Babaçu (Attalea Speciosa) Residue Bio-Oil Repels Livestock Tick Larvae Rhipicephalus (Boophilis) Microplus

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors studied the repellent efficacy of bio-oil pyrolyzed from babaçu waste for Rhipicephalus microplus ticks. This is an interesting manuscript that is well prepared. The methods and results are clear and the discussion is well conducted. The manuscript can be published after minor corrections.

 

1. Instead of Figure 1, a table would probably be more appropriate, in which the % repellency (+- S.E.) would also be expressed. However, the % repellency can also be entered in a graph.

 

2. I suggest combining the Results chapter with the discussion (which is already conducted in the description of the results). The chapter should therefore be called: Results and Discussion.

 

3. Only short-term tests were used. It is therefore important to better (more deeply) discuss the persistence of the effect, which can rapidly decrease in possible practice. This can be increased by a suitable formulation of the potential repellent.

Author Response

The authors studied the repellent efficacy of bio-oil pyrolyzed from babaçu waste for Rhipicephalus microplus ticks. This is an interesting manuscript that is well prepared. The methods and results are clear and the discussion is well conducted. The manuscript can be published after minor corrections.

Thank you for taking the time to review our manuscript and provide feedback for improvement.

1. Instead of Figure 1, a table would probably be more appropriate, in which the % repellency (+- S.E.) would also be expressed. However, the % repellency can also be entered in a graph.

Our data distribution is not normal, it was a Poison distribution once it has a lot of zeros on it (100% repellence), so +/-SE is not recommended. But to clarify in analyzing our data, we used confidence intervals to compare the repellent effect between treatments in Figure 1. We decided to add Table 3 which summarizes the data presented in Figure 1. We are keeping Figure 1 so the data can be presented visually.

2. I suggest combining the Results chapter with the discussion (which is already conducted in the description of the results). The chapter should therefore be called: Results and Discussion.

We have combined the Results and Discussion sections as requested into one “Results and Discussion” section.

3. Only short-term tests were used. It is therefore important to better (more deeply) discuss the persistence of the effect, which can rapidly decrease in possible practice. This can be increased by a suitable formulation of the potential repellent.

We have addressed this in last paragraph of the newly combined “Results and Discussion” section. Past review article by Banumathi et al. 2017 confirms lower efficacy of botanical acaricides on adult ticks for in vivo compared to in vitro studies as you have brought up when these formulations are taken from the laboratory to the field on actual cattle. We also added a sentence here suggesting that a more suitable formulation of the bio-oil could increase persistence and efficacy.

 

Submission Date

09 January 2025

Date of this review

10 Jan 2025 07:51:59

Reviewer 2 Report

Comments and Suggestions for Authors

 

The manuscript presents a novel approach to the problem of chemical acaricide resistance in Rhipicephalus (Boophilis) microplus, a major pest in tropical livestock production. The study explores the use of bio-oil from babaçu residues as a tick repellent, offering a potential alternative to conventional chemical treatments. The research is well conducted and provides valuable insights into the development of environmentally friendly tick control methods. However, there are several areas where improvements can be made to enhance the quality and impact of the study.

1. The authors have carried out a thorough series of experiments, including the production of bio-oil at different concentrations, tick climbing tests and chemical analyses. The inclusion of toxicity tests, in particular the analysis of polyaromatic hydrocarbons (PAHs), is commendable.

2. The use of a standardised tick climbing test to assess the repellency of the bio-oil is appropriate. However, the authors could provide more details on the specific conditions and controls used in the test to ensure reproducibility.

3. The authors could provide more information on the assumptions and robustness of the models used, particularly in the context of the relatively small sample sizes in some of the tests.

4. The table could be made more user-friendly. For example, the compounds could be grouped according to their chemical properties or pot.

5. The table does not provide references for the compounds identified. It would be useful to include citations for the sources of the compound data to support the findings.

6. The table could benefit from the inclusion of comparative data, such as PAH levels in other common bio-oils or environmental standards for PAHs, to provide a benchmark for the results.

7. The study does not clearly define the practical threshold for field applications. The 1.57% concentration, although less effective (85% repellency), is highlighted as potentially more promising due to lower toxicity. This suggests a trade-off between efficacy and safety that requires further investigation.

8. Include a section in the results discussing potential mitigation strategies, such as adapting the pyrolysis process to reduce the formation of toxic compounds. In addition, consider carrying out further testing to assess the long-term environmental and health impacts of the bio-oil.

9. Include a table or figure that directly compares the repellency rates of Babaçu bio-oil with those of DEET and other known repellents. This will give a clearer picture of the performance of the bio-oil compared to existing solutions.

10. Suggest future studies to evaluate the long-term efficacy of the bio-oil. This could include repeated applications over time to assess whether ticks develop resistance or tolerance to the bio-oil.

11. Include a preliminary economic analysis comparing the cost of producing and using Babaçu bio-oil with that of conventional acaricides. This will help stakeholders to assess the economic feasibility of adopting the bio-oil as a tick control measure.

 

Comments for author File: Comments.pdf

Author Response

The manuscript presents a novel approach to the problem of chemical acaricide resistance in Rhipicephalus (Boophilis) microplus, a major pest in tropical livestock production. The study explores the use of bio-oil from babaçu residues as a tick repellent, offering a potential alternative to conventional chemical treatments. The research is well conducted and provides valuable insights into the development of environmentally friendly tick control methods. However, there are several areas where improvements can be made to enhance the quality and impact of the study.

Thank you for taking the time to review our manuscript and provide feedback for improvement.

1. The authors have carried out a thorough series of experiments, including the production of bio-oil at different concentrations, tick climbing tests and chemical analyses. The inclusion of toxicity tests, in particular the analysis of polyaromatic hydrocarbons (PAHs), is commendable.

Thank you.

2. The use of a standardised tick climbing test to assess the repellency of the bio-oil is appropriate. However, the authors could provide more details on the specific conditions and controls used in the test to ensure reproducibility.

We have added more specific details of the methodology and environmental conditions of the tick climbing test in addition to the specific conditions and controls that we used to ensure that the climbing test can be reproduced by future researchers.

3. The authors could provide more information on the assumptions and robustness of the models used, particularly in the context of the relatively small sample sizes in some of the tests.

We have included more detail on the calculation of repellency percentage at the end of the methods section as well more details on the assumptions and the robustness of the methods used. For the tick climbing test, there was adequate sample size (n=40) and repetition (15) to run statistical tests. We have also better justified the methods and sample sizes for both the organic chemical compound analysis as well as the Polycyclic Aromatic Hydrocarbon analysis. Both have 1 repetition, made in triplicate, as indicated for chemical characterization analysis.

4. The table could be made more user-friendly. For example, the compounds could be grouped according to their chemical properties or pot.

Thank you for this suggestion, we changed the table and it is better now.

5. The table does not provide references for the compounds identified. It would be useful to include citations for the sources of the compound data to support the findings.

For both Table 1 and Table 2, we have added a footnote stating citations used for information presented in both tables.

6. The table could benefit from the inclusion of comparative data, such as PAH levels in other common bio-oils or environmental standards for PAHs, to provide a benchmark for the results.

Other studies that evaluated PAH levels of bio-oil did not evaluate PAH levels for specific chemical compounds. Therefore, we decided to keep the aggregate PAH level comparisons between the babaçu residue bio-oil it in our study versus other products in the text to avoid reader confusion. To our knowledge, we do not know of any studies that have measured PAH levels

7. The study does not clearly define the practical threshold for field applications. The 1.57% concentration, although less effective (85% repellency), is highlighted as potentially more promising due to lower toxicity. This suggests a trade-off between efficacy and safety that requires further investigation.

Yes, we have added this as suggested by you to the last paragraph of the newly created Results and Discussion section.

8. Include a section in the results discussing potential mitigation strategies, such as adapting the pyrolysis process to reduce the formation of toxic compounds. In addition, consider carrying out further testing to assess the long-term environmental and health impacts of the bio-oil.

We have added these points to the last paragraph of the newly created Results and Discussion section.

9. Include a table or figure that directly compares the repellency rates of Babaçu bio-oil with those of DEET and other known repellents. This will give a clearer picture of the performance of the bio-oil compared to existing solutions.

The comparison being requested is comparing one percentage to another so we felt it appropriate to contrast this in the writing in the first paragraph of sub-section 2.3. Babaçu Residue Bio-Oil Compared to Other Tick Repellents and Acaricides in the newly created Results and Discussion section.

10. Suggest future studies to evaluate the long-term efficacy of the bio-oil. This could include repeated applications over time to assess whether ticks develop resistance or tolerance to the bio-oil.

We have made these suggestions in a newly added paragraph at the end of the merged Results and Discussion section.

11. Include a preliminary economic analysis comparing the cost of producing and using Babaçu bio-oil with that of conventional acaricides. This will help stakeholders to assess the economic feasibility of adopting the bio-oil as a tick control measure.

Unfortunately, no economic engineering data was collected in this preliminary study so it is not possible to determine basic costs at this time. However, we are planning on writing a grant for additional study on this topic where we would assess babaçu residue bio-oil efficacy against Rhipicephalus (Boophilis) microplus ticks in the field on cattle as well as for longer time periods in the lab. If this grant is funded and this study is done, we would define and set-up collection of material costs, labor use, etc. for both experimental lab production of bio-oil. If babaçu residue bio-oil efficacy in vivo as well as for longer time frames in vitro is promising we would also estimate hypothetical cost of production if the production process were up-scaled to more commercial (industrial) production.

peer-review-43485862.v2.pdf

Submission Date

09 January 2025

Date of this review

14 Jan 2025 15:25:56

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for inviting me to review the article titled “Babaçu (Attalea speciosa) Bio-Oil Repels Livestock Tick Larvae Rhipicephalus (Boophilis) microplus”. Research on innovative botanicals to try and reduce (or, hopefully, eliminate) the constantly applied synthetic acaricides and repellents is so much needed. I find the proposed application of this Babaçu bio-oil worth additional study, especially to exclude safety risks to animals and humans.

Unfortunately, however, I can’t accept the article in this form. Although the results are promising, the text is long and mainly discusses other papers. The original results here included should be better valorised with words and, perhaps, a different statistical analysis. Furthermore, I don’t think the journal Parasitologia is the most suitable. Yes, the repellency test was performed on ticks, and it surely required time, skills, and effort, but the overall manuscript is stronger on the chemical side with the characterisation of BO. Therefore, it would probably fit better in a journal like Molecules.

Here are my detailed comments:

-          The introduction, although well written, is quite long. I would summarise at least the part regarding the resistance, reducing the details about years.

-          From there on, the structure of the paragraphs is confusing to me. I would present the results regarding the composition of BO first, then the repellency test. Accordingly, I would follow the same order in the materials & methods section.

-          Some parts of the results actually belong to the discussion or conclusions. See lines 153-158, 168-188, 192-201, etc. What about combining the results and discussion? I have checked, and the MDPI journals give this opportunity.

-          Figure 1 is hard to understand at first glance (What is the difference between control and active larvae? I can’t find this explanation in the materials & methods), and the caption referring to box plots is wrong. Moreover, there is no trace of the statistical analysis you mentioned in the materials & methods.

-          References in Tables 1 and 2 (e.g., numbers 60, 61, 62, 63) are needed. Please add a column in each table.

-          If the chemical analyses were run in triplicate, you could add the standard deviation to your mean values.

-          What about the supplementary material? It is not mentioned in the manuscript.

 

In the attached PDF are listed some more specific requests.

Comments for author File: Comments.pdf

Author Response

Thank you for inviting me to review the article titled “Babaçu (Attalea speciosa) Bio-Oil Repels Livestock Tick Larvae Rhipicephalus (Boophilis) microplus”. Research on innovative botanicals to try and reduce (or, hopefully, eliminate) the constantly applied synthetic acaricides and repellents is so much needed. I find the proposed application of this Babaçu bio-oil worth additional study, especially to exclude safety risks to animals and humans.

Unfortunately, however, I can’t accept the article in this form. Although the results are promising, the text is long and mainly discusses other papers. The original results here included should be better valorised with words and, perhaps, a different statistical analysis. Furthermore, I don’t think the journal Parasitologia is the most suitable. Yes, the repellency test was performed on ticks, and it surely required time, skills, and effort, but the overall manuscript is stronger on the chemical side with the characterisation of BO. Therefore, it would probably fit better in a journal like Molecules.

Thank you for taking the time to review our manuscript and provide feedback for improvement. We will consult with the managing editor on the appropriateness of transfer from MDPI Parasitologia to MDPI Molecules.

Here are my detailed comments:

-          The introduction, although well written, is quite long. I would summarise at least the part regarding the resistance, reducing the details about years.

We have reduced the length of the Introduction as requested by consolidating 3 paragraphs on acarcide resistance into only one paragraph. We have also made other minor edits to other parts of the Introduction to reduce its length.

-          From there on, the structure of the paragraphs is confusing to me. I would present the results regarding the composition of BO first, then the repellency test. Accordingly, I would follow the same order in the materials & methods section.

As requested, we have in the Results and Discussion section, in the Methods section, and in the objectives stated at the end of the Introduction section changed the order of presentation to 1) composition of BO and then 2) the repellency test.

-          Some parts of the results actually belong to the discussion or conclusions. See lines 153-158, 168-188, 192-201, etc. What about combining the results and discussion? I have checked, and the MDPI journals give this opportunity.

We have combined the Results and Discussion sections as suggested into one “Results and Discussion” section.

-          Figure 1 is hard to understand at first glance (What is the difference between control and active larvae? I can’t find this explanation in the materials & methods), and the caption referring to box plots is wrong. Moreover, there is no trace of the statistical analysis you mentioned in the materials & methods.

The two treatments contrasted were the control versus bio-oil treated in the climbing test. Counts of active larvae were used as a check on viable larvae for the test. We used box plots in an earlier draft of Figure 1 but have corrected this in Figure 1.

-          References in Tables 1 and 2 (e.g., numbers 60, 61, 62, 63) are needed. Please add a column in each table.

For both Table 1 and Table 2, we have added footnotes citing sources used for information presented in both tables.

-          If the chemical analyses were run in triplicate, you could add the standard deviation to your mean values.

We have added standard deviation of larvae counts for control, active larvae, and babaçu residue bio-oil treatments in the newly added Table 3.  We cannot use +/-SE because our data distribution is a Poisson and not a normal distribution. Also, SE represents the population and not samples. So, we add standard deviation (SD) to the newly added Table 3 so the reader can understand better the deviation around the means.

-          What about the supplementary material? It is not mentioned in the manuscript.

We do not have supplementary materials as all data are included in the primary manuscript. MDPI journals do not require manuscripts to include supplementary materials.

In the attached PDF are listed some more specific requests.

Thank you for the edits in the attached pdf and we have addressed these by making the corrections / clarifications requested.

peer-review-43485858.v1.pdf

Submission Date

09 January 2025

Date of this review

13 Jan 2025 11:23:02

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors revised the manuscript in accordance with the review comments. I agree to accept the manuscript.

Author Response

The authors revised the manuscript in accordance with the review comments. I agree to accept the manuscript.

Thank you very much for taking the time to review our manuscript!

Reviewer 3 Report

Comments and Suggestions for Authors

The authors substantially improved the manuscript now titled “Babaçu (Attalea speciosa) Residue Bio-Oil Repels Livestock Tick Larvae Rhipicephalus (Boophilis) microplus”. There are still some parts that can be removed (please, see the red lines in the newly attached PDF) and minor issues to address (still in the PDF).

I still don’t know if Parasitologia is the most appropriate journal, but it’s not up to me to decide…

 

P.S. You uploaded, probably by mistake, an Excel file (name parasitologia-3445313-supplementary) as supplementary materials. I was referring to it in my previous review.

Comments for author File: Comments.pdf

Author Response

Comments and Suggestions for Authors

The authors substantially improved the manuscript now titled “Babaçu (Attalea speciosa) Residue Bio-Oil Repels Livestock Tick Larvae Rhipicephalus (Boophilis) microplus”. There are still some parts that can be removed (please, see the red lines in the newly attached PDF) and minor issues to address (still in the PDF).

Thank you very much for editing the manuscript again and we have made all suggested edits from your pdf file.

I still don’t know if Parasitologia is the most appropriate journal, but it’s not up to me to decide…

We are discussing this with the managing editor and our decision to submit to MDPI Parasitologia instead of MDPI Molecules was based on 1) formatting the manuscript to the topic of tick control which is a parasite where MDPI Parasitologia seemed like the best fit despite being a relative new journal and 2) our feeling that while the analysis of molecules in the babaçu bio-oil is part of the research, MPDI Molecules is focused exclusively on chemistry where submission to MPDI Molecules would have been more appropriate if we were chemically formulating the repellent versus only chemically analysing it.

P.S. You uploaded, probably by mistake, an Excel file (name parasitologia-3445313-supplementary) as supplementary materials. I was referring to it in my previous review.

Sorry about this error in sending the Excel file.

peer-review-43845068.v1.pdf

 

Submission Date

09 January 2025

Date of this review

28 Jan 2025 13:58:40