Whitefly Detected: Light-Emitting-Diode Traps Enhance Monitoring of Trialeurodes vaporariorum in Greenhouse-Grown Tomato

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

It is simple design but very useful experiment on an important pest named green house whiteflies(GWF). The results showed that the GWF catches on LED traps correlate significantly and positive with the population density on the tomato crops. The language and pictures of this paper are good enough for publishing. 

Two small commonts

1) the Temperature and ambient light conditions could in the coloumn of methods.

2) The reason for select green LED trap is not fully explained. Why not select different color for comparison? 

 

Comments for author File: Comments.pdf

Author Response

Reviewer 1

It is simple design but very useful experiment on an important pest named greenhouse whiteflies(GWF). The results showed that the GWF catches on LED traps correlate significantly and positive with the population density on the tomato crops. The language and pictures of this paper are good enough for publishing. 

• Thank you very much for your positive response to our manuscript!

Comments in the text:

Line 57-60: The reason for select green LED trap is not fully explain. Why not chose different color for comparision?

• Thank you. We added a short explanation making it more clear. See line 56.

Line 145 ff.: Temperature and ambient light conditions looks not experimental results? Normally it is part of method condition.

• Thank you for the comment. We have seen these data in both parts of articles and decided to put them into the results section.

Line 208: italic?

• Thank you. Revised

Line 216: italic?

• Thank you. Revised

Reviewer 2 Report

Comments and Suggestions for Authors

I worry more about whether the limited data in this study could support the conclusion that authors claimed. Especially, authors think it's possible to use LED traps to monitor the early low level of GWF. 

Comments for author File: Comments.pdf

Author Response

Reviewer 2

I worry more about whether the limited data in this study could support the conclusion that authors claimed. Especially, authors think it's possible to use LED traps to monitor the early low level of GWF. 

The authors showed that neither mean number of whiteflies per tomato leaf in 2 cabins (Fig.4), nor mean number of whiteflies per LED trap and YST (Fig. 5) were statistically significant. However, the correlation between the mean GWF on LED traps and the sum of whiteflies on the two neighboring plants was significant in second planting, why? How could we understand this? Especially, this significant correlation occurred only in second planting, but not in first planting. I wonder the third planting, if possible. Interestingly, the correlation between the mean GWF on YST and the sum of whiteflies on the two neighboring plants was not significant, even though there is no significant difference between LED and YST in Fig.4 and Fig. 5. I can´t imagine the following negative correlation in YST group.

• Thank you for the comment. The correlation between whiteflies caught and whiteflies present on the traps can be significant even if the numbers between the cabins are similar. This is due to the low number of whiteflies in general, which makes one individual having more influence on the data. The significant correlation being present in the second but not the first planting seems to be due to the very low numbers found on the plants. Of course, more repetitions of this setup, including also higher pest population densities, should be conducted in future studies to get more data for validating our results. Nevertheless low populations densities are of prior importance, since management decisions have to be taken early.

Comments in the text:

Line 18: “caught on yellow sticky traps equipped with and without green LEDs”, this rephrasing is incorrect, because the LED traps were equipped with adhesive tap and yellow plate, but not with YST.

• Thank you. We adjusted the text to make it more clear. See line 17.

Line 67: “A yellow 67 (non-sticky) plate”. Is this setup equal to YSTs? Since the author mentioned in the abstract, “crops and number caught on yellow sticky traps equipped with and without LEDs, respectively”. The author said, “A double-sided 74 adhesive tape and a plastic foil coated with insect glue (Insektenleim; Temmen; Hat-75  tersheim-Edersheim, Germany) was attached to the LED tarps to make them sticky”, I doubt this setup and wonder why the author didn´t set the green LEDs in close to YSTs, Because yellow adhesive taps might have difference in chemical composition.

• Thank you. We adjusted the text to make it more clear (see line 17). As we used the same traps as [9], the non-sticky yellow plate is enlightened by the green LEDs. Therefore, the LEDs are quite close to the yellow plate. The chemical composition might be different, but none of the glues have shown being repellent to greenhouse whiteflies so far. Furthermore, the greenhouse whitefly reacts primarily to visual cues, olfactory cues seem to be of minor importance.

Line 128: “either LED traps (A)or YSTs (B)”, I think when the two traps are set in the same cabin, the result would be more robust and reliable. It´s a two-choice assay and will show the difference and significance in the same experimental context.

• Thank you for the comment. We agree that this might be true. The reason for installing the traps in different cabins was to avoid an interference between the different trap types.

Line 145: “3.1 Temperature and ambient light conditions over time”. In each subsection of the RESULTS, the author just listed the observed data from the beginning to the end, without any background and summary. It seems very straightforward. It doesn´t look like common format. I suggest the authors modify the text to make it more readable.

• Thank you for the comment. We added some more background information to this section. See lines (145/146 and 159/160). Since the data for these paramaters were similar in all cabins, they are well comparable.

Line 171-173: “average 0.01 ± 0.06 (mean ± SD) and 0.05 ± 0.18 adult whiteflies per leaf were counted in cabin-1 and cabin-2, respectively. Maximum number of whiteflies/leaf reached 0.03 ± 0.17 individuals in cabin-1 (calendar weeks 32 and 38) and 0.14 ± 0.45 in cabin-2 (calendar week 35) (Fig. 4A).” With so small number of caught adult whitefly, I doubt the reliability of comparison between two setups.

• Thank you for the comment. Whitefly populations were indeed very low and therefore, numbers per leaf are very low as well. This makes finding one whitefly a rare event. However, it is impossible to sample every leaf in the crop stand to find every whitefly. Unfortunately, we can only work with sub-samples in such greenhouse experiments.

Line 181: “was 5.76 ± 12.04 in cabin-1 (calendar week 50) and 0.58 ± 0.99 in”. Why is the difference so big? No explanation and discussion is included.

• We added a short idea in the discussion. See lines 236-238.

Line 203: “S1), but in the second planting”, why is it correlated in second plant, but not in first? What´s the difference? Which one would be more reliable?

• We assume that this is due to the very low numbers of whiteflies in the first planting. Therefore, the second planting is more reliable.

Line 222: ”whiteflies, LED traps can detect the pest 222 earlier than YSTs,” How do you get this? Fig. 5B indicated the opposite results.

• Figure 5A indicates an earlier monitoring by LED traps, whereas in figure 5B both traps catch whiteflies at the same time. Furthermore, the immigration of whiteflies could be displayed by LED traps only. We encourage future studies to check traps on a daily basis to find out if the earlier monitoring by LED traps can be observed as well (see lines 257-258 and 280).

Line 224: “level. Since just one 224 whitefly/plant was initially released”. I can understand the purpose that the traping sensitivity of LED trap can be tested at such low level of pest, However, at low level, the reliability and repeatability of the experiment conclusions are doubtful. If the author can add more data which are from high level of insects, the conclusion would be more trustable.

• Thank you for the comment. Unfortunately, there are not data with higher population levels available and, moreover, it is not possible to obtain them. The study is, however a starting point for using LED traps for monitoring purposes. Detecting pest insects early is of significant importance, because one can quickly do something against the pest avoiding population growth. Even though numbers of insects were extremely low, traps performed good indicating this weak infestation. Therefore, one could have released beneficial insects early, because LED traps detected the whiteflies early.

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

The authors emphasized that it's important to monitor pests early to decide on pest control strategies. They assessed the number of insects caught in traps and tested whether a green LED trap is as effective as a traditional yellow sticky trap for monitoring. However, the experiments in this study don't seem to be well-suited for achieving the research goals. In this study, the authors tracked the growth of released pests (greenhouse whiteflies) over long periods of plant cultivation in greenhouses. The results showed that the green LED trap attracted and caught more whiteflies compared to the yellow sticky trap used at the same time. Based on these experiments, the authors claimed they could analyze the population growth of whiteflies during the long cultivation period. However, it seems they only observed the results of not taking proper control measures early in the pest's appearance. Based on these results, the paper should be revised to state that the green LED trap can be used to effectively attract and trap greenhouse whiteflies.

 To quickly detect the appearance of whiteflies in greenhouse crop cultivation, it's important to clearly define the functions needed for the green LED trap. In practice, the green LED trap would need to strongly attract whiteflies, but based on the results of this paper, I don't believe the trap has that capability. If the authors are considering the pest-attracting function of LED traps, they should compare a yellow LED trap with a green LED trap and a yellow sticky trap.

The experiments in this study may not be reliable for early pest monitoring. This experiment only shows that the first whiteflies released moved to nearby plants to reproduce, and their offspring did the same. Some of these whiteflies were caught in the green LED traps or yellow sticky traps. The authors kept track of the number of whiteflies caught in the traps over a long period of plant cultivation. However, these results may not be very useful for developing a method to monitor pests in the early stages. To achieve this goal, the authors should determine whether the released whiteflies prefer to move to the green LED trap instead of the plant leaves. This method could help assess if the whiteflies can tell the difference between the green color of the LED trap and the plant leaves.

The results showed that the first generation of flies on the leaves preferred the green LED trap over the yellow sticky trap. However, some of these whiteflies likely moved to nearby leaves. The issue to address is the whiteflies' response to different colors. When the whiteflies are faced with three options (green LED trap, yellow sticky trap, and green leaves) in the same space, the authors need to clarify which one the whiteflies choose. If the authors want to study the whiteflies' color preference between the green of plant leaves and a green LED trap, or their attraction to different colors, they should design different experiments than the one shown in Figure 2.

The main drawback of this study is that the authors only discussed the results from one type of experiment. The results of this experiment might change if different numbers of traps were used or if the traps were placed in different locations. In this experiment, whiteflies are released in the center of the greenhouse, so it can be considered a study of how they spread after entering. However, in reality, whiteflies are likely to enter the greenhouse from the outside. So, traps should be set near the openings (like windows and entrances) to see if early monitoring of the pests is effective.

Comments on the Quality of English Language

No need to edit.

Author Response

Reviewer 3

Comments and suggestions for Authors

The authors emphasized that it's important to monitor pests early to decide on pest control strategies. They assessed the number of insects caught in traps and tested whether a green LED trap is as effective as a traditional yellow sticky trap for monitoring. However, the experiments in this study don't seem to be well-suited for achieving the research goals. In this study, the authors tracked the growth of released pests (greenhouse whiteflies) over long periods of plant cultivation in greenhouses. The results showed that the green LED trap attracted and caught more whiteflies compared to the yellow sticky trap used at the same time. Based on these experiments, the authors claimed they could analyze the population growth of whiteflies during the long cultivation period. However, it seems they only observed the results of not taking proper control measures early in the pest's appearance. Based on these results, the paper should be revised to state that the green LED trap can be used to effectively attract and trap greenhouse whiteflies.

• Thank you for the comment. Indeed, we only observed the populations without taking proper control measures. Releasing beneficial insects in the beginning would have had a big impact on the pest´ population development. This impact was intentionally avoided in the study, because the study aim was not to fight the pest most effectively. Primarily, the study aimed to compare the monitoring performance of the LED traps and YSTs and the possibility of using these traps for assessing the pest population.

 To quickly detect the appearance of whiteflies in greenhouse crop cultivation, it's important to clearly define the functions needed for the green LED trap. In practice, the green LED trap would need to strongly attract whiteflies, but based on the results of this paper, I don't believe the trap has that capability.   If the authors are considering the pest-attracting function of LED traps, they should compare a yellow LED trap with a green LED trap and a yellow sticky trap.

• Thank you for the comment. The results show that LED traps detected the pest earlier (first planting) and at the same time (second planting) compared to YSTs. Even at extremely low population densities. The studies [9,14] show the attraction of these LED traps. Following up on these results, our study focuses on the performance regarding monitoring and assessing the pest in the crop. We fully agree that yellow LED traps would also work as a pest-attracting trap. However, the study aim was not finding the most attractive trap, but pointing out the advantages of LED traps compared to yellow sticky traps for decision support systems.

The experiments in this study may not be reliable for early pest monitoring. This experiment only shows that the first whiteflies released moved to nearby plants to reproduce, and their offspring did the same. Some of these whiteflies were caught in the green LED traps or yellow sticky traps. The authors kept track of the number of whiteflies caught in the traps over a long period of plant cultivation. However, these results may not be very useful for developing a method to monitor pests in the early stages. To achieve this goal, the authors should determine whether the released whiteflies prefer to move to the green LED trap instead of the plant leaves. This method could help assess if the whiteflies can tell the difference between the green color of the LED trap and the plant leaves.

• Thank you for the comment. Please note the comment above. Moreover, the study was designed to assess the pest population development over a long period of time to corrleate the count data on the trap with count data on the crop. The results can potentially be used for predicting the pest population growth and, therefore, better management decisions. We like your idea to determine whether the released whiteflies prefer to move to the LED trap instead of the plant leaves. However, investigating this in the crop would need a different setup. Furthermore, we conducted small experiments in cages to compare the attractiveness of the LED trap and small tomato plants, showing that whiteflies prefer to move to the trap instead of the plant.   

The results showed that the first generation of flies on the leaves preferred the green LED trap over the yellow sticky trap. However, some of these whiteflies likely moved to nearby leaves. The issue to address is the whiteflies' response to different colors. When the whiteflies are faced with three options (green LED trap, yellow sticky trap, and green leaves) in the same space, the authors need to clarify which one the whiteflies choose. If the authors want to study the whiteflies' color preference between the green of plant leaves and a green LED trap, or their attraction to different colors, they should design different experiments than the one shown in Figure 2.

• Thank you for the comment. We agree that an experiment investigating the colour preference should be designed completely different. Please note that our study did not aim conducting a colour preference test. Instead the experiment was designed for observing pest population development on the crop and correlation with trap data. We revised the figure caption to make the setup more understandable (see line 127 and 129).

The main drawback of this study is that the authors only discussed the results from one type of experiment. The results of this experiment might change if different numbers of traps were used or if the traps were placed in different locations. In this experiment, whiteflies are released in the center of the greenhouse, so it can be considered a study of how they spread after entering. However, in reality, whiteflies are likely to enter the greenhouse from the outside. So, traps should be set near the openings (like windows and entrances) to see if early monitoring of the pests is effective. 

• Thank you for the comment. We agree that in some regions pests enter the greenhouse from the outside. In many cases, however, pests are already present on the young plants that are planted in the greenhouse or brought into the greenhouse on the people´s clothes. In these cases, the pest is spread within the crop. Since the aim of our study was to monitor and assess the population development, the traps were installed within the plants instead of the greenhouse openings. However, the results show that the LED traps effectively detected whiteflies entering the greenhouse. Nevertheless, installation of the traps near the openings might be effective for catching as many whiteflies as possible to prevent them entering the crop. This result underlines also the suitabliltiy of LEDs for mass trapping of pest insects, recently investigated by Athanasiadou et al. (2024).

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I think the authors need to be very carefully in writing the conclusion. Without more replications, the authors have to  write exactly based on the biased dataset. 

Comments for author File: Comments.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Unfortunately, even after reading authors’ response to my comment in the initial review, my judgment has not changed. In short, I have to conclude that the present research has not yielded any achievements worthy of being shared with our readers as an original article in Horticulturae.

Comments on the Quality of English Language

No problem.