Air pollution degrades flower scent impacting pollinators

New research reveals the impact of toxic air on honeybees

By Annette J Beveridge

Pollinators have long been at risk due to insecticides, fungicides, and herbicides. These neonicotinoids are coated on seeds or sprayed onto soil and permeate the tissue of plants. This eventually affects pollen and nectar.

These harmful chemicals damage learning and memory in honey bees and also, impacts other pollinators.

According to the Wildlife Trust, honeybees which are mostly kept in hives, pollinate up to 15% of the U.K.’s insect pollinated crops.

All pollinators should be protected because without them, it is unlikely, we would be able to pollinate sufficient levels of crops to feed everyone.

There are many species of butterfly, hover, flies, bees, moths, and beetles that provides this vital service here in the UK. This service equates to an approximate £619 million worth of crops on an annual level.

New research on honey bees and ground-level ozone has recently been published and reveals additional concerns.

What is ground-level ozone?

Ground-level level ozone forms when nitrogen oxide emissions from vehicles and industrial processes react with volatile compounds released from vegetation in sunlight.

The research

Research teams from the UK centre for ecology and hydrology, (UKCEH) and the universities of Birmingham, Reading, Surrey, and southern Queensland discovered that ozone alters the size and scent of floral odour plumes released by flowers.

This reduces honeybees ability to detect odours by up to 90% …even if just a few metres away.

Professor Christian Pfrang from the University of Birmingham who collaborated on the research 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."

Research indicates that it could have a negative impact on crops.

International research had already established that ozone has a negative impact on the production of food because it damages the growth of plants.

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 reply upon for production of food, textiles, biofuels and medicines, for example."

To monitor the size and shape of odour plumes and how it changed in the presence of ozone, an 830 m wind-tunnel was used at Surrey University.

The researchers discovered that the size of the older plume decreased and the scent changed substantially as some compounds reacted much faster than others.

Pollinating insects use floral odours to locate flowers and associate the unique blend of chemicals with the amount of nectar and this learned behaviour allows them to locate the same species of flower going forward.

Training bees

In the experiment, honey bees were trained to recognise the same odour blend and then exposed to the new ozone modified odours.

Research revealed that towards the centre of the plume, 52% of honeybees recognised the odour at 6 m but this percentage decreased at 12 m to just 38%. The edge of the plumes degraded more quickly. 32% of honeybees recognised the flower from 6 m away and just one 10th of the honeybees recognised the flower at 12 m.

Ozone could also impact other behaviours which are odour-controlled such as attracting a mate.

This new research highlights the need to monitor and lower air pollution as soon as is possible if we want to protect pollinators and continue to feed everyone in the UK.

This research comes from…University of Birmingham. "Bees struggle to find flowers because of air pollution." ScienceDaily. ScienceDaily, 8 September 2023. <www.sciencedaily.com/releases/2023/09/230908125955.htm>.