Screening of Nematicides against the Lotus Root Nematode, Hirschmanniella diversa Sher (Tylenchida: Pratylenchidae) and the Efficacy of a Selected Nematicide under Lotus Micro-Field Conditions

Round 1

Reviewer 1 Report

The manuscript describes the screening of nematicides against Hirschmanniella diversa in vitro and micro-plot trials with selected nematicides. I think that the authors did a great job to struggle with the nematode on the lotus in Japan. The experiments were performed logically, and results and statistical analysis were presented clearly and appropriately. The only thing that the authors have to remind for the next study is that each experiment has to be repeated. In the present study, the in-vitro experiments were not repeated although some nematicides were used repeatedly from one screening to another.

 

Following are minor comments;

Line 69: Was the assay repeated?

L77: “plates” maybe “dishes”.

P78-88: Was the nematicidal solution in the dish transferred to the glass vials?

L78: “After 2 weeks”. This exposure period is longer than generally used one (few days). Why? Based on the “lifetime” of nematicides?

Table 1: This table is somehow confusing. The most important thing is “Registered application dose of a.s. per ha” for comparison (without calculation). This should be presented in place of or in addition to “registered amount” in the table. Generally, sources (companies) of used chemicals should be presented. “Dilutions” should be converted to “XX kg/ha”, if possible even by rough calculation. Also, It is not clear for which pests the doses are registered.

L117: What about nematodes on the dish wall? Were they all alive?

L126-129: What about soil characteristics, soil volume, water volume, initial nematode populations (inoculum)??

L130: 200 and 400 kg/ha. How many grams of the nematicides were actually applied to each container? This is very important for calculating nematode concentrations in the soil or water phase of the soil (therefore the soil and water volume are required). How were the application doses (200 and 400 kg/ha) converted to “per plot”? Just based on the surface area? Not soil depth?

L141-146: It is better to add an illustration or picture for the index.

L148: Was the soil in the containers replaced with new soil + nematode inoculum in each year?

Table 2: The number of replicated must be included. Because “active substances” are listed, it is not necessary to write “active substrate” in “Concentration of active substance” (also in Table 3 and 4). “Concentration of formulation” column can be deleted. The exposure period should be included!

L219: No phytotoxicity observed?

Fig. 2: Doses of active substrates per plot should be presented (xx g/plot). “Fosthiazate” and “Benfuracarb” are active substrate names!! 200 and 400 kg are based on the formulations!!! Confusing!!

Fig. 3: Number of replicates? Again, “Fosthiazate” and “Benfuracarb” are active substrate names!! 200 and 400 kg are based on the formulations!!!

Table 5: Application dose of “Benfuracarb” should be clearly presented rather than that of the formulated product. Why were relatively high numbers of uninfected tubers found in 2016 and 2017?

L255-256: Is this sentence relevant here? Does “H. oryzae” mean Hirschmanniella oryzae? If so, it should be spelled. More explication may be required here.

L266-271: LC50s can not be compared simply each other because each experiment might have different exposure periods. Therefore, an exposure period is necessary for each LC50.

L288: I think that the registration of the nematicide for A. besseyi is as seed treatment (soaking in the nematicide solution), and not in the field?

L297-298: Again, how were they calculated? Considering the volume of the water phase of the field? Soil volume? Surface area?

Author Response

Dear Reviewer 1

Thank you very much for the positive and constructive comments provided by the reviewers on our manuscript “Screening of nematicides against the lotus root nematode, Hirschmanniella diversa Sher (Tylenchus: Platylenchidae) and the efficacy of a selected nematicide under lotus micro-field conditions”, now revised under the amended title as “Screening of nematicides against the lotus root nematode, Hirschmanniella diversa Sher (Tylenchida: Pratylenchidae) and the efficacy of a selected nematicide under lotus micro-field conditions”.   

 

The reviewers identified a number of important points, which were considered in the revised version. In the given time, we made our effort to correct the text according the reviewers comments. Major changes are marked in red in the text. We hope that in this current form, the paper will be accepted for publication in the agronomy. We remain at your disposal for any further queries you may have.

 

Best wishes and thank you in advance for considering the current updated version for publication.

 

The authors

Motonori Takagi, Corresponding Author

 

Line 69: Was the assay repeated?

Response: The assay was not repeated however, each pesticide treatment was replicated 5 times. See Line 76.

 

L77: “plates” maybe “dishes”.

Response: revised, see text, Line 78.

 

P78-88: Was the nematicidal solution in the dish transferred to the glass vials?

Response: text was revised 79-81

 

L78: “After 2 weeks”. This exposure period is longer than generally used one (few days). Why? Based on the “lifetime” of nematicides?

Response: exposer period was determined as two weeks. We aimed to evaluate the maximum potential of each nematicides. The long exposure periods does not indicate that lengthy exposure requirements of nematicides.

 

Table 1: This table is somehow confusing. The most important thing is “Registered application dose of a.s. per ha” for comparison (without calculation). This should be presented in place of or in addition to “registered amount” in the table. Generally, sources (companies) of used chemicals should be presented. “Dilutions” should be converted to “XX kg/ha”, if possible even by rough calculation. Also, It is not clear for which pests the doses are registered.

Response: a.s. per ha, companies and target pest are added. See Table 1.

 

L117: What about nematodes on the dish wall? Were they all alive?

Response: no nematodes was observed to be alive on the dish wall (zone 4). Revised, see line 124-125.

 

L126-129: What about soil characteristics, soil volume, water volume, initial nematode populations (inoculum)??

Response: Silty clay was the soil characteristics. Initial nematode populations were not measured because extraction rates from the soil were too low. Inoculum nematode was roughly estimated.

Rsponce: revised. See line 134, 136-137, 146-147.

 

L130: 200 and 400 kg/ha. How many grams of the nematicides were actually applied to each container? This is very important for calculating nematode concentrations in the soil or water phase of the soil (therefore the soil and water volume are required). How were the application doses (200 and 400 kg/ha) converted to “per plot”? Just based on the surface area? Not soil depth?

Response: revised. See line 142-144, 162.

 

L141-146: It is better to add an illustration or picture for the index.

Response: illustration was constructed and added as Figure 2, see 170.

 

L148: Was the soil in the containers replaced with new soil + nematode inoculum in each year?

Response: the soil in the containers were not renewed throughout the study period, but the containers were randomly rotated with each treatments every year to homogenate the initial nematode density. Text added, See line 167-169.

 

Table 2: The number of replicated must be included. Because “active substances” are listed, it is not necessary to write “active substrate” in “Concentration of active substance” (also in Table 3 and 4). “Concentration of formulation” column can be deleted. The exposure period should be included!

Response: revised. See Table 2

 

L219: No phytotoxicity observed?

Response: no phytotoxicity or chemical injuries was observed on the plants as the result of the nematicides used. Text revised, see line 236-237.

 

Fig. 2: Doses of active substrates per plot should be presented (xx g/plot). “Fosthiazate” and “Benfuracarb” are active substrate names!! 200 and 400 kg are based on the formulations!!! Confusing!!

Response: text revised. See Fig 3

 

Fig. 3: Number of replicates? Again, “Fosthiazate” and “Benfuracarb” are active substrate names!! 200 and 400 kg are based on the formulations!!!

Response: text revised. See Fig 4

 

Table 5: Application dose of “Benfuracarb” should be clearly presented rather than that of the formulated product. Why were relatively high numbers of uninfected tubers found in 2016 and 2017?

Response: text revised. See Table 5 and line 263-265.

 

L255-256: Is this sentence relevant here? Does “H. oryzae” mean Hirschmanniella oryzae? If so, it should be spelled. More explication may be required here.

Response: text revised, see line 279-285.

 

L266-271: LC50s can not be compared simply each other because each experiment might have different exposure periods. Therefore, an exposure period is necessary for each LC50.

Response: text revised. See 293-305.

 

L288: I think that the registration of the nematicide for A. besseyi is as seed treatment (soaking in the nematicide solution), and not in the field?

Response: Benfuracarb 8 % granule registration in Japan for A. besseyi is applied to rice nursery boxes 0-3 days before transplanting. Cartap hydrochloride wettable powder registration for A. besseyi in Japan as soaking application in the nematicide solution, but for rice water weevil Lissorhoptrus oryzophilus is applied to field when transplanting. Thus, we think benfuracarb and cartap hydrochloride application in this method would be similar to field application even though in small amounts.

 

L297-298: Again, how were they calculated? Considering the volume of the water phase of the field? Soil volume? Surface area?

Response: text revised, see line 336-340.

Author Response File: Author Response.docx

Reviewer 2 Report

This is an experimental study with specific and rare plant parasitic nematode species attacked specific plant species growing in the specific environmental condition. There are only limited information about H. diversa as pests of lotus plants, however it seems, that this crop is good host for this nematode species. Therefore, eco-friendly control methods are needed, due to known high toxicity many pesticides. I have only several coments. 

Comments for author File: Comments.pdf

Author Response

Dear Reviewer 2

 

Thank you very much for the positive and constructive comments provided by the reviewers on our manuscript “Screening of nematicides against the lotus root nematode, Hirschmanniella diversa Sher (Tylenchus: Platylenchidae) and the efficacy of a selected nematicide under lotus micro-field conditions”, now revised under the amended title as “Screening of nematicides against the lotus root nematode, Hirschmanniella diversa Sher (Tylenchida: Pratylenchidae) and the efficacy of a selected nematicide under lotus micro-field conditions”.   

 

The reviewers identified a number of important points, which were considered in the revised version. In the given time, we made our effort to correct the text according the reviewers comments. Major changes are marked in red in the text. We hope that in this current form, the paper will be accepted for publication in the agronomy. We remain at your disposal for any further queries you may have.

 

Best wishes and thank you in advance for considering the current updated version for publication.

 

The authors

Motonori Takagi, Corresponding Author

 

Page 1, line 3; Tylenchus is genus, and Platilenchidae dot´t exist

Tylenchida: Pratylenchidae

Response: revised, see text, line 3.

 

Page 1, Line 17; Only limited sources about H. diversa as potential pests of lotus are available with no data about yield losses. Therefore you can not state that is "important"

Response: About a million dollars in estimated yield losses have been recorded so far and lotus farmers seem to be moving away from lotus production because of negative impacts of H. diversa. Text added, see text, line 42-44.

 

Page 1, line 42-43; Some data about yield losses of lotus caused by H. diversa or other pest can by added, if exists....

Response: text revised, see line 42

 

Page 2, Line 44; Citation if exist?

Response: text revised, see line 46.

 

Page 3, Line 89; Why did you test pesticides which were withdrawn due to high toxicity to environment and other animal?

Response: Fenthion was a hopeful nematicide to be adopted to control H. diversa when in-vitro assays were implemented. But after completion of nematicide assays, registration was withdrawn. But we hope to show the nematicide effectiveness of fenthion to H. diversa if more eco-friendly substances like chemical structure of fenthion or revised (decreased amounts) application amount are proposed. Text added, see 318-320.

 

Page 11, Line 273; ...suggesting that H .diversa is resistant to these nematicides

Response: text revised, see line 308-309.

Author Response File: Author Response.docx