Moths Are the Unsung Heroes of Pollination

Farmers around the world plant red clover in their fields, using it as a cover crop to help improve soil health and as food for livestock. And, for nearly a century, scientists have believed that bees are solely responsible for pollinating this important agricultural plant.

Now, new research suggests there’s another, often-overlooked player in the red clover pollination game: the moth. These insects are seeking nectar at night, long after the bees have turned in for the evening.

The research, published in the journal Biology Letters earlier this month, focuses only on red clover (Trifolium pratense). But scientists suspect this is just the beginning of our understanding of the important role moths play in pollination.

“I’d wager that moths are thanklessly pollinating hundreds of less famous flower species across Europe,” says Jamie Alison, an ecoscientist at Aarhus University in Denmark and one of the study’s authors, to New Scientist’s Gary Hartley.

To spy on the plant’s nectar-seeking visitors, scientists set up 15 time-lapse cameras capturing images of 36 red clover flowers in the Swiss Alps from June to August 2021. Six of the devices took photos every five minutes, while the other nine snapped pictures in the afternoons and evenings.

At the end of the study period, scientists had more than 164,000 photos to sift through, including 44 that captured insects pollinating the plants. After analyzing the images, they found that 61 percent of the red clover’s visitors were bumblebees and 34 percent were moths, mostly large yellow underwings. Butterflies, wasps and other species of bees made up the remaining 5 percent of visits.

Intriguingly, the moths’ visits were concentrated in the middle of the night, between roughly 1 a.m. and 3 a.m. They also appeared to spend more time foraging among the red clover than the bees did.

Since it would be time- and labor-intensive for a scientist to keep watch over plants for months at a time, the study was also a successful test of using cameras to surveil pollinators, the researchers write in the paper. A camera can be a “very beneficial tool that helps to supplement other more ‘traditional’ methods,” says Richard Walton, a biologist at University College of London who was not involved in the study, to New Scientist.

“This will allow people to set up the equipment to focus on specific plants or larger plant patches and leave the location to allow natural interaction between plants and pollinators to happen,” he says.

The researchers hope to replicate their findings in other parts of Europe, but, for now, their work suggests “the role of nocturnal moths as pollinators of crops has largely been neglected,” as Daichi Funamoto, a biologist at the University of Tokyo who was not involved in the study, tells ScienceNews’ Jake Buehler.

“Future studies will reveal many plant species that are thought to be dependent on pollination by diurnal insects are indeed pollinated by nocturnal moths, to some extent,” Funamoto says.

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