Cienciaes.com: The amazing journey of the lady. We spoke with Gerard Talavera.

2024-09-02 09:58:57

It is interesting to think that some delicate butterflies, discovered on a beach in French Guiana, show that they arrived there after a journey of at least 4,200 kilometers to Africa, flying over the waters of the Atlantic Ocean. And it is possible that the distance traveled is even greater, considering that these insects began their long journey in Europe, crossing the Mediterranean Sea and flying over the Sahara, in a journey that at least 7,000 kilometers. This amazing odyssey is made by the “painted lady” butterfly (Vanessa cardui), also known as the “cardboard butterfly”. But no less surprising, perhaps, is discovering how an international group of researchers, by Gerard Talavera, researcher at the Institut Botànic de Barcelona (CSIC–CCNB), managed, after ten years of study, to uncover the amazing journey of these few butterflies found in French Guiana.

The story begins on October 28, 2013, when a member of the research team discovered twelve butterflies scattered on the beach in French Guiana. Butterflies have damaged wings and are tired; some could not escape, as if they had made a long weary flight. Insects belong to species Vanessa carduiA common butterfly in Europe and North America, but unknown in South America. The researchers collected three specimens and, convinced that the species was not native to the area, wondered how they got there.

Gerard Talavera said during the interview that two origins are possible for those butterflies. One is that its origin is North America, where it is common. A second hypothesis is that these butterflies crossed the Atlantic Ocean from West Africa, traveling at least 4,200 kilometers and possibly up to 7,000 kilometers if they originated in Europe.

To confirm this amazing journey, scientists used a combination of new methods.

First, they analyze wind patterns using a model HYSPLIT of the NOAAwhich allowed them to reconstruct the possible route of the butterflies from Africa to South America. The results show that during the 48 hours before the butterflies were caught, the winds were exceptionally favorable to facilitate their transatlantic dispersal from West Africa.

Genetic analyzes were performed on the collected butterflies, comparing them DNA with samples of Vanessa cardui from North America, Europe and Africa. Genetic results show that South American butterflies are genetically related to Euro-African populations, ruling out a North American origin. This finding was supported by the analysis of pollen grains found on butterflies, which revealed the presence of plant species limited to the Sahel in West Africa, forcing the hypothesis of an African origin.

The researchers also analyzed stable isotopes of hydrogen and strontium in the butterflies’ wings to identify the source of their birth. We know that butterfly caterpillars feed on plants that grow on the ground and that these provide themselves with the amount of isotopes in the environment. Analyzing those isotopic signatures, the researchers discovered that the butterflies may have originated in Western Europe or West Africa, where they evolved before being transported by wind towards the Atlantic and eventually South America.

This study not only documents one of the longest transoceanic flights recorded for insects, but also provides a deeper understanding of the dispersal potential of insects. It is estimated that butterflies complete their transatlantic journey in 5 to 8 days, aided by easterly trade winds. Without this help, the trip would have been impossible, because the butterflies’ energy reserves would have allowed them to fly a maximum of 780 kilometers without fuel.

Gerard Talavera explains that, as we continue to explore these phenomena, it is possible that we will discover more examples of how insects, regardless of their size, have a great impact on the global ecosystem and the distribution of species.

I invite you to listen to Gerard Talavera, researcher at the Institut Botànic de Barcelona (IBB), CSIC–CCNBBarcelona.

References:

Suchan, T., Bataille, CP, Reich, MS A transoceanic flight of over 4200 km by lady butterflies. Nat Commun 15, 5205 (2024).