State of the Field

Our first steps involved getting a deep understanding of the problem we were tackling in order to maximise the chances for our solution to be translated to the real world and appealing to the broader market. This was initially conducted through reviews of pesticide uses around the UK. The UK is considered to have relatively high pesticide use per hectare. Agricultural regions can reach up to 4.5 Kg/ha, which was about 2.5x higher than the global average^[1].

It is important to note there is no strict legal limit on pesticide spraying per unit area, and its use is mainly guided by manufacturer suggestions due to the large variation in efficacy across different pesticides^[3]. However, pesticide use is actively discouraged near water courses, where there are strict legal limits as the water could be used for consumption. There must be no more than 1 part per billion of a single pesticide and no more than 5 parts per billion in total pesticides. Once pesticides leach into watercourses they cannot be easily removed. Expensive GAC-based carbon filtering, alongside dilutions with clean water would be required. 1 gram of active ingredient would need to be diluted with 10 million litres of water^[4].

These legal limits are currently enforced in the UK through large fines; water treatment companies can be fined up to £250 million for breaches in water quality^[5]. This leads to companies like Severn Trent leading large programs to target the problem before pesticides can reach watercourses. Catchment advisors work with farmers in the field to minimise pesticide use and runoffs. This is incentivised though grants. Although pesticide testing through GC/MS is expensive (over £25 a sample), it remains the only option. Find out more in our Human Practices.

Why λ-cyhalothrin?

λ-cyhalothrin was principally chosen due to 3 major factors:

• It is the most commonly used pyrethroid in the UK and the 5th most commonly used pesticide overall^[1]
• Locality of use – λ-cyhalothrin is commonly used on oilseed rape to protect against aphids and beetles in the Avon and Leam catchment in Warwickshire^[6]
• λ-cyhalothrin is also well characterised in literature, with its toxicity, half life, and complementary aptamer sequences being identified^[7][8]

In recent years, bans imposed on neonicotinoids have left λ-cyhalothrin as the only alternative treatment against cabbage stem flea beetles (Psylliodes chrysocephala) and peach-potato aphids (Myzus persicae)^[6]. These pests commonly affect the growth of oilseed rape crops in our local county, Warwickshire, as well as throughout the UK^[1]. However, this overreliance on λ-cyhalothrin has resulted in the accelerated emergency of resistance among aphid populations. This has been further exacerbated by a lack of maximum spray limit imposed on λ-cyhalothrin, which explains the worsening trend of overspraying in an effort to protect yields^[9][10]. This all culminates to large quantities of λ-cyhalothrin residue buildups in soil, which can runoff to water sources and complicate the remediation process. This is where PyRe comes in!

Is Industrial Agriculture Unavoidable?

While the negative effects of pesticide use and buildup on biodiversity are well known, there remains no commercially viable alternative to meet the ever increasing demand for food security. With global food demand predicted to increase by up to 56% by 2050 and ever more stringent regulation on protecting the environment, food security cannot solely rest upon the agricultural industry. In the same manner Fritz Haber revolutionised agriculture by pioneering the Haber-Bosch process for nitrogen fixation into fertiliser, scientific and technological innovation must remain at the forefront during this new era of increasing food demand^[11][12].

Current regulations and public opinion around GMO’s are likely to evolve as climate change inevitably leads to deficits in food production, reducing the quality of food as parts of the globe become non-arable^[12]. This is already underway with changes to the UK’s outlook on GM plants. With aims to become a biotechnology hub following Brexit, there has been notable changes to legislation; with amendments to the environmental protection act of 1990 easing the regulatory process for release^[13]. Such amendments – though far from a blank cheque – are certainly a move in the right direction towards commercial use of GMOs.

In the short and medium term, traditional industrial agriculture still remains as the most viable option. While movements towards organic food help protect biodiversity, it is well established that organic farming reduces yield by around 20%, and therefore requires more land to match output and is simply not viable for all crops^[14]. Nevertheless, this does not justify the overuse of pesticides, and steps should be taken to minimise the effect we have as a society on the environment.

We at PyRe believe our project acts as a stabiliser to minimise the agricultural impact on biodiversity through cheap pesticide sensing and potential residue remediation. Together, this integrated approach provides a solution to clean up toxic environments, enabling us to take the first steps in protecting biodiversity across the world with synthetic biology at its heart.