Research exposes devastating impact of air pollution on pollination

By Sharin Hussain via SWNS

Pollution is disrupting flower species that pollinate at night, warns a new study.

Researchers found that a chemical in the air is affected by pollution, reducing the scent cues that night-time pollinators need to locate flowers.

The burning of gas and coal from cars, power plants and other natural sources like wildfires and lightning creates a chemical reaction to produce nitrate radicals (NO3) in the atmosphere which block a flower's scent.

Around 180,000 species of flowering plants rely on pollinators and more than 70 species of pollinators are endangered or threatened.

Biology Professor Jeff Riffell, of the University of Washington (UW) in the US, said: “The NO3 is really reducing a flower’s ‘reach’ — how far its scent can travel and attract a pollinator before it gets broken down and is undetectable.

“Pollution from human activity is altering the chemical composition of critical scent cues, and altering it to such an extent that the pollinators can no longer recognize it and respond to it.”

The findings, published in the journal Science, come from a study centered on the pale evening primrose, often grown across the western US in dry environments.

The white flowers the team gathered in eastern Washington give off a scent that attracts a range of pollinators like nocturnal moths, one of its most important pollinators.

Researchers found that reacting with NO3 nearly eliminated certain scent chemicals.

Moths can detect scents from miles away similar to dogs and smell several thousand times more strongly than humans can.

The white-lined sphinx and the tobacco hawkmoth were studied using a wind tunnel and a computerized odor stimulus system.

Both easily detected the flower but once NO3 was introduced, the tobacco hawkmoth dropped down to 50 percent and the white-lined sphinx, a popular pollinator for this flower, could not find it at all.

The team found that moths visited a fake flower emitting an unaltered scent as often as they visited a real one.

But, if they treated the scent first with NO3, moth visitation levels dropped by as much as 70 percent.

Their findings show that the sunlight degrades NO3 during daytime pollution on the wildflower.

The areas most likely to have significant problems with plant pollinators include western North America, much of Europe, the Middle East, Central and South Asia, and southern Africa.

Professor Joel Thornton, of UW, added: “Our approach could serve as a roadmap for others to investigate how pollutants impact plant-pollinator interactions and to really get at the underlying mechanisms.

“You need this kind of holistic approach, especially if you want to understand how widespread the breakdown in plant-pollinator interactions is and what the consequences will be.”