Air pollutants put pollination in check

Atmospheric pollutants harm human health, and new research has just confirmed that they also put the arrival of food on the table at risk, because these agents are making it difficult to pollination at a global level.

The study, published this Thursday in the journal of the American Association for the Advancement of Science (AAAS), bases its conclusions on a series of meticulous experiments carried out since 2017 by researchers at the University of Washington State with hawkmoths that pollinate the flowers of pale evening primrose, ‘Oenothera pallida’.

Researchers have shown that the alteration of the floral aroma produced by two of the most common atmospheric pollutants, tropospheric ozone (O3) and nitrogen dioxide (NO2)discourages pollinators from approaching the flowers in search of food.

Origin of contaminants

Both pollutants come from gases emitted in combustion processes related to traffic (especially automobile vehiclesand especially diesel engines) and with transportation in general, as well as in high-temperature industrial facilities and electricity generation of fossil origin.

Its negative impact on vegetation, in addition to human health, has been previously proven in numerous studies: not very high but persistent concentrations can act as a weakening agent or that predisposes vegetation to certain diseases, while in significant accumulations causes premature death of leaves.

Through field observations in eastern Washington state and laboratory experiments, the authors of this study found that NO2 rapidly degrades specific floral scent compounds, making flowers undetectable to nocturnal pollinators.

The deterioration of the aroma due to these contaminants causes the visit of pollinators to be reduced by more than 70%, which weakens the plant’s fruiting process.

The most harmful

According to the results, the nitrogen dioxide It is even more reactive than tropospheric ozone when it comes to altering the components of the floral odor that makes moths recognize the flower and come to it to feed.

What’s more, scientists have seen how high concentrations of NO2 directly eliminate the arrival of pollinators to the flower.

Global atmospheric models of floral scent oxidation due to these pollutants developed by scientists reveal that most urban areas have levels of O3 and NO2 high enough to significantly reduce the distances at which pollinators can perceive flowers.

“These results illustrate the impact of anthropogenic contaminants, caused by human action, on the olfactory capacity of an animal and indicate that such contaminants may be critical regulators of global pollination,” the authors warn.