A method to estimate absolute odorant concentration of olfactory stimuli

Lucie Conchou; Ioan-Cristian Trelea; Jérémy Gévar; Christelle Monsempès; Anne-Claire Peron; Michel Renou; Isabelle Souchon; Philippe Lucas

doi:10.1371/journal.pone.0337336

Peer Review History

Original SubmissionJune 11, 2025
11 Aug 2025 Decision Letter - S Ezhil Vendan, Editor Dear Dr. Lucas, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. ACADEMIC EDITOR: The manuscript needs revision with respect to the reviewers comments and following suggestions. In manuscript title, specify insect species name with respect to the performed experiments and obtained results. In methodology section, lacking of information about insect source, collection and maintenance, which used in this study. Please check and add details. Please submit your revised manuscript by Sep 25 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . 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Additional Editor Comments: The manuscript needs revision with respect to the reviewers comments and following suggestions. In manuscript title, specify insect species name with respect to the performed experiments and obtained results. In methodology section, lacking of information about insect source, collection and maintenance, which used in this study. Please check and add details. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? Reviewer #1: Yes Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #1: Yes Reviewer #2: Yes ****** Reviewer #1: As the accurate quantification and delivery of odorant concentrations remain a significant challenge for many chemosensory biologist, the authors have brilliantly developed a model based on mass transfer theory to predict the concentration of odorants delivered by a simple and versatile odor delivery system commonly used in insect electrophysiological experiments by many researchers to estimate the absolute odorant concentration delivered from a source composed of a vial containing a few mL of odorant solution in mineral oil. . Unfortunately, measurements of sensitivity to odors are difficult to interpret when stimuli are expressed as the dose at the source, which is often the case for studies of insect olfaction. But the authors present a model in this study which is helpful to better design and use odor delivery systems, especially for stimuli required to mimic natural odor environments. The model also considers the dynamic shape of odor stimuli, which affects neuronal responses and must be carefully interpreted, especially when using tools like photoionisation detectors (PID). Their method is based on theoretical work that describes odorant release from a source-solution and its transport by an airflow. They are showing how, for one particular odor delivery system design, a relationship established from small subset of volatile compounds can be generalised to other compounds. Authors have illustrated how their results can be useful to insect sensory ecology research by tackling an issue that is unresolved because of the difficulty to estimate absolute concentrations delivered on the antenna. They have used a calibrated odor delivery device to document the effect of known concentrations of Z3HA on sex pheromone detection by male A. ipsilon and compared the active concentrations of this VPC to ecologically relevant ones. The manuscript is well written in its current form. The authors should take care of the minor suggestions to correct few mistakes: 1. Line 163 -function geeglm() of package geepack in R). Is this an error geeglm() in this line? please correct or specify. 2. Line 265-compartments over time were fed into the differential equation solver function ode() from package. What is ode()? 3. The authors have discussed mineral and paraffin oil in the discussion. What about DMSO that many labs use to dissolve odorants? 4. Use the same nomenclature for (Z)-3-hexen-1-ol everywhere in the manuscript. Check other chemical names as well. 5. Line 837-Table 1 - List of variables and of parameters of the model. Rewrite this as " List of variables and parameters of the model". 6. Line 849- kglob mass transfer coefficient (m.s-1). Make m capital as "M" of mass to keep uniformity with other abbreviations. Reviewer #2: This study, authored by Conchou et al., investigated the estimation of absolute odour concentration for ORN stimuli in A. ipsilon sp. The introduction and discussion sections of the manuscript are well written. However, the manuscript requires a few modifications to improve its readability. Major comment: 1. The manuscript is well written by the authors and the English is acceptable. However, the authors need to simplify a few sentences to make them clearer for readers. For example, on line 22, 'the present model or approach'; on line 33: 'The difficulty'? Line 62: 'Such a solution meets the requirements?' 2. Methods: Line 117: Why did the authors only select 11 VPC compounds for testing, and why did they choose Z3HA for the EAG dose-response and pheromone sensitivity background analysis (Figures 8 and 9)? 3. The authors elaborated on the methodology with a lot of quantification and various formulas for the stimulated system. I suggest that the authors reconsider transferring a few of the more complex formulas to the supplementary information file from the methodology section. 4. The supplementary files are not available for verification (S1 figures). 5. I suggest that the authors provide a conclusion at the end of the discussion rather than with the results. 6. On line 526, the authors state that 'linalool and β-caryophyllene showed sharper dynamics at stimulus onset and offset with the PTR-MS than with the PID'. Why do the authors consider Z3HA rather than linalool and β-caryophyllene? 7. Figure 9: What does ppbv mean in this legend? (C) To the pheromone in the Z3HA background. Are Z3HA backgrounds expressed as both dilution in mineral oil and concentration delivered at a dynamic pseudo-stationary regime (ppbv)? ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #1: No Reviewer #2: Yes: Durairaj Rajesh ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0337336.r001
Revision 1
9 Oct 2025 Author Response The manuscript is well written in its current form. We thank the reviewer for this comment and address the following ones point by point below. The authors should take care of the minor suggestions to correct few mistakes: 1. Line 163 -function geeglm() of package geepack in R). Is this an error geeglm() in this line? please correct or specify. 2. Line 265-compartments over time were fed into the differential equation solver function ode() from package. What is ode()? geeglm() and ode() are standard functions within the R software environment for data analysis and model computation. The sentences are accurate as stated. We believe that most readers will already be familiar with the specific coding syntax employed by the software R. Providing a detailed explanation of R syntax may go beyond the scope of the manuscript. For these reasons, we propose to leave these sentences unchanged. 3. The authors have discussed mineral and paraffin oil in the discussion. What about DMSO that many labs use to dissolve odorants? To our knowledge, DMSO has only been used to dissolve odorants in aqueous solutions (e.g. when working with olfactory receptors expressed in Xenopus oocytes or with olfactory receptor neurons in culture). However, the model we describe is applicable to any solvent, provided that the partition coefficients are determined for each solute–solvent pair. We made this point clear by adding "and solvent" in the manuscript (line 671). 4. Use the same nomenclature for (Z)-3-hexen-1-ol everywhere in the manuscript. Check other chemical names as well. This has been corrected in line 121 of the main text and in Table S1A. 5. Line 837-Table 1 - List of variables and of parameters of the model. Rewrite this as " List of variables and parameters of the model". This mistake has been corrected. 6. Line 849- kglob mass transfer coefficient (m.s-1). Make m capital as "M" of mass to keep uniformity with other abbreviations. This mistake has been corrected. Reviewer #2: This study, authored by Conchou et al., investigated the estimation of absolute odour concentration for ORN stimuli in A. ipsilon sp. The introduction and discussion sections of the manuscript are well written. However, the manuscript requires a few modifications to improve its readability. We thank the reviewer for this comment and address the following ones point by point below. Major comment: 1. The manuscript is well written by the authors and the English is acceptable. However, the authors need to simplify a few sentences to make them clearer for readers. For example, on line 22, 'the present model or approach'; on line 33: 'The difficulty'? Line 62: 'Such a solution meets the requirements?' These mistakes have been corrected. 2. Methods: Line 117: Why did the authors only select 11 VPC compounds for testing, and why did they choose Z3HA for the EAG dose-response and pheromone sensitivity background analysis (Figures 8 and 9)? We clarified it by adding line 126: “This selection of VPCs provides a basis for demonstrating the validity and potential of our model of prediction of the odorant concentration delivered by an odor delivery system. Among the 11 selected VPCs, Z3HA was chosen for electrophysiological experiments to evaluate whether, at ecologically relevant concentrations, it can interfere with sex pheromone detection in A. ipsilon moths. 3. The authors elaborated on the methodology with a lot of quantification and various formulas for the stimulated system. I suggest that the authors reconsider transferring a few of the more complex formulas to the supplementary information file from the methodology section. We have moved a substantial portion of the formulae to the Supplementary Information. 4. The supplementary files are not available for verification (S1 figures). There is one single figure in Supplementary Information. The raw data can be downloaded until November 5, 2025 from: https://filesender.renater.fr/?s=download&token=2ba65324-446d-4f6e-8093-dc5b0b25b6ac However, please not that they were plotted without any specific treatment. 5. I suggest that the authors provide a conclusion at the end of the discussion rather than with the results. The conclusion made at the end of the results was moved to the discussion, in the paragraph spanning lines 683-697. 6. On line 526, the authors state that 'linalool and β-caryophyllene showed sharper dynamics at stimulus onset and offset with the PTR-MS than with the PID'. Why do the authors consider Z3HA rather than linalool and β-caryophyllene? We are sorry, but we do not fully understand the question here. - Maybe ‘not’ is missing and it should read as: ‘Why don’t the authors consider Z3HA rather than linalool and β-caryophyllene?’. The choice of molecules tested by PTR-MS was arbitrary; we selected several compounds with different PID dynamics. If the reviewer regrets that we did not select Z3HA for PTR-MS experiments because we used it for electrophysiology, we would like to point out that we took precautions regarding the equilibration times before opening the valve that delivered the stimulus to the preparation. - If the reviewer did not forget ‘not’, then the answer is that we selected Z3HA because it affects pheromone perception under laboratory conditions. 7. Figure 9: What does ppbv mean in this legend? (C) To the pheromone in the Z3HA background. Are Z3HA backgrounds expressed as both dilution in mineral oil and concentration delivered at a dynamic pseudo-stationary regime (ppbv)? ppbv stands for parts per billion by volume. We have now defined this abbreviation at its first occurrence (line 612). We thank the reviewer for bringing this oversight to our attention. Attachments Attachment Submitted filename: Response to reviewers.pdf https://doi.org/10.1371/journal.pone.0337336.r002
6 Nov 2025 Decision Letter - S Ezhil Vendan, Editor A method to estimate absolute odorant concentration of olfactory stimuli PONE-D-25-31805R1 Dear Dr. Philippe Lucas, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. For questions related to billing, please contact billing support . If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, S Ezhil Vendan, Ph.D Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: Reviewer's Responses to Questions Comments to the Author Reviewer #1: All comments have been addressed ******** 2. Is the manuscript technically sound, and do the data support the conclusions??> Reviewer #1: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #1: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #1: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #1: Yes ****** Reviewer #1: (No Response) ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #1: No ******** https://doi.org/10.1371/journal.pone.0337336.r003
Formally Accepted
Acceptance Letter - S Ezhil Vendan, Editor PONE-D-25-31805R1 PLOS One Dear Dr. Lucas, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS One. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset You will receive further instructions from the production team, including instructions on how to review your proof when it is ready. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few days to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. You will receive an invoice from PLOS for your publication fee after your manuscript has reached the completed accept phase. If you receive an email requesting payment before acceptance or for any other service, this may be a phishing scheme. Learn how to identify phishing emails and protect your accounts at https://explore.plos.org/phishing. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. S Ezhil Vendan Academic Editor PLOS One https://doi.org/10.1371/journal.pone.0337336.r004

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