The Times Australia
The Times World News

.
The Times Real Estate

.

revealing the true origins of the not-so-German cockroach

  • Written by Theo Evans, Associate Professor of Applied Entomology, The University of Western Australia
revealing the true origins of the not-so-German cockroach

German cockroaches thrive in buildings all over the world[1]. They’re one of the most common cockroach species, causing trouble for people both here[2] and overseas. But in nature, they’re nowhere to be found.

Just how this urban pest evolved and populated our dwellings was unknown – until now[3].

We used DNA sequencing to study the German cockroach (Blattella germanica) and trace its origins back to east India and Bangladesh.

It’s a fascinating story about how humans enabled the evolution and spread of one of our most hated pests.

A German enigma

The spotlight fell on the star of our story in eastern Europe when it was spotted in army food stores during the Seven Years’ War (1756–63). Each of the opposing forces named the cockroach after the other – the Russians called it the “Prussian cockroach”, while British and Prussian soldiers called it the “Russian cockroach”[4].

Then in 1767, Swedish biologist Carl Linnaeus classified and named the species (Blatta germanica). Blatta is Latin for “avoids the light” and germanica because the specimens he examined were collected in Germany. (The genus was later changed to Blattella to group the smaller varieties of cockroaches together.)

Eventually scientists discovered related species, with similar anatomy, in Africa and Asia. They variously suggested the German cockroach could have first evolved in either Africa[5] or Asia[6], before going on to dominate the world.

But they had no way to test their theories. We do.

Enter gene sequencing

We took DNA samples from 281 cockroaches in 17 countries around the world.

Then we compared the DNA sequences for one particular genetic region, called CO1. This is known as “DNA barcoding[7]”.

When we compared the German cockroach with similar species from Asia, we found a match. The sequence of the German cockroach was almost identical to that of Blattella asahinai from the Bay of Bengal.

More than 80% of our German cockroach samples matched perfectly. The remaining 20% barely differed.

This means the two species diverged from one another just 2,100 years ago – an eyeblink in evolutionary terms.

A female German cockroach and her babies
German cockroaches have a high reproductive rate. Matt Bertone and Coby Schal of North Carolina State University

From the Bay of Bengal to the world

We think B. asahinai adapted to living alongside people after farmers cleared their natural habitat, just as other species have done[8].

So the ancestors of B. asahinai moved from Indian fields into buildings and became dependent on humans[9]. But how did they then spread across the world?

To answer this question, we analysed another set of DNA sequences from the cockroach genome.

This time we studied DNA sequences known as SNPs (single nucleotide polymorphisms[10]). Using our samples from 17 countries across six continents, we were able to work out how the German cockroach spread from their native lands and around the world.

The first wave of migration emerged from the Bay of Bengal around 1,200 years ago and travelled westwards. It’s likely the cockroaches hitched a ride with the traders and armies of the expanding Islamic Umayyad and Abbasid Caliphates.

The next wave moved eastwards around 390 years ago into Indonesia. They probably travelled with European trading companies, such as the British East India Company[11] or the Dutch East India Company[12]. Several such companies traded across South East Asia and back to Europe from the beginning of the 17th century.

Our research suggests German cockroaches arrived in Europe about 270 years ago, which matches the historical records from the Seven Years’ War.

The German cockroach then spread from Europe to the rest of the world about 120 years ago. This global expansion is consistent with historical records[13] of this new species in various countries.

We believe global trade facilitated this spread because more closely related populations are found in countries with cultural links, rather than countries that are simply close to one another. In keeping with this, we found one other expansion in Asia – north and eastwards into China and Korea – about 170 years ago.

As steam-powered ships[14] replaced sail ships, the hitchhikers were transported[15] more rapidly. Shorter journey times meant they were more likely to arrive alive and invade new countries.

Then improvements in housing, such as plumbing and indoor heating, created conditions conducive[16] to surviving and thriving[17] in buildings all around the world.

Why are cockroaches so hard to kill? (Ameya Gondhalekar, TED-Ed)

The pest control arms race

Of course, people don’t like cockroaches[18], so the invaders’ survival depended on their ability to stay hidden.

The German cockroach evolved to become nocturnal (as their name suggests) and avoid open spaces. It stopped flying[19], yet retained its wings.

These cockroaches are notorious for their ability to rapidly evolve resistance to many of the insecticides[20] used in surface sprays. Resistance can appear within a few years[21]. This makes the challenge of finding new active ingredients difficult, given the high cost of discovery, safety tests and registration[22].

Cockroach baits were cheap and effective when introduced in the 1980s. But they soon became less effective against German cockroaches. That’s because the baits used sugars to tempt cockroaches. Cockroaches with a “sweet tooth” were killed[23], while those that preferred other tastes survived and reproduced.

As we develop new strategies to control German cockroaches, we need to consider how they might evolve to evade attack. If we understand how resistance emerges[24] we can then find better ways to counter-attack. We can identify weak spots to exploit.

After all, the German cockroach will continue to evolve and adapt to stay alive, so the arms race between us and the cockroach will go on for years to come.

References

  1. ^ all over the world (doi.org)
  2. ^ both here (doi.org)
  3. ^ until now (www.pnas.org)
  4. ^ “Prussian cockroach”, while British and Prussian soldiers called it the “Russian cockroach” (www.jstor.org)
  5. ^ Africa (doi.org)
  6. ^ Asia (doi.org)
  7. ^ DNA barcoding (ibol.org)
  8. ^ other species have done (doi.org)
  9. ^ dependent on humans (doi.org)
  10. ^ single nucleotide polymorphisms (doi.org)
  11. ^ British East India Company (www.britannica.com)
  12. ^ Dutch East India Company (www.britannica.com)
  13. ^ historical records (doi.org)
  14. ^ steam-powered ships (doi.org)
  15. ^ transported (doi.org)
  16. ^ conducive (doi.org)
  17. ^ surviving and thriving (doi.org)
  18. ^ people don’t like cockroaches (doi.org)
  19. ^ stopped flying (doi.org)
  20. ^ many of the insecticides (www.pesticideresistance.org)
  21. ^ within a few years (doi.org)
  22. ^ high cost of discovery, safety tests and registration (doi.org)
  23. ^ Cockroaches with a “sweet tooth” were killed (doi.org)
  24. ^ understand how resistance emerges (doi.org)

Read more https://theconversation.com/a-pest-of-our-own-making-revealing-the-true-origins-of-the-not-so-german-cockroach-228001

The Times Features

Understanding the Dangers of Ignoring a Gas Leak

Gas leaks are silent threats lurking within both homes and workplaces. A gas leak occurs when natural gas or any other gaseous substance escapes from a pipeline or containment. T...

Can You Sell Your House Privately in Queensland? Here’s How

Selling a house privately in Queensland is entirely possible and can be a cost-effective alternative to using a real estate agent. While agents provide valuable expertise, their co...

Itinerary to Maximize Your Two-Week Adventure in Vietnam and Cambodia

Two weeks may not seem like much, but it’s just the right time for travelers to explore the best of Vietnam and Cambodia. From the bustling streets of Hanoi to the magnificent te...

How to Protect Your Garden Trees from Wind Damage in Australia

In Australia's expansive landscape, garden trees hold noteworthy significance. They not only enhance the aesthetic appeal of our homes but also play an integral role in the local...

Brisbane Homeowners Warned: Non-Compliant Flexible Hoses Pose High Flood Risk

As a homeowner in Brisbane, when you think of the potential for flood damage to your home, you probably think of weather events. But you should know that there may be a tickin...

Argan Oil-Infused Moroccanoil Shampoo: Nourish and Revitalize Your Hair

Are you ready to transform your hair from dull and lifeless to vibrant and full of life? Look no further than the luxurious embrace of Argan Oil-Infused Moroccanoil Shampoo! In a...

Times Magazine

"Eternal Nurture" by Cara Barilla: A Timeless Collection of Wisdom and Healing

Renowned Sydney-born author and educator Cara Barilla has released her latest book, Eternal Nurture, a profound collection of inspirational quotes designed to support mindfulness, emotional healing, and personal growth. With a deep commitment to ...

How AI-Driven SEO Enhancements Can Improve Headless CMS Content Visibility

Whereas SEO (search engine optimization) is critical in the digital landscape for making connections to content, much of it is still done manually keyword research, metatags, final tweaks at publication requiring a human element that takes extensiv...

Crypto Expert John Fenga Reveals How Blockchain is Revolutionising Charity

One of the most persistent challenges in the charity sector is trust. Donors often wonder whether their contributions are being used effectively or if overhead costs consume a significant portion. Traditional fundraising methods can be opaque, with...

Navigating Parenting Arrangements in Australia: A Legal Guide for Parents

Understanding Parenting Arrangements in Australia. Child custody disputes are often one of the most emotionally charged aspects of separation or divorce. Parents naturally want what is best for their children, but the legal process of determining ...

Blocky Adventures: A Minecraft Movie Celebration for Your Wrist

The Minecraft movie is almost here—and it’s time to get excited! With the film set to hit theaters on April 4, 2025, fans have a brand-new reason to celebrate. To honor the upcoming blockbuster, watchfaces.co has released a special Minecraft-inspir...

The Ultimate Guide to Apple Watch Faces & Trending Wallpapers

In today’s digital world, personalization is everything. Your smartwatch isn’t just a timepiece—it’s an extension of your style. Thanks to innovative third-party developers, customizing your Apple Watch has reached new heights with stunning designs...

LayBy Shopping