Flowers represent one of nature's greatest masterpieces, for grace, beauty, colors and perfume. But air pollution can erase the very scent of flowers. In urban areas, pollination can be reduced by up to 70%, because insects would no longer be able to smell the flowers.
A study led by the University of Washington and published in the journal Science has revealed how pollution produced by human activities could block pollination.
Pollutants include human-caused noise, artificial lights and chemical pollutants.
Air pollutants such as ozone, which in the lower layers of the atmosphere is no longer protective but harmful, and the nitrate radical, dangerous during the night hours, degrade the chemical compounds that are the basis of floral perfumes, but much is still known little about how this might affect insects.
Pollution can destroy the scent of flowers
The authors of the study discovered that the nitrate radical in particular, the dominant compound during the night hours in some more polluted areas, rapidly degrades the aromatic compounds produced by primroses, making them untraceable by moths. This resulted in an average drop of 70% in visits made by insects to flowers, thus damaging their ability to reproduce.
Jeremy Chan, one of the study's authors, said the scientists decided to focus their study on the pollination of Oenothera biennis by moths.
They did this through a series of experiments both in the laboratory and in the field, highlighting how the nitrate radical, particularly dominant at night in the most polluted areas, is able to rapidly deteriorate the aromatic compounds emitted by these flowers.
"Our approach could help others study the impact of pollutants on interactions between plants and pollinators and really get at the underlying mechanisms," said J. A. Thornton, one of the study's authors.
A few years ago, another study from the University of Virginia, using a mathematical model to examine the movement of odorous molecules in the air, gave a similar result
Jose D. Fuentes, one of the authors of the study, said the odorous molecules generated by flowers in lightly polluted environments are able to travel very long distances, while in today's highly polluted places, these same molecules are able to travel a few meters
The molecules produced by car and vehicle emissions trap and destroy the fragrances emanating from the petals and floral buds, effectively canceling their scent.