Metabolome and Transcriptome Analysis Reveals the Effects of Host Shift on Dendrolimus houi Lajonquière Larvae

Round 1

Reviewer 1 Report

Very interesting manuscript, showing not only that there is an effect of host change on insect development but what is affected in the insect.

But some information is needed, in the introduction and methodology. Comments are throughout the text.

Comments for author File: Comments.pdf

Author Response

Point 1: The authors of the manuscript claim that this species of caterpillar has the ability to change hosts during its development. This behavior is not very common in Lepidoptera. Is there any work that supports this claim?

Response 1: Some caterpillar species have the ability to change hosts during its development under food shortage stress, which were frequently reported in previous researches about Lepidoptera species, for example, Ostrinia furnacalis feeds on maize during their younger stages and switches to legumes during their older stages (Yuan et al., 2013); The development of Spodoptera exigua larvae varied after they shiftly infested different host plants (Khamenei-Tabrizi et al., 2020; Yang et al., 2020), and eggs of Plutella xylostella remarkably decreased after they had the choice to simultaneously select Brassica campestris L., B. oleracea L. and B. juncea Coss (Huang, 2014), indicating that host shift probably influenced their population stability. Spodoptera litura Fabricius is prone to causing host shift due to their active migration among the Brassica olerace. L, Gossypium hirsutum. L and Alternanthera philoxeroides (Liu , 2015).

For Dendrolimus houi larvae, a few papers reported that they fed on various host species such as Cryptomeria fortunei, Pinus massoniana, P. yunnanensis, P. kesiya var. langbianensis and Cupressus funebris in different areas, and host shift occurred after their original host needles were eaten up (Wang et al，2023). Additionally, our team also have some direct experimental evidences to support this behavior of this caterpillar species (Figure 1).

Figure 1. The D.houi shifted to Platycladus orientalis and Cupressus funebris nearby from Cryptomeria fortunei and complete their development after all needles of C. fortunei were eaten up.

Point 2: This is part of the methodology and not in the introduction.

In the introduction there is no justification for the importance of metabolomics and transcriptomics studies for insects.

Response 2: Accepted, thank you so much. We have simplified and optimized this part, and added the introduction of transcriptomics and metabolomics.

Point 3: Did the rearing of insects and the evaluated parameters follow any methodology?

Response 3:  Yes, we did. The method of rearing insects was derived from years of rearing methods in our team, and we have also added some references. And the relevant evaluation parameters in this manuscript are the basic biological characteristics, we have added some previous literatures related to our work. 

Point 4: Did this technique follow any methodology already described? If yes add the reference.

Response 4: Accepted, we followed some methodology previously described, it is necessary to add these references. Thank you for your suggestion.

Point 5: Did this technique follow any methodology already described? If yes add the reference.

Response 5: Accepted, this technique has references to previous literatures, and we have added references. Thank you for your suggestion.

Reviewer 2 Report

I see some sentence really hard to understand for example Line 70-71. It will be great if you revisit and thoroughly read your manuscript. Overall, english is fine to me.

Overall, study is well designed. Authors have studied that how host shifting impacting insect herbivores using transcriptomic and metabolomic approaches. Host plants are important for the survival of herbivorous insects, and the quality differing in host species greatly influences the growth and development of herbivorous insects. Since the decrease of host quality due to environmental changes occurs frequently, insects adapt to them in various ways. Feeding on other hosts through short-term migration is a common survival strategy for polyphagous insects. The study explores how Dendrolimus houi Lajonquière larvae adapt to different hosts during multiple life cycles, providing a new plantation mode for mixed forests to suppress D. houi as well. The study also found that D. houi larvae can shift their preference for host plants during multiple life cycles, indicating their ability to adapt to changing environments.

I don’t have many comments about this study. However, I have concern about methodology. I suggest it would be great if authors can draw a sketch for methodology that will help readers to understand the experimental design.

For metabolomic analysis, it will be great if authors can extend their analysis. I understand you have done a great job by analysing transcriptome and metabolome data together. For example, you can make Venn diagram as you have done for both set of data together. Also, you can identify potential candidate metabolites. At this point I really did not understand conclusion from metabolomic analysis?

I don’t see clear differences between methodology and Results. I suggest rearranging transcriptome methodology and results.

Figure 3. I suggest revising figure caption. It should stand alone so reader can understand easily without reading text.

Figure 4. I suggest labelling in Venn diagram should not in abbreviation. I can’t see what is in heatmap. Can you please increase font size of labelling and increase resolution of figure 4C.

Please cite supplementary tables and figures in text.

Author Response

Point 1: I don’t have many comments about this study. However, I have concern about methodology. I suggest it would be great if authors can draw a sketch for methodology that will help readers to understand the experimental design.

Response 1: Thank you very much for your suggestion, but we are worried about this sketch may not be acceptable for the journal. Anyway, I am glad to submit our sketch here, hopefully, this would be very helpful to understand this experimental design.

Point 2: For metabolomic analysis, it will be great if authors can extend their analysis. I understand you have done a great job by analysing transcriptome and metabolome data together. For example, you can make Venn diagram as you have done for both set of data together. Also, you can identify potential candidate metabolites. At this point I really did not understand conclusion from metabolomic analysis?

Response 2: In the first part of the metabolomic analysis, we performed an initial screening of differential metabolites, which was identified when metabolomic techniques were merely considered.  We roughly screened and obtained differential metabolites by merely using transcriptomics, then accurately located and identified the differential metabolites associated with host shift by using joint analysis of transcriptomics and metabolomics. This finding is more accurate and related to host shift, which will be more likely to be the targets for controlling these pests.

Point 3: I don’t see clear differences between methodology and Results. I suggest rearranging transcriptome methodology and results.

Response 3: Accepted, thanks for your suggestion. We have simplified and optimized the current description in the methods and results section of the transcriptome, hopefully, it’s getting much better than before.

Point 4: Figure 3. I suggest revising figure caption. It should stand alone so reader can understand easily without reading text.

Response 4: Accepted, thank you so much. We have revised the caption of the Figure3 section so that readers can better understand without reading text.

Point 5: Figure 4. I suggest labelling in Venn diagram should not in abbreviation. I can’t see what is in heatmap. Can you please increase font size of labelling and increase resolution of figure 4C.

Response 5: Accepted, thank you for your suggestion. We have optimized the labelling of Venn diagram. And we have increased font size of labelling and resolution of figure 4C to improve the legibility.

Point 6: Please cite supplementary tables and figures in text.

Response 6: Accepted, thank you. we have intensively rechecked all citations to supplementary tables and figures in text.

Point 7: I see some sentence really hard to understand for example Line 70-71. It will be great if you revisit and thoroughly read your manuscript. Overall, English is fine to me.

Response 7: Thank you for your encouragement, but as for the content of lines 70-71you mentioned, namely, “…….All the tested insects were collected from Jiangle County, Fujian Province, China (E: 117°35'12.17", N: 26°37'49.54"), and their original hosts were C. fortunei (LL). The eggs were……”, just make sure we have ambiguous description about this sentence here?