Birds, bees and banned pesticides: long term implications of their 'emergency use'

You may have seen recent news regarding neonicotinoids - banned pesticides - being granted for emergency use in the UK. Close monitoring is vital to understand the environmental implications of this, and what it means for the UK and our future.

Protecting crops, but at what cost?

Thiamethoxam, like other neonicotinoids, are effective at protecting crops from chewing and sucking pests like aphids and beetles. Neonicotinoids affect the nervous system of pests by causing paralysis and, ultimately death. At low doses, neonicotinoids are less toxic to mammals and some vertebrates, however they are extremely toxic to many invertebrates including pollinating insects such as bees. 

Neonicotinoids work systemically, meaning that they are readily taken up by and transported throughout the plant, so will be present in the leaves and flowers as well as in pollen. Insects like bees and indeed other pollinators may therefore be exposed these chemicals while feeding on pollen and nectar.

In addition to the risk to pollinators such as bees, the use of neonicotinoids to treat seeds also has the potential to impact the wider environment because they are are known to persist in the environment, since they are mobile in soils due to being carried into surface water by water run-off or soil erosion.

Restricted for use by regulators

Thiamethoxam is one of three neonicotinoids that were banned for outdoor use by the European Commission (EC) in 2018 (imidacloprid and clothianidin were also banned). In 2020, the EU confirmed the non-renewal of approval for a fourth neoicotinoid, thiacloprid. These neonicotinoids have been severely restricted since 2013 following risk assessments undertaken by the European Food Safety Authority (EFSA) that highlighted their risks to bees.

The UK is not in isolation from the approval of emergency use of neonicotinoid pesticides such as thiamethoxam. Since the imposed restrictions on these neonicotinoids, 12 other EU countries have been granted emergency authorisations for their use in sugar beets. The EC continue to monitor the use of such emergency applications and approvals for emergency use and where necessary, the EC have mandated EFSA to examine the use of such emergency authorisations.

Long term effects of 'emergency use'

The use of emergency use approvals is applied when there is a danger (control of pests) that cannot be contained by any other reasonable means. Emergency use approvals place limits on the duration of time that the chemical can be used and conditions of its use. The UK Government’s approval for the emergency use of thiamethoxam is based the identified threat to sugar beet from yellow virus. It considers the use of thiamethoxam to be justified to manage the effective production of sugar beet which it considers to be an economic league important domestic crop.

Notwithstanding this, the use of these neonicotinoids for emergency use must be efficiently monitored. The UK has stated that it has considered alternative control measures (both chemical and nonchemical) and has deemed both approaches, even when used in combination to be less effective for the control of the threat of yellow virus. 

Following the mandate from the EC, EFSA found that for about a third of emergency use approvals from member states for which emergency use approvals were repeatedly granted, alternative plant protection products could have been used.

Undoubtedly the risk assessment undertaken and the approved emergency use of thiamethoxam would not have been taken lightly. The UK’s Health and Safety Executive has identified the risk to bees as being low because the crops will be harvested before flowering, limiting the potential exposure to bees that may feed on the sugar beet crops. However, the persistence of neonicotinoids within soils means that these chemicals will remain in the soil for years and be taken up by other plants in the vicinity.

It is right that we ask crucial questions about the long-term implications of these products on the environment and how their long-term unintended detrimental impacts on invertebrates like bees, soils and water quality will be monitored.