CATDOLL : CATDOLL: There are a lot of crayfish in my rice field. How can I catch them all?

1. There are many crayfish in my rice field. How can I catch them all?

1. Biological Control Law

1. Combine the manpower-focused capture during rice harvesting with the capture during daily farming management.

2. The breeding season of crayfish is generally from August to October. Under natural conditions, parent shrimps begin to dig holes before and after mating. The process of female shrimps laying eggs and fertilization and hatching is mostly completed in the caves. At this time, it is necessary to organize manpower to block the shrimp holes, which will affect the spawning and reproduction of parent shrimps.

3. Combine fish farming in terraced rice fields with fish farming in winter paddy fields and release carp, catfish, black carp, eel, etc. which can directly eat crayfish. Release ducks in the fields which can also eat crayfish.

4. Frogs are the natural enemies of crayfish. Frogs or bullfrogs raised in terraced fields can eat crayfish larvae.

2. Drug Prevention and Control Law

1. Sprinkle quicklime to increase the pH value. The suitable pH value for crayfish is between 7 and 8. When the pH value is lower than 5 or higher than 9, the crayfish will die. The main component of quicklime is calcium oxide, which turns into calcium hydroxide after seeing water and releases heat. Calcium hydroxide is a strong alkali that can cause the pH value of pond water to rise sharply to 12. Use 100-150 kg of quicklime per mu to dissolve water and sprinkle it all over the field, causing the shrimp to die. When applying, drain the field water to a depth of 2-3 inches, dig a few shallow pits in the field, put the quicklime into the pits (you can also put the quicklime into pots, basins and other containers without digging pits), stir it evenly after absorbing water and spreading it, and sprinkle it all over the field while it is hot.

2. Kill with pesticides.

(1) Drug: Deltamethrin (Diamethoxam) emulsifiable concentrate with an active ingredient content of 25 g/L, produced by Bayer CropScience GmbH (Hangzhou, China), 4 ml per tube.

(2) Dosage: Based on the average water depth of 15 m in the terraced fields, the dosage is 400 mg/mu, that is, 4 vials of 4 ml/vial of cypermethrin emulsifiable concentrate are applied per mu.

3. Application method:

Calculate the amount of cypermethrin according to the size of the area, add an appropriate amount of water, and use a sprayer to evenly spray the entire field (including the shrimp holes) or evenly sprinkle the entire field.

3. Drug prevention and treatment period

1. Choose the period when crayfish are out and about to apply pesticides for prevention and control. According to the life habits of crayfish in autumn and winter, they dig holes to lay eggs and reproduce, and the results of drug tests, prevention and control of crayfish in autumn and winter cannot completely kill them. Spring and summer are the growth period of crayfish. Crayfish basically do not dig holes, but feed and grow in the fields. This is the best period for prevention and control of crayfish. Therefore, the prevention and control time should be from February to April, when the fields are prepared in the spring and before planting.

You are rich. You sell rice for only a few dollars a pound. There are so many crayfish, why bother with them? But I feel like I am in a dream...

2. Chinese people like to eat crayfish. Can you tell us about the characteristics of this habit?

Because crayfish are so popular, wild ones can no longer satisfy us, and the crayfish we eat now are basically artificially farmed.

In 2017, more than 10 million mu of land in China was used to raise crayfish, and 1.1297 million tons of crayfish were growing happily (statistics from Hong Kong, Macao and Taiwan are not included).

Although the quantity is so large, people are eating too much. At present, the total demand for crayfish in China is about 1.9 million tons, while the demand gap is nearly 1 million tons.

From 2014 to 2016, crayfish production increased by 30.36%, but consumption increased even more, reaching 32.47%.

In 2016, the production of crayfish was 899,100 tons, more than 3,000 tons were imported, more than 20,000 tons were exported, and finally 879,300 tons were consumed, basically eaten up completely.

How can the price not go up? If something unexpected happens, the price will be even higher.

In July last year, Hunan, Hubei and other places suffered continuous heavy rainfall, and many crayfish were washed away... In addition, the prices of shrimp fry, land, and labor were all rising, and the price of crayfish that originally cost more than 20 yuan per catty became more than 40 yuan.

The bigger the city, the more people love crayfish

So the question is, if crayfish is so expensive, who are the people eating crayfish?

Statistics show that the cities that consume the most crayfish are large and medium-sized cities, concentrated in North China, East China, and Central China. Beijing, Wuhan, Shanghai, Nanjing, Changsha, Hangzhou, and Suzhou can each consume more than 10,000 tons of crayfish per year.

3. The bacteria on crayfish claws are very toxic and can be fatal in severe cases?

It is widely circulated in the circle of friends: "The bacteria on the crayfish claws are very poisonous. This is not an exaggeration! If you are pinched by a crayfish, you must seek medical attention quickly, otherwise it may be fatal!"

The report of "a person was killed by a crayfish" was reprinted by major media. The report said: "A 70-year-old woman in Huzhou died because her finger was bleeding after being pinched by a crayfish and she did not receive timely treatment. Doctors speculated that it may be related to anaerobic infection."

Subsequently, a wave of "black crayfish" craze swept the Internet, with many netizens citing possible bacterial components in crayfish. In addition, it was widely circulated on WeChat: "The bacteria on the crayfish's claws are very toxic, and this is not an exaggeration! If you are pinched by a crayfish, you must seek medical attention quickly, otherwise it may be fatal!" So, is this statement true?

Consumer: "Crayfish bites and death" is just an isolated case

Recently, after reporters interviewed crayfish consumers in many places, they found that most people do not believe the saying that "crayfish can kill people with their claws."

At the Jiqingmen Market in Nanjing, Jiangsu, citizen Aunt Wang is buying lobsters. She said that the price of lobsters in the market is getting higher and higher. If you eat at a restaurant, a small portion will cost more than 200 yuan. It is better to buy lobsters and cook them at home. Aunt Wang said that after buying the lobsters, she would first brush them clean one by one with a brush, especially the abdomen of the lobsters. "It is definitely cleaner to cook at home than to cook outside, but the processing has been simplified a lot now. In the past, we not only had to wash the lobsters, but also peel off the side shells of the lobsters and cut off the claws. Now we don't have to bother with this." Aunt Wang said.

Aunt Wang said she had no idea about the claim that "handling lobsters could be fatal." In her opinion, lobsters are a food that has been eaten for decades, and it's just a little troublesome to handle them, but she was a little surprised if it could really be fatal.

"I often get my fingers pinched by crayfish, and sometimes they bleed, but I'm always fine." Mr. Ding lives in Kuaidamao Town, Tonghua County, Jilin Province. He has been catching crayfish in the river near his home since he was a child. According to him, when he was seven or eight years old, he often went to the river to play and catch crayfish in the cracks of the rocks. Sometimes his fingers were pinched by the crayfish's claws, but he never did any special treatment afterwards, but he never had any bacterial infection.

Mr. Ding believes that the case of the 70-year-old woman in Huzhou is just an accidental and isolated phenomenon. "There are so many people in the country who run crayfish businesses. Whether they are selling or cleaning in restaurants, it is common for fingers to be pinched. It is certain that crayfish carry germs. As long as they are well protected or handled in time, there will be no deaths." Mr. Ding said.

Chef: It’s best to wear gloves when cleaning lobsters

A chef told reporters: "When the restaurant kitchen handles crayfish and some seafood products, they always wear rubber gloves to avoid scratching their fingers and causing infection."

So, do crayfish claws really carry bacteria? How do restaurants and hotel kitchens clean crayfish?

Recently, the reporter went to a restaurant in Changchun to interview chef Jiang Xifeng. "As we all know, crayfish grow in a relatively dirty environment and are definitely carrying bacteria, so we are very careful when handling crayfish." According to him, the kitchen of a general restaurant handles crayfish by soaking them in water for a period of time to make them spit out the mud, then brushing them with a brush and rinsing them with clean water.

"When handling crayfish and some seafood products, the restaurant kitchen staff will wear rubber gloves to avoid scratching their fingers and causing infection." Jiang Xi, who has never heard of any "death by crayfish pinches," told reporters that once a pinching incident occurs, timely treatment and disinfection will not cause serious consequences.

Doctor: Or infected by "anaerobic bacteria"

The picture shows a "diagram of anaerobic infection".

Later, the reporter found Tao Chengjun, the doctor who rescued the patient in the "70-year-old woman being clamped to death" incident and the director of the dermatology department of Hangzhou Traditional Chinese Medicine Hospital. He told the reporter that the old woman's wound was swollen and purple, "just like a snake bite." Afterwards, several doctors who participated in the rescue analyzed the situation and believed that "the old woman died of anaerobic infection."

Tao Chengjun explained that lobsters grow in silt, which is an oxygen-poor environment that easily breeds anaerobic bacteria, and lobsters are likely to carry anaerobic bacteria. If the lobster's "claw" is too deep, an oxygen-free space will be formed in the wound, which is more conducive to the reproduction of anaerobic bacteria and leads to wound infection.

"If the wound is deep and tetanus antitoxin is not given in time, it may cause anaerobic infection, and anaerobic bacteria is a type of tetanus bacteria." Zhou Zhuokang, director of the infection control department of Hangzhou Third Hospital, said that after some injured people were sent to the hospital, doctors would open their wounds to allow anaerobic bacteria to fully expose themselves to the aerobic environment and die. If you are bruised or stabbed by a sharp object, as long as there is a wound, no matter how big or small, it may be infected with various bacteria, and you should take timely prevention and treatment to prevent a minor injury from becoming a major illness.

Another doctor said that pliers injuries are rare, and it is related to the depth of the wound, as well as the person's own resistance and physical condition.

It can be seen that the online rumors are false. The death of a 70-year-old woman in Huzhou City, Zhejiang Province after being pinched by a crayfish is indeed a true story, but it was just an accidental incident. Doctor Yin Guoqing suggested: "If the patient is pinched by fresh crayfish, as long as they disinfect it in time, go to the hospital to treat the wound, and get a tetanus vaccine, they can effectively avoid the infection symptoms caused by being pinched by a lobster."

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