Assessing the Importance of Natural Regulating Mechanisms in Weed Management: The Case of Weed Seed Predation in a Winter Wheat Field and in Adjacent Semi-Natural Habitat in Northern Hungary

Round 1

Reviewer 1 Report

Before publication, the manuscript received for review should be supplemented with important information and explanations regarding the research methodology. A list of reservations regarding the manuscript is provided below.

Title

1. The title of the manuscript does not correspond to its content. There is no single sentence on invertebrates as seed predators in the results and discussion chapter. The title invertebrates are mentioned only in the introduction. Thus, without any empirical data (e.g. captured invertebrates into appropriate traps), the participation of invertebrates as seed predators is speculative and hypothetical.

Abstract

2. Abstract is too extended. Detailed information on the methods and the results obtained are unnecessary. The journal is published in the "open access" system, and there is no reason to write such an extended abstract.

Introduction

3. The introduction is a review. As many as 50 publications are cited (2/3 citations). There is much information about invertebrates (groups, species) related to seed predation. This subject is completely ignored in the results and discussions. Information about invertebrates is vital, but in this case, it is a literature review rather than useful information for future discussion.

4. The introduction should not include unpublished information (including unpublished data in the form of graphs). The introduction should contain an overview of knowledge that the scientific world has accepted due to this knowledge being reviewed by independent reviewers. This information can be "smuggled" into discussion and verified.

Material and methods

5. The methodology used raises reservations. The authors secured the glued seeds with a metal mesh of "hole size 25 mm". The meshes of the wire netting are hexagonal. When giving a value of 25 mm, they meant the diameter, maximum, or minimum diagonal.

6. It does not appear from the photos whether the trays with seeds were placed horizontally or vertically on the soil.

7. Provide more information on the adhesive used. The critical information is water resistance (the seeds can be washed away by rain and even condensation) and the strength of bonding to the sandpaper cards. It is essential to provide information as to whether the invertebrate could tear off the seed with its mouthparts (of different structures) and transfer it to another place or whether it had to eat (feed) it on a card tray. If small invertebrates were able to move the seeds, they did not necessarily have to be consumed. They could have been deposited, for example, in an anthill. When the authors write about the consumption of seeds, do they mean remnants or damaged seeds still stick to the trays or their complete absence?

8. If the mesh protection nets, which were to protect the seeds from vertebrates also eating such food, were 25 mm, how can the authors be sure that they were not fed by small mammals such as voles (Microtus sp., Myodes sp.), mice (Mus sp.) or hamster (Cricetus sp.). Particular problems are the small field birds that feed on seeds, such as the skylark (Aluda sp.) or quail (Coturnix sp.). The suggestion of the possibility of penetration of the trays by small vertebrates, the participation of which may have been crucial, should be clearly explained.

9. The authors provided a whole set of advanced statistical analysis tools that they used to analyze the obtained results. This information slightly impacts the results given (1 short paragraph, and it does not exist in the figures and tables presented).

Results

10. Figure 4 - the graph should be of the point type (or the points could be connected with straight lines) but not the line type. With this type of chart, the data was acquired once daily, and nothing can be said about the values in between. If the curves used were smoothed, the equation based on which they were drawn should be given.

11. Figure 5 does not explain box graphics and points below or above the box.

12. Complete lack of information about potential seed predators (seed predators species, groups).

Discussion.

13. Lack of reference to the information on seed predators in the introduction. Have the authors attempted to verify potential invertebrate species or groups?

14. New references are cited in the discussion (19), which were not included in the introduction. However, the former was omitted (with a few exceptions). Thus, the publication is inconsistent with the information contained in the introduction and the discussion.

Conclusions

 

15. The conclusion (as well as the title of the manuscript) is correct only in the case of falsifying claim 7 from the above list of comments. Authors should provide evidence of the presence of invertebrates in the study plots.

Author Response

To the respected reviewer

The authors would like to express their thanks to your questions, comments, and suggestions which helped us to revise our manuscript.

Notes by authors:

• We would like to kindly mention that our manuscript recived an English language editing during the revision process, through the MDPI English editing service before being peer-reviewed.
• In this report, we responded to all questions and comments, and the suggestions were thoroughly considered and addressed, thus we hope that will fulfill your expectations.

Reviewer 1:

Comments and Suggestions for Authors

Before publication, the manuscript received for review should be supplemented with important information and explanations regarding the research methodology. A list of reservations regarding the manuscript is provided below.

Title

Point1. The title of the manuscript does not correspond to its content. There is no single sentence on invertebrates as seed predators in the results and discussion chapter. The title invertebrates are mentioned only in the introduction. Thus, without any empirical data (e.g. captured invertebrates into appropriate traps), the participation of invertebrates as seed predators is speculative and hypothetical.

Response 1:

We indicated the relevance and importance of invertebrate seed predators in the results (see line 241), in the discussion as well (see lines 397- 406) as well as in the conclusion (see lines 461-463). We wish that could fits and show the relevance of the manuscript contnent with the proposed tilte.

Regarding the participation of invertebrates as seed predators, our study considered and stands on previous study, on the activity density, key mixed feeder species, and their phenology in a winter wheat field and in the adjacent SNHs, by Kiss et al. [50], where they confirmed the occurrence of arthropods invertebrate seed predators, mainly Carabidae. This may provide evidence on the suggested potential role of ground-dwelling arthropods as seed predators in weed seed predation. Also, Szekeres et al. (2006) reported some most common carabids species in arable fields for example: Harpalus distinguendus, Amara spp. Calathus ambiguus, Dolichus halensis, and Trechus quadristriatus.

Although, we did not collect data on seed predators during this study, but, we used the exclusion approach (wire meshes) as a confirmation step to prevent vertebrate predators from consuming the seeds, which was ensured by no damaged or missing seed cards. This indicate that the estimations of seed predation obtained through the mesh were indicative of invertebrate seed predation. Besides, the literature confirmed that invertebrate seed predators, such as carabid beetles (Carabidae), known as a main cause of weed seed predation (see [15]), and observed consuming weed seeds in the laboratory (Petit et al. 2017; 2014; Saska et al. 2019). Harpalus pensylvanicus, Bembidion quadrimaculatum oppositum, Pterostichus melanarius, Chlaenius tricolour, Harpalus herbivagus, and Bembidion rapidum are a some examples (Holland 2002). Also, Gallandt et al. [32] stated that many studies confirmed the superior importance of invertebrate seed predators in seed predation compared to vertebrates; Cromar et al. [31]), and Westerman et al. [15], reported that invertebrates account for 80 to 90 % of seed predation in maize, soybean, and wheat fields. Therefore, we feel that there is agood reason to accept the invertebrats as apotential weed seed predators and consider the present work as a contribution of invertebrate seed predation.

Abstract

Point 2. Abstract is too extended. Detailed information on the methods and the results obtained are unnecessary. The journal is published in the "open access" system, and there is no reason to write such an extended abstract.

Response 2. The abstract was indeed lentghy with very detailed information, thus we tryied to keep it short considering the above suggestions.

Introduction

Point 3. The introduction is a review. As many as 50 publications are cited (2/3 citations). There is much information about invertebrates (groups, species) related to seed predation. This subject is completely ignored in the results and discussions. Information about invertebrates is vital, but in this case, it is a literature review rather than useful information for future discussion.

Response 3. The introduction was adjusted, focusing to those supportive information and literature and also being used in the discussion to evaluate and discuss our results.

Point 4. The introduction should not include unpublished information (including unpublished data in the form of graphs). The introduction should contain an overview of knowledge that the scientific world has accepted due to this knowledge being reviewed by independent reviewers. This information can be "smuggled" into discussion and verified.

Response 4. In fact, we intended to use ”un published information” form one the manuscript co-authors as a refernce for the presence of invertebrate seed predators relevant to the study area/region, but now as acceptance and in response to the reviewer adviced, we agreed and decided to took out the graph (figure 1), and repalced it with a relevant peer-reviewed paper published by the same co-atuthor (see Kiss et al. [47]).

Material and methods

Point 5. The methodology used raises reservations. The authors secured the glued seeds with a metal mesh of "hole size 25 mm". The meshes of the wire netting are hexagonal. When giving a value of 25 mm, they meant the diameter, maximum, or minimum diagonal.

Response 5. We have adjusted the description of the research methodology to be more accurate. The value of 25 mm, of the hexagonal mesh holes was indicated as a maximum diameter.

Point 6. It does not appear from the photos whether the trays with seeds were placed horizontally or vertically on the soil.

Response 6. The description of seed cards placing method was improved by explaining that seed cards were fixed horizontally on the soil serface between crop stands/plants.

Point 7. Provide more information on the adhesive used. The critical information is water resistance (the seeds can be washed away by rain and even condensation) and the strength of bonding to the sandpaper cards. It is essential to provide information as to whether the invertebrate could tear off the seed with its mouthparts (of different structures) and transfer it to another place or whether it had to eat (feed) it on a card tray. If small invertebrates were able to move the seeds, they did not necessarily have to be consumed. They could have been deposited, for example, in an anthill. When the authors write about the consumption of seeds, do they mean remnants or damaged seeds still stick to the trays or their complete absence?

Response 7. We used the glue spray adhesive: 3Ml, 400 ml/282 g, to stick the weed seeds on the seed cards. The glue was agreed to be used in various EU partiner counrtries under research project: QUESSA (Quantification of Ecological Services for Sustainable Agriculture) EU project (2013 to 2017), ( see line 160) in the introduction.

The adhesive strength ensured that the seeds would not be displaced under normal weather conditions (wind and rainfall) or during the placement of the cards. Based on our field observations, the adhesive glue kept holding the weed seeds for (4-5) days without being washed by rain indicating possible level of water resistance. At the same time, the weed seeds has been removed from the cards, and sometimes we found them destroyed on the cards which indicate seed predators tried to feed on their endosperims. This could show the invertebrates was able to take off the seeds with their mouthparts and relocated it to another place or feed it. Besides, our results showed seed predation occurred on all seed cards as we counted the remaining seeds on all cards every 24 hours. There was a decrease in the % of remaining seeds on the cards after first day of exposure.

Furthermore, as a supportive literature “seed predation” described by Janzen (1971) to distinguish between animals indeed consume seeds and destroy them (so called seed consumption) and those animals swallowing the seeds. Also, predation is relating to describe removal of viable seeds from the soil surface. The quantification of consumed seeds varied between studies e.g., Honěk et al. (2007) considered a seed being consumed when >50% of the total seed amount was destroyed, others considered a seed consumed where seed coat was cracked and part of the endosperm damaged (Carmona et al. 1999). Previous studies utilised weed seeds glued to cards placed on the soil surface (Hurst & Doberski 2003), with any removed seeds considered to be predated.

We therefore, feel to consider the examined weed seeds has been either removed and later eaten or immediatly consumed on the seed cards by the abundunt invertebrate seed predators.

Point 8. If the mesh protection nets, which were to protect the seeds from vertebrates also eating such food, were 25 mm, how can the authors be sure that they were not fed by small mammals such as voles (Microtus sp., Myodes sp.), mice (Mus sp.) or hamster (Cricetus sp.). Particular problems are the small field birds that feed on seeds, such as the skylark (Aluda sp.) or quail (Coturnix sp.). The suggestion of the possibility of penetration of the trays by small vertebrates, the participation of which may have been crucial, should be clearly explained.

Response 8. As our concern was to prevent vertebrates from removing the weed seeds, we used the wire meshes as acover and that was insured by observed of no damaged or missing seed cards. This allowed us to consider that the obtained estimations of seed predation as aprticipation of invertebrates to seed predation. Besides, based on visual infield checking, we did not observed the presence of Microtus sp and their feeding damge either.

Hamster (Cricetus cricetus) are rarely present in the region including our study area. Other species such as the small birds attack signs to the seed cards were absent as insured by no damged/missed cards. Therefore, we think there are no supporting information or field adata that would question or disregard the dominance and the potential role of invertebare seed predators/predation in redcuing weed seeds.

Point 9. The authors provided a whole set of advanced statistical analysis tools that they used to analyze the obtained results. This information slightly impacts the results given (1 short paragraph, and it does not exist in the figures and tables presented).

Response 9. Significal classes were indicated on figure 4 and in table 2. Figure 3 does not include statistical analizes only added as a visual demonstration of data-set and trends.

Results

Point 10. Figure 4 - the graph should be of the point type (or the points could be connected with straight lines) but not the line type. With this type of chart, the data was acquired once daily, and nothing can be said about the values in between. If the curves used were smoothed, the equation based on which they were drawn should be given.

Response 10. Figure 4 previously, (currently figure 3.), was created based on the daily data collection where the lines are smooth to demonstrate better the trend of change on seed predation.

Point 11. Figure 5 does not explain box graphics and points below or above the box.

Response 11. Figure 5 previously, (currently figure 4.), Boxes graphics explain minimum, maximum, quartiles and median values, where as dots explain outliers. This information has been added below the figure as well.

Point 12. Complete lack of information about potential seed predators (seed predators species, groups).

Response 12. Indeed, information on species or group levels of potential seed predators is much important. As we described in the introduction (see lines 163-169). Our study indicated previous studies by Kiss et al. [50], on the activity density, key mixed feeder species, and their phenology in a winter wheat field and in the adjacent SNHs where they confirmed the occurrence of arthropods invertebrate seed predator individuals, mainly Carabidae. Another evident example shows the peak of mixed feeder number of individuals of Harpalus and Amara  distinguendus, a species surveyed near to our study area, in a winter wheat field and in its borders in Kartal, Northern Hungary in June-July 1994. [see 47]. Besides, although, we did not collect data on seed predators during this study, but, we used the exclusion approach (wire meshes) as a confirmation step to prevent vertebrate predators from consuming the seeds, which was ensured by no damaged or missing seed cards. This indicate that the estimations of seed predation obtained through the mesh were indicative of potential invertebrate seed predation.

Discussion.

Point 13. Lack of reference to the information on seed predators in the introduction. Have the authors attempted to verify potential invertebrate species or groups?

Response 13. If the reviewer agrees, we may link this point to consider our response in Point.12 as well, where we show we provide information on invertebrate seed predators.

Point 14. New references are cited in the discussion (19), which were not included in the introduction. However, the former was omitted (with a few exceptions). Thus, the publication is inconsistent with the information contained in the introduction and the discussion.

Response 14.

Infact we have cited a new refernce relevant to our study to support and validate our current findings to check how relevant they are. In response to the reviewer suggestion, we involved this new reference and adjusted it to the intorduction part in away that to be more harmonized and consistent with the discussion.

Conclusions

Point 15. The conclusion (as well as the title of the manuscript) is correct only in the case of falsifying claim 7 from the above list of comments. Authors should provide evidence of the presence of invertebrates in the study plots.

Response 15. 

In response to that, we highlighted in the introduction the contribution of invertebrates as seed predators in our study consider the previous studies by Kiss et al. [50], on the activity density, key mixed feeder species, and their phenology in a winter wheat field and in the adjacent SNHs in Hungary, where they confirmed the occurrence of arthropods invertebrate seed predator individuals, mainly Carabidae. Another evident example shows the peak of mixed feeder number of individuals of Harpalus and Amara  distinguendus, a species surveyed in a winter wheat field and in its borders in Kartal, Northern Hungary in June-July 1994. [47]. This indicate the potential role of ground-dwelling arthropods as seed predators in weed seed predation. Besides, although, we did not collect data on seed predators during this study, but, we used the exclusion approach (wire meshes) as a confirmation step to prevent vertebrate predators from consuming the seeds, which was ensured by no damaged or missing seed cards. This my indicate that the estimations of seed predation obtained through the mesh were indicative of invertebrate seed predation.

Accordinglly, we feel that we responded to the remark here and in point 7, and we thus hope that it fulfills and fits with the expectations of the reviewer.

 

 

Osman et al (06 October 2022)

Reviewer 2 Report

The manuscript reports on a weed seed predation experiment in a wheat field and an adjacent non-habitat patch (or multiple Semi-natural habitats, I cannot tell from the manuscript if there was only one or more). My main concern with this experiment is that there was only one measurement of predation in time in each of the two years, which gives a very narrow snapshot of what happened at that particular time. Therefore, the results and conclusions are not very indicative of the real impact of weed seed predation in those systems but rather a very time-specific report on predation. Even if the time chosen to measure predation is relevant, the authors should at least acknowledge the very limited inference that can be made of such a snapshot, in the discussion.

Also, I think that the discussion is a collection of references but authors fail to really discuss their findings. For example, why was predation so different across years? Why do you think that predation rates were the same in the wheat field as in the SNH, contrary to your expectations? Why was predation higher in the first 2 days and then decreased? Why was there some preference for some species in 2019 but not in 2021? How real do you think that the reported high predation rates of P. rhoeas are? (since the size of the seed is so small that exposure time in real conditions may be less than some hours).

Also, there are a number of comments in the other sections that authors should address. The authors state that there were some “unfavorable meteorological conditions· that caused the exposure period to be one day longer in 2021 than in 2020 but they do not explain what happened and the impact that those bad weather conditions may have caused to the seeds exposed and reported rates. Since there not appears to be any control cards, this is impossible to assess. In that regard, why didn't you add control cards? how reliable are your measurements since there were no control cards?

The introduction is very general and spends more time defining what a weed is and what IPM is than focusing on weed seed predation, why natural areas may be important for predators, what do these predators need and how we can use this information to enhance seed predation, which I think would be more relevant to the paper. Also, there is some repetition of concepts, for example about SNHs (L77-80 and L117-122).

Figure 1. Needs a y-axis label and x-axis is not clear. Those are dates, right? So, for how long were those traps open? The whole time? Or some days each month?

Materials and methods. It is not clear how many SNHs there were and if the placement of the seed cards in the SNH was the same as in the wheat field. How many seed cards of each species did you place on the SNHs? Also, there lacks some description of what the SNH(s) looked like in terms of vegetation or cover that could help understand the results.

Also, how did you secure the seed cards to the ground? Did you use nails?

Explain why you chose to exclude vertebrates from the experiment.

For the reasons stated above, I do not think that the manuscript is suitable for publication as it is now. I would encourage authors to take the suggested points into account and maybe resubmit the manuscript once they have been addressed.

Author Response

To the respected reviewer

The authors would like to show their thanks to your questions, comments, and suggestions which helped us to revise our manuscript.

Notes by authors:

• We would like to kindly state that our manuscript recived an English language editing during the revision process, through the MDPI English editing service before being peer-reviewed.
• In this report, we responded to all questions and comments, and your suggestions were thoroughly considered and addressed, thus we hope that will fits with your expectations.

 

Comments and Suggestions for Authors

Point 1. The manuscript reports on a weed seed predation experiment in a wheat field and an adjacent non-habitat patch (or multiple Semi-natural habitats, I cannot tell from the manuscript if there was only one or more). My main concern with this experiment is that there was only one measurement of predation in time in each of the two years, which gives a very narrow snapshot of what happened at that particular time. Therefore, the results and conclusions are not very indicative of the real impact of weed seed predation in those systems but rather a very time-specific report on predation. Even if the time chosen to measure predation is relevant, the authors should at least acknowledge the very limited inference that can be made of such a snapshot, in the discussion.

Response 1.

In fact, in this work we only investigated 1 SNH type (non-habitat type) indicated as small forest patch adjacent to the wheat field.

With regard to measurement of seed predation, as we explained in material and methods (see lines 217-224) that identifying the optimum exposure period for estimating weed seed predation levels in our study was challenging. Most of relevant studies assessed seed predation during long-term exposure periods from a couple of weeks to several months [52,53,54]. In our study, to achieve accurate estimates of seed predation levels, data on seed predation from day 0 to day 2 (48-hour exposure period) were used, due to the low number of remaining seeds left on the final days of the field exposure. This supported the that a suitable exposure time for estimating weed seed predation in winter fields could be 2 days (48 hours) after first field exposure.

We also highlighted this in the discussion and conclusion that although our measurement on seed predation was found for specific time which proofed by data to be (48 h after field exposure), however, our findings indicate the workability of seed predation on the examined weed species. We discussed and compared our results with the previous relevant studies to validate its relevance and importance and they showed level of relevance and consistence. Therefore, these results could act as a new finding/report for weed seed predation in winter wheat fields in Hungary.

Point 2. Also, I think that the discussion is a collection of references but authors fail to really discuss their findings. For example, why was predation so different across years?

Response 2. In response to the reviewer comments and questions we adjusted the discussion of our findings with the relevant studies and reconsidered them in the manuscript.

Regarding the variability in seed predation patterns between time e.g., (years), it could be attributed to the different foraging and feeding behaviors of seed predator species/groups, for example Westerman et al. [71] mentioned that some vertebrate species are quick in respond to changes in seed availability than invertebrate seed predators. Besides, seed preference and availability of weed species and alternative food sources could directly affect seed predation rates over the time.

Point 3. Why do you think that predation rates were the same in the wheat field as in the SNH, contrary to your expectations?

Response 3.

In consideration with our hypothesis that habitat type may influence seed predation rates, especially when we have investigated seed predation levels in two different habitat types, we expected predation levels to vary accordingly, which didn’t happen. That contradicts with our expectations. A possible explanation is that we think that some seed predators selectively prefer and thus consume specific seed species than others (so called seed selectivity/preference); however, such selectivity is not always a persistent pattern. Therefore, it is highly possible that the weed seeds to be similarly consumed with similar consumption rates due to the generalist seed predators and the non-persistent pattern of seed selectivity.

Point 4. Why was predation higher in the first 2 days and then decreased?

Response 4.

Seed predation intensity is could be associated with seed predators’ populations density. Thus, the difference in seed predation rates might be related to fluctuations in the number of seed predator populations over time and their reaction and response to weed seeds density and availability. We think similar scenario happened in our study case. Another reason because of a positive association between ecosystem services e.g., seed predation and invertebrate predator activity-density, they may also be seen as a direct reaction to high food resource availability (Frank et al. (2011).

Point 5. Why was there some preference for some species in 2019 but not in 2021?

Response 5. Feeding behaviour and preference on certain seeds to another are vary according to seed predators’ groups and species.

We may kindly take the reviewer permission to link our response here with our responses in 2,3, and 4. Since some seed predators selectively prefer and thus predate specific seed species than others (seed selectivity/preference). That may explain those variations of feeding preference.

Point 6. How real do you think that the reported high predation rates of P. rhoeas are? (Since the size of the seed is so small that exposure time in real conditions may be less than some hours).

Response 6. Practically, we have daily counted the remining seeds on the cards, the results took us to fund seed predation occurred start from 48 hours after 1 st day of field exposure. There were no possibilities or we didn’t intend to have exposure time less than 48 hours, that could be consider as a new set up for different experiment. However, for small size seeds e.g., P. rhoeas we used a manual magnifier to count the remining seeds on the cards, although it was challenging process and time consuming, but eventually we could be able to accurately count small seeds as well and then estimate seed predation accordingly. Therefore, we feel the reported high predation rates of P. rhoeas are relevant and occurred.

 

 

Point 7. Also, there are a number of comments in the other sections that authors should address. The authors state that there were some “unfavorable meteorological conditions· that caused the exposure period to be one day longer in 2021 than in 2020 but they do not explain what happened and the impact that those bad weather conditions may have caused to the seeds exposed and reported rates. Since there not appears to be any control cards, this is impossible to assess. In that regard, why didn't you add control cards? how reliable are your measurements since there were no control cards?

Response 7. The mentioned unfavorable meteorological conditions here indicate to the rainfall at the end of the exposure period which make the sampling process (checking the seed cards and seed counting) difficult to perform in those days, that caused the exposure periods to be one day longer in 2021 than in 2020. Thus, we have not collected any meteorological data either (wind, rainfall, etc.,).

Furthermore, we didn’t include control cards, that to reduce number of seed cards and materials costs as well. But, we delt with this situation, by converting the number of remaining seeds on the cards into a proportion of seed predation relative to the total number of glued seeds to get more relevant estimations.

Point 8. The introduction is very general and spends more time defining what a weed is and what IPM is than focusing on weed seed predation, why natural areas may be important for predators, what do these predators need and how we can use this information to enhance seed predation, which I think would be more relevant to the paper. Also, there is some repetition of concepts, for example about SNHs (L77-80 and L117-122).

Response 8. Introduction length was resized, and kept relevant to the topic, and in consideration of the above-mentioned issues.

SNHs concepts were reviewed and cited many times, but that was within different context based on different findings in order to highlight their importance and significance to seed predators and impacts on seed predation.

Point 9. Figure 1. Needs a y-axis label and x-axis is not clear. Those are dates, right? So, for how long were those traps open? The whole time? Or some days each month?

Response 9. Figure (1) was replaced with another relevant information as published data (see Kiss et al. [47]).

Point 10. Materials and methods. It is not clear how many SNHs there were and if the placement of the seed cards in the SNH was the same as in the wheat field. How many seed cards of each species did you place on the SNHs? Also, there lacks some description of what the SNH(s) looked like in terms of vegetation or cover that could help understand the results.

Response 10. Although the adjacent SNHs were different, but here we only investigated the small forest patch for seed predation.

We described that in the material and methods (see lines 200-201), the sampled SNHs were those habitats wider than one meter adjacent to the crop field (small forest patches).

See lines (202-205) in material and methods, a total of 240 seed cards were placed on the ground for 2 sampling rounds, (120 card /round), (60 cards) inside wheat field and in the adjacent SNHs, (20 cards for each species), along 20 transects, with 3 cards / transect (1 card for each species).

 

 

 

Point 11. Also, how did you secure the seed cards to the ground? Did you use nails?

Response 11. Seed cards were fixed manually to the soil surface in a Horizontal position, without using the nails. Plants stand save form winds effect.

Point 12. Explain why you chose to exclude vertebrates from the experiment.

Response 12.

Vertebrates’ exclusion was chosen in order to allow us fulfill our study aim to measure the invertebrate seed predation. The exclusion of vertebrates will ensure and facilitate the actual participation and contribution of invertebrate seed predators to cause seed predation so that we can be able to measure the levels of seed predation which is the focal aim of our presented study. Moreover, many studies indicated the dominance of invertebrate seed predators in agricultural systems (see [14], [31], [27], [32]) and their contribution reported as 80-90 % of the total seed predation.

 

Point 13. For the reasons stated above, I do not think that the manuscript is suitable for publication as it is now. I would encourage authors to take the suggested points into account and maybe resubmit the manuscript once they have been addressed.

Response 13.

We tried to responded to your question and comments, and your suggestions were thoroughly considered and addressed, accordingly we hope that would meet your expectations.

 

Round 2

Reviewer 1 Report

Comment 2 for the authors

Comments on the manuscript submitted for re-review “Assessing the importance of natural regulating mechanisms in weed management: the case of weed seed predation by ground-dwelling arthropods in a winter wheat field and in adjacent semi-natural habitat in Northern Hungary” - Mohammed Gaafer Abdelgfar Osman, Mark Szalai, Mihaly Zalai, Zita Dorner and Jozsef Kiss.

1. The published results still do not prove the participation of arthropods in seed predation. Small mammals and birds could also be involved in this process. Their participation is regular for seed predation - vertebrates are often responsible for more than 50% of this process. The net used, with a mesh of 25 mm, could not be an obstacle.

2. The amount of arthropods participating in the described experiment is hypothetical, and the presented results cannot be assigned only to this group of animals. The participation of ground-dwelling arthropods may be the subject of a discussion in which the authors can present their arguments. The arguments presented in the responses to the reviewer's comments are unconvincing. They do not constitute formal proof and scientific results.

3. Most works cited in which seed predation was presented empirically confirm the participation of arthropods, which were usually caught with appropriate traps.

4. To be removed from the title "by ground-dwelling arthropods". After a few minor corrections, they allowed the article to be published.

5. Table 2 and Figure 4. Do the same alphabet letters in the columns mean no statistically significant differences for a given day (except for day 3)? Should the significance also be read between days for each species separately? The meaning of the letters used should be clearly explained. In the table's header, the value of N trials used to calculate the SD should be given.

6. The presentation of trends can be discussed in the discussion. If we want to present smoothed curves, the equation for each curve should be presented or at least the tool with which they were drawn. Equations will allow other researchers to recreate the curves.

 

Detailed comments.

Lines 59, 61 - unnecessary names of the authors of the publication.

Line 239 - how should the sentence "Our findings showed occurrence of invertebrate seed predation on the soil surface" be understood if the authors did not include any arthropod species in the results? Or does this conclusion only follow from previously published articles?

 

Lines 290-292: "Our study showed invertebrate (arthropod) weed seed predation in all investigated seed cards…" - the conclusion is not authorized. There is no information about the recorded invertebrates in the presented results. The last sentence of the conclusion should be exposed. It should also find excellent justification for discussing the future of organic farming.

Author Response

To the respected reviewer

 

The authors would like to thank the reviewer for the questions, comments, and suggestions that indeed helped us to revise and make our manuscript more clear and scientifically sound.

 

• Our manuscript undergone an English language editing through the MDPI English editing service, before being peer-reviewed, thus we hope that will be acceptable for the readers.
• In this report, we are responding to all questions and comments. The suggestions were considered and addressed in the revised manuscript, thus we wish that meets the expectations.

Comment 2 for the authors

Comments on the manuscript submitted for re-review “Assessing the importance of natural regulating mechanisms in weed management: the case of weed seed predation by ground-dwelling arthropods in a winter wheat field and in adjacent semi-natural habitat in Northern Hungary” –

Mohammed Gaafer Abdelgfar Osman, Mark Szalai, Mihaly Zalai, Zita Dorner and Jozsef Kiss.

 

 

1. The published results still do not prove the participation of arthropods in seed predation. Small mammals and birds could also be involved in this process. Their participation is regular for seed predation - vertebrates are often responsible for more than 50% of this process. The net used, with a mesh of 25 mm, could not be an obstacle.

Response1. In fact, we used the exclusion technique (wire meshes) as a precaution tool to secure the seed cards from vertebrates not to consume the seeds, that was probably successful as we did not observe damaged or missing seed cards. We thus feel the present estimations indicate the potential role of invertebrate seed predators as their activity density was justified earlier by Kiss et al, 1993, in wheat fields and SNHs in the region of our study area. However, we acknowledge the presence of vertebrates e.g., mammals and birds as well, and their potential contribution in seed predation.

Therefore, we adjusted the relevant sentences throughout the manuscript accordingly.

2. The number of arthropods participating in the described experiment is hypothetical, and the presented results cannot be assigned only to this group of animals. The participation of ground-dwelling arthropods may be the subject of a discussion in which the authors can present their arguments. The arguments presented in the responses to the reviewer's comments are unconvincing. They do not constitute formal proof and scientific results.

Response2. As we highlighted in point 1.  We agree on referring the contribution of other animals’ groups to the reported seed predation rates rather than considering only arthropods. Also, the ground-dwelling arthropods issue addressed in the discussion (see lines 246-247).

Thus, we kindly ask the reviewer to accept our response here with that of point 1.

 

3. Most works cited in which seed predation was presented empirically confirm the participation of arthropods, which were usually caught with appropriate traps.

Response 3. Thank you for the acknowledgement. The cited studies using pitfall traps were supportive to indicate the possible contribution of invertebrate seed predators to the current results.

4. To be removed from the title "by ground-dwelling arthropods". After a few minor corrections, they allowed the article to be published.

Response 4. In response to the reviewer suggestion regarding the contribution of arthropods, we feel comfortable to exclude the "by ground-dwelling arthropods" from the manuscript title, expanding the possible participation of other seed feeders’ groups besides the invertebrates.

5. Table 2 and Figure 4. Do the same alphabet letters in the columns mean no statistically significant differences for a given day (except for day 3)? Should the significance also be read between days for each species separately? The meaning of the letters used should be clearly explained. In the table's header, the value of N trials used to calculate the SD should be given.

Response 5. The level of significance (e.g., meaning of letters) important to be explained, we agree with the reviewer. The different alphabet letters provided in the columns in table 2 and figure 4. shows there were significant difference in seed predation over years, for days and among weed species. Some information added to the table 2 and figure 4.

N value is the number of seed card for one cell (n = 40 for one species in one year).

 

Reviewer 2 Report

The introduction and the discussion have improved after the revision. However, there are still some points that have not been properly addressed.

 L159-161. Calculating the proportion of remaining seeds compared to the inicial number is not an alternative to control cards. Control cards are those that cannot be accessible to predators but are still exposed to the weather, so they measure how many seeds may be removed by other causes than predation (rain, wind, glue not gluing,etc). Seeds remaining on control cards are then used to correct the predation rates. For example, if you leave 20 seeds in a control card and after 48 hours there are 19, that means than 1 seed has been lost to other causes than predation. Then, when you calculate predation in your other cards, your base number of seeds is 19 and not 20. So please delete the sentence: (as an alternative of control seed cards).

 L279. What do you mean by “the non-persistent pattern of seed selectivity”? What I understand is that you are discussing about why predation was the same in the wheat field and the SNH and you say that maybe predators were generalists, that eat everything but they also change preferences… I am not sure I am following. If predation rates are the same in both places may be because populations are the same in both places or both habitats provide equally suitable habitats for the predators.. it is not so much about the preference.

L283-287. This sentence is too long and confusing. I think that the authors did not understand Point 1 where I referred to the duration of the experiment, or maybe I was not clear enough. When I said that I was concerned that there was only one measure of predation in time I was not refering to the duration of the exposure period (48 hours, which is fine) but rather to the fact that you only measured predation two times over a period of 2 years. Most seed predation studies have at least two or three measurements of predation per year to understand how important and relevant this service really is. Maybe if they would have measured predation one month later, they may have seen differences between the wheat fields and the adjacent forests or maybe predation rates would have been lower… I asked authors to acknowledge in the discussion that the experiment is very narrow and only reports on what happened in a very specific moment of the year.

L152. The design of the experiment is still not clear to me. In how many SNHs did you put seed cards? Also, you say you use “60 seed cards inside the wheat field and the adjacent SNH at 10 m from the field edge”, so, how many cards were in the wheat field and how many in the SNH?

Author Response

 

To the respected reviewer

The authors appreciate the questions, comments, and suggestions helped us on revise our manuscript.

• Kindly, be informed our manuscript received an English language editing, through the MDPI English editing service before being peer-reviewed.
• Questions, comments, and suggestions were considered to revise the manuscript, we wish that would fulfill the expectations.

 

Comments and Suggestions for Authors

 

The introduction and the discussion have improved after the revision. However, there are still some points that have not been properly addressed.

 

Authors response: We are pleased to acknowledge your suggestions and comments which resulted in improving the introduction and discussion parts. Moreover, we kept our consideration to respond to the all points raised in this second review.

 L159-161. Calculating the proportion of remaining seeds compared to the initial number is not an alternative to control cards. Control cards are those that cannot be accessible to predators but are still exposed to the weather, so they measure how many seeds may be removed by other causes than predation (rain, wind, glue not gluing, etc). Seeds remaining on control cards are then used to correct the predation rates. For example, if you leave 20 seeds in a control card and after 48 hours there are 19, that means than 1 seed has been lost to other causes than predation. Then, when you calculate predation in your other cards, your base number of seeds is 19 and not 20. So please delete the sentence: (as an alternative of control seed cards).

Authors response: We appreciate the reviewer clarification. Indeed, the use of control cards would have act as a correction tool for calculate the number of removed seeds by other factors (wind, rain, etc.) rather than seed predation, and even to assess seed predation rates as well.

In our study, we used the total number of glued seeds to refer remaining seeds on cards, thus we follow the reviewer to remove the sentence (as an alternative of control seed cards). (See Lines 162-163).

 

 L279. What do you mean by “the non-persistent pattern of seed selectivity”? What I understand is that you are discussing about why predation was the same in the wheat field and the SNH and you say that maybe predators were generalists, that eat everything but they also change preferences… I am not sure I am following. If predation rates are the same in both places may be because populations are the same in both places or both habitats provide equally suitable habitats for the predators. it is not so much about the preference.

Authors response: Actually, observing same levels of seed predation in both habitats (inside crop field and SNH) was contrary to our expectations as we were assuming that seed predation will vary due to habitat types. However, in this case, we agree with the reviewer that same predation rates could be due to the presence of same predators’ population/individuals in both habitats, or both habitats were comfortable and preferred by the involved seed predators.

Thus, we accept to take out the explanation “the non-persistent pattern of seed selectivity” from the text (See lines 283-285).

 

L283-287. This sentence is too long and confusing. I think the authors did not understand Point 1 where I referred to the duration of the experiment, or maybe I was not clear enough. When I said I was concerned that there was only one measure of predation in time I was not referring to the duration of exposure period (48 hours, which is fine) but rather to the fact that you only measured predation two times over a period of 2 years. Most seed predation studies have at least two or three measurements of predation per year to understand how important and relevant this service really is. Maybe if they would have measured predation one month later, they may have seen differences between the wheat fields and the adjacent forests or maybe predation rates would have been lower. I asked authors to acknowledge in the discussion that the experiment is very narrow and only reports on what happened in a very specific moment of the year.

Authors response: In accordance to the reviewer comment that multiple measurements/estimation of seed predation could give large view on further actions and differences of seed predation in both habitats. In our study, however we conducted a single measurement of seed predation one time in each 1 year, that was useful to evaluate the effectiveness of seed predation focusing on the main seed spread period of the assessed weed species. Yet, we agree with reviewer that more measurements would have given broader picture on what was happening, thus we are planning to consider this though in our next research activities for more investigation and analysis.

In response to reviewer suggestion, we acknowledge the single measurement of seed predation obtained by our study in the discussion (please see lines 235 and 290).

 

L152. The design of the experiment is still not clear to me. In how many SNHs did you put seed cards? Also, you say you use “60 seed cards inside the wheat field and the adjacent SNH at 10 m from the field edge”, so, how many cards were in the wheat field and how many in the SNH?

Authors response: In response to that, we have adjusted the description of the experimental design in the manuscript to be clear enough for the readers (see lines 149-156).

In our study we sampled 1 SNH, described as small forest patch adjacent to the wheat field. We placed same number of 60 seed cards inside winter wheat field and in SNH.

 

Osman et al (20 October 2022)