In the early stages of brainstorming for the project, our team found that most of the willow trees in Shahu Park near the school (longitude :114.33936 latitude :30.56327) were affected by unknown pests. So the team members directly in the park to find the relevant staff to ask, through them we learned that sand lake suffered from this pest willow area of up to 90%, because it is not clear what kind of specific pests, there is no good control measures.
Figure 1 ：Communicate with relevant personnel
So the team collected a small number of nibbled leaves and asked the school's pest control expert, Mr. Zhang Jiang, who pointed out that most of these willow trees were harmed by Plagiodera versicolora, which is a common forest pest, mainly chewing the leaves of poplar and willow trees, which has a certain threat to China's forestry harm. After Teacher Zhang's initial popularization of our pest control, the team members developed a strong interest in it, and conducted a lot of literature reading and group discussion.
Figure 2： Professor Zhang Jiang explains to us
After literature investigation, the anti-insect team members with questions about various pest control methods, found teacher Zhang Jiang. The teacher answered the questions for us one by one and introduced the popular RNAI technology to us in detail.
RNAi technology is a phenomenon of gene silencing induced by double-stranded RNA (dsRNA) in eukaryotes. The dsRNA is cleaved by the endonuclease Dicer in the cytoplasm into multiple small interfering RNAs (siRNA) with specific lengths (21-24 nt) and structures, Then siRNA and Argonaute (AGO) protein form RNA-induced silencing complex (RISC), and then cut the messenger RNAs of corresponding genes to promote the degradation of mRNA and induce gene silencing. The use of RNAi technology for entomology research and pest control has become a research hotspot, by inhibiting the expression of essential genes of pests, thereby reducing the fitness of pests or killing pests. This technology is highly targeted, harmless to crops and humans and animals, and has good application potential.
After introducing RNAi technology to us, the teacher shared with us a new discovery in their lab - a pseudomonas with anti-insect effect. After learning about the environmental friendliness of the biocontrol bacteria against insects, the Insecticide Pro Max team tested the insect-resistant Pseudomonas bacteria against insects. However, after a period of bioassay, it was found that although this anti-insect pseudomonas had much better anti-insect ability than the wild-type pseudomonas, the anti-insect effect still did not reach the expected value. Therefore, at Mr. Zhang's suggestion, we decided to go to Hubei Academy of Forestry for expert inquiry.
We explained our anti-pest plan and the anti-pest results of using anti-pest pseudomonas and our confusion to the experts. The experts recognized the environmental friendliness of using this anti-pest pseudomonas and mentioned the popular RNAi technology, hoping to provide reference for our research program. Then, the relevant experts of the Academy of Forestry led the anti-insect + team members to visit the Jiufeng National forestry long-term scientific research base.
Figure 3： Group photo of team members in the Academy of Forestry
During the visit, the Anti Pest+team members noticed that the problem of pests on trees was still significant, as well as the residue of some chemical pesticides in plastic bottles, which gave the Anti Pest+team members a more intuitive understanding of the negative effects of chemical pesticides. This trip to the Forestry Academy has further strengthened our research on biological control as a pest resistance method.
After returning to the School of Biological Sciences, our team had a discussion and proposed the combination of insect-resistant Pseudomonas and RNAI technology for anti-insect research. We told our idea to Mr. Zhang, who was very supportive of our idea, and the research direction of our team was determined.
Observed in the surrounding environment, willow trees suffer from willow blue leaf beetle damage has been very serious, how can resist the harm of willow blue leaf beetle, protect willow trees, is there any good control willow blue leaf beetle method? We can't help but wonder. We asked Professor Jonathan Nimal.S about his views on insect resistance with some questions. He introduced to us that the international insecticides are mainly polluting chemical pesticides in insect resistance, and confirmed our idea of making a green and pollution-free biopesticide. He suggested that we go to large pesticide companies for field exchanges after consulting relevant literature, which is more conducive to understanding how to make a product beneficial to human friends.
Figure 1： Photo with professor Jonathan Nimal .S
Using the Internet, we found that the current means of prevention and control of Plagiodera versicolora is generally the use of chemical pesticide. Here are specific means. In the serious harm period of larvae and adults, foliar spray with crystal trichlorfon (90%, 600PPM), omethoate (40%, 800 PPM), tortoise (30%, 1000PPM) or transdermal (1.8% 1500PPM), and the time of prevention and control is best after 4 PM.How effective are chemical pesticide, can they be a good control of Plagiodera versicolora, and what is their impact on its surroundings? With questions, we came to the Saronda production base of Adama Co. Ltd.
Figure 2: Team members arrive at Adama Co. Ltd
Adama Co. Ltd is one of the companies with the most extensive and diversified original drug products. It has strong research and development capabilities, production facilities and formulation processes in the world. It is a global leader in plant protection industry, providing farmers and others around the world with solutions to weeding, insecticide and bactericide. Adama Saronda Production Base, formerly known as Saronda Co. Ltd, belongs to CHEMCHINA, which has rich experience in chemical pesticide manufacturing and R&D.
With questions, we went to the Saronda production base, and visited the base backbone technician for in-depth exchanges. Led by the backbone technician, we visited the Saronda production base. Through the explanation of the technician, we had a primary understanding of the productive process of this company and its products. We have learned that the products produced in this base are mainly chemical pesticide, and the technical product of pesticide for production are mainly from ores, which are non-renewable resources. At this time, we have questions. Why do they use ore resources as raw materials? Are there other renewable resources that can replace ore resources as raw materials for production? The backbone technician explained that the main components of the product can also be synthesized by chemical synthesis, but the cost of chemical synthesis is high, which will lead to an increase in production costs. And the chemical synthesis method is not suitable for large-scale production. Therefore, using ore resources to refine the main components of the product is easy to establish large-scale production lines with low costs.
Figure3: Team members visit the base production line with the base backbone technicians
During the visit, we had to wear safety helmets and protective clothing throughout the visit. We observed that safety signs were posted in many parts of the base, including easy-to-explode signs, dangerous gas and dangerous liquid signs, etc., which made us personally experience and feel that there are many safety hazards in the production process of chemical pesticide. According to the backbone technician, attention should be paid to safety at all times during the production process, and the operation during the period must conform to the specifications. The production equipment involved in the production process, including the air conditioners used in the production workshop, etc., need to be strictly explosion-proof and anti-leakage, otherwise it is easy to occur safety accidents. In order to ensure the safety of the production line and base operators, the base has adopted advanced exhaust gas treatment equipment and explosion-proof measures, and has a series of safety management regulations, which will be updated yearly by the base safety management personnel according to the actual situation. We really realized that chemical pesticide production is not easy.
Figure 4: safety signs in the base
After visiting the Saronda production base, we came to the conference room to communicate with the backbone technicians of the base. The technicians introduced to us the mechanism of action of the products of the base. The chemical pesticide produced in the base directly act on the eggs of the pests and are sprayed during the specific period of crop growth. The purpose of preventing insect pests by restricting the reproduction of pests can be achieved. And the harm of chemical pesticide to the environment can be reduced through this control method. Then we asked the base's backbone technicians about the harm of chemical pesticide to the environment. The backbone technicians said that chemical pesticide may affect some beneficial insects while killing pests, and have more or less some impacts on crops. There will also be pesticide residues, pollution of nearby waters and other problems. And long-term use of chemical pesticide will cause pests to develop certain pesticide resistance. At the same time, the backbone technician also mentioned Adama Co. Ltd’s method of reducing the harm of chemical pesticide. Firstly, it is to reduce the usage of technical product of pesticide and improve pesticide activity, while carrying out the research and development of new products, combining chemical pesticide with greener and safer biopesticide. The company is also committed to developing more accurate and effective pesticide spraying technology in order to reduce the use of pesticide. Through this we noticed that biopesticide is greener and safer than chemical pesticide, which triggered our thinking, can we use biopesticide to control Plagiodera versicolora?
Figure 5, Figure 6: Discussion between team members and base backbone technicians
We consulted the backbone technicians about the current means of prevention and control of Plagiodera versicolora, the results of prevention and control, and some existing problems. The backbone technicians said that chemical pesticide is currently mainly used to control Plagiodera versicolora, which has a good effect on pest control, but has a greater impact on the environment. Forest protection is different from crop protection. Compared with farmland, forest environment is less influenced by human beings. Therefore, forests have more complex ecosystem and richer biological community. Chemical pesticide may cause toxicity to non-target organisms in soil, water and air during use, thus destroying ecological balance. Chemical pesticide also has a negative impact on microbial flora, resulting in nutrient loss in the soil, decrease of soil fertility, and impediment to plant growth and development. In forest protection, due to more prominent problem of large area, long period of application, toxic effect and pesticide resistance, most chemical pesticide are designed to be easier to degrade, in order to protect the ecological environment of forests. As it difficult for chemical pesticide to maintain long-term effective control effects, the frequency and cost of application are increased.
Is there a safer and more effective means of control? Can the mentioned greener and safer biopesticide be more effective and cheaper than chemical pesticide? The backbone technicians introduced the manager of the R&D department to us. Then we had an in-depth exchange with the manager. The manager said that the R&D of chemical pesticide needs various verification, experiments in different field, which often take several years or even decades. Moreover, the R & D process of chemical pesticide and the construction of subsequent product production facilities are expensive and accompanied by certain risks. As a result of pesticide resistance easily produced by target pests, products and production lines need to be updated frequently. So it costs a lot in production and R&D of chemical pesticide.
According to the manager, biopesticide has less impact on the environment than chemical pesticide and is the main research and development direction of Adama Co. Ltd. However, the efficacy of biopesticide is not ideal now and there are limitations in the actual use process.
Figure 7: Team members communicated with the managers of R&D Department
So, is it possible to develop a kind of biological pesticide that is friendly to the environment and also effective in killing pests? In response, we launched a brainstorming, proposed ways to increase the efficacy of biopesticide, such as biopesticide improvement or a combination them with chemical pesticide. Then we discussed the feasibility of the idea with the managers of R&D. The manager affirmed our idea and encouraged us.
Through this trip to Adama, we found that chemical pesticide can prevent and control Plagiodera versicolora. But in the control process, there will be environmental pollution, chemical residues, resulting in pest resistance to pesticide and many other problems. Meanwhile, we learned that biological pesticide is a greener and safer means of control, but there are poor efficacy and other limitations in practical application. Therefore, we launched a brainstorming and proposed the idea of designing a biopesticide that is environmentally friendly and has excellent pesticidal efficacy.
In the early stage, through our research on the prevention and control of poplar’s and willow’s pests around the Shahu Lake in Wuhan City, we learned that forest rangers mainly use chemical control and artificial capture but less biological control for the prevention and control. Now, through the interview with the forest rangers responsible for Shahu Road, we learned that the methods of poplar’s and willow’s pest control are basically chemical control. In order to have a more comprehensive understanding of the actual situation of poplar and willow pest control in our province, after communicating with Ms. Hu Yumei, she suggested that we go on a field trip.after careful thinking and screening, our team decided to go to Xiaogan Municipal Forestry Bureau and make a survey in Sanyang Forest Farm in Xiaxindian, Yunmeng.
Figure 1: Talk with Teacher Hu Yumei
On the one hand, Xiaogan is one of the main forest bases planting poplar and willow in Hubei province. The poplar and willow are the main planting trees in the local forestry economy and ornamental planting, accounting for an important proportion, about 50%, of the local forestry planting. On the other hand, Sanyang Forest Farm in Xiaxindian of Yunmeng County is the largest forest farm in terms of planting area and operation scale. It is also the largest forest farm in terms of planting area of poplar and willow. The income from Poplar and willow accounts for about 60% of the forest income of Sanyang Forest Farm. Therefore, our team chose the two places to research, which is of great help to us to study about the disease and pest control of poplar and willow.
Figure 2 Team members visited Mr. Huang, the owner of the forest farm
After sufficiently learning about the background of Sanyang Forest Farm and communicating with Mr. Huang, the owner of the forest farm, our team went to Sanyang Forest Farm for field research on July 12, 2023. Xiaxindian Sanyang Forest Farm in Xiaogan City, established on March 25, 2008, has a planting area of more than 2000 mu. Its business scope includes wholesale and retail of flowers, plantlet and timber trees. There are many kinds of trees planted in Sanyang Forest Farm, including poplar and willow, that our team wants to investigate. After the team members arrived at the forest farm, Mr. Huang was very enthusiastic to lead us to the forest farm. During the visit, Mr. Huang was very active in communicating with us, so that we could have a deeper understanding of the growth of poplar and willow trees and how the forest farm prevented and controlled the diseases and pests of trees. In the communication, we learned that the forest farm mainly uses chemical means to control pests. And the initial chemical control method is to evenly apply whitewash to the trunk, which effects on preventing the trunk from freezing crack, sterilization and insect killing, preventing sunburn, preventing moss and other multiple functions. At the same time, a large number of chemical pesticides will be used, such as methamidophos, stone sulfur mixture and so on. However, long-term use of chemical pesticides can pose some potential environmental threats, such as a slow decline in soil fertility. Excessive use of chemical pesticides will lead to soil compaction, soil heavy metal pollution, soil acidity, soil structure destruction, water pollution and other problems. And the overuse of pesticides, but also is easy to make pests and bacteria resistance, as a result, increase the difficulty of control. Besides, due to the random disposal of degradable pesticide bottles, itself as a pollutant, further damages the ecological environment. In addition, the residual chemical pesticides difficult to degrade in the pesticide bottle will also penetrate into the soil, which will cause excessive local pesticide concentration in soil. This will cause serious pollution to the soil. Then we explained our biological products to Mr. Huang and presented the concept of biological control that biological control will not cause pollution to the environment. Mr. Huang suggested that our team make products that can degrade and do no harm to the soil ecology. Producing environmental-friendly products is also one of the first factors our team considers in the research. Plagiodera versicolora mainly eats the leaves of the poplar and willow trees. Due to its reproductive rate, large amount of food required and a large number of poplar and willow trees planted in the forest farm, the pest problem of Plagiodera versicolora in the forest farm is serious. The adult and larvae of Plagiodera versicolora feed on the leaves, and live in groups to eat the leaves into gaps or holes. In serious cases, the leaves are reticular and only the veins are left, which seriously affects the growth of trees. About 80% of poplars and willows in the forest farm are seriously affected by Plagiodera versicolora. In order to control Plagiodera versicolora, except the artificial capture and chemical pesticide control mainly used in the forest farm, such as the application of thiacloprid powder for control, we introduced to Mr. Huang the biological control method, the use of natural enemy insects, such as wasp, hunter bug, lacewings and spiders, and the use of microbial control, such as our product, Pseudomonas spray. The use of biological control will not pollute the environment.
Figure 3：Pesticide bottles discarded in a forest farm
Mr. Huang, the owner of the forest farm, gave us very good suggestions. In order to have a more in-depth understanding of the overall actual and large-scale use of forestry protection in the location of the investigation, the planting of poplar and willow trees, and the situation of pests and diseases, as well as the proportion of biological control used in forestry protection in Xiaogan City and the possibility of biological control being promoted and other problems, we went to the Xiaogan City Municipal Forestry Bureau with questions to understand the actual situation with the person in charge, Director Zhou.
What we learned:
1.The situation of Xiaogan City poplar, willow planting
The willow trees planted in Xiaogan City are mainly weeping willows, which are generally used for environmental afforestation and ornamental purposes. According to the data of Xiaogan Municipal Forestry Bureau, the planting area of willow trees in Xiaogan City is 177.6 hectares, with a total accumulation of 28,276.0 cubic meters. The willows planted in Xiaogan City are generally scattered around the edges of rivers and lakes. According to official data, Xiaogan city poplar trees planted a total area of 26,780.0 hectares, a total of 199,566.0 cubic meters of storage. The poplars planted in Xiaogan City are mainly white poplars, which are used for windbreak and sand fixation, and are generally planted as shelterbelts. Poplar and willow are the main source of income for the local forest farm, contributing to about 50% of the local forestry economy, and play an important role in the economic development of the local forestry.
Figure 5 Team members talk with Director Zhou of the Forestry Bureau
2.The diseases and pests of Xiaogan City poplar willow
Because the area of planted willow is mainly around lakes and rivers, the humidity of growth environment is high. Therefore, the disease and pest situation of willow is more serious. More than 80% of the willow trees planted in Xiaogan City have suffered varying degrees of diseases and pests. The harmful pests were mainly leaf-eating Plagiodera versicolora and tree-boring Anoplophora glabripennis. About 70% of poplars planted in Xiaogan were encountered by different types of pests and diseases, mainly the leaf-eating pests Plagiodera versicolora and Clostera anachoreta.
Figure 6： The scars of willow leaves after being fed by Plagiodera versicolora
Figure 7： Eggs laid by pests on poplar leaves
3.Types of forestry protection
The main types of forestry protection in Xiaogan City are artificial control, chemical control and biological control, and most of them are artificial control and chemical control. In the process of forestry protection, biopesticides are used, that is, preparations that use living organisms (fungi, bacteria, insect viruses, genetically modified organisms, natural enemies, etc.) or their metabolites (pheromones, auxin, naphthalene acetic acid, 2, 4-D, etc.) to kill or inhibit agricultural pests, such as alkaloids and rotenones. Chemical pesticides, including organophosphorus, organochlorine, carbamate, etc. And biological chemical pesticides, that is, biological pesticides and chemical pesticides are mixed in a certain proportion, such as composite microbial fertilizers, plant growth regulators, etc. Among these, chemical pesticides are the most widely used and the most frequent.
4.The reasons why forestry protection is mainly for chemical control
There are four main reasons why forestry protection is mainly for chemical control.
Firstly, it includes the low production cost of chemical pesticides, the large scale of production, guaranteed quality, and convenient storage, transportation and use, which can meet the needs of large-scale production. Currently, the cost of chemical control is only 30% to 40% of the high cost of biological control. If you want to use a lot of biological control, you need to consider the high-cost budget.
Secondly, it is because there are many control objects of chemical pesticides and the control effect is good. One pesticide can prevent and control a variety of harmful organisms, and it is effective for different growth and development stages of a certain harmful organisms. Chemical pesticides can be processed into a variety of pesticide formulations and adopt different methods, which can adapt to various production conditions and control different harmful organisms. When the number of harmful organisms is close to the economic allowable level, the spread and damage of pests can be controlled for several hours or 1-2 days after the use of chemical pesticides, so as to minimize economic losses.
After the interview with Xiaogan City Municipal Forestry Bureau director Zhou, we knew that most of the forestry protection in Xiaogan City adopts chemical means for prevention and control, at present, due to the production cost, control effect and other multiple factors, although the harm of chemical pesticides to the environment is larger. Because of the long-term use of chemical pesticides to control pests and diseases, especially only use of a certain pesticide, it is easy to make pest produce resistance. At the same time, long-term use of chemical pesticides to control pests and diseases is easy to pollute the environment, kill natural enemies, and reduce farmland biodiversity. In addition, the extensive use of chemical pesticides can easily lead to pesticide residues, causing food safety problems. Many chemical pesticides seriously pollute water, air and soil, and enter the human body through the food chain, endangering human health. Director Zhou mentioned that, actually, Xiaogan Municipal Forestry Bureau has considered increasing the use of biological control. However, the cost of biological control is more than twice the cost of chemical control, and its control object is more specific, and its control method is not as simple as chemical control. It is only use of biological control under a necessary and convenient circumstance. Therefore, Director Zhou suggested that we appropriately reduce the costs if we subsequently want to put the product our team developed, which effectively targets Plagiodera versicolora pest in poplar and willow trees into production. As a result, more people can afford it.
The product we studied is a Pseudomonas spray agent for biological control of the leaf-eating pest of poplar and willow. Combined with present circumstances and the valuable suggestions put forward by Mr. Huang and Director Zhou to our team, team members made a collective discussion and brainstorming to solve problems after the human social practice activities in Xiaogan City and Yunmeng County.
Conclusions:
Firstly, poplar and willow are the main commercial tree species in the local area, and they are planted in a large number, which makes an important contribution to the local forestry economy.
Secondly, Plagiodera versicolora is very common in the local forest farm, which is harmful to poplar and willow trees. It mainly eats the leaves of poplar and willow trees, which seriously affects the survival rate of trees, and then affects the income of local foresters and the development of local forestry economy.
Thirdly, the local control of Plagiodera versicolora is mainly chemical pesticide control, because the cost of chemical pesticides is low. The local forestry bureau and local people have realized that chemical pesticides cause great harm to the environment, but the cost of biological control is too high, so that the local forestry economy is not strong enough to support the comprehensive promotion and use of biological control.
The above questions provide a good direction for our team to design research work to defeat Plagiodera versicolora—how to design safe, effective, and low-cost biological control methods.
After communication with the company and on-site research, we have identified the loopholes in our study. In response to the above issues, our team brainstormed and proposed our own solutions.
First, the spraying agent we researched is a microbial agent. When it is sprayed on the leaves of poplar and willow trees, it will not cause harm to the growth of the leaves. If it is sprayed excessively and the agent seeps into the soil, it will not cause destruction to the soil and will not contaminate it.
Second, we have designed two safety switches to minimize its impact on the environment. (Read about it)
The product we have researched is based on Pseudomonas fluorescens as the host cell, which is used to cultivate and synthesize dsRNA. The production cost is very low. In addition, due to the advantages of flexible selection of RNAi target sequences and relatively specific targets, it can overcome the adaptability of pests to insecticides and update more quickly, resulting in lower costs. (Read about it)
If our researched agent is put into production, we will seriously consider reducing its cost and strive to ensure that the cost is within the acceptable range for the general public in the biocontrol agent market.