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How cockroaches took over the world


They emerge from hiding at night and run around the house, looking for starchy crumbs on the floor, sticky candy stains on the counter, and sometimes even a sip of toothpaste or soap.


However, of the 4,500 species of cockroaches, the German cockroach may be the main cause of your frustration. It overwhelms other cockroach species and is considered the most popular indoor pest in the world. How exactly this wild insect came to be our own personal question – so well-adapted to live in human habitations and barely found in nature – has long puzzled scientists.

A new research Describes the scavenger’s origin story and reveals the genetic variation that makes the insect “different from other cockroaches”, says QiantangAn evolutionary biologist at Harvard University and one of the authors of the study was published Monday in the Proceedings of the National Academy of Sciences. “This then helps us find solutions to control them.”

The German cockroach got its name in Central Europe in the late 1700s. Scientists later concluded that the species, the German cockroach, originated in northeastern Africa.

But there is another species of cockroach, the Asian cockroach, or Blattella asahinai, Scientists believe it is a good candidate for the ancestor of Berkeleyella germanica. It looks almost identical to the German cockroach, although it has unique characteristics such as its attraction to light, its ability to live outdoors, and its ability to fly. As technology advances, genetic analysis shows that B. germanica is more similar to B. asahinai than just appearance.

Dr. Tang was eager to understand the family tree of German cockroaches, so his team extracted DNA from 281 German cockroaches from 17 countries to study their genetic differences. They then traced the pest’s journey on Earth, from where it first evolved until it crawled into your kitchen.

Calling this a “landmark study” Li QiuyangUrban entomologists at the University of California, Riverside, who have studied German cockroaches for 30 years, were not involved in this study.

The data confirms that German cockroaches evolved from Asian cockroaches somewhere in India or Myanmar about 2,100 years ago, when human settlements were booming. Dr. Tang speculates that some Asian cockroaches live near human settlements or plantations and may turn to eat crops grown by humans. Then, since human homes have similar food sources, they move indoors and eventually become household pests.

“It was around that time that the Asian cockroaches started to turn into German cockroaches,” Dr. Tang said.

The bugs moved westward in two waves. Dr Tang said they first traveled to the Middle East in soldiers’ bread baskets 1,200 years ago, much earlier than previously thought. Only 270 years ago they probably arrived in Europe on European colonial ships, where they took their name.

Global trade in the 19th and 20th centuries allowed scavengers to penetrate most of the world’s nooks and crannies, while indoor plumbing and heating systems beckoned them to stay.

“That makes sense,” said Deeney MillerProfessor of Urban Pest Management at Virginia Tech, who was not involved in the study. “We provide them with food, moisture and warmth. They’ve basically been with us ever since.”

She worked on cockroach management projects across the United States, often finding 700 cockroaches in traps set in infested buildings in a single night. “They’re quite capable of reproducing,” Dr. Miller said, and they’ve become resistant to almost every pesticide they’ve been exposed to over the past 60 years.

To understand what makes the German cockroach such a powerful invader of urban spaces, scientists must unravel the insect’s ancient genetic history, say Erich Bornberg-BauerProfessor of Molecular Evolution and Bioinformatics at the University of Münster in Germany, who was not involved in the study.

“Then you can reconstruct the adaptive pathways,” Dr. Bornberg-Bauer said, and see which genes have been dormant throughout history, waiting to come into play with each new challenge.

his own research German cockroaches were found to possess genes for many olfactory receptors and a large number of proteins that help them resist toxic substances. These are likely the genes that make them so cunning at sensing new food sources and quickly developing resistance to pesticides.

“They have a very high number of genes, so they have a very, very high adaptive potential,” Dr. Bornberg-Bauer said. “Quickly evolve into anything.”

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