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  • In the Egyptian Book of the Dead, there’s a banishment spell that declares, "Be far from me, O vile cockroach.”

  • More than 3,000 years later, were still trying to oust these insects.

  • But from poison traps to hastily brandished slippers, cockroaches seem to weather just about everything we throw at them.

  • So what makes cockroaches so hard to kill?

  • There are nearly 5,000 cockroach species.

  • 99% of them live in a range of habitats where they play important ecological roles by recycling dead or decaying organic matter and nourishing other animals.

  • But a couple dozen species adapted to live in close association with humans.

  • German and American cockroaches are among the most common.

  • And they owe their resilience to a combination of physical and chemical adaptations.

  • When it comes to old-fashioned removal methods, they're troublingly tenacious.

  • An American cockroach’s sensory hairs or structures pick up subtle air currents and rapidly send signals to its central nervous system.

  • The roach can then turn and sprint away within a few milliseconds.

  • And it’s among the fastest invertebrates ever recorded, reaching speeds of up to 50 body lengths per second.

  • This would be the human equivalent of running more than 300 kilometers per hour.

  • And finding a hiding place is no problem.

  • With its flattened, flexible body, an American cockroach can squeeze into spaces less than a quarter of its height.

  • Even if we do land a hit, it can withstand compressive forces of up to 900 times its own weight by distributing the impact along its body.

  • And the cockroach’s toughness doesn’t end there.

  • Cockroaches can eat a variety of organic matter, including hair, dead skin, adhesives, and paper.

  • This is made possible by an expansive set of digestive enzymes.

  • Cockroaches are able to thrive even in nutrient-poor environments.

  • Roaches often eat decaying foods that are low in nitrogenan essential component of DNA and proteins.

  • But they survive by storing nitrogen-containing wastes in their bodies and having a resident group of bacteria recycle the nitrogen into useful molecules for them.

  • Meanwhile, German cockroaches will eat their own poop, vomit, and dead or dying colony members without hesitation.

  • An American cockroach will frolic in sewers, consuming excrement and toting microbes like Staphylococcus aureus and E.coli.

  • But theyll rarely suffer any consequences.

  • This is because theyre equipped with genes that provide immunity against numerous pathogens.

  • These genes are often duplicated many times over.

  • So when infected, the cockroach’s immune system efficiently unleashes many antimicrobial molecules.

  • Cockroaches also have a slew of defenses against pesticides.

  • When a non-resistant roach walks on a surface that’s been sprayed with a pyrethroid insecticide, for example, the results will likely be fatal.

  • Once absorbed, the chemical binds to sodium channel proteins, which help propagate nerve impulses.

  • The pyrethroid keeps the sodium channels open, so the nerves fire repeatedly.

  • And soon, the cockroach dies.

  • But if a resistant roach is exposed to pyrethroids, itll be just fine.

  • Genetic mutations have given them sodium channels that the pyrethroids can’t bind to.

  • The cockroach also produces more detoxification enzymes, which render the pesticide harmless, and the cockroach simply excretes it as a waste.

  • Because German cockroaches reproduce especially quickly, populations may evolve resistance to a new pesticide within months.

  • So far, they're already resistant to 43 different chemicals.

  • But contrary to popular belief, cockroaches would probably not survive a nuclear apocalypse.

  • Compared with other insects, cockroaches are only mildly tolerant to radiation.

  • They would die near the sites of nuclear explosions and would still be severely compromised miles away.

  • Moreover, disasters that threaten humanity also jeopardize the habitats and buffets we provide roaches.

  • Perhaps the only way to beat them is through our mutual destruction.

  • Or maybe cockroaches would find even more surprising ways to thrive long after were gone.

In the Egyptian Book of the Dead, there’s a banishment spell that declares, "Be far from me, O vile cockroach.”

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C1 US TED-Ed cockroach roach nitrogen sodium resistant

Why are cockroaches so hard to kill? - Ameya Gondhalekar

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    たらこ posted on 2022/04/17
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