The world's most common cockroach is 'a monster of our own creation,' study finds

Despite its name, the German cockroach isn't from Germany. In fact, it's not really from anywhere.

Blattella germanica, the most prevalent species of cockroach on the planet, was named for specimens collected in Germany in the 1700s. But it's not native to any one country. Its only true home is inside our homes — and our workplaces, and our schools, etc.

In fact, according to a new study, its entire evolution is tied to human history. 

"It's the most widespread, yuckiest pest we can think of inside — but it's a monster of our own creation," Edward Vargo, an urban entomologist at Texas A&M University, told As It Happens host Nil Köksal.

"It's basically everywhere in the world that has buildings, but there are no natural populations of this species that we can find in nature. So it's been a mystery as to where did these come from."

Vargo and his colleagues set out to solve that mystery. Their new study, published in the Proceedings of the National Academy of Sciences, details the surprisingly rapid and successful evolutionary history of the world's most common roach.

By analyzing the genes of over 280 cockroaches from 17 countries and six continents, the researchers determined the German cockroach branched off from its closest wild relative — the Asian cockroach — about 2,100 years ago. 

That makes it "a relatively new species in biological time," Vargo said. 

"It became adapted to human built-environments and then completely lived inside of those buildings and then spread around through military conquests and commercial activity throughout the world." 

It likely spread out from southeast Asia alongside humans, the study notes, hitching rides with travelling armies, merchants and trade ships.

Essentially, everywhere humans have gone, the mighty cockroach has followed. And despite our best efforts, it's only getting mightier. 

"They've spread very rapidly, and they developed resistance very quickly against almost all insecticides that are used against them," Vargo said.

Michael E. Scharf, a retired urban entomologist from the University of Florida, welcomed the research that sheds light on what he calls "one of the most important, and long-standing, invasive pests that we have."

"As the urban entomology field seeks to understand how fast insecticide resistance builds in German cockroach populations and spreads to new locations, this new knowledge provides insights into the adaptability of the roach genome that enables such rapid changes at a population level," he told CBC in an email.