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Scientists find human activity essentially blocks 'reach' of flowers to pollinators: 'Altering the chemical composition of critical scent cues'

"Altering it to such an extent that the pollinators can no longer recognize it and respond to it."

"Altering it to such an extent that the pollinators can no longer recognize it and respond to it."

Photo Credit: iStock

In the world of pollination, it's often said that bees work the day shift while moths take the night watch. However, recent findings suggest there's more to the night shift than meets the eye — or nose. As nocturnal pollinators navigate through the darkness, they encounter a surprising adversary: nighttime air pollution.

What's happening?

The decline in nighttime pollination is linked to the interference caused by nighttime air pollution, particularly nitrate (NO3). Nitrate disrupts the scent cues released by flowers that guide pollinators to them. Research conducted in Eastern Washington reveals that the presence of NO3 in the air significantly impairs the effectiveness of scent cues, reducing the ability of insects like hawkmoths to locate flowers by up to 70%.

"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," said Jeff Riffell, a neurobiologist and ecologist at the University of Washington, said, according to Anthropocene

He added: "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."

Why is declining pollination concerning?

Pollination is a fundamental process that sustains ecosystems and agriculture, contributing to the reproduction of around 85% of all flowering plants. The decline in pollination poses a severe threat to global food security and ecosystem stability. 

Furthermore, the disruption of pollination by air pollution exacerbates existing challenges faced by pollinators. 

One of the major challenges pollinators face is habitat loss. As we develop more land for housing and industry, we're reducing the natural spaces where pollinators can live and find the variety of plants they need to survive. For instance, the Butterfly Pavilion is working with property developers to create pollinator districts, which are areas designed to conserve pollinator populations and educate residents about their importance.

Another significant challenge is pesticide exposure. These chemicals, designed to protect crops from pests, can also harm nontarget insects like pollinators. The unchecked use of such insecticides could potentially lead to a decline in pollinator populations, which in turn affects food production. 

What is being done about air pollution and pollination?

Addressing the issue of nighttime air pollution's impact on pollination is crucial to helping pollinators, our health, and the environment's health.

Scientists emphasize the need for comprehensive investigations into the relationships between pollutants and plant-pollinators. 

"Our approach could serve as a road map for others to investigate how pollutants impact plant-pollinator interactions and to really get at the underlying mechanisms," said Joel Thornton, an atmospheric scientist from the University of Washington.

Additionally, initiatives to reduce air pollution from sources such as vehicle engines and wildfires can mitigate its detrimental effects on pollination. Individuals can also contribute by advocating for policies aimed at reducing air pollution and supporting sustainable practices that minimize environmental harm. 

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