INTRODUCTION
Cereals, such as barley, play a crucial role in global food security. Have you ever considered their importance in our daily diet? Barley, for instance, is one of the oldest and most widely cultivated crops worldwide. It is essential for both human and animal nutrition, and is also a key raw material for beer production. However, like many other crops, barley is threatened by various pathogens, and with global warming, these threats continue to grow. Indeed, rising temperatures and shifts in seasonal patterns create favorable conditions for the emergence of new pathogens. Moreover, vector insects, such as aphids, are becoming an important topic in discussions about climate change, as they are key vectors for numerous plant viruses and integral players in multi-trophic agricultural systems. The rising global temperatures and fluctuating weather patterns have had a marked impact on aphid population dynamics, their reproduction rates, and interactions with both host plants and natural enemies. According to research by Joan van Baaren, Cécile Le Lann, and Jacques JM van Alphen in “Consequences of Climate Change for Aphid-Based Multi-trophic Systems”, climate change directly affects aphid life cycles through temperature-dependent processes such as development speed and fecundity.
In addition to temperature, shifts in seasonal patterns also influence the timing of aphid migrations and the synchronization with their host plants and natural enemies. Warmer winters, for example, can reduce the mortality of aphid populations, allowing them to thrive earlier in the growing season. This leads to greater opportunities for virus transmission, especially in crops like barley and wheat, which are particularly vulnerable to aphid-borne diseases such as the Barley Yellow Dwarf Virus (BYDV). As these changes ripple through the ecosystem, they can disrupt the balance between aphids, their parasitoids, and predators, creating feedback loops that favor pest outbreaks and increase the challenge of managing aphid populations in a changing climate.
Consequently, understanding these shifts in aphid dynamics is critical for predicting future virus transmission patterns and developing effective agricultural management strategies.
One of the most significant examples of this threat is the Barley yellow dwarf virus (BYDV) is a significant viral disease that affects autumn-sown cereals, including barley and wheat, and is part of the Luteoviridae family.
One of the most notable vectors of the virus is Rhopalosiphum padi, which transmits the virus, particularly the PAV strain (Padi avenae virus), responsible for 90% of autumn infections (Fabre et al., 2005). The environmental conditions during autumn and winter play a crucial role in determining the primary infections of BYDV. Temperature greatly influences both the population dynamics of the aphid vector and the virus transmission process. For instance, the developmental threshold for R. padi is around 5°C, while the take-off threshold for alatae (winged aphids) is around 15°C. Warmer conditions from January to August correlate with higher percentages of viruliferous aphids in autumn, likely due to increased population growth rates (Simon et al., 2002; Fabre et al., 2005). Studies also indicate that virus incidences in spring are often linked to aphid populations from the preceding autumn, showing a clear relationship between climate, aphid activity, and virus spread (Foster et al., 2004). As climate change continues to alter temperature patterns, it is expected that the incidence and spread of BYDV will increase, primarily due to changes in aphid biology and the timing of virus transmission within agroecosystems.
In response to this growing threat, the most common method to control the spread of BYDV is the use of pesticides. However, as with other crops, this approach raises serious environmental and public health concerns. Pesticides, in addition to their impact on biodiversity, contribute to soil degradation and groundwater pollution. They also promote the emergence of resistance in pests, making these products less effective over time.
The widespread use of pesticides also affects pollinator insect populations, which are essential to the health of ecosystems. These practices, combined with the effects of climate change, create a vicious cycle where the destruction of ecosystems accelerates, threatening not only crops but also biodiversity and human health. With the increase in global warming and consequently BYDV, it has become crucial to find a sustainable solution to combat this virus.
Aware of the urgency of this situation, we have decided to focus our efforts on this issue by developing Bac’Attack, a project aimed at fighting the spread of BYDV and strengthening the protection of agricultural fields.
WHEN WE STARTED
When we started the project, we wanted to understand the public’s knowledge about phytopathogens, French agriculture, the emergence of new plant diseases, and how these are linked to phytopathogenic agents. Do people know that phytopathogens are on the rise in France? Are they aware that losses related to aphids are increasing in the country? To gather the public’s opinion on our project, we conducted a survey that we shared on our various social media platforms in both English and French. We were able to collect feedback from 112 people, mainly living in France. Although the sample size is small, the results should be considered cautiously, yet we believe it is still fairly representative of the population in terms of age and gender.
In terms of profession, the majority of respondents are students or employees; however, a wide range of professions is represented.
This survey is divided into several sections. After gathering background information on the respondents to enable a more precise analysis of the collected data, we assessed their knowledge of phytopathogens and the losses they cause.
It is noticeable that for each question asked, the responses vary greatly, and for some questions, the age and socio-professional distribution differ significantly. In the case of Chart 2, the predominant response is the increased use of pesticides, mainly mentioned by students, while price increases are more frequently cited by working professionals. This difference in perception between students and professionals is particularly interesting, as it not only reflects distinct priorities based on the context in which these groups operate, but also different sensitivities to environmental and economic issues. Students, who are often more exposed to courses focused on ecological impacts and sustainable development, may be more inclined to consider environmental aspects, such as pesticide use. In contrast, professionals who face economic constraints seem more focused on financial implications and production costs.
In the case of Chart 1, all three responses are present in varying proportions, with a more balanced distribution across different socio-professional categories. What is surprising is that some non-students also selected the "climatic conditions" response, whereas we expected them to favor other options, such as water or pest factors. This observation shows that awareness of environmental issues extends beyond the academic sphere and also reaches professionals, indicating an evolution in the perception of agricultural risks and strategic priorities, even among groups traditionally less exposed to academic discourses on climate change.
In Chart 3, the two predominant responses correspond either to the most well-known agricultural practices (such as crop rotation or intercropping) or to those currently generating a lot of interest, like biocontrol. Here, a clear divergence is observed based on respondent profiles: the majority of students favor biocontrol, an ecological management method that relies on the use of living organisms to control pests, while employees and business executives lean more towards conventional solutions such as the use of insecticides or adopting resistant plant varieties.
This distribution of choices can be explained by several factors. Students, often more aware of sustainability and agroecology issues through their studies, are more likely to adopt innovative and environmentally friendly approaches. On the other hand, professionals, who are confronted with yield requirements and market pressures, prefer well-established strategies known for their immediate effectiveness. This highlights how priorities shift depending on the professional context and experience, illustrating the need for intergenerational dialogue to promote more sustainable agricultural practices.
We also asked various questions related to our topic to gather the general public’s opinion about our project.
In most cases, BYDV is little or not known by the public, yet it is one of the main causes of yield losses in barley crops, both in France and across Europe. According to our survey, 88% of respondents reported not knowing about BYDV, which indicates a lack of awareness and communication around the issue. This lack of knowledge is concerning, as it may delay the implementation of appropriate control and prevention strategies.
The perception of the damage caused by the virus is also highly underestimated. Indeed, the majority of respondents believe that yield losses caused by BYDV range between 30% and 50%, whereas in reality, they can reach 50% to 70%, or even more under certain conditions. Such massive losses can lead to significant production declines, compromising not only the profitability of farms but also food security in heavily affected regions.
Finally, as our project aims to implement a genetically modified bacterium (GMO), it is important to note that GMOs are the subject of much debate in France, where a large part of the population is resistant to their use. According to an INSEE study published in 2017, in 2016, 51% of French people believed that GMOs posed a high risk to the environment, a figure comparable to the 50% who perceived nuclear power plants as equally dangerous. Based on this observation, we wanted to assess the perception of biotechnology use more broadly among the respondents of our survey.
Participants were asked to evaluate, using 6 options (Very Unfavorable, Unfavorable, Neutral, Favorable, Very Favorable, Don't Know), the level of risk associated with the use of biotechnologies. Almost 75% of them selected a Favorable or Very Favorable response, which does not reflect a strong distrust of biotechnologies and therefore GMOs. However, a larger sample size would be necessary to confirm this trend.
A notable element of our study is the difference in opinion between generations: young people aged 25 and under show greater confidence in biotechnologies compared to older respondents. However, the idea of releasing these bacteria into the environment remains a common concern across all age groups.
These results once again highlight the importance of scientific outreach: ensuring a proper understanding of safety mechanisms is crucial to gaining public trust and eventually considering the commercialization of our project.
SENSIBILISATION AND COMMUNICATION
To raise awareness among the public and future stakeholders about these issues, it is crucial to emphasize that, barley production must be protected today to ensure global food security tomorrow. Viruses like BYDV pose a serious threat, but coordinated actions can help mitigate their impact. However, these threats are exacerbated by an often-overlooked factor: climate change.
The impact of climate change on aphid populations and plant virus transmission is significantly underappreciated in public and scientific discussions. While much focus is placed on the direct consequences of climate change on crop yields due to drought or heat stress, the indirect effects, such as altered pest dynamics, are less visible but equally damaging. Aphids, driven by warmer temperatures and extended growing seasons, are transmitting viruses like BYDV at higher rates, threatening global cereal production. This risk is often overlooked, yet the economic and ecological consequences are enormous, and they could worsen over time, further exacerbating food insecurity in vulnerable regions. As climate change drives aphid population growth and virus transmission, global cereal production faces increasing threats. Effective management of this issue requires heightened attention to the intricate interactions between pests, viruses, and climate to prevent large-scale agricultural losses and mitigate the growing challenges posed by food insecurity.
However, there is still a serious lack of communication with the public: barley production and agriculture are not attractive topics for the media, and the farming profession is severely underrepresented. With climate challenges and the emergence of phytopathogens resistant to chemical and biological controls, it has become necessary to educate the public and show them the importance of quickly focusing on sustainable solutions for the future of French agriculture. According to Robin COMTE, public communication should be given more attention because 'without this communication, it is impossible to raise public awareness of the current and future problems faced by farmers'.
Chart A
This lack of communication was particularly evident in our survey. In Chart A, it can be seen that almost 94% of respondents do not know of any emerging phytopathogens or those currently causing damage in France. This percentage is even more alarming when we consider that BYDV is responsible for yield losses every year. One of the reasons why this percentage is so high can be explained by Charts B and C.
Chart B
Chart C
Charts B and Chart C clearly highlight the lack of public awareness regarding phytopathogens. In Chart B, just over half of the respondents indicate that they rarely hear about plant diseases, while 21% hear about them only occasionally, and nearly 20% have never heard about them at all. This lack of visibility is even more concerning when we look at Chart C, where 60% of respondents believe that the general public is not sufficiently informed about the risks that phytopathogens pose to crops.
An aspect of our project was also to inform the public about several biology themes. The realization of the lack of information for the consumers gave us the idea of posting on social media about food security and agriculture, and to integrate those aspects in our education actions.
LEGISLATION
In Europe, the use of plant protection products is regulated by Regulation (EC) No. 1107/2009, which governs their placement on the market. Introducing a new method for controlling plant pests in the French market requires the active substance to be approved at the European level and the product itself to receive national market authorization. In France, plant protection products are authorized by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) after a comprehensive risk assessment. The applicant must demonstrate that the active substance meets the approval criteria set out in Article 4 of the aforementioned regulation. On average, it takes 5 to 6 years for a new product to be reviewed, approved, and marketed. Although these timelines may seem lengthy, they are necessary to ensure the product’s safety and effectiveness in the field .
The approval of a new product in an EU country is based on European institutions. Few stakeholders would support deviating from the harmonized European framework, as having a standardized regulation is crucial given that the EU is a single market. This harmonization reduces competition between Member States and simplifies product launches throughout Europe. Once a substance is approved, its approval must be renewed after a few years. In some cases, a previously authorized substance may be banned if it no longer meets the approval criteria. This is because new scientific and technical knowledge can lead to unforeseen issues post-market launch.
In recent years, more criteria have been considered during product reevaluation as new scientific findings shape the evaluation standards. For instance, the EFSA's guidance for identifying endocrine disruptors was only adopted in 2018. The approval criteria for reaching the European market are highly stringent to ensure a high level of protection for human and animal health and the environment. As a result, some companies may prefer to turn to other markets with less strict standards and regulations. Introducing a product to the European market can involve substantial financial and resource investment with uncertain outcomes, although it is a guarantee of quality and safety.
These new restrictions create increasing challenges for producers, who face a lack of alternative solutions to treat their crops. Anticipation plans are therefore being implemented to find solutions and prepare for the phase-out of certain products, in collaboration with research institutes like INRAE, agricultural unions, industry players, and other stakeholders.
Producers also bear a significant responsibility, as they are required to supply healthy, high-quality crops each year while complying with stringent regulations governing both the plants they cultivate and the pest control methods they employ. Their role is in constant flux, demanding ongoing innovation to combat plant diseases while navigating increasingly rigorous standards.
These evolving regulations add further strain, as viable alternatives to traditional treatments are not always available. Additionally, farmers must contend with the challenges posed by climate change, striving to sustain high yields with reduced pesticide use, even as conventional chemical solutions are progressively being eliminated.
OUR PROJECT
As part of our participation in the iGEM competition, we formed a multidisciplinary team bringing together diverse skills and students from various scientific backgrounds. After several brainstorming sessions, we were inspired by the 'ARBO-BLOCK' project of iGEM Aix-Marseille 2021, which helped us define the scientific fields to explore. Instead of targeting mosquitoes, our approach focuses on aphids, by leveraging a bacterium naturally present in their microbiome. We propose using a specific toxin released in the aphid’s gut after virus recognition, which would allow us to target only aphids infected by BYDV, while preserving those that pose no threat. Our project aims to develop an innovative and environmentally friendly solution addressing a regional need, with a focus on protecting cereal crops. The development of Bac’Attack reflects our commitment to combining science, ethics, and community engagement.
UNDERSTANDING The needs
Food security is the challenge of the 21st century. Throughout our work, we tried to understand the needs of the people in charge of producing and selling food to the population. The aim was to identify precisely the challenges they have to face, in order to design a tool in line with the current issues
Because of global warming, the agricultural field is facing changes at an unprecedented rate. It has never been so difficult to adapt agricultural behaviors to minimize crops’ losses.
We decided to focus on a less known, yet equally devastating consequence of global warming on crops: the proliferation of new pathogens. During our meeting with Robin COMTE, a specialist in pests and pest control techniques, he explained that one of the main reasons for the increase in cases of BYDV (Barley Yellow Dwarf Virus) in France and Europe is linked to climate change. Indeed, "with increasingly warm and longer autumns, the virus and the aphids have more time to interact", thereby increasing the risk of virus transmission to cereal crops. To curb the rise of BYDV in France, several actions are being implemented: chemical measures, including "the use of certain families of pesticides such as pyrethroids"; biological approaches using resistant plant varieties and biocontrol; as well as "human strategies advising farmers on the best times to treat their fields". Nevertheless, "in terms of cereal viruses, BYDV is the virus that poses the most problems in France".
“Various stakeholders are aware of the consequences of climate change on barley production security”, particularly with the increase in diseases like BYDV. Numerous efforts are being made, but the obstacles are many: it takes time, and "to sustain the different solutions, it would be necessary to combine chemical and biological levers", according to Robin COMTE.
The first thing Robin COMTE explained to us during our initial meeting was the two types of barley found in France, as well as the different methods implemented to combat BYDV. In both cases, we primarily rely on pesticide control, sometimes using prophylaxis or resistant strains, but mostly on the elimination of the aphid reservoir through insecticides.
For forage barley, there has been a development of tolerant varieties with good yields that are less susceptible to other diseases over the past decade. This is evident during severe infestations of BYDV:
In contrast, for brewing barley, the implementation of tolerant varieties has taken longer, as the introduction of resistance genes resulted in decreased yields and increased susceptibility of the crops to other diseases. Today, the majority of brewing barleys grown in France are still not tolerant varieties.
In addition to what Robin refers to as "the biological lever", meaning resistant barley varieties, "the chemical lever" corresponds to pesticides and insecticides. Chemical control is less expensive than using resistant plants, and the primary family of pesticides used as a first line of defense against viral diseases is pyrethroids. This is a contact insecticide, meaning it does not penetrate the plant to provide ongoing 'protection' during its growth; rather, it protects the plant for a window of 10 to 15 days. Therefore, there is a certain limitation to the use of this chemical lever: in addition to not being ecological, the timing of the treatment must be precise—"not too early and not too late, otherwise the farmer risks losing their crop".
Robin COMTE also reminded us that developing new varieties resistant to emerging threats is a long process.
The major challenge is that the evolution of the pathogen may occur faster than the development of the variety, which is why "the cereal sector in France is asking us to prioritize the issue of JNO very highly". This evolution can result from the virus mutating and overcoming the resistance found in the plant, thus bypassing the biological lever.
Alternatively, there may be mutations in the insect that allow it to overcome the chemical lever and become less sensitive to pesticides. An example of this is the KDR (KnockDown Resistance) mutations, which have posed problems in Europe since 2016 and reduce the effectiveness of field treatments. These KDR mutations confer resistance to insecticides, particularly those from the pyrethroid family, which are the first line of defense in protecting barley crops, by affecting the gene coding for the voltage-gated sodium channel. Normally, pyrethroids work by disrupting the function of these sodium channels, leading to hyperactivation of nerve cells, which paralyzes and ultimately kills the insect. However, in aphids with KDR mutations, the structure of these channels is altered, reducing the pesticide's effectiveness.
Despite this, "JNO causes damage every year, everywhere in France, regardless of barley categories", adds Robin COMTE. The evidence is compelling: in 2016, Arvalis launched an online questionnaire to gather testimonies from farmers across France to estimate the extent of the damage caused by JNO. Out of 4,000 respondents, 95% reported observing symptoms of BYDV, with nearly half of the plots showing signs of dwarf plants and about 15% of the plots being completely lost due to BYDV.
We realized that these solutions take quite a long time to test and implement, but more importantly, they won't be usable in the fields for some time. This is why we still need faster solutions, such as Bac’Attack, to develop more specific and effective treatments as a long-term preventive measure.
BIOCONTROL
When we spoke for the second time with Robin COMTE, the discussion centered around biocontrol methods, which "aim to protect without eradicating the pest". The example he provided, relevant to our topic, was that of Bacillus thuringiensis. This beneficial bacterium produces natural antimicrobial compounds that inhibit the growth of pathogens while stimulating the plant's natural defenses. This bacterium is registered with ANSES (the French Agency for Food, Environmental and Occupational Health & Safety) as a biocontrol agent, primarily in agriculture to combat various pests and pathogens.
Using this technique, crops are protected by utilizing living organisms or natural products to fight against plant pests and diseases. It is an agroecological approach that aims to "reduce the use of pesticides and favor practices that are more respectful of both the environment and human health".
More generally, biocontrol products accounted for over 13% of the crop protection market in France in 2021. Biocontrol is one of the keys to agroecological transition, helping to limit the use of conventional phytopharmaceutical products, which raise concerns for the environment and human health. The goal is to promote the use of biocontrol solutions as sustainable alternatives to traditional phytopharmaceutical products. Biocontrol methods have rapidly developed for large-scale crops, replacing chemical control solutions.
The only caveat is that there is a tendency to implement biocontrol products in the same manner as conventional products. These products are more sensitive, degradable, unstable, and there are specific success factors that need to be identified. "We should be able to combine biocontrol products with more traditional methods, such as resistant plants, and keep biocontrol as a reserve for situations where we have no other options." said Robin COMTE.
APPLICATION : USING OUR TOOLS
Back’Attack can be used directly by producers in their fields. It will also be useful to scientists who work on treatments for crop diseases. Our solution brings new opportunities for research: it allows for targeted treatment of infections while preserving the plant’s integrity and development. It will especially be useful to research organisms for barley seed growers, and Arvalis, research organisms for consumption of barley and wheat producers.
Robin COMTE expressed his enthusiasm for the potential of Bac'Attack to develop long-term strategies against emerging cereal pathogens, particularly those affecting barley. He emphasized that relying solely on chemical control or genetic resistance is not sustainable, as pests like aphids eventually develop resistance through mutation, even in light of current restrictions. “We need to stack different control methods to ensure sustainable solutions,” he explained. While genetic tools offer promising solutions, they are not infallible and can be circumvented over time.
He suggested that our project could serve as a new type of biocontrol. For example, Bac'Attack could be applied alongside non-tolerant varieties to provide direct protection in the field.
“The beauty of your project lies in its ability to anticipate future challenges. Just because current regulations restrict certain technologies doesn’t mean we shouldn’t prepare for the day when these constraints might change,” he stated. This forward-thinking mindset aligns with the goals of agroecological transition, where having a diverse set of tools is essential for overcoming future deadlocks in plant protection.
It would be interesting to test our tool in a controlled environment: inoculating the bacterium either through spraying or in water, to understand how it reaches the plants and how it can best do so. Of course, this would take place in isolated and secure plots to ensure that our bacteria do not interact with the external environment. Reproducing field conditions in the laboratory remains a challenge.
In vitro, it is essential to recreate conditions similar to those in the field, such as contact with vector aphids, irrigation, various substrates, and other factors to determine which conditions favor BYDV transmission. We could also study how the virus spreads within plants at different stages of maturity, which would allow us to define the optimal timing for intervention and protection of crops.
This would help identify the pathways of viral contamination, for example, by observing the speed at which aphids transmit the infection or analyzing the influence of humidity, the distance between plants, and environmental conditions such as UV exposure.
BRINGING IT ALL TOGETHER
We started with a straightforward idea: to develop a treatment tool that would enable farmers and researchers to design more effective solutions without resorting to pesticides. Initially, we hadn’t fully considered its practical application in farmers' biocontrol methods, its flexibility of use, or how it could benefit future iGEM teams. However, by revisiting our work and reflecting on the ethical and human discussions we’ve had, each meeting with Robin COMTE, piece of advice, and suggested adjustment allowed us to evolve our project. We managed to bridge the gap between the needs on the ground and what we were capable of developing.
While we are very proud of our tool, we must acknowledge that there are still some limitations to keep in mind during its use. Bac'Attack cannot be directly utilized in a standard field setting, as it consists of genetically modified bacteria; placing it directly into the environment would neither be safe nor permitted. Our tool must be employed in a laboratory under the careful supervision of scientists, which requires recreating a realistic context. To replicate the actual soil conditions, with all its bacteria and, notably, the aphids, many interactions must be considered, which is a limiting factor.
The final limitation we considered is an ethical one.
Bac'Attack was designed to generate knowledge, but we cannot oversee what that knowledge may lead to. Our tool could, for instance, be misused to create toxic products for the environment, despite that not being its intended purpose. Science can never be neutral, and innovation can always be diverted from its original intent.
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