The butterfly that accidentally brought three other species to the Baltic Sea

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In 1991, a group of scientists decided to introduce a new butterfly specimen to an island in the Åland archipelago – an independent province of Finland in the Baltic Sea – to study how insects spread in the environment. Unexpectedly, when the study began, the researchers realized that some of the larvae (or larvae) inhabited a parasitic insect, which in turn harbored another parasitic organism and an unknown type of bacteria in the local ecosystem. The result was that on the small island of Sutunga, about a third of the area of ​​large Pantelleria, four new species were introduced instead of one.

newly studio published in the scientific journal Molecular ecology He highlighted some interesting aspects related to the introduction of this species, again with some surprise, as well as some concern.

The larvae introduced to Sutunga in 1991 were Melitia sinxia, a butterfly of the family Nymphalidae. Unbeknownst to scholars, some of them contained one parasitic wasp, The Hyposoter horticola, Which emerges from the caterpillar before it turns into a cocoon and then into a butterfly. In contrast, some parasitic wasps lived other organisms inside some parasitic wasps Parasite overgrowth Because they are parasites parasites that kill the wasp emerging from the carcass of the larva after 10 days. In addition, the females Hyposoter horticola It harbored certain bacteriaAnd Which increases the possibility that the wasp will not survive the excessive parasite due to the mechanisms that remain unclear.

The team of scientists, led by University of Helsinki researcher Anne Dobloi, noted that the species of butterfly, wasp, hyperparasite and bacteria survived thirty years after entering the island: although the four populations have declined over time, and although butterflies in particular have several periodic drops.

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Duplouy, lead author of the study, Al . said guardian This is due to the “exceptional” decrease in the population Melitia sinxia The researchers had expected to find very low genetic diversity among the butterflies studied today. On the contrary, they noted an “extraordinarily high” genetic diversity, which shows how its inhabitants managed to recover from various depressions, however, they could not fly more than 7 km, and therefore never went far from an island.

samples Hyposoter horticola With genotypes similar to those introduced at Sutonga, on the other hand, they have also been observed on another island of the archipelago, where they have never been found, and where they could have arrived due to better flying skills or because they were carried by the wind.

Duplouy said that although introducing new species to an area or reintroducing endangered species comes “with good intentions,” “we have a lot to learn” from the history of Melitia sinxia in Öland. For example, bacteria hosted by a parasitoid wasp (Wolbachia pipientis) is present in at least 40 percent of arthropod species, the most widespread group of animals on Earth, which includes insects, spiders and crustaceans: if accidentally introduced among species you don’t know, it can be harmful to their reproduction or thwart No attempts at resettlement.

At the same time, Duplouy noted that the butterflies in Sottunga are still present at the moment, but their conditions are greatly exacerbated by the long droughts associated with climate change, which in the future could cause a significant loss of genetic diversity and a more systematic decrease in their numbers, which It prevents the species from recovering as it has so far.

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