Bees have serious problems living and working in polluted environments such as those caused by combustion vehicles and some industries. This statement seems obvious, almost truism, but studies like the one published this week by British experts were needed to prove it with data.
After various modeling and field tests, the team led by Ben Langford, from the United Kingdom Center for Ecology and Hydrology (UKCEH), concludes that air pollution drastically reduces the ability of insects such as bees to pollinate because it degrades the aroma of flowers, which affects the bees' ability to find them. The results of this work have been published (online edition October 4) in the Environmental Pollution journal.
A research team made up of experts from the UKCEH and the Universities of Reading, Surrey, Birmingham and South Queensland discovered that, in particular, ozone that forms and accumulates in the lower layers of the atmosphere substantially changes the size and the aroma of columns of floral scent. In contaminated environments, the ability of bees to recognize odors was reduced by up to 90% from just a few meters away, the authors of the research indicate.
Ben Langford points out that the new research indicates that ozone is likely having a negative impact on wildflower abundance and crop yields. In a parallel view of the subject, it should be remembered that several previous international studies have already established that ozone has a negative impact on food production because it damages plant growth.
"About 75% of our food crops and almost 90% of our wildflower plants depend, to some degree, on animal pollination, particularly by insects. Therefore, understanding what negatively affects pollination, and how, is essential to help us preserve the critical services to which we respond, for example, for the production of food, textiles, biofuels and medicines", says Professor Langford in a note released by the UKCEH.
James Ryalls, a professor at the University of Reading and co-author of the study, points out that the data now presented "provide clear evidence of how ozone pollution can reduce pollinator visits to flowers."
The researchers used a wind tunnel to monitor how the size and shape of the odor plumes changed in the presence of ozone. In addition to decreasing the size of the odor column, the scientists discovered that the odor of the column changed as certain compounds reacted faster than others.
The bees, which were trained to recognize the same mixture of odors, were then exposed to the new ozone-modified odors. Pollinating insects use floral odors to find flowers and learn to associate their unique mix of chemical compounds with the amount of nectar they provide, allowing them to locate the same species in the future.
The research showed that in the center of the columns, 52% of the bees recognized a scent at six meters, decreasing to 38% at 12 meters. At the edge of the plumes, which were degrading more quickly, 32% of the bees recognized a flower 6 meters away and only a tenth of the insects 12 meters away.
The researchers say their findings indicate that ozone could also affect other odor-controlled behaviors in insects, such as their ability to attract and find a mate. Last year, the same research team published the first study to find that common air pollutants, including ozone and diesel exhaust, had a negative impact on pollination in the natural environment.
