How hoverflies connect distant plant populations across Europe

On a remote oil rig in the North Sea, an unexpected discovery has shed light on the surprising reach of one of nature’s smallest pollinators. Migratory hoverflies, often overlooked compared to bees and butterflies, are proving themselves capable of extraordinary journeys.

A new study has revealed that these insects are not just drifting across borders, but carrying vital cargo with them – pollen that helps connect ecosystems separated by hundreds of kilometers.

The research focused on marmalade hoverflies landing on a rig in the Britannia oil field, about 200 kilometers from Scotland’s coast. With no vegetation on the rig and no nearby land, the presence of pollen on the insects was striking.

Out of 121 hoverflies studied, 92 percent carried pollen grains. This demonstrates their ability to move genetic material far beyond ordinary distances, linking plant populations across vast stretches of sea.

Hoverflies spread pollen across seas

The pollen carried by the hoverflies came from up to 14 different plant species, including crops crucial to human food supply. This finding highlights the insects’ role not only in wild plant diversity but also in global agriculture. By acting as airborne couriers, hoverflies may bridge genetic gaps between isolated plant populations.

“By analyzing the pollen samples and wind patterns, we estimate that many of the hoverflies had flown from places including the Netherlands, northern Germany and Denmark – over 500km away,” said Toby Doyle, from the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall.

“The most common pollen types were common nettle, black elder and meadowsweet – but they also carried pollen from crops including vegetable, legume, cereal, nut and fruit species.”

Partners in biodiversity

The significance of these findings extends beyond pollination. Hoverflies are also natural allies in agriculture due to their diet. Their larvae consume pests such as aphids, which can damage crops.

This dual role, as both pollinators and pest controllers, means that hoverflies are highly valuable contributors to ecosystems and farming.

“By flying all over Europe – from northern islands and Norway to Spain and Portugal – these migratory hoverflies are probably providing a range of vital benefits both to humans and to plant biodiversity,” noted Dr. Eva Jimenez-Guri.

“As well as being beneficial pollinators, marmalade hoverflies are also natural pest controllers – eating prey including aphids, helping to reduce crop damage.”

Following the wind

The research team observed that hoverflies landed on the oil rig during both their northward journeys in early summer and their southward return migrations later in the season. This revealed that the rig served as a waypoint at multiple stages of their travels.

Rather than flying continuously without strategy, these insects carefully time their departures. They wait for favorable winds, using natural air currents as supportive pathways.

Once the wind direction matches their intended route, they take off, conserving valuable energy while covering vast distances that would otherwise be impossible for such small fliers.

Their stopovers on offshore platforms likely serve as much-needed resting points, or perhaps as failed attempts to locate food in barren steel landscapes.

This behavior paints a picture of resilience and adaptation. Despite the absence of flowers at sea, hoverflies persist, showing just how determined and resourceful they are during migration.

Hoverflies, pollen, and gene flow

The study’s findings emphasize the broader ecological role of migratory hoverflies. By transporting pollen across seas and countries, they contribute to long-distance gene flow among plants, a process essential for biodiversity.

This connectivity may influence ecosystems at scales that are much larger than previously recognized.

“The results highlight the important role of migratory hoverflies in long-distance gene flow. The next stages of investigation should look at the ecological and agricultural implications of this phenomenon at the continental scales at which these species move,” said study co-author Dr. Karl Wotton.

The importance of migratory hoverflies

The Royal Society-funded research highlights the hidden importance of migratory hoverflies. Though small and often overlooked, these insects play an extraordinary role in sustaining ecosystems and agriculture.

Their long flights across seas carry pollen that connects distant plant populations, strengthening biodiversity and food security. Each journey demonstrates nature’s intricate balance, where even the smallest wings help maintain global networks.

Unnoticed by most, hoverflies provide quiet yet powerful services, linking fields, forests, and crops separated by vast distances. Their persistence shows how life depends on delicate travelers, ensuring plants thrive, crops flourish, and ecological systems remain resilient across continents and oceans.

The study is published in the Journal of Animal Ecology.

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