The blackboard writing of the text biological invaders

I. Independent investigation, one, two, three

1. Keyword concentration

① Read the following pronunciations correctly.

Robbery (lü) Habitat (QΙ) Hedging (fān) Blame (JiΙ)

② Explain the following words.

Strange: strange.

Fence: Fence. Metaphor portal or barrier.

Whistle and greet each other in the mountains, and get together where there are mountains.

Imbalance: Out of balance.

Plunder: To plunder by force.

Habitat: Stay and rest. (especially birds)

Monitoring control.

I'm doomed to suffer, and I can't escape. Now it means that bad things will happen and cannot be avoided.

Colorful: refers to the five colors of blue, yellow, white, red and black. It refers to all kinds of bright and colorful colors.

Natural selection: Everything in nature is competing for survival. Survival of the fittest, this is the British biologist Darwin's view of evolution.

Helpless: metaphor is powerless or helpless. Hands tied, hands tied.

Do whatever you want: the original intention is to do what you want. Now it means doing what you want to do, and more means doing bad things. Do sth. Desire, thinking.

Unexpectedly: I didn't expect this ending at first. Expect, predict, estimate. Also, yes.

Bad luck: a difficult encounter.

Brewing: refers to the fermentation process in liquor brewing, which is used to express prior consideration or consultation in order to unify understanding.

2. Comprehensive search of background information

The Biological Intruder by Mei Tao, a contemporary popular science writer, is a rational exposition of the knowledge that biological migration may do harm to human beings through unnatural ways.

In the highly developed 2 1 century, our home, the earth, is facing more and more severe challenges. Environmental problems have become an urgent problem for human beings, and ecological problems are the central issues of environmental problems in the world today. I hope that learning the article "Biological Invaders" can help us improve our awareness of protecting the ecological environment.

The structural illustration of this article is ingenious.

Second, the text is completely divergent.

1. Global perception

[theme]

This paper is a rational exposition of the understanding that biological migration through unnatural ways may cause harm to human beings. Starting with the explanation of the concept of "biological invader", this paper introduces the harm that "biological invader" brings to human beings, its destructive effect on the ecological environment, the reasons for its formation, the different views of the scientific community on "biological invader" and the measures taken by various countries in the world at present.

[level]

Introduce the topic (1) to introduce what a biological invader is.

Phenomenon (2-4) Introduction of biological intruders and abiotic intruders.

Explore the reasons (5) fresh fruit and vegetable trade, transnational pet trade.

Reveal attitudes (6-7) Two different attitudes (diametrically opposite).

Take measures (8) to pass bills and set up departments.

[Explain the order]

This article is explained in a logical order. First introduce the topic (topic), then put forward the phenomenon, then discuss the cause and effect, and finally discuss the countermeasures. Basically, it is carried out in accordance with the logical thinking of asking questions, analyzing problems and solving problems.

2. Question inquiry

(1). Why do biologists and ecologists think it is "no small matter" to find one or two beetles that ordinary people have never seen?

Clear: ordinary people will only be surprised when they find one or two beetles they have never seen before, and will not consider more problems; Biologists and ecologists will consider many questions about this: Where did beetles come from? How did the beetle come from? What is the ecology of beetles? Will beetles affect local ecology and human life? Wait a minute. They will not turn a blind eye.

⑵. How to understand "human intervention" in the process of species migration?

Clear: The second paragraph of the article has written that the natural reproduction and migration of biological species, due to the slow progress and the limitation of time and space span, will not cause the imbalance of the ecological environment. If this kind of migration is caused by human cross-regional activities, then their migration speed will be greatly accelerated, and it is easy to break through the limitation of time and space span, and the consequences are unimaginable. Therefore, "human intervention" should be fully considered when preventing "biological intruders".

⑶. Why emphasize the two conditions of "no competition from similar foods" and "no harm from natural enemies" in the process of forming "biological invaders"?

Mingming: The natural existence and development of living things have certain laws, which are summarized by British biologist Darwin as "natural selection" and "survival of the fittest". The species in a certain area are all part of the local biological chain and have been in a state of balance for a long historical period. If human intervention breaks this balance, it is equivalent to breaking the balance of the biological chain, which may have two consequences: one is to reach a new balance after a long time; The other is to produce "biological invaders", which will bring harm to local ecology and human life.

(4) Do you know other "biological invaders"? Have you ever found biological invasion in your life?

Clear:

① In China, a South American aquatic plant, Water hyacinth, greatly reduced the water area of Dianchi Lake in Kunming, and the local climate was obviously dry. There were 68 species and 38 species of fish in the lake.

(2) In Western Europe, a North American shrimp disease is attacking local shrimps, causing local shrimps to disappear in many rivers.

In the Mediterranean Sea and Adriatic Sea, a Pacific seaweed covers 3000 hectares of the sea floor.

④ From East Africa to the Indo-Pacific region, a A Lang grass from South Asia invaded millions of hectares of tropical forests, seriously affecting the natural regeneration of local trees.

⑤ A pathogenic fungus from Australia, possibly from Papua New Guinea, invaded from 1920, resulting in the destruction of thousands of hectares of forests. This fungus is harmful to three quarters of plants, including tall trees and short shrubs.

In New Zealand, a nocturnal kangaroo from Australia is estimated to eat 265,438+0 tons of local forest every night.

⑦ The palm tree snake from Papua New Guinea made the wild 1 1 species of birds and some lizards and bats extinct in Guam in the Pacific Ocean.

Please summarize the knowledge about biological invaders introduced in this article in your own words.

Clear: Biological invaders refer to "immigrants" who originally lived in a foreign country and moved to a new ecological environment by unnatural means. The harm of biological invaders is enormous, causing incalculable economic losses to human beings and posing a great threat to other invasive species and species diversity. So how did these biological intruders invade? Why is it increasing? Due to the growing prosperity of international trade, biological intruders "sneak" into China by hitchhiking in transnational trade; In addition, transnational pet trade also provides convenience for "biological invaders". At present, biology and ecology have different attitudes towards biological invaders: some people think that through "natural selection", the harm of "biological invaders" can be limited and a new ecological balance can be achieved; Others believe that letting "biological invaders" develop freely will cause serious harm to local ecology and human life. Countries all over the world are taking corresponding measures against "biological invaders".

Three. Cooperative learning a and b

A. Summary of classroom knowledge

How to summarize the main content of the article?

In short, the main content of an article is "what to write". For example, a chronicle article generally needs to know when and where it happened, who participated, what caused it, what happened and what the result was. For example, write an article about people to get a general idea of what kind of person this is and where it is mainly manifested. Another example is an article about things, so we need to know the shape, color, size and characteristics of this thing. Write an article about scenery, and know what kind of scenery it is.

In reading, if we grasp the main content of the article, we can understand the main idea of the article concisely and lay the foundation for further understanding the center of the article and summarizing the central idea. Therefore, summarizing the main contents of the article is helpful to improve our ability of analysis, understanding and generalization and to develop our thinking.

How to summarize the main content of the article? First, we should pay attention to an article as a whole. To grasp the whole, we should sum it up from the whole, instead of generalizing, giving priority to the secondary and replacing the whole with the local. Second, analyze the topic and then summarize the main content. The title of the article is closely related to the content. The title is the "window" of the article, through which we can often know the content of the article. Analyzing the topic is to start with the topic, expand it appropriately, and find out the main content of the article. The specific way is: on the basis of understanding the meaning of the topic, put forward some questions about the topic, and then summarize the answers to these questions to become the main content of the article. Generally speaking, this method can be used for any topic that can inspire and help us understand the text. Third, grasp the key paragraphs and summarize the main contents. An article has several paragraphs, including major paragraphs and minor paragraphs. The main paragraph is a paragraph that plays a key role in expressing the center of the article. Grasping the key paragraphs can summarize the main content. Fourthly, the main content can also be summarized by paragraph merging.

What is paragraph merging? Merging paragraphs is the main idea of merging paragraphs. For an article, the general idea of a paragraph is "part", the main content is "whole", and the whole is always composed of parts. If the paragraphs of an article are juxtaposed and written around the same content, then the main content can be summarized by combining paragraphs.

Summarize the main contents, viewpoints and tips of the article.

① Analysis according to different styles.

(2) to grasp the topic, you can use the method of topic expansion.

3. Grasp the key sentences in the article, especially the sentences that directly reveal the theme of the article.

Because it is the main content, it must be summarized from the perspective of content and distinguished from the central idea. (The main content refers to "what to write" and the central idea is to answer the author's "why to write" and cannot be equated. )

⑤ Grasp the key paragraphs to summarize the content of the article and read the wonderful chapters.

6. Grasp the main content of the article according to the tips before class, the notes after class and the exercises after class.

Example 1: What does the Language of Nature mainly introduce?

Analysis:

1. Pay attention to the stylistic features. This is a popular science article and an expository one. To read expository texts, we must first understand the object of interpretation through overall perception. By reading the full text, we can know that the object of the article is natural language, that is, the article introduces a science-phenology.

2. Analyze the title and author. The title of the article is "The Language of Nature", which is novel, unique and fascinating. Language is a tool for people to exchange ideas and transmit information. How can there be language in nature? After reading the article, we suddenly realized that the original phenological phenomena in nature, such as the rise and fall of vegetation, the coming and going of migratory birds, the singing of flowers and birds, the dancing of grass and so on, actually played a role in predicting agricultural time. From this perspective, phenology seems to be a "natural language" for transmitting information. The author Zhu Kezhen is an outstanding scientist in modern China. He has made great achievements in meteorology, climatology, geography and the history of natural science all his life, and phenology is one of his great contributions. According to these, the content of this paper should focus on introducing the knowledge of phenology, such as what is phenology, what is phenology, what are the factors affecting phenology, and what is the significance of phenological observation to agriculture.

3. Clarify the thinking of the article and clarify the level. The article can be divided into four parts. Part I (paragraph 1-3): What are phenology and phenology? Part II (paragraphs 4-5): Explain the importance of phenology to agriculture. The third part (paragraph 6- 10): explain the factors that determine the arrival of phenology. The fourth part (paragraph 1 1- 12) explains the significance of studying phenology. The idea of the whole paper is clear: describing phenology-making a scientific explanation-investigating causality-expounding the research significance.

Answer:

This paper focuses on phenology, phenology, factors affecting phenology and the significance of phenological observation to agriculture. Phenology mainly refers to the growth, development and activities of animals and plants and the response of abiotic changes to seasons and climate. Phenology, also known as "bioclimatology", is a science that studies the relationship between biological life activities and seasonal changes. There are four factors that affect phenology: latitude, longitude, height difference, and ancient and modern difference. The significance of phenology to agricultural production: the first is to predict the agricultural season. Phenological data has important reference value for arranging crop zoning and determining the date of afforestation and seed collection. It can also be used to introduce plants into areas with the same phenological conditions, and can also be used to avoid or reduce the harm of pests.

Style is to explain how to summarize the main points of the text, mainly in the following three ways:

1. Analyze the title to understand the description object.

Close to the author. Know the author's identity, occupation, achievements, etc. It will help to grasp the content of the article.

3. Clarifying the structural level and summarizing the general idea of the paragraph can help us understand the text better.

Example 2: What are the benefits of cloning technology for human beings?

Analysis:

Magic Cloning is an expository article, which was rewritten by biologist Tan according to several related articles, focusing on the scientific knowledge about cloning. To sum up how cloning technology benefits mankind, you can start with the subtitle. Glancing at the subtitle of the text, the fourth part of the article introduces "cloning technology brings great benefits to mankind" from three aspects.

Answer:

First, cloning can effectively breed "high value-added livestock"; Second, cloning can be used to save rare animals; Third, cloning is of great significance to the prevention and treatment of human diseases and the extension of life span.

Problem solving method link

Read through the whole text, divide the text into paragraphs and find out the main content of each part. If there are subtitles, start with the headline directly.

Example 3: What is the reason for the extinction of dinosaurs?

Analysis:

These two popular science essays are selected from Asimov's later work Xinjiang Region. The author strongly proves that "different scientific fields are closely related" with two examples in scientific research. A new discovery in one scientific field will certainly have an impact on other fields. These two essays are all about the extinction of dinosaurs, but the materials used are different and the main problems expounded are different. Dinosaurs Everywhere proves the "plate tectonic theory" through the discovery of Antarctic dinosaur fossils. "Dinosaurs can't live independently on every continent, so how did they cross the ocean to another continent?" The answer to this question is straightforward: "It is the continental drift, not the dinosaurs themselves". "There are many continents on the back of the plate. When the plate moves in one direction or the other, the mainland moves with it. " Obviously, some dinosaurs came to the South Pole on this "ship". So why did the dinosaurs that lived on the earth for 1.6 years 65 million years ago suddenly become extinct? In the second article, the author makes an in-depth discussion. "Broken sand" became evidence. "Broken sand", also known as timely, has two properties: (1) timely is not very stable and will become ordinary sand, but its "rebound" in natural state is very slow and can last for millions of years; On the other hand, it will soon turn back to ordinary sand at high temperature. (2) Timely "only appears where it is strongly squeezed", and its formation comes from great pressure. The author discusses these topics in order to rule out the "volcano theory" and confirm that the "impact theory" provides a scientific basis. Finally, the author uses the results of "research" and "detection" of McHorne of Arizona University and several collaborators to strongly prove that there was a huge impact 65 million years ago, which formed a time that weighed several tons. ..... Then the reason for the extinction of dinosaurs is not volcanic activity, but "impact".

Answer:

The reason for the extinction of dinosaurs was not volcanic activity, but impact.

Example 4: What is the theme of Biological Intruder?

Analysis:

What is a "biological intruder"? Many people will not be familiar with it. You know, this is a war initiated by human beings without smoke, which cannot but arouse our high vigilance. This paper introduces the knowledge that biological migration through illegal natural channels may cause harm to human beings. Starting with the explanation of the concept of "biological invader", this paper introduces the harm brought by "biological invader" to human beings, the destructive effect on the ecological environment and the reasons for the formation of "biological invader". Different views of the scientific community on "biological invaders" and the measures taken by countries all over the world at present.

A: The theme of Biological Invaders is ecological environment. Learning this article can not only help us understand some knowledge of ecological environment, but also cultivate our scientific consciousness of caring about the life around us.

To write a good article, you must arrange the order reasonably. Let's take the explanatory text as an example. To tell people something accurately and clearly, we must grasp its characteristics. But if it is "nonsense", then others are still unclear and don't understand what is introduced. Therefore, in order to express the characteristics of things accurately, clearly and clearly, the order of interpretation must be arranged reasonably. So what is the basis for arranging orders reasonably? Take expository writing as an example to show that things always have a purpose and intention. For example, the purpose of introducing a commodity is to let others know the value and use of the commodity, with the intention of opening up the market and making the commodity enter thousands of households. The purpose of explanation is varied. Therefore, what to say first, what to say later and what to say again should be arranged according to the specific purpose of explanation. This arrangement is appropriate and reasonable.

What is the common order of instructions? The common order of interpretation is chronological order (including procedures), spatial order and logical order.

In order to clarify the development and change process of things or the production process of things, time sequence is often used, so that articles can be written clearly and clearly. Explain the shape and structure of things, generally according to the spatial position of things in turn. Everything at rest exists in space. Such as various buildings, places of interest, etc. They all have a certain orientation, shape and structure, and spatial order is usually used to explain these things. Logical order is to arrange the order of interpretation according to the internal relations of things, which is often used to explain abstract things. It includes from total to division, from phenomenon to essence, from sensibility to rationality, from quantity to quality and so on. Generally speaking, words representing time change, words representing space change and words describing the internal relations of things are linguistic symbols of time order, spatial order and logical order respectively.

The writing order of narrative, argumentative and expository styles is generally chronological, spatial order and logical. Narrative is usually organized in chronological order or the development order of things, while argumentative is mainly in logical order, adopting the structural form of asking questions, analyzing problems and solving problems. The structural forms of various styles often include total score, juxtaposition and layering. To sort out its order is to look for language symbols, and sometimes we can start with analyzing the structure and sorting out the ideas.

B. Extracurricular knowledge development

Globalization of biological pollution (Hu deposit)

On Neilingding Island, the southwest coast of Shenzhen, Mikania micrantha, a "plant killer", is spreading rapidly and has become an irresistible trend. In the past, this shady and leafy island was covered with Mikania micrantha. They are like huge nets, shrouded in the darkness of beautiful litchi trees, banana trees and acacia trees. Trees die silently because they can't get sunshine, flowers and green grass wither because they can't get fresh air, and the land on the island is becoming a wasteland. Neilingding Island, known as the "plant paradise", may be destroyed by Mikania micrantha.

This horrible "plant killer" originated in Central and South America. In 1980s, Mikania micrantha spread to Southeast Asia, causing immeasurable losses to farmers who planted cash crops such as bananas, tea, cocoa and rice. In the early 1990s, Mikania micrantha's magic feet set foot on Hainan Island in China. A few years later, I arrived in Shenzhen. Almost 80% of the 4 000-mu plantation in Baoan, Shenzhen was ravaged by Mikania micrantha. Some fir forests have been blocked by Mikania micrantha and some hilltops have been completely covered by Mikania micrantha.

Scientists call this kind of event similar to Mikania micrantha "biological pollution". It refers to the invasion of some harmful alien creatures and the destruction of the original ecology. Different from chemical pollution, exotic organisms can proliferate and spread to new places, and gradually adapt to the new environment and take advantage, thus endangering native species.

The invasion of these harmful alien creatures is often simply regarded as an accident, and people's understanding of their threats is not enough. In fact, this kind of invasion happens all the time on the earth, and with the globalization of transportation and the increasing world trade, the frequency and scope of this kind of invasion are still expanding, and there is a trend of globalization.

At present, alien life can be found in most lakes and river systems, most coasts and major islands on the earth, and spread to all continents, some of which have been polluted.

In western Europe, a North American shrimp disease is attacking local shrimp, causing local shrimp to disappear in many rivers. In the Mediterranean Sea and Adriatic Sea, a Pacific seaweed covers 3000 hectares of the sea floor. In southern Europe, Nigeria, South Africa, New Zealand, Australia, Brazil and the southeastern United States, Asian tiger mosquitoes may increase the risk of spreading many dangerous diseases. This aggressive biting mosquito can carry at least 17 viruses, including dengue fever, yellow fever and other encephalitis. From East Africa to the Indo-Pacific region, a A Lang grass from South Asia has invaded millions of hectares of tropical forests, seriously affecting the natural regeneration of local trees. A pathogenic fungus in Australia, probably from Papua New Guinea, has invaded since 1920, resulting in the destruction of thousands of hectares of forests. This fungus is harmful to three quarters of plants, including tall trees and short shrubs. In New Zealand, a nocturnal kangaroo from Australia is estimated to have eaten 2 1 ton of local forests (bark, tree buds, leaves, etc. ) Every night. Palm tree snakes from Papua New Guinea made wild 1 1 species of birds and some lizards and bats extinct in Guam, Pacific Ocean. Scientists are worried that this snake will spread to the whole Pacific region. In China, a South American aquatic plant (water hyacinth) greatly reduced the water area of Dianchi Lake in Kunming. The local climate has obviously become drier, and 38 of the 68 species of fish in the lake no longer exist.

In addition to active transmission, artificial blind introduction of species is also one of the causes of biological pollution. In Lake Victoria, Africa, the introduction of Nile perch led to the extinction of more than 200 local species, which was the largest extinction of vertebrates on record. The introduction of Pinus tabulaeformis and Sophora japonica was originally for afforestation, but now it consumes the groundwater used to supply Cape Town.

Although human beings have studied biological pollution for 40 years, ecologists have not found the natural law of biological pollution process.

First of all, little is known about "invaders". Weeds can be said to be the most common invaders, but there are also very special intruders. We know very little about the "family" of invaders, and we don't know what kind of creatures will be successful "invaders".

Secondly, the location and time of the invasion are unpredictable. Generally speaking, unbalanced ecosystems are usually more fragile than complete ecosystems. One of the reasons why Pennisetum can dominate the 25 million hectares of land in the northwest of the United States is overgrazing by local herders. But there are many exceptions. For example, in the existing undisturbed Hawaiian rainforests, the dominant insects are usually exotic. In the Great Lakes, the improvement of water quality may have helped the sea eel, because the larvae of this carnivorous fish are quite sensitive to pollution. Exotic organisms can lurk for decades after invasion, and the change of ecological balance can lead to explosive invasion. The incubation period of this plant invasion is relatively common, and it is almost certain that many exotic creatures exist, but we have not noticed that according to an American expert who studies weed invasion, exotic weeds are usually discovered after 30 years of invasion, or spread to 4000 hectares.

In addition, the extent of our harm to biological invasion cannot be estimated. Because the harm of foreign invasion is not only to replace local species, but also to have amazing consequences. Let's take a look at the introduction of tiny mysid shrimp in Pingtou River, Montana. In order to increase the feed quantity of another imported species of KOKANEE salmon, wildlife conservationists introduced mysium shrimp around 1970. However, the habit of salmon is to prey on the water surface, and the bran shrimp only surfaced at night, and no bran shrimp was seen at night. In turn, mysids also eat plankton on which salmon fry depend. As a result, the number of salmon decreased, leading to the extinction of bears, carnivorous birds and other animals dependent on salmon, and many eagles starved to death.

The harm of biological pollution goes far beyond this. It is a great threat to the balance of the whole ecosystem and the development of human society.

Threatening biodiversity. Mountains, deserts and streams are natural boundaries that separate different ecosystems. Biological pollution caused by human trade, travel and other activities destroys the function of these natural boundaries. Exotic organisms threaten local species, resulting in the reduction or even extinction of local species. Biological pollution is a great threat to biodiversity. An experiment in the United States shows that new genetically engineered plants can transfer herbicide-resistant genes into weeds faster than people expected. Bt plants will not only kill the target pests, but also kill some beneficial insects and threaten their natural enemies. Therefore, a large number of experiments and strict examination and approval must be carried out before approving transgenic plants for field planting.

Threaten human health. Various ways have caused the spread and prevalence of alien bacteria in the world. Global AIDS, British mad cow disease, Japanese "0 157 bacteria", avian influenza in Hong Kong and enterovirus in Taiwan Province Province all threaten human health greatly. In recent years, the United States has taken a series of measures to strengthen food hygiene management, implemented the Hazard Analysis and Critical Control Point (HACCP) plan, and invested 43 million US dollars in food safety monitoring, research and education in 1998.

Threaten economic development. The invasion of exotic pests and diseases will cause huge economic losses. In the United States, the loss caused by exotic pests to forests is as high as $4 billion a year. Recently, the United States found that Anoplophora glabripennis caused damage to some trees. The United States believes that it was imported from China through wooden packaging materials, and plans to take stricter measures against China, including requiring China exporters to provide certificates issued by relevant departments on treatment (heating, fumigation, etc.). ) wooden packaging materials. It is estimated that the new regulations of the United States will affect 30%-50% of China's exports to the United States, and will also have a negative impact on China's economy.

Although many scientists and land managers are worried about biological pollution, they seldom attract the attention of decision makers. Recently, the U.S. government is formulating a strategy to coordinate more than 30 federal agencies to deal with the invasion of foreign creatures. Some developed countries in western Europe are also actively seeking countermeasures, mainly including the following aspects: perfecting international treaties such as the International Plant Protection Convention and reducing loopholes; Cut off the invasion channel of alien creatures; Establish an international biological monitoring system and database to overcome the scattered information of infringing species; Stop the introduction of exotic species by natural resource managers, such as exotic forage plants in pastoral areas and exotic grass species for soil protection; Improve the overall ecological awareness of the population, so that people can understand the value of local natural scenery and resist the invasion of exotic creatures.

(Selected from Guangming Daily, June 2000 12)

Early warning mechanism to prevent biological invasion

Invasion of alien harmful species is a global problem. According to the reports submitted by the United States, India and South Africa to the United Nations, the losses caused by the invasion of alien species in the three countries are $654.38+37 billion, $654.38+30 million and more than $80 billion respectively. China is also one of the countries where the invasion of alien harmful species has caused serious harm. With the increase of imported goods, the risk of introducing harmful species into the forest through various hidden forms such as wooden packing boxes is increasing, and the task of preventing harmful species from invading Shanghai is arduous.

There are about 700 kinds of local and exotic natural plant resources in Shanghai. The number of seed plants in Sheshan decreased from 80 families 147 genera 184 species in 1960s to 1996 species, which was related to the invasion of alien species.

In recent years, the flood of water hyacinth in the upper reaches of Huangpu River has affected the safety of waterway, the appearance of water area and the ecosystem of Pujiang River system. In addition, malignant alien species such as Solidago canadensis and Alternanthera philoxeroides are also ready to move.

Experts suggest that Shanghai should establish a risk early warning mechanism for imported plants and their products as soon as possible, and establish a database of exotic species and their impact on local organisms.

"Outsiders" robbed "locals" of their houses.

Pomacea canaliculata is native to the Amazon River basin in South America. It looks like a snail, with a thin shell and a lot of meat. It is a big edible snail. In 1980s, Weishan County introduced it as delicious food. However, the entry of Ampullaria gigas broke the balance of the local natural ecological environment. At present, Ampullaria canaliculata is breeding wildly in local waters, causing seedling damage and losses to agricultural production.

It is understood that this phenomenon of ecological environment destruction caused by the entry of alien species is not uncommon in China. According to the statistics of relevant departments, there are hundreds of alien invasive species in China, which have caused great damage to China's agricultural ecosystem, biodiversity protection and human health. Among the alien invasive plants, Alternanthera philoxeroides can make the yield loss of rice, wheat and corn reach 45%, 36% and 19% respectively, and the toxin contained in Eupatorium adenophorum can cause asthma in horses and sheep. Statistics from the State Environmental Protection Administration show that the economic losses caused by only a few major alien invasive species in China are as high as 57.4 billion yuan per year on average.

In recent years, the invasion of alien species has destroyed the ecological environment of our province. Spartina alterniflora, commonly known as "man-eating grass", has been flooded in the estuary of the Yellow River in Dongying City, with the affected area of 6,543.8+0.3 million mu, the scattered grass area of 50,000-60,000 mu, and the grass seed drifting area of 654.38+0. 1 10,000 mu. Wherever the rice grass goes, shellfish, crabs, fish and other organisms suffocate and die, and the developed roots block the waterway, which brings a lot of inconvenience to transportation and fisheries.

At present, the alien species that are seriously harmful to our province mainly include Spartina, water hyacinth and Hyphantria cunea. Researcher Wang Hongtao, director of the EIA Office of the Provincial Agricultural Environmental Protection Monitoring Station, said that although the harm caused by exotic species in our province is not very serious, there are also many economic losses. In the 1940s, with the introduction of Okinawa 100, sweet potato black spot was introduced into our province.