Air pollution impacts bees' ability to find flowers

Researchers from the UK and Australia have found that ozone substantially changes the size and scent of floral odour plumes given off by flowers, reducing honeybees’ ability to recognise odours by up to 90% from just a few metres away. Their findings, published in the journal Environmental Pollution, suggest that ozone is likely to be having a negative impact on wildflower abundance and crop yields.

Ground-level ozone typically forms when nitrogen oxide emissions from vehicles and industrial processes react with volatile organic compounds (VOCs) emitted from vegetation in the presence of sunlight. It has already been established that ozone has a negative impact on food production because it damages plant growth, and the research team last year found that common air pollutants, including ozone and diesel exhaust fumes, have a negative impact on pollination in the natural environment.

“Some 75% of our food crops and nearly 90% of wild flowering plants depend, to some extent, upon animal pollination, particularly by insects,” said study leader Dr Ben Langford, an atmospheric scientist at the UK Centre for Ecology & Hydrology.

“Understanding what adversely affects pollination, and how, is essential to helping us preserve the critical services that we rely upon for production of food, textiles, biofuels and medicines.”

The researchers used a 30-metre wind tunnel at the University of Surrey to monitor how the size and shape of odour plumes changed in the presence of ozone. As well as decreasing the size of the odour plume, the scientists found that the scent of the plume changed substantially as certain compounds reacted away much faster than others.

Honeybees were trained to recognise the same odour blend and then exposed to the new, ozone-modified odours. Pollinating insects use floral odours to find flowers and learn to associate their unique blend of chemical compounds with the amount of nectar they provide, allowing the insects to locate the same species in the future.

The research showed that towards the centre of plumes, 52% of honeybees recognised an odour at six metres, decreasing to 38% at 12 metres. At the edge of plumes, which degraded more quickly, 32% of honeybees recognised a flower from six metres away and just 10% of the insects from 12 metres away. The study indicates that ozone could also affect insects’ other odour-controlled behaviours, such as attracting a mate.

“We know that air pollution has a detrimental effect on human health, biodiversity and the climate, but now we can see how it prevents bees and other pollinating insects from carrying out their key job,” said team member Professor Christian Pfrang, from the University of Birmingham. “This should act as a wake-up call to take action on air pollution and help safeguard food production and biodiversity for the future.”

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