Insect Repellents Mediate Species-Specific Olfactory Behaviours in Mosquitoes

2020 ◽  
Author(s):  
Ali Afify ◽  
Christopher John Potter
Keyword(s):  
Mosquito Species ◽  
Anopheles Coluzzii ◽  
Olfactory Neurons ◽  
Olfactory Responses ◽  
Close Proximity ◽  
Lemongrass Oil ◽  
Mosquito Repellents ◽  
Receptor Neurons ◽  
High Concentrations ◽  
Species Specific

Abstract Background The species-specific mode of action for DEET and many other mosquito repellents is often unclear. Confusion may arise for many reasons. First, the response of a single mosquito species is often used to represent all mosquito species. Second, behavioural studies usually test the effect of repellents on mosquito attraction towards human odorants, rather than their direct repulsive effect on mosquitoes. Third, the mosquito sensory neuron responses towards repellents are often not directly examined. Methods A close proximity response assay was used to test the direct repulsive effect of six mosquito repellents on Anopheles coluzzii, Aedes aegypti and Culex quinquefasciatus mosquitoes. Additionally, behavioural assay and calcium imaging recordings of antennae were used to test the response of An. coluzzii mosquitoes towards two human odorants (1-octen-3-ol and benzaldehyde) at different concentrations, and mixtures of the repellents lemongrass oil and p-menthane-3,8-diol (PMD) with DEET. Results An. coluzzii mosquitoes were repelled by lemongrass oil and PMD, while Ae. aegypti and Cx. quinquefasciatus mosquitoes were repelled by lemongrass oil, PMD, eugenol, and DEET. In addition, high concentrations of 1-octen-3-ol and benzaldehyde were repellent, and activated more olfactory receptor neurons on the An. coluzzii antennae than lower concentrations. Finally, changes in olfactory responses to repellent mixtures reflected changes in repulsive behaviours. Conclusions The findings described here suggest that different species of mosquitoes have different behavioural responses to repellents. The data further suggest that high-odour concentrations may recruit repellent-sensing neurons, or generally excite many olfactory neurons, yielding repellent behavioural responses. Finally, DEET can decrease the neuronal and behavioural response of An. coluzzii mosquitoes towards PMD but not towards lemongrass oil. Overall, these studies can help inform mosquito repellent choice by species, guide decisions on effective repellent blends, and could ultimately identify the olfactory neurons and receptors in mosquitoes that mediate repellency. Methods: Here, we used a close proximity response assay to test the direct repulsive effect of six mosquito repellents on Anopheles coluzzii , Aedes aegypti , and Culex quinquefasciatus mosquitoes. Additionally, we used this behavioral assay and calcium imaging recordings of antennae to test the response of An. coluzzii mosquitoes towards two human odorants (1-octen-3-ol and benzaldehyde) at different concentrations, and mixtures of the repellents lemongrass oil and p-menthane-3,8-diol (PMD) with DEET. Results: We found that An. coluzzii mosquitoes were repelled by lemongrass oil and PMD, while Ae. aegypti and Cx. Quinquefasciatus mosquitoes were repelled by lemongrass oil, PMD, eugenol, and DEET. In addition, we found that high concentrations of 1-octen-3-ol and benzaldehyde were repellent, and activated more olfactory receptor neurons on the An. coluzzii antenna than lower concentrations. Finally, we found that changes in olfactory responses to repellent mixtures reflected changes in repulsive behaviors. Conclusions: Our findings suggest that different species of mosquitoes have different behavioral responses to repellents. We further suggest that high-odor concentrations may recruit repellent-sensing neurons, or generally excite many olfactory neurons, yielding repellent behavioral responses. Finally, we show that DEET can decrease the neuronal and behavioral response of An. coluzzii mosquitoes towards PMD but not towards lemongrass oil. Overall, these studies can help inform mosquito repellent choice by species, guide decisions on effective repellent blends, and could ultimately identify the olfactory neurons and receptors in mosquitoes that mediate repellency.

scholarly journals Insect Repellents Mediate Species-Specific Olfactory Behaviors in Mosquitoes

2020 ◽  
Author(s):  
Ali Afify ◽  
Christopher John Potter
Keyword(s):  
Mosquito Species ◽  
Behavioral Responses ◽  
Anopheles Coluzzii ◽  
Olfactory Neurons ◽  
Insect Repellents ◽  
Olfactory Responses ◽  
Behavioral Studies ◽  
Lemongrass Oil ◽  
Mosquito Repellents ◽  
Species Specific

Abstract Background: The species-specific mode of action for DEET and many other mosquito repellents is often unclear. Confusion may arise for many reasons. First, the response of a single mosquito species is often used to represent all mosquito species. Second, behavioral studies usually test the effect of repellents on mosquito attraction towards human odorants, rather than their direct repulsive effect on mosquitoes. Third, the mosquito sensory neuron responses towards repellents are often not directly examined. Methods: Here, we used a close proximity response assay to test the direct repulsive effect of six mosquito repellents on Anopheles coluzzii , Aedes aegypti , and Culex quinquefasciatus mosquitoes. Additionally, we used this behavioral assay and calcium imaging recordings of antennae to test the response of An. coluzzii mosquitoes towards two human odorants (1-octen-3-ol and benzaldehyde) at different concentrations, and mixtures of the repellents lemongrass oil and p-menthane-3,8-diol (PMD) with DEET. Results: We found that An. coluzzii mosquitoes were repelled by lemongrass oil and PMD, while Ae. aegypti and Cx. Quinquefasciatus mosquitoes were repelled by lemongrass oil, PMD, eugenol, and DEET. In addition, we found that high concentrations of 1-octen-3-ol and benzaldehyde were repellent, and activated more olfactory receptor neurons on the An. coluzzii antenna than lower concentrations. Finally, we found that changes in olfactory responses to repellent mixtures reflected changes in repulsive behaviors. Conclusions: Our findings suggest that different species of mosquitoes have different behavioral responses to repellents. We further suggest that high-odor concentrations may recruit repellent-sensing neurons, or generally excite many olfactory neurons, yielding repellent behavioral responses. Finally, we show that DEET can decrease the neuronal and behavioral response of An. coluzzii mosquitoes towards PMD but not towards lemongrass oil. Overall, these studies can help inform mosquito repellent choice by species, guide decisions on effective repellent blends, and could ultimately identify the olfactory neurons and receptors in mosquitoes that mediate repellency.

scholarly journals Insect Repellents Mediate Species-Specific Olfactory Behaviors in Mosquitoes

2020 ◽  
Author(s):  
Ali Afify ◽  
Christopher John Potter
Keyword(s):  
Mosquito Species ◽  
Behavioral Responses ◽  
Anopheles Coluzzii ◽  
Olfactory Neurons ◽  
Insect Repellents ◽  
Olfactory Responses ◽  
Behavioral Studies ◽  
Lemongrass Oil ◽  
Mosquito Repellents ◽  
Species Specific

Abstract Background: The species-specific mode of action for DEET and many other mosquito repellents is often unclear. Confusion may arise for many reasons. First, the response of a single mosquito species is often used to represent all mosquito species. Second, behavioral studies usually test the effect of repellents on mosquito attraction towards human odorants, rather than their direct repulsive effect on mosquitoes. Third, the mosquito sensory neuron responses towards repellents are often not directly examined.Methods: Here, we used a close proximity response assay to test the direct repulsive effect of six mosquito repellents on Anopheles coluzzii, Aedes aegypti, and Culex quinquefasciatus mosquitoes. Additionally, we used this behavioral assay and calcium imaging recordings of antennae to test the response of An. coluzzii mosquitoes towards two human odorants (1-octen-3-ol and benzaldehyde) at different concentrations, and mixtures of the repellents lemongrass oil and p-menthane-3,8-diol (PMD) with DEET.Results: We found that An. coluzzii mosquitoes were repelled by lemongrass oil and PMD, while Ae. aegypti and Cx. Quinquefasciatus mosquitoes were repelled by lemongrass oil, PMD, eugenol, and DEET. In addition, we found that high concentrations of 1-octen-3-ol and benzaldehyde were repellent, and activated more olfactory receptor neurons on the An. coluzzii antenna than lower concentrations. Finally, we found that changes in olfactory responses to repellent mixtures reflected changes in repulsive behaviors.Conclusions: Our findings suggest that different species of mosquitoes have different behavioral responses to repellents. We further suggest that high-odor concentrations may recruit repellent-sensing neurons, or generally excite many olfactory neurons, yielding repellent behavioral responses. Finally, we show that DEET can decrease the neuronal and behavioral response of An. coluzzii mosquitoes towards PMD but not towards lemongrass oil. Overall, these studies can help inform mosquito repellent choice by species, guide decisions on effective repellent blends, and could ultimately identify the olfactory neurons and receptors in mosquitoes that mediate repellency.

Citrate Enhances Olfactory Receptor Responses and Triggers Oscillatory Receptor Activity in the Channel Catfish

2000 ◽  
Vol 83 (5) ◽  
pp. 2676-2681 ◽  
Author(s):  
James M. Parker ◽  
Qinhui Chang ◽  
John Caprio
Keyword(s):  
Amino Acid ◽  
Binary Mixture ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Olfactory Receptor ◽  
Barium Chloride ◽  
Strontium Chloride ◽  
Olfactory Responses ◽  
Receptor Neurons ◽  
High Concentrations

Citrate, a normal constituent of cellular metabolism, in a binary mixture with an amino acid enhanced asynchronous olfactory receptor responses in the channel catfish, Ictalurus punctatus. In addition, high concentrations of either citrate (≥3 mM) alone or an amino acid (≥0.1 mM) in a binary mixture with citrate (≥1 mM) triggered synchronized voltage oscillations of olfactory receptor neurons (ORNs) known as “peripheral waves” (PWs). Binary mixtures containing lower concentrations of an amino acid also triggered PW activity if the concentration of citrate in the mixture was increased. Both the enhancement of asynchronous activity and the generation of PW activity were the result of citrate chelating calcium, which lowers the surface potential of ORNs making them hyperexcitable. These effects of citrate are replicated by EGTA. Inactivation of the chelating ability of citrate and EGTA with 1 mM calcium chloride, barium chloride, or strontium chloride abolished both the enhancement of asynchronous olfactory responses and PW activity, while not affecting olfactory receptor responses to the amino acids alone.

scholarly journals Circadian regulation of light-evoked attraction/avoidance in day- vs. night-biting mosquitoes

2019 ◽  
Author(s):  
Lisa Soyeon Baik ◽  
Ceazar Nave ◽  
David D. Au ◽  
Tom Guda ◽  
Joshua A. Chevez ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Mosquito Species ◽  
Behavioral Responses ◽  
Time Of Day ◽  
Disease Vectors ◽  
Anopheles Coluzzii ◽  
Long Wavelength ◽  
Species Specific ◽  
Wavelength Light ◽  
Specific Control

AbstractMosquitoes pose widespread threats to humans and other animals as disease vectors. Day- vs. night-biting mosquitoes occupy distinct time-of-day niches and exhibit very different innate temporal attraction/avoidance behavioral responses to light, yet little is known about their circuit or molecular mechanisms. Day-biting diurnal mosquitoes Aedes aegypti are attracted to light during the day regardless of spectra. In contrast, night-biting nocturnal mosquitoes Anopheles coluzzii avoid short, but not long wavelength light. Attraction/avoidance behavioral responses to light in both species change with time-of-day and show distinct sex and circuit differences. The basis of diurnal versus nocturnal behavior is driven by clock timing, which cycle anti-phase between day-biting versus night-biting mosquito species. Disruption of the circadian molecular clock severely interferes with light-evoked attraction/avoidance behavior in mosquitoes. In summary, attraction/avoidance mosquito behaviors are circadian and light regulated, which may be applied towards species specific control of harmful mosquitoes.

The Caenorhabditis elegans odr-2 Gene Encodes a Novel Ly-6-Related Protein Required for Olfaction

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 211-224 ◽  
Author(s):  
Joseph H Chou ◽  
Cornelia I Bargmann ◽  
Piali Sengupta
Keyword(s):  
Caenorhabditis Elegans ◽  
Motor Neurons ◽  
Amino Terminus ◽  
Signaling Proteins ◽  
Related Protein ◽  
Olfactory Neurons ◽  
Unique Role ◽  
C Elegans ◽  
Founding Member ◽  
High Concentrations

Abstract Caenorhabditis elegans odr-2 mutants are defective in the ability to chemotax to odorants that are recognized by the two AWC olfactory neurons. Like many other olfactory mutants, they retain responses to high concentrations of AWC-sensed odors; we show here that these residual responses are caused by the ability of other olfactory neurons (the AWA neurons) to be recruited at high odor concentrations. odr-2 encodes a membrane-associated protein related to the Ly-6 superfamily of GPI-linked signaling proteins and is the founding member of a C. elegans gene family with at least seven other members. Alternative splicing of odr-2 yields three predicted proteins that differ only at the extreme amino terminus. The three isoforms have different promoters, and one isoform may have a unique role in olfaction. An epitope-tagged ODR-2 protein is expressed at high levels in sensory neurons, motor neurons, and interneurons and is enriched in axons. The AWC neurons are superficially normal in their development and structure in odr-2 mutants, but their function is impaired. Our results suggest that ODR-2 may regulate AWC signaling within the neuronal network required for chemotaxis.

scholarly journals Culicidae-centric metabarcoding through targeted use of D2 ribosomal DNA primers

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9057 ◽  
Author(s):  
Pedro M. Pedro ◽  
Jandui Amorim ◽  
Martha V.R. Rojas ◽  
Ivy Luizi Sá ◽  
Allan Kardec Ribeiro Galardo ◽  
...  
Keyword(s):  
Sampling Methods ◽  
Mosquito Species ◽  
Pcr Primers ◽  
Degraded Dna ◽  
Ribosomal Operon ◽  
Dna Pools ◽  
Current Sampling ◽  
High Concentrations ◽  
Dna Primers ◽  
Generation Sequencing

A practical limitation to many metabarcoding initiatives is that sampling methods tend to collect many non-target taxa, which become “amplicon noise” that can saturate Next Generation Sequencing results and lead to both financial and resource inefficiencies. An available molecular tool that can significantly decrease these non-target amplicons and decrease the need for pre-DNA-extraction sorting of bycatch is the design of PCR primers tailored to the taxa under investigation. We assessed whether the D2 extension segment of the 28S ribosomal operon can limit this shortcoming within the context of mosquito (Culicidae) monitoring. We designed PCR primers that are fully conserved across mosquitos and exclude from amplification most other taxa likely to be collected with current sampling apparatuses. We show that, given enough sequencing depth, D2 is an effective marker for the detection of mosquito sequences within mock genomic DNA pools. As few as 3,050 quality-filtered Illumina reads were able to recover all 17 species in a bulk pool containing as little as 0.2% of constituent DNA from single taxa. We also mixed these mosquito DNA pools with high concentrations of non-Culicidae bycatch DNA and show that the component mosquito species are generally still recoverable and faithful to their original relative frequencies. Finally, we show that there is little loss of fidelity in abundance parameters when pools from degraded DNA samples were sequenced using the D2 primers.

scholarly journals The “good, the bad and the double-sword” effects of exposure to MPs and their organic additives on N2-fixing bacteria

2020 ◽  
Author(s):  
Víctor Fernández-Juárez ◽  
Xabier López-Alforja ◽  
Aida Frank-Comas ◽  
Pedro Echeveste ◽  
Antoni Bennasar-Figueras ◽  
...  
Keyword(s):  
Posidonia Oceanica ◽  
Dioctyl Phthalate ◽  
Benthic Organisms ◽  
Protein Overexpression ◽  
Organic Additives ◽  
Physical Interactions ◽  
High Concentrations ◽  
Species Specific ◽  
Micro Organisms ◽  
First Time

AbstractThe accumulation of microplastics (MPs) pollution at depths suggests the susceptibility of benthic organisms (e.g. seagrasses and their associated macro- and micro-organisms) to the effects of these pollutants. Little is known about the direct effects of MPs and their organic additives on marine bacteria, e.g. in one of the most ecologically significant groups, the diazotrophs or N2-fixing bacteria. To fill this gap of knowledge, we exposed marine diazotrophs found in association with the endemic Mediterranean seagrass Posidonia oceanica to pure MPs which differ in physical properties (e.g. density, hydrophobicity and/or size), namely, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS) and to their most abundant associated organic additives (e.g. fluoranthene, 1,2,5,6,9,10-hexabromocyclododecane [HBCD] and dioctyl-phthalate [DEHP]). Growth, protein overexpression, direct physical interactions between MPs and bacteria, phosphorus (P) acquisition mechanisms and N2-fixation rates were evaluated. Our results show species-specific responses of the autotrophic and heterotrophic N2-fixing bacteria tested and the responses were dependent on the type and concentration of MPs and additives. N2-fixing cyanobacteria were positively affected by environmental and high concentrations of MPs (e.g. PVC), as opposed to heterotrophic strains, that were only positively affected with high concentrations of ∼120 µm-size MPs (detecting the overexpression of proteins related to plastic degradation and C-transport), and negatively affected by 1 µm-size PS beads. Generally, the organic additives (e.g. fluoranthene) had a deleterious effect in both autotrophic and heterotrophic N2-fixing bacteria and the magnitude of the effect is suggested to be dependent on bacterial size. We did not find evidences that specific N2-fixation rates were significantly affected by exposure to MPs, albeit changes in bacterial abundance can affect the bulk N2-fixation rates. In summary, we reported for the first time, the beneficial (the “good”), deleterious (the “bad”) and/or both (the “double-sword”) effects of exposure to MPs and their organic additives on diazotrophs found in association with seagrasses.

scholarly journals In Silico Karyotyping of Chromosomally Polymorphic Malaria Mosquitoes in the Anopheles gambiae Complex

2019 ◽  
Vol 9 (10) ◽  
pp. 3249-3262 ◽  
Author(s):  
R. Rebecca Love ◽  
Seth N. Redmond ◽  
Marco Pombi ◽  
Beniamino Caputo ◽  
Vincenzo Petrarca ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
In Silico ◽  
Mosquito Species ◽  
Chromosomal Rearrangements ◽  
Small Subset ◽  
Anopheles Coluzzii ◽  
Strongly Correlated ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Malaria Mosquitoes

Chromosomal inversion polymorphisms play an important role in adaptation to environmental heterogeneities. For mosquito species in the Anopheles gambiae complex that are significant vectors of human malaria, paracentric inversion polymorphisms are abundant and are associated with ecologically and epidemiologically important phenotypes. Improved understanding of these traits relies on determining mosquito karyotype, which currently depends upon laborious cytogenetic methods whose application is limited both by the requirement for specialized expertise and for properly preserved adult females at specific gonotrophic stages. To overcome this limitation, we developed sets of tag single nucleotide polymorphisms (SNPs) inside inversions whose biallelic genotype is strongly correlated with inversion genotype. We leveraged 1,347 fully sequenced An. gambiae and Anopheles coluzzii genomes in the Ag1000G database of natural variation. Beginning with principal components analysis (PCA) of population samples, applied to windows of the genome containing individual chromosomal rearrangements, we classified samples into three inversion genotypes, distinguishing homozygous inverted and homozygous uninverted groups by inclusion of the small subset of specimens in Ag1000G that are associated with cytogenetic metadata. We then assessed the correlation between candidate tag SNP genotypes and PCA-based inversion genotypes in our training sets, selecting those candidates with >80% agreement. Our initial tests both in held-back validation samples from Ag1000G and in data independent of Ag1000G suggest that when used for in silico inversion genotyping of sequenced mosquitoes, these tags perform better than traditional cytogenetics, even for specimens where only a small subset of the tag SNPs can be successfully ascertained.

scholarly journals DNA-Biofunctionalization of CTAC-Capped Gold Nanocubes

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1119 ◽  
Author(s):  
Nicole Slesiona ◽  
Sophie Thamm ◽  
H. Lisa K. S. Stolle ◽  
Viktor Weißenborn ◽  
Philipp Müller ◽  
...  
Keyword(s):  
Ligand Exchange ◽  
Cetyltrimethylammonium Bromide ◽  
Clinical Diagnostics ◽  
Enhanced Fluorescence ◽  
Nanoparticle Surface ◽  
Modified Dna ◽  
Close Proximity ◽  
Biological Recognition ◽  
High Concentrations ◽  
Field Enhancements

Clinical diagnostics and disease control are fields that strongly depend on technologies for rapid, sensitive, and selective detection of biological or chemical analytes. Nanoparticles have become an integral part in various biomedical detection devices and nanotherapeutics. An increasing focus is laid on gold nanoparticles as they express less cytotoxicity, high stability, and hold unique optical properties with the ability of signal transduction of biological recognition events with enhanced analytical performance. Strong electromagnetic field enhancements can be found in close proximity to the nanoparticle that can be exploited to enhance signals for e.g., metal-enhanced fluorescence or Raman spectroscopy. Even stronger field enhancements can be achieved with sharp-edged nanoparticles, which are synthesized with the help of facet blocking agents, such as cetyltrimethylammonium bromide/chloride (CTAB/CTAC). However, chemical modification of the nanoparticle surface is necessary to reduce the particle’s cytotoxicity, stabilize it against aggregation, and to bioconjugate it with biomolecules to increase its biocompatibility and/or specificity for analytical applications. Here, a reliable two-step protocol following a ligand exchange with bis (p-sulfonatophenyl) phenyl phosphine (BSPP) as the intermediate capping-agent is demonstrated, which results in the reliable biofunctionalization of CTAC-capped gold nanocubes with thiol-modified DNA. The functionalized nanocubes have been characterized regarding their electric potential, plasmonic properties, and stability against high concentrations of NaCl and MgCl2.

scholarly journals 31P-NMR Metabolomics Revealed Species-Specific Use of Phosphorous in Trees of a French Guiana Rainforest

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3960
Author(s):  
Albert Gargallo-Garriga ◽  
Jordi Sardans ◽  
Joan Llusià ◽  
Guille Peguero ◽  
Dolores Asensio ◽  
...  
Keyword(s):  
Tree Species ◽  
French Guiana ◽  
31P Nmr ◽  
Principal Component ◽  
Distinct Species ◽  
Community Diversity ◽  
N:P Ratios ◽  
High Concentrations ◽  
Species Specific ◽  
Total P

Productivity of tropical lowland moist forests is often limited by availability and functional allocation of phosphorus (P) that drives competition among tree species and becomes a key factor in determining forestall community diversity. We used non-target 31P-NMR metabolic profiling to study the foliar P-metabolism of trees of a French Guiana rainforest. The objective was to test the hypotheses that P-use is species-specific, and that species diversity relates to species P-use and concentrations of P-containing compounds, including inorganic phosphates, orthophosphate monoesters and diesters, phosphonates and organic polyphosphates. We found that tree species explained the 59% of variance in 31P-NMR metabolite profiling of leaves. A principal component analysis showed that tree species were separated along PC 1 and PC 2 of detected P-containing compounds, which represented a continuum going from high concentrations of metabolites related to non-active P and P-storage, low total P concentrations and high N:P ratios, to high concentrations of P-containing metabolites related to energy and anabolic metabolism, high total P concentrations and low N:P ratios. These results highlight the species-specific use of P and the existence of species-specific P-use niches that are driven by the distinct species-specific position in a continuum in the P-allocation from P-storage compounds to P-containing molecules related to energy and anabolic metabolism.

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