Metabarcoding, a technique of mass DNA sequencing, allows for tracing migratory routes of insects, an understudied subject due to technical limitations. A small DNA fragment of the pollen that insects transport is used as a barcode to identify the plant species they visited previously.
This British Ecological Society-funded study shows that transcontinental pollination mediated by migrating insects is possible and, therefore, various plants located very far apart can mix.
The migration of insects is a natural phenomenon as important as it is unknown. In fact, it has only been studied in depth in some emblematic species, such as the migratory locust and the monarch butterfly. The reasons, in short, are the technical limitations to study this behaviour.
By means of this DNA metabarcoding technique, a small DNA fragment can identify the plant species to which the pollen belongs to, analogously to a barcode. By knowing the geographic distribution of the plant species detected, we can infer the place where the insect was feeding and, therefore, its migratory route.
The researchers used the metabarcoding technique to study the pollen from 47 specimens of migrating painted lady butterflies (Vanessa cardui), which have been captured on the Spanish Mediterranean coast during spring.
The analysis revealed pollen of 157 species of plants of 23 different orders; the vast majority were African and not present in Europe.
The results of this study represent an important discovery from the point of view of the plants, because it demonstrates, for the first time that the transcontinental pollination by migratory insects is possible. It is a phenomenon to be taken into account both in wild and in cultivated plants because it enables plants from very distant locations to mix.
Read more about this study at Science Daily.