Why cockroaches are so hard to kill

Scientists discover a set of genes that makes them able to regrow lost limbs, eat toxic food and survive in filthy conditions

 They seem to thrive in the darkest, filthiest corners of Earth.

Now, scientists have revealed the secrets to how cockroaches can live in such disgusting conditions - and why they are so hard to kill.

By studying their DNA, researchers have identified specific genes that allow them to do everything from eat toxic food to regrow lost limbs. 

The American cockroach (Periplaneta americana) is an omnivorous scavenger and one of the largest insect species that lives in close proximity to humans.

Shui Zhan, who works at the Institute of Plant Physiology and Ecology in Shanghai, has worked out the genes that make this creature so difficult to destroy. 

It has one of the largest genomes known to exist among insects, second only to the common locust.

In total, the species has 20,000 genes - which is the same number as a human.

It's genes make it able to sense smells coming from food - especially food that is fermenting.

Other genes control its internal detoxification system, which means the cockroach doesn't get ill if it eats toxic food.

More genes help it combat infections, meaning it is resilient to living in filthy conditions, writes the Guardian.

It even has genes that mean it can regrow limbs if they're broken off.

Scientists say that identifying this creature's genes will mean they can control them better in the future.

Now scientists have deciphered the entire DNA of an American cockroach and although it can't survive a nuclear armageddon, it can survive almost anything else (stock image)

However, researchers say there is no evidence they could survive a nuclear armageddon.

'I think this is an overstatement and has not been proved,' Dr Zhan said.

Researchers also found the American roach was genetically closely related to two species of termite.

It could be used as 'a valuable model to study the evolutionary relationships between cockroaches and termites', researchers wrote in the paper.

Last year researchers revealed female cockroaches are so resilient they don't need a male partner. 

The American cockroach (colony, pictured) is an omnivorous scavenger and one of the largest insect species that lives in close proximity to humans

Females can reproduce for years and have several generations of all-female young - without needing a single male, researchers found.

Japanese scientists used 15 virgin females to produce an all-female colony that stuck together for more than three years.

Unlike male roaches who fight if they are housed together, females huddle together and harmonise their reproductive cycles, producing more young than they would if they were alone.

Experts believe this behaviour is a primitive example of female cooperation.

Female American cockroaches can produce eggs by parthenogenesis, which is a type of asexual reproduction, according to research by Hokkaido University in Japan.

Their offspring develop from the maternal egg alone so are always female but they survive and can produce offspring themselves.

HOW COULD CYBORG COCKROACHES HELP IN DISASTER ZONES?

In November 2014, researchers at North Carolina State University fitted cockroaches with electrical backpacks complete with tiny microphones capable of detecting faint sounds.

The idea is that cyborg cockroaches, or ‘biobots’, could enter crumpled buildings hit by earthquakes, for example, and help emergency workers find survivors.

‘In a collapsed building, sound is the best way to find survivors,’ said Alper Bozkurt, an assistant professor of electrical and computer engineering at North Carolina State University.

North Carolina State University researchers have developed technology that allows cockroaches (pictured) to pick up sounds with small microphones and seek out the source of the sound. They could be used in emergency situations to detect survivors

‘The goal is to use the biobots with high-resolution microphones to differentiate between sounds that matter - like people calling for help - from sounds that don't matter - like a leaking pipe. 

‘Once we've identified sounds that matter, we can use the biobots equipped with microphone arrays to zero-in on where those sounds are coming from.’

The ‘backpacks’ control the robo-roach's movements because they are wired to the insect’s cerci - sensory organs that cockroaches usually use to feel if their abdomens brush against something.

By electrically stimulating the cerci, cockroaches can be prompted to move in a certain direction.

In fact, they have been programmed to seek out sound.

One type of 'backpack' is equipped with an array of three directional microphones to detect the direction of the sound and steer the biobot in the right direction towards it.

Another type is fitted with a single microphone to capture sound from any direction, which can be wirelessly transmitted, perhaps in the future to emergency workers.

They ‘worked well’ in lab tests and the experts have developed technology that can be used as an ‘invisible fence’ to keep the biobots in a certain area such as a disaster area, the researchers announced at the IEEE Sensors 2014 conference in Valencia, Spain.