Insight into Trophic Interactions of Spiders in Olive Groves with Integrated and Ecological Pest Management Using DNA Metabarcoding

Round 1

Reviewer 1 Report

“Insight into trophic interactions of spiders in olive groves with integrated and ecological pest management using DNA metabarcoding”

General comments

Spiders are a beneficial group of invertebrates, very abundant in agrocenosis, which can play an important role as a factor limiting occurrence of pest in crop fields. In the presented paper, the authors try to assess the diet of spiders inhabiting olive groves in Croatia. In general, the studies are very interesting and important for the development of sustainable agriculture. More specific, the results of this paper supplement the knowledge gap regarding the specific diet of this beneficial group of arthropods. This is very important and could be useful in understanding the interactions between a predator and a prey and could be use in different pest control programs in EPM models of crop production.

The introduction provides with a sufficient overview of the scientific background of the paper with well-chosen references. The basic aim of the study and the hypotheses are well-defined. The results are described accurately and are discussed in a throughout manner, taking into account an adequate number of references.

One thing in the results in very interesting for me and was not comment by Authors. This is the presence of the spiders as a prey in spring observations in IPM combination. Why only in spring and in IPM? In my opinion in IPM is allowing to use a pesticide (of course after exceed the economic damage threshold) and some pesticide was used to control pests in olive grove in spring. Some spiders may have been killed and then eaten by other spiders. It could be pointing that spiders do not hunt for another spiders but can eat fresh, dead bodies of invertebrates too. Of course, only hypothetically.

The Authors wrote that :Spider specimens were collected during spring and autumn in two consecutive years (2018 and 2019) …” [L 116 – 117]. And in L: 122 – 123 they state that “Sample collection was done from April to July and from September to November in 2019”. The same period was in 2018? If so, please indicate that. Why were spiders not caught for research throughout the season?

Detailed comments

L 67;; Why the: “European Green Deal” is in blue font and underline?

L 72:; It means after exceed the economic damage threshold?

L 82: Remove the year: (2015)

L 229 – 270: Please check the text style of the manuscript section.

Table 1

Table 1 lacks the names of people who described the species and year of description

Author Response

All comments and suggestions of the reviewer 1 have been accepted. Here is the reply to the comments of the reviewer 1:

General comments

One thing in the results in very interesting for me and was not comment by Authors. This is the presence of the spiders as a prey in spring observations in IPM combination. Why only in spring and in IPM? In my opinion in IPM is allowing to use a pesticide (of course after exceed the economic damage threshold) and some pesticide was used to control pests in olive grove in spring. Some spiders may have been killed and then eaten by other spiders. It could be pointing that spiders do not hunt for another spiders but can eat fresh, dead bodies of invertebrates too. Of course, only hypothetically.

Reply: In the Discussion section a small paragraph has been added regarding the upper comment: "Higher intraguild predation in spring season could be also due to higher abundance of some predatory arthropods (spiders, carabid beetles, etc.) in spring season [40,59] or scavenging on dead animals (i.e. after agricultural measures undertaken in spring), but gut content analyses applied in this study cannot distinguished predation from scavenging events.“

The Authors wrote that: Spider specimens were collected during spring and autumn in two consecutive years (2018 and 2019) …” [L 116 – 117]. And in L: 122 – 123 they state that “Sample collection was done from April to July and from September to November in 2019”. The same period was in 2018? If so, please indicate that. Why were spiders not caught for research throughout the season?

Reply: 2018 was omitted and now have been added. Due to summer estivation of the fauna the spiders were not caught for research during the warmest days in summer.

Detailed comments

L 67: Why the: “European Green Deal” is in blue font and underline? - corrected

L 72: It means after exceed the economic damage threshold? - yes, have been clarified

L 82: Remove the year: (2015) - corrected

L 229 – 270: Please check the text style of the manuscript section – corrected

Table 1 lacks the names of people who described the species and year of description

- added

Reviewer 2 Report

General comments:

The authors present an interesting paper I can recommend for publication in 'Diversity' with minor remarks. The manuscript concerns trophic interactions of spiders in olive groves with integrated and ecological pest management using DNA metabarcoding. It is an interesting study on a very current topic when we want to know the veritable role of predatory arthropods, in this case, spiders, in limiting pests in agricultural/horticultural areas. Molecular methods make it possible to determine the precise composition of spider prey and assess the role of spiders in natural pest reduction. I am sure that the results are thus potentially interesting for a broad public.

Detailed comments:

The title is clear and adequately reflects the content.

Keywords: It would be best if you did not repeat words from the title: spiders, trophic interactions –you can use some alternatives: Araneae, trophic links, relationships, or something like that.

The abstract is suitable and sufficient.

The introduction is comprehensive.

The methods are appropriately chosen and described, and the material is well collected and prepared for further analysis.

The results are clearly presented, but I have a few remarks:

Lines 233-234: 'Of all prey taxa detcted in their gut, spiders from IPM and EPM sites shared only three species (6,25%, Table 1)' - to me, this is unclear. I didn't find it in Table 1. Can you explain it? (and: detected, not detcted)

Line 353: '3.2. Consumption of phytophagous….' - In this chapter, you describe all the groups studied, not just phytophagous, so please consider this.

Line 359: 'pretation' – should be predation

Line 362: 'significan' – should be significant

Line 516, Table 1. I have noticed that some species are repeated, for example:

Alopecosa albofasciata - Integrated - Autumn – Ground hunters - Neuroptera Chrysoperla carnea

Alopecosa albofasciata - Integrated – Autumn – Ground -hunters - Diptera Bradysia brevispina - Neuroptera Chrysoperla carnea

Also: Hogna radiata - Integrated –spring - Loboptera decipiens;

Pardosa hortensis - Integrated - Autumn -Harmonia axyridis

Xysticus acerbus – Ecological – Autumn – Aphaenogaster balcanica

Xysticus marmoratus – Ecological – Spring – Tetramorium semilaeve)

I understand that these are collections from different sites, but I don't know if it makes sense to enter them twice, given that Table 1 is very extensive.

Check that the formatting is the same as throughout the manuscript. In my opinion, the line spacing is wider than in other chapters. Please normalize.

The discussion is interesting and comprehensive.

References: Pay attention to how you cite and follow the journal's requirements. In some chapters, there is only the number of the cited article (Introduction); in others, the number, name and year (Material and Methods, Discussion). Check this carefully and correct it.

Author Response

All comments and suggestions of the reviewer 2 have been accepted. Here is the reply to the comments of the reviewer 2:

Keywords: It would be best if you did not repeat words from the title: spiders, trophic interactions –you can use some alternatives: Araneae, trophic links, relationships, or something like that.

– corrected as suggested

The results are clearly presented, but I have a few remarks:

Lines 233-234: 'Of all prey taxa detcted in their gut, spiders from IPM and EPM sites shared only three species (6,25%, Table 1)' - to me, this is unclear. I didn't find it in Table 1. Can you explain it? (and: detected, not detcted)

Reply:  “Table 1” is moved and we have added additional text for clarification; misspelling is corrected

Line 353: '3.2. Consumption of phytophagous….' - In this chapter, you describe all the groups studied, not just phytophagous, so please consider this. – agree, “phytophagous” has been removed from the subtitle

Line 359: 'pretation' – should be predation - corrected

Line 362: 'significan' – should be significant - corrected

Line 516, Table 1. I have noticed that some species are repeated, for example:……

I understand that these are collections from different sites, but I don't know if it makes sense to enter them twice, given that Table 1 is very extensive.

Reply: The Table 1 style has been changed to make it clearer, but the repetition in some cases were necessary because of different sites or prey being consumed. All surplus repetition has been removed.

Check that the formatting is the same as throughout the manuscript. In my opinion, the line spacing is wider than in other chapters. Please normalize.

- corrected

References: Pay attention to how you cite and follow the journal's requirements. In some chapters, there is only the number of the cited article (Introduction); in others, the number, name and year (Material and Methods, Discussion). Check this carefully and correct it.

-corrected