Review History


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Summary

  • The initial submission of this article was received on September 3rd, 2015 and was peer-reviewed by 3 reviewers and the Academic Editor.
  • The Academic Editor made their initial decision on September 26th, 2015.
  • The first revision was submitted on October 13th, 2015 and was reviewed by 2 reviewers and the Academic Editor.
  • The article was Accepted by the Academic Editor on October 29th, 2015.

Version 0.2 (accepted)

· · Academic Editor

Accept

Both the authors strongly agree that this manuscript should be published without delay, given the potential importance of its findings. Although this work is preliminary, it appears to be scientifically sound, and this phenomenon should be examined at greater depth ASAP.

·

Basic reporting

Now the papers appears to be well structured highlighting the issues involved. I urge the authors for more detailed investigations in future. Of course this suggestion may not affect the final acceptance of this MS in anyway

Experimental design

Its ok

Validity of the findings

seems convincing

Comments for the author

I recommend the acceptance of the MS now

Reviewer 3 ·

Basic reporting

Excellent

Experimental design

Appropriate

Validity of the findings

Robust

Comments for the author

I am happy with the changes made by the authors. I think that this paper will be of broad interest to the community.

Version 0.1 (original submission)

· · Academic Editor

Major Revisions

All of the reviewers agreed that the findings in this manuscript are important and should be widely known. At the same time two of the reviewers raised methodological concerns that need to be addressed.

My reading of Table 1 differs from that of Reviewer 1 in that I think it shows that all of the exposed carcasses have treated have nematodes. If I am wrong here, this issue needs to be addressed.

The issue of replication is an important one. It is be important to clearly state all sample sizes: how many colonies, and how many times each treatment was repeated, etc.

I would personally like to see a discussion of whether the concentrations of nematodes used in the experiment are reasonable with respect to field conditions. In the discussion, the authors mention that "the conclusions of scientists advising the European regulatory body OECD in 1996 were that entomopathogenic nematodes were safe for wildlife: however, potential effects insect pollinators were not specifically considered (Ehlers and Hokkanen, 1996". However, the effect described in the manuscript are not obviously pollinator-specific. So, why do your results differ so much from earlier recommendations? Is it because bumblebees are particularly sensitive?

Minor point:
After referring to a latin name for an organism, it is customary abbreviate the genus (e.g., B. terrestris).

·

Basic reporting

In this ms the authors report the effect of entomopathogenic nematodes (Steinernema spp. and Heterorhabditis sp.) on Bombus terrestris. They reported that both nematode products caused ≥ 80% mortality in bees within the 96 hours at the recommended field concentration. Since the paper focus on Entomopathogenic nematodes as a new threat to bees? . I think they need to validate these findings with care . Nevertheless i commend the work of authors and is not posing any doubt about their finding. The most serious concern is there is no report of these nematodes being infective to bombus, although they have coevolved a way back and present in soil. The author must check it. Of course i agree that may be that very few studies have been undertaken which would reveal the extent of such a phenomenon. The basic findings on Koch postulates, infective mode and proliferation of each species of nematode must be adhered before it get attention and made a subject of debate.

Experimental design

My another concern about the paper is that author stated that Individual bees were captured at the hive entrance and cold anaesthetised to facilitate transfer into the treatment boxes. How, it was ensured that these bees were already not carrying natural infection of nematodes or latent one. May be these bees have been used already in the area. The author must clarify. Since GYO is mixture of two species of nematodes, it is difficult to ascertain what actually caused mortality with special reference to Heterorhabditis sp. The authors should mention the species of Heterorhabditis and Steinernema in the product “Grow Your Own”. Also composition in term of proportion will put more light on our understanding on this aspect. No doubt the data is given on the count of nematode but sometimes in case of mixed infection only one species will outcompete the other.

Validity of the findings

I am unable to understand that in table 1 in case of VW a large number of carcasses were collected but nematodes were recovered from a very few one. What caused the mortality then? How lowest number is 0 while highest is about 3-6000. Interstingly no difference in mortality between the different nematode concentration treatment groups in GYO but not VW. The author needs to justify .
In the abstract authors mention ≥ 80% mortality within the 96 hour. But under methodology section it is written that bee mortality was measured 24, 48 and 72 hours after nematode exposure. Please check

Comments for the author

Of course the paper is well written and i do not find any critical issues about the presentation but the author needs to address these issues before considering the same for publication.

Reviewer 2 ·

Basic reporting

No comments

Experimental design

No comments

Validity of the findings

No comments

Comments for the author

This is an interesting paper in the absence of effect entomopathogenic nematodes on mortality of bumble bee Bombus terrestris. It is important to using safe biological control agents pay attention to the unlimited availability and also affects beneficial insects.
The article is interesting, but I have one attention, this research is more as a short comunnication, not the regular publication.

Reviewer 3 ·

Basic reporting

The paper is very clearly written with sufficient background to orientate readers. I would like more details in the methods.

Some details I would like to see are:
1 How many colonies are used. I suspect one, which is a bit limiting in terms of predicting how general this is, although the mortality rate is quite amazing.
2 the level of replication is not clear in text. According to the included spreadsheet it looks as if only 5 individuals were exposed to each condition. This is a pretty small sample size. I would rather like to see higher replication and more colonies.
3 How are they housed during exposure? All together or individually?

Experimental design

In general, the design is sensible. Unfortunately, it appears to have very little replication with a single colony and only five workers per condition.

Validity of the findings

The analyses seem appropriate, and the strength of the effect is quite shocking. The only issue is the low replication.

Comments for the author

This is a very clear and striking report but I worry about the small sample size and the use of what appears to be a single colony.

I’m a bit torn on this ms. One one hand, if true, these results are very interesting, important, and should get out to the community quickly. But, the lack of replication is a bit troublesome. It becomes hard to assess how important this is based on so few bees from a single colony.

One point which I think bears a bit of discussion, although I leave that up to the authors’ discretion, is the importance this may have to queen hibernation survival. While workers may be exposed to this while foraging (perhaps) or by entering and leaving the colony. I wonder if queen hibernation spots would be more likely to be exposed to these agents, and even if not, this is where queens will spend a great deal of time so may be more susceptible.

ps. there seems to be a superfluous sheet in the supplementary excel file about feeding which is not discussed in the ms.

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