BUTTERFLY -STUDENTS- BOULEVARD : OCEANIC GLOBAL ESSAY

 

LIGHT TRAVELERS : On the wings of a butterfly - an ocean crossing :

Early one morning in late October 2013, Gerard Talavera, an entomologist, noticed something unusual - a flock of painted lady butterflies stranded on a beach in French Guiana.

The painted lady is a butterfly with a broad range, but it isn't found in South America, Yet there they were in the sand of the continent's eastern shores, their wings riddled with holes.

Judging by their condition, Dr. Talavera, with the Institut Botanic de Barcelona in Spain, guessed they were recovering from a long flight.

The insect routinely crisscrosses the Sahara on the track from Europe to sub-Saharan Africa, covering up to 9,000 miles, or almost 14,500 kilometers. Could they have also made the 2,600-mile trip across the Atlantic without any place to stop and refuel?

FOLLOWING the long-range movements of insects is challenging. Tools like radio-tracking devices are too large for insects' small and delicate frames, and radar allows for monitoring only of specific locations.

In 2018, Dr. Talavera developed a way to use a common genetic sequencing tool to analyze pollen DNA.

Pollen grains stick to pollinating insects when they feed on nectar from flowers. Dr. Talavera used a method called DNA metabarcoding to sequence the pollens' DNA and determine which plants they came from.

Later, the DNA could be traced to geographical flora to chart the insect's path.

In a new paper, Dr. Talavera and his team describe a crucial clue to cracking the mystery of the stranded butterflies :

Pollen clinging to the butterflies in French Guiana matched flowering shrubs in West African countries. These shrubs bloom from August to November, which matches the timeline of the butterflies' arrival. 

That suggested the butterflies had crossed the ATLANTIC.

Researchers sequenced the butterflies' genomes to trace their lineage and found they had European -African roots. This rules out the possibility that they had flown over land from North America.

Then, they were able to confirm that the butterflies' natal origins were in Western Europe, North Africa and West Africa.

The World Students Society thanks Monique Brouillette.