Optimization of Hermetia illucens (L.) egg laying under different nutrition and light conditions

Laura I. Macavei; Giacomo Benassi; Vlad Stoian; Lara Maistrello

doi:10.1371/journal.pone.0232144

Peer Review History

Original SubmissionDecember 31, 2019
18 Feb 2020 Decision Letter - Humberto Lanz-Mendoza, Editor PONE-D-19-36053 Optimization of Hermetia illucens (L.) egg laying under different nutrition and light conditions PLOS ONE Dear Dr. Macavei, 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. 1) The authors require to incorporate longevity in their analysis to ensure that you do not have a trade-off between longevity and reproduction, 2) The authors need to show data regarding egg hatchability and larval survival for the females treated with MSW. We would appreciate receiving your revised manuscript by Apr 03 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'. Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out. We look forward to receiving your revised manuscript. Kind regards, Humberto Lanz-Mendoza Academic Editor PLOS ONE Additional Editor Comments (if provided): The authors require to incorporate longevity in their analysis to ensure that you do not have a trade-off between longevity and reproduction, and the authors need to show data regarding egg hatchability and larval survival for the females treated with MSW. Journal Requirements: When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at http://www.journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and http://www.journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf [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? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. 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 requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: Egg Hatchability is a reference to colony efficiency for a mass rearing industrial purposes, and so is the larvae survival. In my opinion in order to conclude that the nutrition and light treatment (MSW) is be the best treatment for industrial purposes, the authors need to show data regarding egg hatchability and larvae survival for the females treated with MSW. They only show data regarding the light but not the nutrition treatment. The authors mention that egg hatchability is not influenced by adult nutrition, according to reference 28. However, the mentioned reference does show a positive impact of the nutritional treatment enhancing the hatching performance of H. illucens eggs. Therefore, it is necessary to present egg hatchability results regarding their MSW treatment, and the other treatments, along with the control, since it could be an interesting reference for optimizing rearing methods. On the other hand, the percentage of hatchability seems to be low for H. illucens, and the authors do not show a reference nor control data. Reviewer #2: Dear Authors and Editor. First at all my apologist for taking so long reviewing this paper. I was very. Very ill, and just now I take the time to read it. The paper is intersecting. As a major comment are: a) I propose you to better present your results and b) incorporate longevity in your analyze just to ensure that you do not have trade-off between longevity and reproduction. Line 27-30. Please be more specific here. Which gaps? Line 95-97. Did you test all? Results are very difficult to read. Maybe you can use a figure to explain it graphically. In addition, you may present the PCA first, and then, you can use ANOVAS with more interested results revealed in the PCA. That depends from you. My point is to you present much better your results. Discussion, could you compare longevity between treatments. According to life-history theory, reproduction is traded of with longevity: The more eggs, the less longevity ****** 6. PLOS authors have the option to publish the peer review history of their article (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: No [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 to be viewed.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. 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Revision 1
3 Apr 2020 Author Response Reviewer #1: 1) Egg Hatchability is a reference to colony efficiency for a mass rearing industrial purpose, and so is the larvae survival. In my opinion in order to conclude that the nutrition and light treatment (MSW) is be the best treatment for industrial purposes, the authors need to show data regarding egg hatchability and larvae survival for the females treated with MSW. They only show data regarding the light but not the nutrition treatment. The authors mention that egg hatchability is not influenced by adult nutrition, according to reference 28. However, the mentioned reference does show a positive impact of the nutritional treatment enhancing the hatching performance of H. illucens eggs. Therefore, it is necessary to present egg hatchability results regarding their MSW treatment, and the other treatments, along with the control, since it could be an interesting reference for optimizing rearing methods. On the other hand, the percentage of hatchability seems to be low for H. illucens, and the authors do not show a reference nor control data. We totally agree that providing data on hatchability would have been an interesting reference for optimizing rearing methods. However, verifying the conditions to improve egg hatching was not the purpose of the present study. Certainly this will be the aim of our future research. We rewrote the paragraph and specified this in lines 425-430. As well, we stated that the MSW treatment registered the highest amount of eggs produced. However, based on data provided by the oviposition rate (80% egg), we recommend the MW treatment for industrial purposes. Besides, we rewrote many other parts to add specific useful information, as follows: Line 68-71 we added and highlighted the information: ‘’Egg hatchability seemed to be positively influenced by LED lighting compared to fluorescent tubes (15)while a positive influence was observed by feeding adults with a combination of sugar, milk powder and bacteriological peptone, although the difference was not significant if compared to agar, water or no nutrition (18).” Line 183-186 we added details: ‘’Considering that light source is a key factor for BSF mating and for obtaining fertilized eggs (23,26) and that no significant differences on egg hatchability have been observed for different adult feeding strategies (18), we assessed the influence of different lights on egg hatching with a single diet treatment (W treatment).” Line 192-195 we added details: ‘’10 mg of eggs (<24 h old) were collected, weighed on a Petri dish (90 mm diameter) and placed directly on the rearing substrate, consisting in Gainesville House Fly diet (29,30). Controls were performed twice a week, when fresh substrate and tap water were added. After 14 days the larval biomass was removed and counted (15)’’. Lines 425-430 we added explanation: “The low number of larvae that survived might be due to the negative effects of fungi or other microbial growth as previously reported in literature (14,38), also because in our case the fresh eggs (<24 h) were placed directly on the rearing substrate. In this work the aim was to test the egg hatchability after the flies were exposed to different lights and not to verify the best conditions to increase hatching. Therefore, in the view to improve egg hatching success for the implementation of industrial mass rearing further specific studies are needed.’’ Reviewer #2: Dear Authors and Editor. First at all my apologist for taking so long reviewing this paper. I was very. Very ill, and just now I take the time to read it. The paper is intersecting. As a major comment are: 1) a) I propose you to better present your results Thank you very much for your suggestion, we reorganized all the ‘’Material and methods’’, ’’Results’’ and ‘’Discussion’’ sections. The article now has a better flow and the results are easier to follow. 2) b) incorporate longevity in your analyze just to ensure that you do not have trade-off between longevity and reproduction. Due to the fact that the overall egg amount and the life span or BSF females and males were already individually analyzed and presented, we introduced a Non-metric analyze for the trade-off between longevity and reproduction of BSF flies, under the influence of nutrition and light, in a graphical way (Fig 4 - 5). A whole paragraph has therefore been added to ‘’Results’’ (lines 244-266). 3) Line 27-30. Please be more specific here. Which gaps? The sentence has been modified and several issues/elements were added. Currently lines 51-54: ‘’Although abundant studies were performed on the optimization of larvae rearing (3,14–17), while additional information on the adults breeding strategies, such as individual reproductive potential of females or adult density and nutrition needs must be deepened (18,19), in order to increase egg production and achieve a successful industrial process.’’ 4) Line 95-97. Did you test all? After the changes made, the lines correspond to the numbers 119-122. Neon tube is the common name of fluorescent lamp. The emission of these type of light source is due to the excitation of different atoms and, therefore, the spectrum emission consists in a series of several specific wavelength or lines (as we measured with a spectrometer). We did not try different fluorescent light because their spectrum is always due to the same atoms: mercury, terbium and europium. Different mixes of these atoms can produce on the human eye the effect of different colors. In reality, the characteristic wavelengths are the same, and, the color effect is due to the different relative intensity of the atoms. For the purpose of our experiment we are interested only in the effect of different wavelengths on the BSF, for this reason we can conclude that the effect of the lamp, used in the article, can be representative for all the fluorescent lamp family. 5) Results are very difficult to read. Maybe you can use a figure to explain it graphically. In addition, you may present the PCA first, and then, you can use ANOVAS with more interested results revealed in the PCA. That depends from you. My point is to you present much better your results We began the ‘’Results’’ presentation by exposing the Life Span of adults and we improved the interpretation of PCA analysis (lines 213-227). Further, starting with Line 244, we continued with the presentation of Trade-off analysis. 6) Discussion, could you compare longevity between treatments. According to life-history theory, reproduction is traded of with longevity: The more eggs, the less longevity. Please see previous comments at point 2)-b) and we added more discussions in lines 384-395. Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0232144.r002
8 Apr 2020 Decision Letter - Humberto Lanz-Mendoza, Editor Optimization of Hermetia illucens (L.) egg laying under different nutrition and light conditions PONE-D-19-36053R1 Dear Dr. Macavei, We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements. Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication. Shortly after the formal acceptance letter is sent, an invoice for payment will follow. 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With kind regards, Humberto Lanz-Mendoza Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: All comments have been addressed Reviewer #2: All comments have been addressed ******** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: In my opinion the manscrit is ready for publication, all the comments were addressed. The insect industry is a new fast growing insdutry, and this kind of research is needed. Reviewer #2: Dear authors, Thank for your effort. All comments were responded and the paper is interesting. I am happy to accept this paper. ****** 7. PLOS authors have the option to publish the peer review history of their article (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: No https://doi.org/10.1371/journal.pone.0232144.r003
Formally Accepted
13 Apr 2020 Acceptance Letter - Humberto Lanz-Mendoza, Editor PONE-D-19-36053R1 Optimization of Hermetia illucens (L.) egg laying under different nutrition and light conditions Dear Dr. Macavei: I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, 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. For any other questions or concerns, please email plosone@plos.org. Thank you for submitting your work to PLOS ONE. With kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Humberto Lanz-Mendoza Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0232144.r004

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