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Buzzkill: How air pollution is affecting bees

Unless you’ve been living under a rock for several decades, the number of bees facing extinction isn’t new information. The latest figures from Friends of the Earth show 13 species of bees no longer exist and 35 are currently endangered.

And if bees weren’t already struggling with habitat loss, climate change and pesticides, they are also falling victim to air pollution, which is preventing them from pollinating our plants and flowers, posing a threat to our food supply and ecosystem.

‘To put it simply, bees are critical pollinators, essential for the reproduction of numerous flowering plants, including key agricultural crops such as apples and strawberries,’ Dr James Ryalls, Senior Research Fellow at the University of Reading explains. ‘Their pollination services support biodiversity by facilitating plant reproduction, which in turn sustains various species, including birds and mammals.

‘From an economic perspective, insect pollination supports around 8% of the total value of agricultural food production worldwide, and 70% of all crop species rely on it. If bees face continued risks, such as from air pollution, their decline could lead to reduced plant diversity and lower crop yields.’

However, to prevent the worst from happening, Dr Ryalls, who has been part of the University of Reading’s Department of Sustainable Land Management since 2018, helped conduct a research project that examined how air pollutants are affecting pollinators – including bumblebees and honeybees. The study was the first real-world field project to look into such a topic.

‘My curiosity of insect-plant interactions, climate change and air pollination grew when I was doing my PhD in Australia, so when a postdoc opportunity came up in Reading focused on air pollution and plant-insect interactions I jumped at it,’ Dr Ryalls explained.

‘The study took place over two summers in 2018 and 2019, and the majority of the work involved researchers standing in a field and recording different groups of pollinators landing on flowers within different field pollination rings that we constructed at the university.

‘We also conducted a number of control experiments within the study, to ensure the effects we were seeing were robust. One of the three control experiments demonstrated that the mechanisms causing the negative effects of air pollutants on flower visits by pollinators were most likely associated with the degradation of odours that pollinators use to find flowers and forage.’

To give context, bees rely on the smell of flowers to be able to locate them so they can feed on their nectar and carry pollen (which sticks to their fur) to other flowers. However, the team discovered two particular air pollutants were hindering this progress: ozone and emissions produced from diesel exhausts. Ozone pollution forms from chemical reactions between pollutants from cars and factories.

‘The main results of the study revealed 62-70% fewer pollinator visits to the plants within diesel- and ozone-polluted air,’ Dr Ryalls explains. ‘When we tracked the number of flower visits by individual pollinators, the decrease was even more severe (83-90%). This led to a 14-31% reduction in pollination, based on plant yield metrics.’  

While the findings from the research are worrying, Dr Ryall adds that they helped spark conservations about how we can work to address the issue. He says: ‘The research received worldwide media attention, [and] the paper also won the University’s 2023 Research Output prize, which was a nice nod from my colleagues. The recognition has even encouraged us to look into the matter further.

‘For example, I am currently working on meta-analysis to demonstrate how projected ozone concentrations over time will impact pollinator foraging behaviour. My team is also trying to identify mitigation strategies in the form of soil amendments that could limit the damaging effects of ozone on plant-pollinator interactions, and we are seeking extra funding for this.’ 

On the subject of bringing the issue to people’s attention, Dave Goulson, Professor of Biology at the University of Sussex who specialises in bee ecology and has published more than 300 scientific articles on the conservation of bumblebees and other insects, has also expressed an interest in researching how pollution is affecting bees. 

‘Three quarters of the crops we grow depend on bees and other insects to pollinate them, but they’re declining,’ Professor Goulson says. ‘My research has been on trying to understand why and has majorly centred around pesticides and habitat loss.

‘However, though I haven’t completed any research into air pollution myself, one thing I have noticed is that flowers which are planted outside of people’s homes and on roadsides aren’t feeding bees as well anymore because of pollutants from passing cars. This thought has led to me toying with the idea of applying for funding to research the toxic effects of particulates on bees generally. They breathe through little holes in their sides which lead into the trachea (branching tubes in bees that carry oxygen through their body), which could easily be clogged by particles.’  

New research from the University of Leicester has revealed how toxic air affects gut health in bees. To conduct the study, which was led by Postdoctoral Research Associate Hannah Sampson and published earlier this month, the team examined adult worker bees and split them into two separate groups.

The researchers tested faeces samples from both groups of bees to check their gut health. Following this, one group of bees were exposed to black carbon particulate pollution before having their faeces examined again. The team found that this black carbon exposure was disrupting the established bee gut microbiome – the normal balance of bacteria and other microorganisms that naturally live in the gut, protecting against harmful bacteria.

While a lot more work needs to be done into protecting bees’ health and their ability to pollinate, you don’t have to be a qualified scientist to help. In addition to his research work, Professor Goulson founded the Bumblebee Conservation Trust in May 2006.

‘I created the charity because I was getting a bit frustrated with just doing research on insect declines, which is all very well, but publishing scientific papers in journals doesn’t directly help the bees very much, or at all, in fact,’ Professor Goulson remarks. ‘So, with a hope to do something useful, in 2006 I decided I was going to set-up the Bumblebee Conservation Trust.

‘I didn’t have much money and the charity took a few years to really get going, but with a few little grants and through employing a small amount of staff it finally took flight.’

Now, 19 years later, the charity has 12,000 members and around 60 staff members all over the UK. Professor Goulson says: ‘It is an organisation that has encouraged thousands of people to plant meadows full of flowers, created educational programmes for school kids and even inspired people to grow wildflowers in their gardens, all with an aim to helping save the bees.’

‘I was in charge of the charity for the first five years, although I was doing it in my spare time which became really stressful,’ Dr Goulson continues. ‘Eventually I had to take a step back, which was a hard decision to make, but I’m more than pleased with how well the charity is doing. I hope its legacy continues for as long as possible and people continue to dedicate their time to helping our environment.’

Emily Whitehouse
Writer and journalist for Newstart Magazine, Social Care Today and Air Quality News.
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