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Ozone pollution makes it difficult for bees to find flowers

In addition to their struggle with habitat loss, pesticides, and climate change, bees are now facing yet another threat – ozone pollution. A new study reveals that bees and other pollinators are having difficulty locating flowers due to air pollution’s degradation of floral scents.

The extensive research involved a collaboration between the UK Centre for Ecology & Hydrology (UKCEH) and several academic institutions including the University of Birmingham.

Ozone pollution 

One of the key findings was the significant impact of ozone on floral odor plumes. Ozone was found to reduce the size of these odor plumes and significantly alter their scent. 

The most alarming revelation was the discovery that ozone pollution could reduce the ability of honeybees to identify odors by up to 90 percent.

Ozone forms at ground level when nitrogen oxide emissions from vehicular and industrial sources interact with volatile organic compounds emitted by plants, catalyzed by sunlight.

“Our study provides robust evidence that the changes due to ground-level ozone on floral scent cause pollinators to struggle to carry out their crucial role in the natural environment also with implications for food security,” said Professor Christian Pfrang, who was actively involved in the research.

Detrimental impacts

With previous studies highlighting ozone’s detrimental impact on plant growth and subsequent food production, this research further emphasizes the scale of the problem.

Dr. Ben Langford, an atmospheric scientist at UKCEH and the lead author of the study, pointed out that 75% of our food crops and nearly 90% of wild flowering plants depend, to some extent, upon animal pollination – particularly by insects. 

“Therefore, 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, for example.”

Focus of the study 

To measure the impact, the research team set up an experiment in a 30-meter wind tunnel at the University of Surrey. This allowed them observe changes in the size and structure of odor plumes in the presence of ozone. 

The experts found that certain compounds in the scent plume decayed faster than others due to ozone, leading to a significant change in the overall scent.

Floral scents

The role of floral scents is pivotal in the world of pollinators. Honeybees, for instance, associate the unique blend of chemical compounds in a flower’s scent with the nectar it provides. 

This association assists them in locating the same species of flower in later searches. But, with ozone-modified scents, the research disclosed a worrying pattern. 

At the center of scent plumes, only 52% of honeybees could recognize a scent from 6 meters away, dropping to 38% at 12 meters. Even more concerning, at the edges of these plumes, which decayed faster due to ozone, just 32% of the bees could identify the scent from 6 meters, and only 10% could do so from 12 meters.

Study implications 

Beyond the hunt for flowers, the research hints at potential disruptions in other odor-controlled behaviors of insects, such as mating.

This pivotal research was funded by the Natural Environment Research Council, which operates under UK Research and Innovation, and the findings are published in the journal Environmental Pollution.

“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 Professor Pfrang.

“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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