Exposure and adverse effects of pesticides on honeybees in the environment

Woodcock, Ben A.; Dos Santos Pereira, Gloria; Shelton, Jenny; Sleep, Darren; Savage, Joanna; Pennington, Olivia; Gibbons, Sam; Carter, Heather; Billings, Alex; Campbell, Helen; Pywell, Richard F.

Exposure and adverse effects of pesticides on honeybees in the environment

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Abstract/Summary

Pollinators contributing £0.5 billion to the UK economy though pollination services are a priority for the Pesticides Policy Hub, wider Defra policy teams and a range of stakeholders. There are over 248,000 hives in the UK making honeybees a key insect pollinator. They are however exposed to pesticides when foraging on crops, amenity land and domestic gardens. To support the government’s 25 Year Environment Plan Defra have been developing outcome indicators, including a H4: Exposure and adverse effects of chemicals on wildlife indicator. This document reports findings from the pilot honeybee H4 pesticide exposure indicator that has been running from 2019 to 2022. This report focuses on 2021 to 2022, the most recent year where pesticides have been quantified. Trends in arable & horticultural land 2021-2022. There has been an overall drop in the mass of pesticides found in honey from 2021 to 2022, as well as a significant reduction in the total number of pesticide active ingredients. There was a significant reduction in the acute (immediate effects) and chronic (long term effects) risk to honeybees resulting from pesticide exposure. Risk accounts for both exposure to pesticides and differences in their relative toxicity. Overall levels of acute risk were below levels of concern, however, when chronic risk accounted for synergisms between different pesticides there was evidence that levels of concern were exceeded in 2021 but not 2022. Urban pesticide risk to honeybees in 2022. Honeybee hives are kept in urban and sub-urban environments. Amenity and domestic use of pesticides in gardens is widespread and poses a risk to honeybees. On average honey sampled from urban environments had 16 different pesticides, a number comparable or higher than that of arable & horticultural landscapes. There was a peak in the number of pesticides found in June and September. Both acute and chronic risk to honeybees do not typically exceed levels of concern in urban localities. Changes in risk associated with individual insecticides. Currently approved pyrethroids dominate the risk to honeybees from pesticides in all landscapes. Residues of insecticides withdrawn from UK use remain frequently detectable in honey. This includes those withdrawn since 2017, such as neonicotinoids, as well as pesticides like organophosphates and carbamates withdrawn before this period. Of these the neonicotinoid clothianidin contributes significantly to honeybee risk from pesticides in arable & horticultural landscapes but is largely absent from urban situations. There is evidence of ongoing declines in the neonicotinoid thiacloprid since its 2020 withdrawal. The historical legacy of no longer used pesticides contributes to the risk from pesticides for honeybees. Summary. This pilot honeybee H4 indicator is currently the only national and multi-year data set on environmental exposure of pollinators to pesticides. It has demonstrated temporal patterns in the reduction of pesticide risk to honeybees from 2021 to 2022, although this may be due to the 2022 drought year reducing floral resource availability and so exposure to pesticides. We show that honeybees are exposed to a cocktail of pesticides resulting from their ability to forage over large areas and so aggregate different residues from multiple crops and amenity areas. Although the acute risk of exposure is low, in some years like 2021 chronic long-term exposure to pesticides may be high enough to exceed a level of concern but only when synergistic interactions between pesticides are accounted for. We show that measuring real world exposure risk to pesticides cannot easily be predicted from current application of approved products, as historical residues withdrawn from sale remain prevalent. Such risks can only be quantified by direct assessments undertaken by this honeybee H4 indicator. This indicator supports the strategic goals of the UK National Action Plan for the Sustainable Use of Pesticides (NAP) that aims to enhance the environment and biodiversity to improve quality of life.

Item Type:

Publication - Report

UKCEH and CEH Sections/Science Areas:

Biodiversity (Science Area 2017-24)
Pollution (Science Area 2017-24)

Funders/Sponsors:

defra

Additional Information:

On publication, full text should be openly available via Defra website.

NORA Subject Terms:

Ecology and Environment
Zoology

Date made live:

04 Dec 2025 11:52 +0 (UTC)