Pollution impact on nighttime pollinators

Anthropocene just posted a summary of a research study published in Science, “Olfaction in the Anthropocene: NO3 negatively affects floral scent and nocturnal pollination.” Science. Feb. 8, 2024. This goes along with other posts on animal perception (and human’s inability to do same), as well as looking at unintended consequences from human actions – part of climate justice.

This study is all about moths, flowers and how flowers ‘communicate’ to pollinators about where to find the ‘good stuff’. Through meticulous research the team identified both the methodology of scents traveling several kilometers in the desert and how pollution is disrupting that sequence.

Here’s the set up … Pollination is not only important, it’s essential for life as we know it on earth.

Pollination from animals such as insects is critical to supplying many of the fruits and vegetables in our kitchens. It plays a role in reproduction for around 85% of all flowering plants. This vital process is threatened by everything from pesticides to domestic beekeeping.

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Air pollution impacts nighttime pollinators. First, because they cannot see in the dark they smell the good stuff. Second, specific pollution, NO3 (nitrate), is worse at night because sunlight breaks down the pollutant. A double dose of problems

“Much of the concern about the loss of the world’s pollinators revolves around the declining numbers of bees, butterflies and other insects. But what if a big part of the problem is that the bugs we do have are flying blind?”

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Researchers went through a series of experiments to discover the methodology and any problems

To understand what drew the moths to the flowers, first the researchers identified the chemical makeup of the scent. In a lab, they exposed two species of hawkmoths wired to instruments that detect electrical activity in the insects’ antennae, to see which molecules were triggers. The moths were particularly tuned to two different flavors of monoterpenes, a class of chemicals found in plant oils. In the natural world, these chemicals are an ideal way to create a chemical trail. They evaporate quickly in the air. Moths, whose antennae are roughly as sensitive as a dog’s nose, can pick up the scent several kilometers away from a flower.

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To verify preliminary findings, back to the desert for real life trials, and the culprit remained nitrates in night air.

To see how this translated into changes in moth behavior, the researchers tested moths’ attraction to flowers with natural odors versus ones altered to simulate exposure to urban levels of NO₃, first in a wind tunnel and then in the eastern Washington desert. The effect was dramatic. In the desert, nighttime visits to artificial flowers with the pollutant-altered chemistry fell by 70%. That would translate into roughly 28% less fruit forming from those flowers, the researchers reported last week in Science. “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 Riffell.

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The authors acknowledge that a solution to the problem is not immediately forthcoming, but if a problem can be identified, it’s easier to solve. Nitrates in the air will have increasing problems for listed hot spots.

Hotspots included much of Europe, the Middle East, India, eastern China, and North America. In many of these places, the distance from which an insect can pick up the smell of a flower has fallen more than 75% compared to preindustrial times, the scientists found.

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Animals perceive the world differently than we do, obviously. Our human actions have unintended consequences that build up, pile up, and eventually breakdown systems we rely on – like pollination, and those nighttime creatures that perform such a necessary activity. The better we understand the earth and our interactions on it, the less we damage – sadly, we often learn from the craters of our damage.

Featured image generated by Edge copilot