Toxicity of Bioactive Compounds of Strychnos pseudoquina (Loganiaceae) in Spodoptera frugiperda (Noctuidae)
, Antônio C. S. Menezes 2, Cássia K. G. Santos 2, Flávio G. Jesus 3, Ednaldo C. Rocha 1 and Márcio S. Araújo 1,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this article, Souza et al. reported the insecticidal effect of bioactive compounds of Strychnos pseudoquina. It is a well-written, well-organized, and timely article. It is not the first article reporting bioactive compounds of Strychnos pseudoquina, but it will add to the consideration of the potential of these bioactive compounds as natural insecticidal molecules in addition to other applications. The article reads well; however, a minor revision should be made by considering the following points to improve the quality of the manuscript.
In line 92, add “ethyl acetate and methanol” since both solvents were used for bark. Otherwise, the information provided in the following lines 96 and 97 is difficult to understand.
Line 190, “These two flavonoids were satisfactorily dilute”, which dilution is “satisfactory” dilution? Mention some parameters.
Line 229, “Figures 2A and D”.
Lines 227-230: What about crude bark extract treated with 5% crude bark (figure 2A)? The figure shows that crude bark extract was the most potent. Please mention this in the results as you mentioned the “crude leaf extract (2.5 and 5%) were significantly less consumed by larvae”.
Figure 2: What is “HL” for? HL is on the X-axis of all figures which are part of Figure 2 but is not mentioned in the figure legend.
Figure 2: what is control? It is not mentioned in section 2.4 if the corresponding solvent was the control to show the effect of metabolites in a particular solvent.
Line 266: Ethyl acetate “ethyl acetate” and fracton should be “fraction”.
Table 2: The table contains superscripts “a” and “b,” but “a” and “b” are not defined in the table legends.
It needs to be discussed, why, in contrast to pure strychobiflavone, low concentration of 3-O-methilquercetin is more potent.
As the author indicated, the indirect or synergistic deleterious effect of compounds together instead of in a pure form, what are the future suggestions?
The major revision point is “figures” quality. The resolution of Figures 2 and 4 is very low and values on X-axis are hard to read. Improve the quality of figures.
Comments on the Quality of English LanguageThe English language is clear. Only minor spelling corrections are required. One is mentioned in the comments.
Author Response
"Please see the attachment"
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript investigated the pesticidal effect of Strychnos pseudoquina extract on Spodoptera frugiperda and established that ethanolic crude extract and its ethyl acetate fraction could be further explored in pest management as they demonstrated toxicity to Spodoptera frugiperda without repellence of S. frugiperda larvae. The study is in general executed and the conclusion is supported by the data. A few suggestions/questions:
1. Line 230 'Maize leaves treated with crude leaf extract (2.5% and 5%) were significantly less consumed by larvae'. Should it be leaves treated with ethyl acetate extract based Figure 2d?
2. In Figure 3, there are different number of data points in each extract concentration. Why? and it would add clarity to revise the legend to Larval toxicity of Strychnos pseudoquina.
3. Line 276 to 280, this paragraph is confusing to reviewer. Table 2 summarizes the pupae mortality fed with maize leaves treated with crude bark extract and its fraction. Figure 2F displays pupal weight decrease upon ingestion of maize leaves treated with S. pseudoquina leaf crude extract and its fraction.
4. The reviewer wonders why authors used different organic solvent for bark and leaf, e.g. hexane and methanol in the experiment design.
Author Response
"Please see the attachment"
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
Comments and Suggestions for Authors
The paper is well written and presented. However, it cannot be accepted at this current form.
Some major issues
Line 28 The introduction should add to the literature by strengthening the articulation of the research background and the purpose of the study. And check the reference and update.
Line 108, 111, 115, 124, 132. the author information should be added. i.e. described by author et al. [30].
Line 134 Better, more detailed description is needed. A photo or figure would greatly improve this part.
Line 153 Better, more detailed description is needed. A photo or figure would greatly improve this part.
Line 217 How did the larvae choose between bark and leaf? Are there any results?
Line 304 Strychnos pseudoquina is traditionally used in Brazil for the treatment of malaria and is widely used as a tonic, antipyretic, etc. Although the bark extract is more effective, the leaves appear to be more productive than the bark from a raw material production point of view, can the raw material supply meet the needs of agricultural pest control? Is the raw material supply sustainable? How can this be achieved? What is the cost of raw material production and is it cost effective? Has the increased demand affected the price of the herbs? Can you show readers more information in the discussion?
Line 325 Leaf and bark extracts should be tested for their chemical composition by GC-MS or some other method.
How does the insecticidal efficacy of the extracts compare with the efficacy of locally used chemical controls?
Author Response
"Please see the attachment"
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsArticle Tainá A. A. Souza , Antônio C. S. Menezes , Cássia K. G. Santos , Flávio G. Jesus , Ednaldo C. Rocha, Márcio S. Araújo " Toxicity of bioactive compounds of Strychnos pseudoquina (Loganiaceae) in Spodoptera frugiperda (Noctuidae)" (sustainability-2986218), submitted to the journal Sustainability, focuses on the possibility of using plant secondary metabolites to control insects harmful to agriculture. The article is organized according to the rules of the journal and contains all the necessary sections.
The article is of undoubted interest and can be published, but after making some corrections to this version of the article.
1) The authors need to indicate how widespread and sustainable the population of Spodoptera frugiperda is and whether intensive harvesting of the bark of this species will not have a detrimental effect on the biodiversity of the Cerrado region. Especially since articles on the development of conservation strategies for S. pseudoquina have already been published - – Leite, J. P. V., Xavier, A. A., Batista, D. S., Vital, C. E., de Oliveira Ramos, H. J., & Otoni, W. C. (2021). Embryo culture, callus induction, and flavonoid profile of Strychnos pseudoquina A. St.-Hil., an important medicinal species from the Brazilian Cerrado biome. Plant Cell, Tissue and Organ Culture (PCTOC), 145, 579-589.
2) The authors need to expand chapter 3.3. Larvicidal effect of secondary metabolites isolated from S. pseudoquina extract on S. frugiperda. In the presented version of the paper this chapter consists of only one sentence. It is also necessary to explain how larval mortality on the control (3.44%) and larval mortality on the Crude extract 5% w/v (40%) variant can be not statistically different (Table 2) - "by the same letter in the columns are not statistically different from the control treatment by the Mann-Whitney test, at p<0.05.". Similar question on Table 3 - why is larval mortality on the control (0%) and on the variants (16.6%) statistically insignificant?
3) Authors need to move graphs and tables in the text to places after their first mentioning.
Comments for author File: Comments.pdf
Author Response
"Please see the attachment"
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsAfter revised, the introduction provides sufficient background and include all relevant references. The methods are adequately described. I think the paper can be accepted in present form.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors of the article "Toxicity of bioactive compounds of Strychnos pseudoquina (Loganiaceae) in Spodoptera frugiperda (Noctuidae)" (sustainability-2986218), have modified the original version of the article and corrected the noted deficiencies.
The article may be published in the journal Sustainability
