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The pollination night shift

A new Danish study shows that moths play an unexpected and important role as bee ‘assistants’ by pollinating flowers. The insects, which are perceived as a scourge to textiles in people’s homes, actually contribute to biodiversity and sustain important plant species. Researchers at Aarhus University have discovered an addition to the cast list of the story of the birds and the bees. Literally.

[Translate to English:]
A moth on a red clover flower head (Trifolium pratense). Photo: Jeff Kerby.

Since antiquity, people have been talking about ‘the birds and the bees’ in one way or another. But despite the importance of the theme and its retelling through the history of mankind, we actually don’t know much about insects and the pollination of the planet's crops and wild plants.

We do know that insects are better than their reputation. In any case, their importance has become clearer to us in recent decades, as their role as pollinators garners more and more attention. Unfortunately, this attention follows news that the world's pollinating insects are under increasing pressure from changes in climate, landscapes and habitats.

Due to this, several research groups around the world have focused their efforts on finding out more about how the earth’s plants are pollinated, and by whom. Because the tale has two main characters, and they’re both dependant on each other.

In an article in the scientific journal Biology Letters, a research project in Aarhus has demonstrated that there is an insect species that might need to be let out of the doghouse (and the closet), and take its place on the pollination cast list. Because in the Swiss Alps, the research group has filmed a moth species that, after dark, plays the role of pollinator to one of the most important wild plants in the region.

Unexpected visitors
Jamie Alison, a postdoc at the Department of Ecoscience, is the first author of the article ‘Moths complement bumblebee pollination of red clover: a case for day-and-night insect surveillance’. He has spent an entire summer photographing a flower meadow, around the clock, to obtain new data and expand our knowledge on the interplay between plants and pollinators. He set up several cameras over the plant species red clover, which is well known due to many years of research across Europe and North America. The plant was an obvious choice for the team to find out if automatic camera surveillance would show something new.

And it did. The many photos captured the large yellow underwing, a type of moth that is also quite common in Denmark, as it pollinated the clover in the late evening and early morning.

"This discovery is important because it expands the group of well-known pollinators of red clover, where previously we have almost exclusively seen different bee species as pollinators. It’s also important because it shows that this method can collect data that will help us truly understand which insect species act as pollinators - especially at night," says Jamie Alison.

There are several thousand different moth species in Europe, including the large yellow underwing, which is quite common in the European countryside. This species is not commonly regarded as an important pollinator, but there are examples such as Darwin's Hawkmoth, which is famous for having a particularly long tongue to collect nectar from special orchids in Madagascar.

The project has not only shown that moths supplement pollination by bees and other insects. It has also shown that the method of setting up cameras for a longer period of time can provide completely new information that would otherwise be almost impossible to detect. A total of almost 165,000 photos were taken over the summer in the Alps, and only 44 of those had pollinators in them.

"It shows how few opportunities each flower has to be pollinated, and how stubborn you have to be to observe it. But our cameras were successful, and the project has demonstrated how large amounts of imagery can shape the future of pollinator research. The next step is to use artificial intelligence to identify insect species automatically and in real time. This will help to unravel even more pollination mysteries," says Jamie Alison.

Click here to read the article on the Biology Letters website.

Contact:
Postdoc Jamie Alison,
Department for Ecoscience,
Email: jalison@ecos.au.dk 

Type of study

A study of the pollination of red clover Trifolium pratense in Swiss alpine meadows using insect surveillance cameras.

External collaborators

ETH Zürich, Switzerland

External funding

Foundations, funders. This research was funded through the 2019–2020 BiodivERsA joint call for research proposals, under the BiodivClim ERA-Net COFUND programme, with the funding organizations Innovation Fund Denmark (grant no. 0156-00022B), the Department of Science and Innovation Republic of South Africa, the Research Council of Norway, the Swiss National Science Foundation (grant no. 20BD21_193809), the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning and the German Research Foundation.

Link to the scientific article

TBC

Contact information

Jamie Alison jalison@ecos.au.dk