Shulou(Shulou.com)11/24 Report--

(photo Source: pixabay) you may have heard this rumor:

When you see a cockroach at home, it means that hundreds of cockroaches have settled in your house, eating and living with you.

It's creepy to think about it, right?

Cockroach is not only an ancient insect, but also the natural enemy of human beings.

After thousands of years of evolution, cockroaches have fully adapted to human living environment and food, and have bred a large number of offspring.

Humans call cockroaches "Xiaoqiang", which is worthy of the name. Although this pest is small, it has strong vitality.

There are two main kinds of cockroaches in our life, namely, Blattella germanica (Blattella germanica) and American cockroach (Periplaneta americana). The former is distributed all over the country, while the latter is mainly distributed in the south of China.

They are not afraid of the cold, do not choose a place to live, there are people where they are.

No matter how clean your house is and how many pesticides you have used, you will inevitably look at one "Xiaoqiang" when you open the cupboard or wardrobe one day.

(photo Source: "Tang Bohu points Qiu Xiang") cockroaches can be said to be the insects that are most closely related to us and the most troublesome.

So the question is, why are cockroaches so hard to kill?

First of all, cockroaches have a first-class escape speed. Their tentacles can feel a slight airflow, and if there is any movement, they will run.

They can run 1.3 meters per second, which doesn't look far, but the distance is 50 times their average length.

Secondly, they are also very carrying and treading.

The cockroach's exoskeleton is made up of many overlapping plates, each connected by a flexible membrane, which allows the cockroach to easily change the shape of its body.

Not only can they squeeze into gaps less than 1/4 of their height, but they can also withstand stress of up to 900x their weight by changing the shape of their bones.

So, when you hit a cockroach with a slipper, be sure to check whether it is dead or not.

The body structure of a cockroach. (photo source: Vedantu) what's more, cockroaches have the ability to regenerate amputated limbs during the nymph period.

In a study, Professor Li Sheng of South China normal University amputated some cockroaches to observe their limb regeneration.

The experiment was divided into a control group and five experimental groups, the lightest group only amputated the tail of the chest limb, resulting in rapid regeneration; the most serious group amputated the entire chest limb, some cockroaches could not regenerate.

This shows that the ability and degree of recovery of the missing limbs of Periplaneta Americana depend on the severity of the trauma.

According to this characteristic of cockroaches, Professor Li Sheng's team is studying whether cockroach extracts contain growth factors that can be used to develop drugs for human wound healing and tissue repair.

Regeneration of cockroaches under different amputation degrees. (photo Source: reference [1]) what is even more frightening is that cockroaches can survive for five to six days after losing their head.

Because they breathe through small holes in the body, but after losing their head, they are unable to ingest food and gradually die of dehydration and hunger.

"the immortal Xiaoqiang" really lives up to its reputation.

Cockroaches not only can't be killed, but they also eat everything. Human hair, dead skin, glue, paper, wood, all kinds of building materials, and even eat their own feces and vomit.

When there is not enough food, they will also kill each other and eat the bodies of their companions.

Therefore, even if they live in a nutrient-deficient environment, they can still get food and breed.

(photo source: giphy) the lifespan of Periplaneta Americana is about one year, while that of Blattella germanica is 100,200 days.

Their reproduction rates are also different. A Periplaneta Americana and its offspring can produce 800 new cockroaches in a year, while a pair of Blattella germanica and its children can produce more than 300000 offspring in a year.

Periplaneta Americana also has the ability to parthenogenesis, also known as asexual reproduction. As the name suggests, female cockroaches produce offspring in an unfertilized state.

A team of entomologists at Hokkaido University in Japan observed a population of only 15 female cockroaches that continued to breed for three years, with 1000 offspring, each female.

The researchers believe that the amazing reproductive ability of Periplaneta Americana partly explains the ability of cockroaches to survive in harsh environments.

Two mating cockroaches. (photo: Futurity) the strength of cockroaches is also reflected in their strong adaptability to the environment.

Because they live in dirty, dark and humid places, cockroaches inevitably carry all kinds of bacteria, fungi and viruses. But cockroaches themselves do not get sick because their genes are immune to many pathogens.

Some scholars believe that cockroaches frequently come into contact with a large number of different bacteria, resulting in the formation of this unique innate immune system.

Professor Richard D. Karp of the University of Cincinnati conducted an experiment in which he injected cockroaches with bee venom and the result was almost wiped out.

But if he first injects cockroaches with inactivated melittin, which is equivalent to vaccinating them, and then comes into contact with melittin, the survival rate of cockroaches is 85%, which is much higher.

This suggests that cockroaches have a complex immune system, and their immune cells also have specificity and memory-just like humans.

The pathogens carried by cockroaches can easily cause allergic asthma. (photo: Victoria Roberts) not only are pathogens in the environment unable to kill them, but even pesticides developed by humans to deal with pests cannot threaten them.

Because the genes of some cockroaches mutate so quickly, they can evolve antibodies to pesticides within a month.

In 2016, a team of Professor Michael Scharf from Purdue University found a dense residential area in Indiana and Illinois and conducted a six-month insecticidal experiment aimed at Blattella germanica.

The experiment is divided into three stages. In the first stage, three different pesticides are used in turn for residential areas within three months; in the second stage, a mixture of two pesticides is used and sprayed once a month. In the final stage, a single insecticide, avermectin, is used.

Avermectin is a common insecticide and is used because local cockroaches are less resistant to it.

The results showed that the spraying of insecticides in the first two stages had no effect on the number of Blattella germanica, even increased instead of decreasing. Only when avermectin is used can the number of cockroaches in some residential areas be controlled.

They then studied the surviving cockroaches and found that they developed cross-resistance to a variety of pesticides. Moreover, the number of drug-resistant cockroaches has increased four-to six-fold in just one generation.

Professor Michael Scharf was amazed at the evolutionary ability of cockroaches and sighed, "it's almost impossible to control these pests by chemicals alone."

The evolution of Blattella germanica is very fast. (photo source: TED-ed) although cockroaches are almost impossible to kill, we can still do some small things in our daily life to keep cockroaches from becoming too rampant.

It mainly includes the following points:

1. Seal or block the seams that enter the house, such as drainage pipes, vents, windows, etc.

2. Repair and seal the cracks outside the house.

3. Put food and ingredients in sealed containers to cover up the smell and prevent cockroaches from entering.

Don't leave food out for the night, including pet food.

5. Clean food crumbs and leftovers on the surface of tables and counters. Empty the garbage every day and throw it outdoors.

6. Remove a large amount of paper or cardboard from the house, which is the hiding place and food source for cockroaches.

7. If you see a cockroach somewhere in the house, clean that place immediately.

(photo source: giphy) P.S. I don't know whether human beings or cockroaches will live longer in the future.

Reference:

[1] Li, S., Zhu, S., Jia, Q. Et al. The genomic and functional landscapes of developmental plasticity in the American cockroach. Nat Commun 9, 1008 (2018).

[2] Fardisi, M., Gondhalekar, A.D., Ashbrook, A.R. Et al. Rapid evolutionary responses to insecticide resistance management interventions by the German cockroach (Blattella germanica L.). Sci Rep 9, 8292 (2019).

[3] Why are cockroaches so hard to kill-Ameya Gondhalekar. TED-ed

[4] News, ABC. 2022. "Cockroaches Are Becoming 'Almost Impossible' To Kill, Researchers Say". ABC News.

[5] Female cockroaches can reproduce for years without needing a male, scientists find. Independent.co.uk.

[6] Solutions, Holistic. 2022. Why Are Cockroaches So Hard To Kill-Holistic Pest Solutions. Holistic Pest Solutions.

[7] "Why Is It So Hard To Kill A Cockroach? Page 1 Of 0 | Foundation Pest Control". 2022. Foundation Pest Control.

[8] "Cockroach Reproduction Has Taken A Strange Turn" 2022. Nytimes.Com.

[9] "In A Cockroach Genome, Little Mighty' Secrets (Published 2018)". 2018. Nytimes.Com.

[10] A Pest, but Maybe Also an Immunological Clue. Washingtonpost.com.

This article is from the official Wechat account: bring Science Home (ID:steamforkids), author: everything.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.