A new look at how ozone impacts honeybees’ ability to pollinate

Building on work published at the start of 2021, a team from UK Centre for Ecology & Hydrology (UKCEH) and the Universities of Birmingham, Reading, Surrey and Southern Queensland, have used  a 30m long wind tunnel to examine the effects of ozone on bee’s ability to pollinate.

They found that ozone substantially changes the size and scent of floral odour plumes given off by flowers, and that it reduced honeybees’ ability to recognise odours by up to 90% from just a few metres away.

Ground-level ozone typically forms when nitrogen oxide emissions from vehicles and industrial processes react with VOCs emitted from vegetation in the presence of sunlight.

The researchers used the wind tunnel at Surrey University 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 it provides, allowing them to locate the same species in the future.

The research showed that towards the centre of plumes, 52% of honeybees recognised an odour at 6m, decreasing to 38% at 12m. At the edge of plumes, which degraded more quickly, 32% of honeybees recognised a flower from 6m away and just a tenth of the insects from 12 m away.

There are implications that ozone could also affect insects’ other odour-controlled behaviours such as attracting a mate.

Professor Christian Pfrang from the University of Birmingham who was also a co-author on the earlier work said: ‘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.’

Dr Ben Langford, an atmospheric scientist at UKCEH who led the study said: ‘Some 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.’