Charlotte Chivers

Charlotte Chivers

 

On Friday 8th January, the UK government decided to allow the use of a neonicotinoid-based pesticide, thiamethoxam in emergencies. They had previously pledged to maintain a ban on this chemical in line with the EU’s stance towards neonicotinoids.

The UK is not the only country to make this decision, with 11 others also permitting the use of this pesticide in emergencies. These countries include Belgium, Denmark and Spain. These are not the first European countries to lift the ban of thiamethoxam on sugar beet fields; France has already lifted their ban on neonicotinoids.

The news headlines and Twitter uproar resulting from this decision suggests that the public are unhappy with this decision.

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This disapproval appears to derive largely from the knowledge that these pesticides are harmful to bees. There are, however, further complexities which have been largely unnoticed or ignored by these commentators, both in support of and against this decision. This article attempts to unravel some of these complexities.

 

What does ‘emergency’ use mean?

Emergency use means that the pesticide may only be used where it is indispensable for protecting the crop. Even when it is applied, it will be done in a limited and controlled way, informed by an independent scientific forecast which will prove it is needed. In this case, Defra has claimed that the pesticide will only be allowed on sugar beet as it is non-flowering. There will also be controls to minimise risks to pollinators.

 

Why are people upset about the re-authorisation of thiamethoxam?

Those who disagree with the use of thiamethoxam mostly refer to the impacts it has on insects, and water quality. Matt Shardlow of Buglife, an environmental charity, argues ‘nothing has changed scientifically since the decision to ban neonics from use on sugar beet in 2018. They will still harm the environment’. Several studies have found that thiamethoxam has severe impacts on bees. Research has found that it can weaken the immune systems of bees, harm the development of their brains, and impair their flight.  Some commentators have also argued that instead of growing crops prone to disease, farmers should instead focus on those already well adapted to the environment.

 

 

Why do some support the emergency use of the pesticide?

Virus yellows disease is having huge impacts on the ability of British farmers to grow sugar beet. Campaigners, including the NFU and British Sugar, argue that the pesticide is needed in emergencies to allow these farmers to stay afloat.

The weather
The mild weather across England last year (2020) meant that record numbers of aphids survived winter. It is these aphids that transmit virus yellows disease. As a result of the spread of this disease, some farmers are have stopped growing sugar beet for the first time in 100 years.

A nature-friendly farmer who supports the decision
Tom Clarke is a self-professed ‘nature-friendly farmer’, stating that over 15% of his farm is dedicated to enhancing nature. He supports the decision to reinstate thiamethoxam for emergency use. This is despite a general dislike of insecticides and a keen interest in seeking alternatives such as biological controllers. He points out that there are currently few alternatives, and until we have some solutions such as disease-resistant varieties, we need these pesticides. He also argues that sugar beets have provided some ecological benefits within his rotation. For example, it provides a food source for migratory swans.

Are the environmental impacts as bad as the media suggests?
Neonicotinoids are known to have severe impacts on the environment, with particular impacts for pollinators. However, sugar beet is a non-flowering plant. This means that the impacts on pollinators may be less than they would be on other crops. There will, however, be at least some effect on pollinators due to surrounding wildflowers.

 

Why don’t we just import sugar?

We could import sugar. However, these imports would come from countries that already use seed treatments, or from imported sugar cane. Cane plantations have also caused substantial environmental damage due to habitat removal, soil erosion, pesticides, and the high carbon footprint of exporting the resulting sugar. 

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The sugar debate

An additional complexity surrounding this debate is the notion that we should be reducing our dietary intake of sugar. In this context, is a reduction in how much sugar beet is grown such a bad thing, particularly if beet farmers can grow an alternative crop on their land?

 

Conclusion

In conclusion, this debate is far more complicated than it first appears. Whilst there is a clear need to find alternatives to pesticides, there are several arguments which support the use of thiamethoxam in the meantime.

SPRINT recently attended a fascinating talk at the Oxford Real Farming Conference. Researchers from the University of Edinburgh shared their findings surrounding why pesticides may, paradoxically, benefit crop pests. The research was born from the work by a French agronomist, Francis Chaboussou. 

Who was Chaboussou?

Chaboussou was an agronomist who observed that agrochemicals were leading to more pressure from pests than without them. He wondered: why is this? He then dedicated his life to finding out both through experiments and reviewing the literature. 

What were Chaboussou’s findings?

The central idea developed by Chaboussou is that most pests depend on the availability of amino acids, which are the building blocks for proteins, which are vital for plant growth and repair.

Plants make proteins out of amino acids through a complex process. Before amino acids have been used up in this process, they provide a good source of food for pests and parasites.

Amino acid concentrations in plant cells are usually kept at low levels because they are quickly used up by the plant when making proteins. Applying pesticides can temporarily prevent the plant from producing proteins and result in proteins converting back to amino acids. These applications can paradoxically result in increased food availability for pests.

This means that pesticides may feed the very problem they attempt to solve. For example, whilst the spray may kill the pest which was originally causing a problem (e.g., greenfly), it then inadvertently be providing food for fungi, resulting in fungal infection. The result is a treadmill of pesticide applications. You can read Chaboussous’ book for free here.

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Re-evaluating Chaboussou’s findings in the present day

Daisy Martinez and colleagues from the University of Edinburgh recently completed a literature review exploring whether Chaboussou’s conclusions are true.

The results of their review confirm many of Chaboussou’s  findings. The review indicates that in addition to providing amino acids which feed pests, crops may become biochemically stressed by pesticide applications. This stress may not be obvious as these changes are subtle and occur within the plant’s cells. The outcome of this shift is an accumulation of amino acids in crop tissues. Again, increasing the availability of food for pests and pathogens.

Similar results have been found in response to Nitrogen fertiliser applications. Further research is needed to explore the effects of fertilisers and pesticides in combination.

Based upon the findings of this research, we conclude that the paradoxical effects of pesticides should be considered when deciding whether and how to apply them. This research also underpins the need to look at the complex nature of ecological interactions when farming. This evidences the importance of the unified global health risk assessment toolbox being developed by SPRINT for helping regulators to decide whether or not to approve pesticides.

Speakers: Ulrich Loening, Daisy Martinez