Sampling Methodology of a Key Pest: Technique and Sampling Unit for Evaluation of Leafhopper Dalbulus maidis Populations in Maize Crops

Round 1

Reviewer 1 Report

Comments given on PDF

Comments for author File: Comments.pdf

Minor

Author Response

Review 1

Title

• severe pest? What does that mean? A pest can be a key pest, a major pest, or a minor pest. It is clear that this pest is an important one and that means it may be classified as key or .. pest. "Severe" better refer to the damage inflicted (severity of damage).

 

Ok.  

 

Introduction

 

• Page 2 line 89: sampling plans have not been determined. OK. Should also "Dispersion" be determined?

 

Pest dispersal is also important and should be studied. However, in this work, you determine the sampling unit and technique which are two important components of the sampling plan to carry out the sampling and verify the density of the pest in the crop.

 

Results

• These zero values should not be in the table and better state them as footnotes or in the text. Example, for plants in the V10 stage, leaf positions 3 up to 10 did not have the pest and there was no need to tabulate no data. V8, from positions 4 and above. 

 

Table rows with zero density were excluded.

 

Discussion

 

• Page 9 line 277: keep unit and number one space apart

 

Ok.

 

• Page 10 line 286: Above you discussed that this pest is favored by lower humidity and intense rains impact it negatively. Here you want to justify that the cartridge is suitable for the pest. The problem is that the cartridge is relatively more humid than other positions. And D. maidis does not prefer high humidity.  What do you want to say about this contradiction?

 

Rainfall has several direct and indirect effects on insect populations. Some of these effects are positive and some are negative. One of the positive effects of rainfall is that it increases humidity which is beneficial to most insect populations. Thus, the insects that are located in the corn cartridge are favored by the higher humidity in that part of the corn plant. On the other hand, the mechanical impact of raindrops has a negative effect on insect populations due to the mortality caused to these organisms. Thus, the insects that are inside the cartridge suffer less from this negative effect of raindrops.

 

• Page 10 line 296: What about accessing them, given that the leaves in the cartridge roll over and hide the insects?

 

Yes, this is true! However, due to the fact that we observed higher densities of D. maidis in this part of the plant, they were more accurate and more representative of the absolute density of this insect.

• Page 10 line 309: Kind of dispersion analysis could be done. And from that sample size could be determined. Also, Taylor's power law gives the nature of the distribution.

Taylor's power law deals with the mean relationship and variance of the data. In the case of data with greater precision, the mean tends to be greater than the variance and the errors in these data tend to have a normal probability distribution.

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

Some recommendations are given on an attached file on methodology and results where some sentences are repeated or need more information. Some references need more information. 

Comments for author File: Comments.pdf

Author Response

 

Review 2

Line 46-47: Write species author and order and family after Dalbulus maidis

Ok.

Line 49-50: Delete: During its life cycle, this insect goes through the stages of egg, nymph and adult. This is unnecessary information.

Deleted.

Line 57-58: It is written: and adults. And this…, must be written: and adults, this causes…

Ok.

Line 91-92: The following sentences must be moved to Material and Methods section: For this purpose, populations of this insect were monitored during two years in sixteen commercial corn crops in two biomes.

Ok.

Line 117: Adults and nymphs of D. maidis were directly counted?

Yes.

Line 118-119: Cardboard yellow sticky traps are also used to monitor pest densities

Yes, the cardboard yellow sticky traps technique is also used for sampling sucking insects. However, in this work it was not studied.

Line 147-148: How were plants selected?

Groups and plants were randomly selected. This part of the Material and Methods was changed to insert this information.

Line 150-151: How was the counting? Did you count the number of insects adults and nymphs per leaf or per plant?

The nymphs and adults present in the plant whorl were counted. This was done because this sample was selected in the previous part of the work. This information was inserted in Material and Methods.

Line 152: Did you apply any liquid inside the plastic tray to retain the insects?

The technique of shaking the plant in a plastic tray was carried out as it is done when sampling other insects and no liquid was used at the bottom of the tray.

Line 154: Must be 1 m2.

The beating cloth used was 1 m long and a plant was sampled on it.

Line 157-158: How you calculate the degree of damage in plants caused by the sampling technique?

In the damaged plants the leaves were torn and the stem was injured. This information has been inserted in the Results to make this information clear.

Line 202-203: Delete: Therefore, in all stages and biomes the densities of D. maidis in the plant cartridge 202 showed relative variances smaller than 25%. This sentence is mentioned in lines 196-197.

Deleted.

Line 222-224: It is written: In both biomes and in all stages of the plants, higher densities of D. maidis were detected when we evaluated it using the direct counting technique than when we used the techniques of shaking the apex of the plants in a plastic tray and the beating cloth.

Suggested text: In both biomes and in all stages of the plants, higher densities of D. maidis were detected when the direct counting technique was used, than when the techniques of shaking the apex of the plants in a plastic tray and the beating cloth were used.

The sentence was rewritten.

Line 229-230: This sentence may be deleted it is repeated: Therefore, in all stages and biomes, the densities of D. maidis evaluated by the direct counting technique showed relative variances smaller than 25%.

Deleted.

Line 239: Replace: conducted, with: studied…

Ok.

Line 241-242: How long the shortest and longest times?

In general, the sampling time for the direct counting technique was less than half of the time spent using the beating cloth technique. This information was inserted in the Results to respond to this suggestion.

Line 243: After: two extremes; add: (Figure 3A)

Ok.

Line 260: Were there any difference in damage between corn stages?

Several factors affect the intensity of D. maidis attack on corn crops, such as climatic elements and plant age. In this context, our working group has a manuscript submitted for publication on this subject. In this work, it was possible to identify that there is a trend towards an increase in the density of D. maidis during the vegetative phase of the plants.

Line 262-265: The following sentence: Therefore, based on precision criteria (relative variance < 25%), shorter sampling time and of do not causing damage on the plants, the best technique for sampling D. maidis in corn crops was direct counting of insects in the plant cartridge… Must be moved to discussion section.

This sentence was removed from the results section.

Line 269: What types of crop cultivation systems were different between the two biomes that resulted in higher densities of D. maidis in Cerrado biome?

As reported in the Discussion the highest densities of D. maidis in corn crops in the Cerrado biome are related to the occurrence of meteorological conditions (mainly air temperature and rainfall), relief and size of crops.

Line 280-281: But what will be the impact if the sucking insects such as leafhoppers, use to feed in the abaxial side of the leaves? Then raindrop would not have a negative impact on leafhopper survival.

Undoubtedly, the mechanical impact of raindrops on the organisms found on the adaxial surface of the leaves is greater. However, these drops also have an impact on the organisms that are on the abaxial side of the leaves. This is due to the inclined position of the leaves in the canopy of the corn plants and to the winds during the occurrence of rains. Furthermore, the nymphs and adults of D. maidis that are in the whorl are both on the adaxial and abaxial sides of the leaves.

Line 293-295: I do not agree that typical spatial alignment of the corn leaves protect D. maidis from natural enemies, always they are exposed to any predator or parasitoid.

This portion of the Discussion was withdrawn to address this suggestion.

Line 319-320: Delete the following sentence: On the other hand, the use of the direct counting technique did not damage the corn plants.

Deleted.

Line 332-335: Once you define the sampling unit and technique, what is next? Any discussion about populations pest density (economic threshold) that control activities must be initiated to reduce pest increases, considering that this is a vector of plant pathogens.

Pathogens cause damage due to their incidence and severity. Thus, depending on the severity of the disease, greater or lesser yield losses occur in the plants. Control decision-making systems are based on sampling plans and control decision-making indices. In surveys carried out by our research group in southern Brazil, it was found that farmers in this region are adopting cultural practices, tolerant corn hybrids, biological control with entomopathogenic fungi and chemical control (insecticides applied in seed treatment and spraying). . In this context, it is important to propose scientifically based decision-making systems. It is to be expected that for severe pests such as insect vectors of pathogens that the densities of the economic injury levels are small, as with whiteflies and thrips in vegetables.

Line 385: For all References write species names with lower cases, for example reference No. 3-6: Maidis…

Ok.

Line 425: Reference 16, Pedigo, L.P., it is not well cited, it is a book not a journal.

Thanks. Ok.

Line 453: More information for reference 26 is needed.

Ok.

Author Response File: Author Response.docx

Reviewer 3 Report

The Manuscript [agriculture-2488698] entitled (Sampling methodology of a severe pest: Technique and sampling unit for evaluation of leafhopper Dalbulus maidis populations in corn crops) found that the most suitable sampling unit for evaluating the pest populations were the cartridge leaves and the best technique was the direct counting and can be used in sampling plans for D. maidis in corn crops. The manuscript is well designed with good explanation and has good data those are introduced and written very well. BUT, some comments for the authors that are considered as minor revision.

 

 

1-     In methods, separate the statistical analysis in sub-section as: 2.4, statistical analysis

2-     Conclusion: It should be separated as section (5)

3-     In Figures (2A, 3A), indicate in methods (statistical analysis) how you did this analysis (on-way ANOVA), indicate in results DF, F, P for each stage.

Author Response

The Manuscript [agriculture-2488698] entitled (Sampling methodology of a severe pest: Technique and sampling unit for evaluation of leafhopper Dalbulus maidis populations in corn crops) found that the most suitable sampling unit for evaluating the pest populations were the cartridge leaves and the best technique was the direct counting and can be used in sampling plans for D. maidis in corn crops. The manuscript is well designed with good explanation and has good data those are introduced and written very well. BUT, some comments for the authors that are considered as minor revision.

  

• In methods, separate the statistical analysis in sub-section as: 2.4, statistical analysis

Ok.

• Conclusion: It should be separated as section (5)

Ok.

3-     In Figures (2A, 3A), indicate in methods (statistical analysis) how you did this analysis (on-way ANOVA), indicate in results DF, F, P for each stage.

The values of DF, c² and p were inserted in these Figures for the analyzes carried out for the four plant stages (V4, V6, V8 and V10) and the two biomes (Atlantic Forest and Cerrado) to meet this request.

 

Author Response File: Author Response.docx