They come out of their hiding places at night and run around the house looking for starchy crumbs on the floor, sticky sugary stains on counters, and sometimes a mouthful of toothpaste or soap.
cockroach.
But among the 4,500 species of cockroaches, the German cockroach is probably the main culprit for your irritation. They dwarf other cockroach species and are considered the most prevalent indoor pest in the world. How did this wild insect, so well adapted to life in the presence of humans and rarely seen in nature, become a problem for us humans? has not been elucidated for some time.
Qiantang, an evolutionary biologist now at Harvard University and an author on the study, said the new study explains the scavenger's origin story and explains the genetics that make this insect “different from other cockroaches.” It was published in a journal on Monday. National Academy of Sciences. “And that will help us find solutions to control them.”
The name German cockroach was given in central Europe in the late 1700s. Scientists later concluded that this species, Blattella germanica, originated in northeastern Africa.
But there is also another species, the Asian cockroach, or Blattella asahinai., Scientists considered it a likely candidate for an ancestor of B. germanica. Although they look similar to the German cockroach, they have unique characteristics such as an attraction to light, the ability to live outdoors, and the ability to fly. As technology has advanced, genetic analysis has proven that B. germanica has more in common with B. asahinai than just physical appearance.
Dr Tan was itching to get to the bottom of the B. germanica family tree, so his team obtained DNA from 281 German cockroaches from 17 countries to study genetic differences. They then traced the path the pests took across the globe, from where they first evolved until they entered the kitchen.
This is a “groundbreaking study,” said Chouyang Lee, an urban entomologist at the University of California, Riverside, who has studied German cockroaches for 30 years but was not involved in the study.
The data confirms that B. germanica evolved from the Asian cockroach, somewhere in India or Myanmar, where human settlements flourished about 2,100 years ago. Some Asian cockroaches live near human settlements and farms, and Tan speculates that they probably came to eat crops planted by humans. Later, as human dwellings had similar food sources, they moved indoors and eventually became household pests.
“That's when the Asian cockroach started becoming the German cockroach,” Dr Tan said.
The insects moved west in two waves. Dr Tan said they first traveled to the Middle East in soldiers' breadbaskets 1,200 years ago, much earlier than previously thought. They reached Europe only 270 years ago, probably on a European colonial ship, where they received their name.
Global trade in the 19th and 20th centuries allowed scavengers to invade almost every corner of the world, and indoor plumbing and heating made them a home.
“It makes perfect sense,” said Dini Miller, a professor of urban pest management at Virginia Tech who was not involved in the study. “We provided them with food, moisture and warmth. And they've basically been with us ever since.”
She works on cockroach management projects across the United States, often with up to 700 cockroaches in traps left overnight in infested buildings. “They're pretty prolific,” says Dr. Miller, and they've evolved resistance to almost every pesticide they've been exposed to over the past 60 years.
Professor Erich Bornberg-Bauer, professor of molecular evolution and bioinformatics at the University of Münster in Germany, and who is not involved with the German cockroach, says that in order to understand why the German cockroach has become a formidable invader of urban spaces, said scientists need to uncover the insect's ancient genetic history. study.
“Then we can reconstruct the path of adaptation,” Dr. Bornberg-Bauer said, explaining what genes have been lying dormant throughout history, waiting to spring into action with each new challenge. You can check whether
His own research found that the German cockroach has many odor receptor genes and a number of proteins that help it resist toxic substances. Perhaps these genes make them so cunning at sensing new food sources and quickly developing resistance to pesticides.
“Because they have so many genes, the potential for adaptation is very high,” Dr. Bornberg-Bauer said. “To achieve further evolution”