If there is an insect that has become synonymous with disgust, it is the cockroach, also called cockroach. However, its genetics demonstrate an unusual capacity for adaptation.
The little creature was believed to originate from Europe. In reality, it arrived from South Asia a little over two millennia ago, genetic analysis reveals. And the insect spread so quickly because of its “affinities” with humans. Or more precisely, with human habitats, whether it is a house and its food waste or a ship leaving for a distant destination.
This last aspect did not need genetics to be observed. Since the very first scientific description of Blattella germanica in 1776 by the Swedish biologist Carl Linnaeus, it was noted that she greatly appreciated the company of humans, much to their dismay.
The team of researchers in question, led by evolutionary biologist Qian Tang of Harvard University, analyzed the genomes of 281 of these “German cockroaches” collected in 17 countries, including the Australia, Ethiopia and the United States. Comparisons between these genomes made it possible to establish that the closest cousin of the European is the Blattella asahinaiwhich can still be found in South Asia.
The separation between the two branches dates back 2100 years. Subsequently, around 1200 years ago, a sub-branch would have migrated westward, to the Middle East. And other cousins of the B. asahinai would have migrated east 390 years ago. It turns out that these moments in history correspond to times of great military and commercial movements: those of the new Muslim world 1,200 years ago, and those linked to the expansion of European colonialism in Asia 3 centuries ago — therefore suggesting how the cockroach traveled.
The study was published on May 20 in the American journal Proceedings of the National Academy of Sciences. It is an adaptable and opportunistic species, summarizes ecologist Franz Essl, of the University of Vienna: a “perfect combination of ingredients to bring success to a species in a planet shaped by humans”.
