In the strong sun, farmers are still spraying pesticides in the fields, just for the crops to have a good harvest. On the other hand, consumer rights protection accidents caused by pesticides are very common. Oversprayed pesticides pose a great threat to the ecological environment and people's life safety in today's society. At the same time, the resistance of pests has also accumulated and increased from generation to generation. In response to the above contradictions, we intend to solve it by means of synthetic biology.

In order to solve the problem of overspraying of pesticides polluting the natural environment and pesticide residues threatening the safety of consumers, we intend to reduce the use of pesticides by transforming yeasts in biological control methods. In order to solve the problem of farmers not spraying pesticides in a timely manner and the spraying workload is too large, we intend to design our yeast to automatically sense pest infestation. Since we are in Hangzhou, Hangzhou's Longjing tea is world-famous and one of the city's business cards. So we decided to take the tea garden as our goal and use biological means to control tea garden pests. However, we hesitated for a long time about what kind of pests in tea gardens. Pests such as tea leafhopper and tea aphid are relatively common in tea gardens, and it is necessary to control them. After consulting a lot of data, we found that the threat of aphids to crops is common in southern China. Nepetalol and nepetalactone are the sex pheromones of tea aphid, which have a strong impact on the mating interference of tea aphid. And as the main components of catnip, these two substances also have great utilization value in other aspects. Based on the above, we decided to set our project as using the modified yeast to sense the benzyl alcohol released when tea is attacked by the tea aphid, and then secrete the sex pheromone of the tea aphid to avoid tea aphid and attract natural enemies.

Before we begin our human practice, we discuss the general framework within which we conduct it. We need to widely absorb the opinions of stakeholders in society, but also maintain communication with government departments and discuss project experiments with technical experts. Our project for Hangzhou is related to the city's business card and involves the development of the city's cultural tourism industry. For the aphid pest-prone South, our project also has great application prospects. Therefore, social feedback is crucial for us. Their opinions will have an impact on the development of the entire phase of our project's experiments.

We approach human practice in four steps, each of which is connected, and after the completion of the previous phase, we make timely summaries and adjustments to ensure that our final solution meets the advice of stakeholders and technical experts.

Cooperation with government departments and tea industry chain played an important role in the design of our project. Here we present summaries and snippets of our conversations with those who have been influential on our projects. These suggestions and comments are either integrated into our projects or shape the direction of our projects.

Tea Industry Chain

Tea farmers in Longwu Tea Village

During the on-site visit to Longwu Tea Village, we learned from the tea farmers that the current pests are under unified control, and the government will specially arrange people to spray pesticides. Tea farmers will also take tonic measures according to the situation on the spot, but they still rely on the government in general. In the previous tea planting process, it was often plagued by pests such as tea aphid. Tea farmers expressed that they are willing to accept new pest control measures on the premise of ensuring their interests, and hope that our project can be applied in practice.

Through our on-the-spot investigation of the situation in the tea garden, we found that the current pest control methods in the tea garden include traps, swatches, insecticidal lamps, etc.

Tea farmers in Longjing Village

This time we walked into the famous Longjing tea garden. We observed in the field that some tea farmers had to go to the tea garden to catch insects in addition to spraying pesticides. Despite government subsidies, tea farmers still need to enter tea gardens to spray pesticides on hot days and under the scorching sun. And in order to avoid pesticide accidents, it is not possible to spray pesticides in the first few months of tea picking. Most tea farmers are still unfamiliar with this new model of biological control, and they still focus on spraying pesticides to eliminate pests.

Miao Mo Teahouse

In the chat with the clerk, we realized that a large number of customers come to drink tea in the teahouse every day, and the safety of the tea itself is an issue that the teahouse attaches great importance to, which is related to the protection of the brand. Therefore, for teahouses, the tea leaves that have undergone biological control will be safer and more reliable.

Consumer Survey

Based on the content of our project, we publish a questionnaire to investigate the community's response to our project.
Our questionnaire survey investigated the public's awareness, attitudes towards pesticide residues in tea products, attitudes towards our project and the consumption habits of some consumers towards tea products. We collected 107 questionnaires, mainly from consumers of tea products. Now, we have selected some of the survey results of the questionnaire to display.

1   Consumers' understanding and attitude towards pesticide residues

It can be seen from the above results that half of consumers have heard of pesticide residues, but they are not very clear about which pesticides are. In the survey, most consumers said that pesticide residues will affect their tea tasting experience. However, when buying tea, there is little concern about pesticide residues, but more attention is paid to the variety of tea. To this end we decided to cooperate with the local Longjing Tea Village in Hangzhou, using its internationally renowned brand to promote our project.

2   Attitudes of consumers towards our project

Most of the respondents support the promotion of biological control in tea gardens to reduce the use of pesticides, but the acceptable price difference for consumers is less than 200, which requires our project to pay attention to cost input while taking into account the effectiveness.

3   Consumer spending habits

Most of the tea comes from gifts from relatives and friends. Tea has gradually become a symbol of blessing, which has higher requirements for the quality and safety of tea. There are relatively few people who buy tea by themselves, so we will focus on the production base of tea.

Government Department

Longjing Villagers Committee

We interviewed Master Liu, a local plant protection expert in Longjing Village, who specializes in managing tea gardens. He told us that the general pest control mainly focuses on spraying pesticides and placing swatches, but swatches can only kill flying pests, and have no effect on pests such as tea inchworm and tea aphid. Pesticides are also restricted by the government. The list of pesticides that can be sprayed and the corresponding doses are listed by the tea department. Farmers must strictly abide by the regulations of the tea department. It is absolutely not allowed to spray other pesticides outside the list to ensure the absolute safety of tea quality. We asked about the local spending on pesticides. The pesticide fees for one acre of tea garden and the labor costs for pesticide spraying, excluding government and village subsidies, still require more than 1,000 farmers to invest, and the expenses will be even greater in summer. This huge labor cost makes local farmers distressed.

Soil and Solid Waste Division,
Ecological Environment Bureau, Yuhang District, Hangzhou City

At present, the soil and surface water pollution in some rural areas is relatively serious, and a large part of the reason comes from the fertilizers and pesticides used in the cultivated land. If we can reduce the use of pesticides and promote the rational use of chemical fertilizers by farmers, it will be of great help for the control of environmental pollution sources.

Law and Regulations Division ,
Environmental Protection Bureau, Hangzhou City   Researcher Chen

At present, there are no clear and detailed laws and regulations on biological products for environmental governance. Biological products only need to meet the regulations of the laboratory and pass the evaluation of professional institutions before they can be considered for use. For the government, the quality control of these products should be the responsibility of the upstream, so there is no need for specific policy restrictions.

Tea Research Institute ,
Chinese Academy of Agricultural Sciences   Researcher Zongxiu Luo

Tea aphid is a common pest in tea gardens. At present, measures to control tea aphid in tea gardens include spraying systemic pesticides or manually cutting off affected leaves. The use of synthetic biology to control pests is very promising, and no other team has explored this aspect so far. In addition, as a scientific research and government agency specializing in tea gardens, they believe that it is necessary to popularize popular science knowledge among farmers. Compared with the development of science and technology, farmers' thinking is still relatively backward. The development of synthetic biology is still in the growth stage. There are still many problems to be solved, and attention should be paid to the convenience and low cost of the product. In the experimental stage, you can go to the greenhouse for cultivating tea seedlings for research. There are many tea aphids growing in the environment of the greenhouse.

The harvest of the interview

Through interviews with the government, we learned that the pest control measures currently applied in the fields actually have their shortcomings, and our project can well complement these shortcomings. The advanced nature of synthetic biology determines that there will be a certain disconnect between us and farmers, and we will conduct specific popular science publicity for this. At present, the government has no specific policy restricting the application of our project. If the experiment successfully achieves the expected effect, we will contact the Tea Seedling Cultivation Center for further experiments.

Ensure that the modified engineering yeast
can effectively control the tea aphid

As the goal and core of our project, we must first ensure that the strains we transform are effective, and pest control is not a joke. Once our strains fail to achieve effective control of tea aphids, it will bring immeasurable direct economic losses to tea farmers. Confidence in biological control will also be gone. Therefore, whether facing the present or facing the future, we must ensure the validity of our mean.

Safe for surrounding ecosystems and people

Security is another very important point. We absolutely do not allow any negative impact on the eternal name of Hangzhou Longjing and the safety of people in the surrounding areas. Synthetic biology has certain safety problems. We must ensure that our strains will not have a negative impact on the growth of tea, nor excessively interfere with the ecosystem of the tea garden, nor allow our strains to directly enter the environment to grow freely. The hardware design will also have a certain reflection.

Be as relatively low at cost as possible

As a project that has the potential to be directly applied to the field, we must consider the feasibility of promoting it in the field. The most important point of this is that our products should be as cheap as possible. The main reason why the original pesticide spraying can be widely used all over the world is because it is cheap. Biological control will inevitably increase the cost, but we still need to find ways to reduce the cost to facilitate promotion. We have conducted extensive research on the price difference of biological control tea for consumers, which can be found in the consumer questionnaire survey for details.

Minimum impact on the appearance of the tea garden

Longjing tea in Hangzhou has evolved from a simple tea tasting in the past, through the vigorous promotion of the government and industrial upgrading, into a comprehensive business model that integrates leisure tourism, tea picking experience, tea making and tea tasting. This also puts forward higher requirements for the appearance of the tea garden, so our hardware design must be able to maintain the overall appearance of the tea garden.

Technical experts

Professor Liu Shusheng
Zhejiang University, Institute of Insect Sciences

Professor Liu Shusheng (Professor and Doctoral Supervisor of Zhejiang University) Professor Liu has a deep understanding of the effect of sex pheromones. In the conversation with Professor Liu, we learned that sex pheromones are not inter-species intercommunication, and different concentrations of nepetalol and nepetalactone have different effects on different species of tea aphids. The species of tea inchworms in Zhejiang are mixed. If the intraspecific variation is obvious, the applicability will be limited. Therefore, we hope to design switches in our chassis cells to achieve mixed secretion in specific concentration ratios.

Professor Mo Jianchu
Zhejiang University, Department of Plant Protection

As an insect expert, Professor Mo Jianchu told us that aphids alternate parthenogenesis and bisexual reproduction (spring and autumn). After entering parthenogenesis, the aphids insert their mouthparts (piercing-sucking) into the leaves and stop for a month or two, and then go to mate in the fall, which means that we can arrange our products in advance for a specific season to play a preventive role. He also told us that evasion may require sustained high concentrations, which requires our production and release to meet certain standards. Since the requirements for attracting natural enemies are not harsh, we can also attract natural enemies after meeting the conditions for avoiding them.

Professor Lou Yonggen
Professor and Doctoral Supervisor of Zhejiang University

Professor Lou Yonggen told us that cistrihexenol is not only released by tea trees when aphids come, but also released by other pests. To find aphids-specific substances, after searching the literature in the later period, we finally determined Benzyl alcohol was used as our test substance. At the same time, Professor Lou also told us that if a single ratio of sex pheromones is used to control pests, the ratio may change over time. In response to this, we used live yeast for production, and designed a detection feedback and release pathway to flexibly change the ratio of nepetalol and nepetalactone.

Professor Huang Jia
Zhejiang University, Chief Expert of Public Welfare Industry Research Project,
Post Scientist of Rice Industry Technology System

Professor Huang believes that nepetalactone is a component of catnip and is a repellant for most insects. Nepetalactone as an activator can stimulate the temperature-sensing ion channel of insects, so it can avoid many insects. Therefore, our choice of nepetalol and nepetalactone is correct, and our idea is also novel, but we need to pay attention to the release of nepetalactone. We were also inspired by our follow-up exchanges and discussions with other teams.

Professor Chen Xuexin
Zhejiang University, School of Agriculture and Biotechnology

Professor Chen Xuexin told us that the use of synthetic biology to control pests in the field is a very advanced way, which is definitely promising, but we need to pay attention to how to transmit the signal to the aphid pheromone produced by engineering yeast after sensing benzyl alcohol, This signal transduction route is not found in engineered yeast. Therefore, we designed the use of G protein-coupled receptors to conduct external stimuli.
At the same time, Professor Chen also proposed to be a carrier in terms of hardware design, as well as a releaser. To take into account the sun, wind and rain, can not affect the function. At the same time, it is necessary to prevent some birds from accidentally eating the engineered yeast. This provides great inspiration and help for our hardware design.

Professor Zhang Yan
Zhejiang University, medical school

Professor Zhang Yan is an expert in GPCR. He told us that the G protein in yeast is very special, and people can only recognize his unique G protein. Therefore, we chose to transfer the olfactory receptor HarmOR10 (which can specifically recognize benzyl alcohol) gene from Helicoverpa armigera into yeast.

The harvest of the interview

Through interviews with six biology professors, our team has gained a lot of experimental knowledge, which has clarified the feasibility of our project and the advanced nature of synthetic biology. We have obtained a lot of valuable suggestions on detection, construction of pathways and secretion, which laid the foundation for our subsequent construction of a complete experimental system.

Evaluate the guiding value of our projects

The methods that can control tea aphid in the field have their own shortcomings: the types of pests that can be captured by the color plate are limited, and the placement season is limited, and complete removal cannot be guaranteed; pesticides are convenient and broad-spectrum but pose a threat to the environment, and cannot be sprayed in some seasons pesticide. In contrast, our project can be green and pollution-free, and has the function of automatic detection and release, which greatly liberates the productivity of agricultural labor. Our products are not limited by seasons, have good adaptability to the environment, and can meet the needs of field applications. After our initial tests, our products basically meet our expectations.

Ensure that the engineering yeast
can effectively control the tea aphid

After the yield analysis and actual test results of our project, we have successfully produced vitexol and vitexolactone using yeast, and we believe that our engineered yeast can achieve effective control of tea aphids in tea gardens

Safe for surrounding ecosystems and people

After our evaluation of our project hardware, we were able to ensure that our engineered yeast do not leak into the ecosystem under normal circumstances. Our engineered yeast use yeast, which is harmless to humans, and we have designed suicide switches to ensure that engineered yeast do not pollute the environment in the event of a leak.

Be as relatively low as possible financially

Throughout the design of the project, we have maintained the principle of lowest cost, on the one hand, we have used relatively inexpensive yeast as our chassis yeast, on the other hand, we have developed an active and effective plan to reduce the cost of our experiments.

Minimum impact on the appearance of the tea garden

In this regard, we design reasonable hardware facilities, from the results of field field investigations, because the distribution of tea gardens is relatively sparse, mountain tea gardens are not regular, and our small volume of hardware equipment will not affect the appearance of tea gardens.

In the course of our human practice, we have found that the vast majority of farmers do not understand modern biotechnology. Their thinking is relatively backward and conservative, and they know little about nascent biotechnology and are unwilling to change traditional agricultural models. In discussions with government departments, they are also quite distressed about this. Therefore, we hope to disseminate basic biological knowledge and advanced biotechnology in the form of farmers' science education, so that everyone can feel the charm of synthetic biology. Please refer to our Education section for details