Effects of a Salicylic Acid Analog on Aphis gossypii and Its Predator Chrysoperla carnea on Melon Plants
, Elisa Garzo 2, Alberto Fereres 2,3, Elisa Viñuela 1,3 and Pilar Medina 1,3,*Round 1
Reviewer 1 Report
60-82: The three paragraphs that contain the objective of the project could probably be reduced to two, the paragraph that starts on line 60 can probably be combined with the one starting on 67; there is some redundancy on stating the objective on C. carnea on the paragraph that starts in line 60 and the one on 76.
121: Why five week old plants?
156: spell EPG on first mention
179: I suggest a re write of this paragraph. It can be a bit confusing. For example, the authors mention 32 parameters were calculated, and then proceed to describe four. Also, C seems to stand for intercellular apoplastic stylet pathway, but later C also stands for control plants.
199: paragraph is redundant
282, 284: don’t repeat the F and P values, they are in the table.
382: no repellency, no contact effect. But the non-probe behavior had a higher NWEI, WDI, and WDE for B0 than B4, how does that relate to thee no contact effect statement?
389: the reference here may be problematic. The work referenced is stated as showing “control” of an aphid species in tomatoes, and the authors seem to equate their results to that work. While the manuscript shows a reduction in population growth in the greenhouse, this does not mean control. If the referenced work produced a reduction in population growth, then state that rather than control.
404: The description on paragraph 374 keeps coming up in my mind when thinking on the effects of BTH on the aphid. If there is plant tissue injury, there might be an effect on the capacity of the aphids to feed, but not necessarily on their behavior. Is the reduction in population growth just a result of plant tissue damage, and not an elicited plant response? Please address this in the discussion.
430: direct toxicity of the product on the aphid or on the plant?
Author Response
60-82: The three paragraphs that contain the objective of the project could probably be reduced to two, the paragraph that starts on line 60 can probably be combined with the one starting on 67; there is some redundancy on stating the objective on C. carnea on the paragraph that starts in line 60 and the one on 76.
We agree with the reviewer and we have reduced from three to two paragraphs the background to explain the objective of the project (L61-L89, tracking system activated).
121: Why five week old plants?
Now, L128.
We performed three different experiments (aphid fitness, aphid feeding behaviour and Chrysoperla carnea feeding efficiency), so we had to homogenise the growth stage of the host plant to be the same in every experiment.
In the aphid fitness experiment, we needed plants with strong leaves to support the weight of the clip cage without breaking the petiole.
In the EPG experiment, it is necessary to work with small plants to be able to keep them inside the Faraday cage. We had to place 8 plants per EPG recording, so pot diameter and plant growth stage were limiting factors.
In the predator experiment, we needed plants with sufficient development of the leaf to support the aphid infestation and the larva of C. carnea to move freely on the leaf.
In our specific laboratory conditions, first to third true leaves of melon cv. Sancho are smaller and thinner than more developed leaves. Therefore, we had to work with a more developed growth stage. According to BBCH scale (Feller et al., 1995), five-week-old melon plants are in phenological growth stage 15. It means that the principal growth stage is leaf development (main shoot), exactly, fifth true leaf on main stem unfolded. Thus, this growth stage was chosen to be adequate for the correct perform of the three experiments.
156: spell EPG on first mention
Done. We have moved the complete name of the acronym from L166 to L163.
179: I suggest a re write of this paragraph. It can be a bit confusing. For example, the authors mention 32 parameters were calculated, and then proceed to describe four. Also, C seems to stand for intercellular apoplastic stylet pathway, but later C also stands for control plants.
We have made some changes in the paragraph (L187-198) to clarify the information. In Table 2 and Table 3 it is written “variables” instead of “parameters”, so we have changed this word in the paragraph. The PPW, WDI, WDE, NWEI parameters are those described by Backus et al. [41] that we have used to organize the information obtained with the MS Excel workbook and to compare the different treatments within each EPG non-sequential or sequential variable.
Furthermore, in order to avoid confusion with the acronym “C”, we have kept the “C” for the waveform type and, in Figure 1 and in its legend (L284-288), we have changed C1 and C2 to Control 1 and Control 2.
199: paragraph is redundant
We incorporated the information of the paragraph in the next one to avoid redundancy (L208-214).
282, 284: don’t repeat the F and P values, they are in the table.
Due to the intrinsic rate of natural increase (rm) and the mean relative growth rate (RGR) are related by the formula [rm = 0.86 RGR] they have the same F and P values, so we have maintained only once the information. We prefer to highlight the values of the main parameters in the text, to be independent of the table information (L296-298).
382: no repellency, no contact effect. But the non-probe behavior had a higher NWEI, WDI, and WDE for B0 than B4, how does that relate to thee no contact effect statement?
To clarify, we have replied and included some information in this paragraph and in the next one (L402-410, L415-425).
389: the reference here may be problematic. The work referenced is stated as showing “control” of an aphid species in tomatoes, and the authors seem to equate their results to that work. While the manuscript shows a reduction in population growth in the greenhouse, this does not mean control. If the referenced work produced a reduction in population growth, then state that rather than control.
We agree with the reviewer. Therefore, according to the reference cited, we have changed “control” to “reduce the population growth” (L411-412).
404: The description on paragraph 374 keeps coming up in my mind when thinking on the effects of BTH on the aphid. If there is plant tissue injury, there might be an effect on the capacity of the aphids to feed, but not necessarily on their behavior. Is the reduction in population growth just a result of plant tissue damage, and not an elicited plant response? Please address this in the discussion.
This is an interesting question, nevertheless, we are not able to reply it with our data. In order to have the specific information to elucidate how the phytotoxicity could affect the insects, we must have done a biochemical study of plants and insects. First of all, we would not have expected phytotoxic effects of BTH on melon plants, therefore, it was not the objective of our study. Moreover, EPGs recordings should have been done every day coinciding with the duration of fitness experiment, in order to relate to a possible change in feeding behavior due to phytotoxic effects. Thus, the biochemical analysis and continuous EPGs had increased experiment and personal costs, and we had not been able to afford the expenses.
Phytotoxicity could affect aphids as they grow and feed continuosly on host plants. However, in our study we observed a decrease in aphid fitness when A. gossypii grew on B4 plants, but not when aphid grew on B7 plants. Therefore, the negative effect seems to disappear when the product was applied three days earlier.
We have incorporated some information in the text to address this question (L399-401).
430: direct toxicity of the product on the aphid or on the plant?
Briefly, the sequence of BTH-effects observed in our experiment was: on the one hand, total mortality in B0, reduction of development and growth in B4 and no effect in B7. On the other hand, only an impairment on the feeding behavior of aphids fed on B0 was observed. Therefore, we have demonstrated with our results a direct effect of fresh residue of BTH (B0) on the aphid. We have also observed phytotoxicity (direct effect on the plant); although we did not perform specific analysis to study it (see previous comment). If the effects observed are the result of a rapid activation of defenses or more closely to a plant protection product (that degrades and therefore causes less and less effects), is something that we cannot demonstrate in this article.
We have incorporated some information to clarify this comment in the Conclusions section (L454-459).
Reviewer 2 Report
This study was aimed to study the effects of a salicylic acid analogue on Aphis gossypii and its predator Chrysoperla carnea on melon plants. The study is well designed and prepared in an appropriate level. The study seems original and it contains new and valuable results. The manuscript can be considered for publication after revisions.
Suggestions and comments:
Abstract L16-19: Give a more clear and one sentence objective in the Abstract. The sentence should start as ’The objective of this was …’
L113, L146, L259, L292: Here Aphis gossypii is not italic as the title is italic.
L198, L350: Here Chrysoperla carnea is not italic as the title is italic.
L285, L329, L354: Give in full BTH in the title.
L289, L330, L347, L348: Give in full BTH, EPG in the title.
L289, Aphis gossypii should be in italic.
L520-522, L597-599: All words in the title is with big capital letters.
Author Response
Abstract L16-19: Give a more clear and one sentence objective in the Abstract. The sentence should start as ’The objective of this was …’
We have clarified the objective of the study in the abstract (L16-17).
L113, L146, L259, L292: Here Aphis gossypii is not italic as the title is italic.
Corrected (L120, 153, 271, 308).
L198, L350: Here Chrysoperla carnea is not italic as the title is italic.
Corrected (L207, 367).
L285, L329, L354: Give in full BTH in the title.
Information added (L284, 299, 371).
L289, L330, L347, L348: Give in full BTH, EPG in the title.
Information added (L304, 345, 363).
L289, Aphis gossypii should be in italic.
Done (L304).
L520-522, L597-599: All words in the title is with big capital letters.
Now, L544 and L626)
It is true, but the titles of these two papers are originally written with an initial capital letter in some specific words. Please, check the following links to verify:
https://doi.org/10.1046/j.1439-0434.2003.00798.x
https://doi.org/10.1007/s10886-014-0503-4
In the website, if you go to “About this article” and then “Cite this article”, the title is with capital letters, so we prefer to maintain at it is.
