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A third of global crop production is dependent on pollinators such as bees. Yet bee populations face a number of threats, including habitat loss, disease and environmental pollution.
While research suggests that agrochemicals such as pesticides endanger bees, the actual risk and impact hadn’t been effectively quantified.
To address this, the EU-funded PoshBee project convened researchers, beekeepers, farmers, agrochemical industries, small businesses and charities to establish investigation methodologies to identify key threats and their likely impact on bee health.
“Our work has implications for policies and practices on pesticide use, and the tools we’ve developed for monitoring bee health are game changers,” says project coordinator, Mark Brown, from Royal Holloway, University of London, the project host.
Methodology and tools
PoshBee looked at two crop systems: apple and oilseed rape. Both rely on effective pollination and are a valuable food source for bees.
To study the impacts of agrochemicals, pathogens, and nutritional stress on bees, PoshBee set up a network of 128 field sites across Europe, populated by colonies of honey, bumble and red mason bees. These were complemented by seven laboratories.
While some of the work modified pre-existing pollinator risk assessments, novel lab, semi-field and field methodologies were also developed. This included, for the first time, enabling a ground-nesting solitary bee species (Anthophora plumipes) to act as a model to test agrochemical exposure through soil.
Matrix-assisted laser desorption ionisation mass spectrometry imaging (MSI) was shown to be useful for analysing bee blood to measure exposure to agrochemical and parasite stressors, as well as for assessing health implications. Proteomic approaches were also used to identify molecular markers for use in a tool to enable the long-term monitoring of bee health.
To ensure the collection of quality data from semi-field and field experiments, industrial collaborators developed a range of innovative research assets. These included an integrated field study system, a cost-effective bee-handling box, a dead-bee trap, and a new air-sensor that monitors pesticide exposure inside honeybee hives.
Noteworthy results
The team discovered that while a diet of pollen can mitigate the impact of some agrochemicals in some bee species, it was not the case for all. Furthermore, floral diversity and abundance can enhance, mitigate or have no influence on pesticide impacts, and these impacts remain unpredictable across pesticides and bee species. Also somewhat intriguingly, it seems that sometimes non-active agrochemical ingredients can be more impactful on bees than active ingredients.
Looking at honeybees, while it was found that low nectar quality could dramatically enhance the damage pesticides cause, the team didn’t find significant impacts as a result of exposure to glyphosate, the most commonly used pesticide on farms.
“We found that pesticide impacts on honeybee colonies are challenging to assess – as tiny, largely unmeasurable, and unpredictable differences in starting conditions lead to different health outcomes. So not surprisingly, the long-term effects of pesticides, such as on the reproductive units of social bee colonies, are not captured reliably,” adds Brown.
Making the results count
Having developed a range of evidence-based policy briefs, the PoshBee team has so far met with the European Food Safety Authority and a range of European Commission departments, including the Directorate-General for Environment and Directorate- General for Agriculture and Rural Development.
“We stressed the need for new pesticide regulations and risk assessments, as these currently don’t pick up the full spectrum of pesticide impacts across bee species,” explains Brown.
To make the project findings accessible to a wide audience, the project co-created with stakeholders, infographic-style research summaries, made available just after the publication of the research paper on that topic.