News from IBE (CSIC-UPF)
Painted Lady butterflies have a regular migratory cycle - the longest recorded in these insects. They travel from Mediterranean Europe to tropical Africa during autumn and, as a recent study led by IBE researchers has discovered, they travel back to the Mediterranean in early spring, covering an annual distance of 12,000 km across the Sahara Desert.
This conclusion, published in the journal Biology Letters, was reached after studying the natal origin of the butterflies that arrived to the Mediterranean region in early spring. To do so, the researchers analysed the stable hydrogen isotopes of the butterflies sampled in Morocco, Andalusia and Catalonia in Spain, Crete, Egypt and Israel.
The proportion of hydrogen and its stable isotope in water depends on the geographical location. When plants absorb water, this proportion is maintained; it later remains in the caterpillars that feed on these plants and, eventually, in adult butterflies. Thus, knowing the isotope content in the wings of adult butterflies, their origin can be determined. As Gerard Talavera, IBE researcher and leader of this study, explained “it is difficult to study the movement of insects by means of observations, marking or radio tracking, since there are millions of individuals and they are very small. This is why finding out where a butterfly grew up by means of stable isotope analysis turns out to be extremely useful”.
On a related note, a global citizen science project called The Worldwide Painted Lady Migration has just been launched to gather observations of the Painted Lady Migration. More information on this project is available here: http://www.butterflymigration.org. - Carlos Sierra / PRBB
Talavera, G.; Bataille, C.; Benyamini, D.; Gascoigne-Pees, M.; Vila, R. (2018) Round-trip across the Sahara: Afrotropical Painted Lady butterflies recolonize the Mediterranean in early spring Biology Letters 20180274 http://dx.doi.org/10.1098/rsbl.2018.0274
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