Unexpectedly, this butterfly flew more than 7,000 km to South America, escaping the cold European winter.

They decipher the route and origin of migrating butterfliesJean Paul Grandmont

International team led by Higher Council for Scientific Research (CSIC) documented a transoceanic flight of over 4,200 km, completed Carderas butterflies (Vanessa Cardui), which is a record for an insect. The study was published in the journal Natural communications ( )documentation a journey that lasted from five to eight days, which was energetically possible thanks to the help of the trade winds. And perhaps this trip could be the longest, up to 7000 kmbetween insects and very excellent these are monarch butterflies (Danaus plexippus ), which was considered one of the most spectacular in the world.

Connected

Researchers from Botanical Institute of Barcelona (IBB)a joint centre between CSIC and the Consorci Museu Ciències Naturals in Barcelona, ​​and Botanical Institute of V. Shafer (Poland), from University of Ottawa (Canada), from Institute of Evolutionary Biology (IBE, CSIC-Pompeu Fabra University) and Harvard University (USA).

A specimen of the Carder butterfly (Vanessa cardui), which has a migration route of over 4,000 km.

In October 2013 Researcher at the Barcelona Botanical Institute CSIC Gerard Talavera andidentified several carder butterflies in Atlantic beaches French GuianaThese sightings were quite unusual, as the species had not been recorded in South America. Where did they come from?

New methods solve the mystery

A interdisciplinary approach allowed us to decipher the route and origin of these butterflies. Two initial hypotheses were or came from North Americawhere are the nearest cities located, or Africa or Europe crossing the Atlantic. Analysis wind paths demonstrated a steady direction from West Africa, which confirms the second possibility.

When studying genetic diversity butterflies, after collecting samples from populations from all continents, it was established that South American specimens relating to the population of Europe and Africa. The researchers also analyzed Pollen DNA what the butterflies carried on their bodies, identifying two plant species endemic to tropical Africa, demonstrating that the butterflies visited the region.

Finally, the team analyzed stable isotopes of hydrogen and strontium from butterfly wings. They retain isotopic signals typical for that location. where they were raised in the larval phase, like human teeth, which allows draw a conclusion about his native origin. It was concluded that its origin was most likely in Western European countries such as France, Ireland, the UK or Portugal. This may add another 3000 km to the migration route. “It’s a remarkable milestone for such a small insect,” he explains. Clement Bataille, professor at the University of Ottawa in Canada and co-author of the paper. “We usually see butterflies as symbol of the fragility of beautybut science shows us that they can do it incredible feats“, basic moments Roger Vila, researcher at the Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) and co-author of the study.

With the help of the winds

The researchers modeled energy costs of travel and they calculated that the flight across the ocean This lasted from 5 to 8 days. This was made possible thanks to favorable wind currents. “Butterflies could only make this flight with the help of a strategy that alternated between minimal effort avoid falling into the sea, which is facilitated by the rising winds, and active flightwhich requires more energy consumption. We expect that windlessbutterflies could fly maximum 780 km until they use up all their fat and therefore their energy,” he says. Eric Toro-Delgadoone of the authors of the article.

The researchers emphasize the importance of the Sahara air layer as potential air booster lineThese wind currents, which prevail throughout the year, carry large quantities of Saharan dust from Africa to America and They participate in important biogeochemical cycles. However, the proportion of transported biological components, including living organisms, requires more in-depth study.

Millions of insects cross the Pyrenees every year via a 30-metre pass.

Migration in the context of global changes

This finding suggests that there may be air corridors natural ones that connect continents and that can be foundpromoting the dispersal of species on a much larger scale than previously thought. “This discovery opens up new perspectives on the ability of insects to disperse over long distances, even across seas and oceans. We may be underestimating the frequency and impact of these movements on our ecosystems,” says Gerard Talavera, who led the study. “Throughout history, migratory phenomena have played an important role in determine the distribution of species “as we see them today,” he adds.