‘German’ cockroaches most likely came from India around 2,000 years ago, say researchers

This writer has an unreasonable(?) fear of cockroaches. Any views shared here are hers alone and do not reflect the platform’s or general humanity’s sentiments on the insect.

Let me start off by asserting that roaches are creatures with ‘very’ limited real-world use, put on Earth purely to torment us. There are few things as horrible as watching that nasty bug skittering across your kitchen in the middle of the night. And while many of us blamed the British for bringing roaches to India over 200 years ago, a new study indicates that this couldn’t be further from the truth.

Today, roaches are striking terror in every continent of the world except for Antarctica (one reason to move there). German cockroaches (Blattella germanica), in particular, are among the most common household pests worldwide. Chances are, if you see a light brown coloured roach with two dark stripes on its back in some public place, it’s a German cockroach.

But what’s puzzling about these insects is that as commonplace as they are in human-built structures, they’re completely absent from any natural habitats. This is what drove scientists to dig into the subject and determine once and for all the story behind the origin and near world dominion of these pesky species. And the revelations are gut punches.
German cockroaches evolved in India?
Scientists sampled DNA from 281 German cockroaches from 17 countries across all six human-inhabited continents. What they found was that, despite their names, they had very little European in them and were actually more desi.

The genetic makeup of the German cockroach was nearly identical to its Asian counterpart (Blattella asahinai) from the Bay of Bengal. More specifically, over 80% of their samples matched the Asian ones perfectly, with just the remaining 20% differing.

As per the study’s authors, these ‘German’ roaches evolved from Blattella asahinai roughly 2,100 years ago, likely by adapting to human settlements in India or Myanmar! Like many other species, B. asahinai migrated from Indian fields to buildings as farmers began clearing their natural habitat, becoming more and more dependent on humans.
But how did they spread world-wide?
Time for the second gutting. Cockroaches did not hike everywhere themselves, and mainly hitched a ride with us. Yep.

Another DNA analysis revealed two routes that the bugs might’ve taken. The first one was to West Asia around 1,200 years ago, “coinciding with various Islamic dynasties”. The second one was about 390 years ago, “coinciding with the European colonial period,” probably aided by the Dutch and British East India Companies. The German cockroach did not appear anywhere close to the country until around 270 years ago.

The progress we made in terms of transport, like the steam engine, trade globalisation and the plumbing and heating provided in houses, all might’ve made it very easy for the cockroach to colonise the entire world between the late 1800s and early 1900s.

However, being public enemy number one to humans wasn't exactly a recipe for success. To survive, these roach invaders had to become masters of disguise. The German cockroach took to the night and began to avoid well-lit areas. Interestingly, they ditched using their wings for flight, but kept them around anyway (probably just to spite me).

What makes these roaches even more troublesome is their ability to quickly become immune to the bug sprays we use. In just a few short years, they can develop resistance, making it tough to find new ways to stop them. Unfortunately, coming up with new roach-killing ingredients is expensive and takes a long time, what with all the safety checks and registrations involved.

The only bright spot in this all is that understanding how they’ve evolved will help us develop new strategies to control them. Gaining more intel on how resistance emerges in them does give us better ammunition to eliminate them.

The findings of this study have been detailed in Proceedings of the National Academy of Sciences and can be accessed $4.