the cost of daily applications of even the most affordable and the gold standard of insect repellents, DEE...
Article
Full-text available
How chemical signals are integrated at the peripheral sensory system of insects is still an enigma. Here we show that when coexpressed with Orco in Xenopus oocytes, an odorant receptor from the southern house mosquito, CquiOR32, generated inward (regular) currents when challenged with cyclohexanone and methyl salicylate, whereas eucalyptol and fenc...
Preprint
Full-text available
One of the strategies of integrated vector management is to lure gravid mosquitoes for surveillance purposes or to entice them to lay eggs in water containing toxins that kill the offspring (attract-and-kill or trap-and-kill). Typically, the major challenge of this approach is the development of a lure that stimulates oviposition plus a toxin with...
Article
Full-text available
Olfaction is a key component of the multimodal approach used by mosquitoes to target and feed on humans, spreading various diseases. Current repellents have drawbacks, necessitating development of more effective agents. In addition to variable odorant specificity subunits, all insect odorant receptors (ORs) contain a conserved odorant receptor co-r...
Article
With the advent of next-generation sequencing, it is now possible to rapidly identify the entire repertoire of olfactory genes likely to be involved in chemical communication of an insect species. It remains, however, a challenge to identify olfactory proteins, such as odorant receptors and odorant-binding proteins (OBPs), vis-à-vis the odorants th...
Article
Rhodnius prolixus is one of the most important vectors of Chagas disease in Central and South America for which repellents and attractants are sorely needed. Repellents like DEET, picaridin, and IR3535 are widely used as the first line of defense against mosquitoes and other vectors, but they are ineffective against R. prolixus. Our initial goal wa...
Data
PROCHECK results from predicted 3D model of RproOBP27.
Data
Device used in female recognition bioassay. A polystyrene tube (10 × 2 cm) divided into three zones: female zone (FZ), intermediate zone (IZ), and male release zone (MZ). A gate divides the MZ from IZ. A protective mesh was used to separate MZ and IZ from FZ. An adult female was placed in front of the protection mesh attached by a tape on the tube....
Data
Verify3D results from predicted 3D model of RproOBP27.
Data
RproOBP27 sequence. The signal peptide is highlighted in red.
Data
Oligonucleotides used in the PCR, qPCR and dsRNA synthesis reactions.
Data
Expression profile of (A) RproOBP22; (B) RproOBP22 and RproOBP23; (C) RproOBP22 and RproOBP26; (D) RproOBP29 and RproOBP27 in different R. prolixus tissues evaluated by conventional PCR. Original 1% agarose gel stained with GelRedTM. M, molecular weight; N, negative control; FA, female antennae; MA, male antennae; FP, female proboscis; MP, male pro...
Data
Expression profile of (A) RproOBP1 and RproOBP24; (B) RproOBP26; (C) RproOBP11 and RproOBP13; (D) RproOBP12 and RproOBP7 in different R. prolixus tissues evaluated by conventional PCR. Original 1% agarose gel stained with GelRedTM. M, molecular weight; N, negative control; FA, female antennae; MA, male antennae; FP, female proboscis; MP, male probo...
Data
Expression profile of (A) RproOBP14 and RproOBP6; (B) RproOBP17; (C) RproOBP18 and RproOBP20; (D) RproOBP21 in different R. prolixus tissues evaluated by conventional PCR. Original 1% agarose gel stained with GelRedTM. M, molecular weight; N, negative control; FA, female antennae; MA, male antennae; FP, female proboscis; MP, male proboscis; FH, fem...
Data
Expression profile of (A) RproR18S; (B) RproOBP27, RproOBP26, and RproOBP21 in different R. prolixus tissues evaluated by conventional PCR. Original 1% agarose gel stained with GelRedTM. M, molecular weight; N, negative control; FA, female antennae; MA, male antennae; FP, female proboscis; MP, male proboscis; FH, female head; MH, male head; FL, fem...
Data
3D model of RproOBP27 docked with metasternal gland volatile compounds (putative sex pheromones). (A) RproOBP27 docked with (3E)-2-methyl-3-penten-2-ol. (B) RproOBP27 docked with (2R/2S)-4-methyl-3-penten-2-ol.
Article
Full-text available
Olfactory proteins mediate a wide range of essential behaviors for insect survival. Odorant binding proteins (OBPs) are small soluble olfactory proteins involved in the transport of odor molecules (=odorants) through the sensillum lymph to odorant receptors, which are housed on the dendritic membrane of olfactory sensory neurons also known as olfac...
Article
Full-text available
Insect repellents are widely used to fend off nuisance mosquitoes and, more importantly, to reduce or eliminate mosquito bites in areas where viruses and other vector-borne diseases are circulating. Synthesized more than six decades ago, DEET is the most widely used insect repellent. Plant-derived compounds are used in a plethora of commercial form...
Data
Dataset for figures. This file contains the original data that generated figures 2–7 and spectral data for methyl dihydrojasmonate. (PDF)
Article
Full-text available
Chemosensory proteins (CSPs) have been considered to play a key role in chemoreception in insects. As stated in our earlier study, three CSPs genes from rice leaf folder Cnaphalocrocis medinalis have been identified and showed potential physiological functions in olfaction. Here, we conducted western blot, immunolocalization, competitive binding as...
Article
Chemical ecology has grown as a scientific discipline from its earliest days of tracking the exquisitely potent chemistry of insect pheromones to a deep understanding of the molecular, physiological, and behavioral interactions governed by naturally occurring small molecules. The current practice of the field relies on knowledge of genomes and gene...
Article
Full-text available
Culex mosquitoes are primarily found in temperate and tropical regions worldwide where they play a crucial role as main vectors of filarial worms and arboviruses. In Recife, a northeast city in Brazil, high densities of Culex quinquefasciatus are often found in association with human populated areas. In marked contrast to another part of the city,...
Article
Full-text available
Under laboratory conditions, mating activity in Asian citrus psyllid (ACP) started 4 days after emergence, peaked at day 7, and showed a clear window of activity starting 8 h into the photophase and extending through the first hour of the scotophase. We confirmed that ACP males are attracted to emanations from conspecific females. Traps loaded with...
Data
Supplementary Information for Putative sex pheromone of the Asian citrus psyllid, Diaphorina citri, breaks down into an attractant
Article
Full-text available
Pheromones and other semiochemicals play a crucial role in today's integrated pest and vector management strategies. These semiochemicals are typically discovered by bioassay-guided approaches. Here, we applied a reverse chemical ecology approach; that is, we used olfactory proteins to lead us to putative semiochemicals. Specifically, we used 7 of...
Preprint
Full-text available
How chemical signals are integrated at the peripheral sensory system of insects is still an enigma. Here we show that when coexpressed with Orco in Xenopus oocytes, an odorant receptor from the southern house mosquito, CquiOR32, generated inward (regular) currents when challenged with cyclohexanone and methyl salicylate, whereas eucalyptol and fenc...
Article
Full-text available
Anecdotes related to preferential mosquito bites are very common, but to date there is no complete explanation as to why one out of two people systematically receives more mosquito bites than the other when both are equally accessible. Here we tested the hypothesis that two constituents of skin emanations, 6-methyl-5-heptan-2-one (6-MHO) and gerany...
Article
Full-text available
The insect repellent N,N-diethyl-3-methylbenzamide (DEET), is a multimodal compound that acts as a spatial repellent as well as an irritant (contact repellent), thus being perceived by the insect’s olfactory and gustatory systems as an odorant and a tastant, respectively. Soon after DEET was developed, almost 6 decades ago, it was reported that it...
Data
Illustration of DEET-elicited feeding deterrence. (MP4)