What is a biological intruder?

Biological invasion refers to the phenomenon that a certain organism is introduced naturally or artificially from other places and becomes wild, which causes certain harm to the local ecosystem. These creatures are called alien species. Exotic species refer to those species, subspecies or taxonomic units below that have appeared in the past or now beyond their natural distribution and diffusion potential, including all parts, gametes or propagules that may survive and then reproduce. Alien invasive species have the characteristics of strong ecological adaptability, strong reproductive ability and strong communication ability. Invasive ecosystem has the characteristics of abundant available resources, lack of natural control mechanism and high frequency of human entry. The "exotic" of alien species is defined by the ecosystem.

First of all, alien species include: invasive microorganisms: mainly refer to pathogenic microorganisms that bring harm to crops, trees and economic fish and shrimp, excluding human and animal diseases. Invasive plants: mainly refer to harmful plants that bring harm and threat in different ecosystems such as agriculture, forestry, wetlands, grasslands, fresh water and oceans, such as herbs, vines, shrubs, algae and some trees with obvious harm. Invasive animals: mainly refer to harmful insects, mites, fish, amphibians and reptiles that are harmful to agriculture, forestry, animal husbandry and fishery production. Blattella germanica, native to Germany, is called Blattella germanica. Due to international trade, it is imported into China in the process of commodity circulation and transportation. Because its posture is very similar to that of cockroaches, its individual size is a quarter of that of ordinary cockroaches, and it belongs to a kind of cockroaches. biological invasion

The reproductive speed of Blattella is thousands of times faster than that of common cockroaches. After about half a month, its young eggs can grow into adults, and the population is several times or even thousands of times that of ordinary cockroaches. The living habits of cockroaches are similar to those of ordinary cockroaches, and they like to move in hotels, Chinese and western kitchens, bars, restaurants, private rooms and other places. Its harm to people is similar to that of cockroaches, mainly because they spread many harmful substances and germs into people's food and utensils during their activities, endangering people's life and health. Blattella germanica is the smallest indoor cockroach, with a body length below15 mm. The adults are brownish yellow. There are two parallel brown longitudinal stripes on the back plate of the chest. Blattella germanica can experience 4-5 generations a year. Blattella germanica egg sheath has been dragged at the end of the female insect until the nymph is hatched. Nymphs therefore spread everywhere with their mothers. After molting for 5-7 times, the nymph becomes an adult, and the nymph period is 30-56 days. It has been nearly twenty years since Blattella germanica officially settled in China on a large scale, and it has spread from a few big cities to almost all small and medium-sized cities, even small market towns and rural areas. According to the data of the National Center for Disease Control and Prevention, a female Blattella germanica can breed up to one million offspring a year. With the extensive use of pesticides for control, Blattella germanica has developed strong drug resistance, and most pesticides are ineffective. Because of the existence and uncontrollable of Blattella germanica, cockroaches have replaced mice as the first of the four pests! With the increasingly frequent and close economic and cultural exchanges between countries and regions, and with the increasing global environmental instability, all ecological wars without smoke-"biological invasion" are quietly starting all over the world, and the ecological disasters caused by them are seriously threatening the economic development and global ecological security of all countries in the world. Known as the "Purple Devil", the water hyacinth (commonly known as "Water hyacinth" in China) is rampant in waters around the world, which is the most typical example of alien species invasion. From 65438 to 0884, Eichhornia crassipes, originally from Venezuela in South America, was sent to the World Expo in New Orleans, USA. People from all over the world saw its gorgeous flowers and brought them back to their respective countries as ornamental plants. As everyone knows, Eichhornia crassipes with strong reproductive ability has since become the number one harmful plant in all countries. In Africa, Eichhornia crassipes is all over the Nile; In Thailand, Eichhornia crassipes covers the Chao Phraya River; In the southern United States, the inland rivers along the Gulf of Mexico are also blocked by dense Eichhornia crassipes, which not only leads to the impassability of ships, but also leads to the extinction of fish and shrimp and the stink of river water. Dianchi Lake in Yunnan, China was also accused by experts of suffering from "ecological cancer" because of the crazy spread of water hyacinth. In addition, kudzu vine was introduced into the United States, which not only has strong growth ability, but also can improve the soil environment. 1930 was introduced from the United States and Japan, and many damaged farmland and sand slopes became fertile fields with lush vegetation, which was known as "the doctor of the earth". In the mid-1950s, there were nearly ten thousand kudzu vines in the United States. However, kudzu vine is like a wild animal. "Wildfire never completely devours them, and they grow taller in the spring breeze." In just 20 years, he changed from a doctor on the earth to a green monster wanted by the United States, and the Alabama government declared kudzu an illegal immigrant. In addition, the rabbit disaster in Australia, poisonous algae in the Mediterranean, zebra mussels in the Great Lakes of the United States, frogs in Hawaii, and invasive cases of exotic species such as Eupatorium adenophorum, Spartina, Bursaphelenchus xylophilus, Solidago canadensis, crayfish and Hyphantria cunea. Due to the lack of natural enemies, these foreign invaders not only destroy the food chain, threaten the survival of other creatures, but also bring huge economic losses to the world. According to the report of the International Union for Conservation of Natural Resources (IUCN), the global economic losses caused by the invasion of alien species exceed 400 billion dollars every year.

Current situation of biological invasion in China

China has a vast territory, diverse habitats and diverse ecosystems. Most exotic species can easily find suitable growth and breeding sites in China, which makes China more vulnerable to the invasion of exotic species. For a long time, due to the lack of sufficient understanding and systematic investigation and research on the invasion of alien species, China has still been unable to provide authoritative catalogue materials reflecting the invasion of alien species into China. Although the State Environmental Protection Administration announced the first batch of 16 "alien invasive species" [7], the actual number of invasive animals and plants is far more than these. According to preliminary statistics, at present, the known alien invasive species in China include at least 300 invasive plants, 40 invasive animals and 1 1 invasive microorganisms. Among them, eight invasive plants such as water hyacinth, Alternanthera philoxeroides, Spartina alterniflora and Mikania micrantha have brought serious harm to agriculture and forestry, and the most serious pests are American white moth, pine wood nematode and potato beetle 14 species. The harmful alien species announced by the State Environmental Protection Administration 16 are Eupatorium adenophorum, Mikania micrantha, Alternanthera philoxeroides, ragweed, poisonous wheat, Spartina alterniflora, Eupatorium odoratum, Eichhornia crassipes, false sorghum, sugarcane borer, Pinus elliottii, bark beetles, Hyphantria cunea and African snails. The 20 most dangerous alien invasive species in China and their distribution and harm: species distribution, host plants/harm.

Bemisia tabaci (B type and Q type) has more than 600 kinds of vegetables, flowers, tobacco and cotton in Guangdong, Guangxi, Hainan, Fujian and Yunnan.

Rice water weevil, such as rice in Hebei, Shanxi, Shaanxi, Shandong and Beijing.

Apple moth Xinjiang, Gansu apple, Shaguo, Korla fragrant pear, peach, pear, etc.

Potato Beetle Xinjiang Potato, Tomato, Eggplant, Pepper, Tobacco, Solanum nigrum

Bactrocera dorsalis has more than 250 kinds of fruits and vegetables in Guangdong, Guangxi, Yunnan, Sichuan and Guizhou.

Pinus in Taiwan Province, Hongkong, Macau, Guangdong, Fujian and Guangxi.

Brontispa longissima: Palmae, from Hainan, Yunnan, Guangdong, Guangxi, Taiwan Province and Hongkong.

Dendroctonus valens in Shanxi, Hebei and Henan, Pinus tabulaeformis, Pinus armandii and Pinus bungeana in Shaanxi.

Red imported fire ants bite villagers in Taiwan Province, Guangdong, Guangxi, Fujian, Hong Kong and Macao, endangering public facilities.

In more than 20 provinces, municipalities and autonomous regions except Tibet, Qinghai and Inner Mongolia, indigenous species are endangered and dams have been destroyed.

Bursaphelenchus xylophilus in Yunnan, Sichuan, Guangdong, Guangxi, Guizhou and Fujian.

Banana perforation nematodes have been found in Fujian and Guangdong, but more than 350 economic and ornamental plants have been exterminated.

Pomacea canaliculata harms rice fields and farmland in Hainan, Fujian, Guangdong, Guangxi and Sichuan, and spreads human diseases.

Eupatorium adenophorum harms agriculture, forestry and animal husbandry in Yunnan, Guizhou, Guangxi, Sichuan and Chongqing, making the ecosystem single.

The ragweed in Hunan, Hubei, Sichuan, Chongqing and Fujian destroys agricultural production and affects ecological balance and human health.

Water hyacinths in Zhejiang, Fujian, Taiwan Province, Yunnan, Guangdong and Guangxi blocked rivers, resulting in eutrophication and decreased biodiversity.

Alternanthera philoxeroides in Hunan, Hubei, Sichuan, Chongqing, Fujian and other places blocked rivers, affected drainage and flood discharge, reduced crop production and spread of livestock diseases.

Spartina alterniflora destroyed the marine ecosystem and aquaculture in all coastal provinces except Hainan and Taiwan Province.

Mikania micrantha harms natural secondary forests and artificial forests in Guangdong, Yunnan, Hainan, Hong Kong and Macao.

Solidago canadensis is distributed in Henan, Liaoning, Sichuan, Chongqing and Hunan. It makes species single, encroaches on farmland and affects the natural restoration process of vegetation.

These alien invasive organisms have become the number one enemy of agriculture, forestry and animal husbandry production and biodiversity protection in China. On the one hand, it has caused huge economic losses to agriculture, forestry and animal husbandry in China. It is estimated that only a few major alien invasive species cause direct economic losses to China as high as 50 billion yuan every year. On the other hand, it also makes the task of maintaining biodiversity in China more arduous. According to the survey, about half of the alien invasive species in 100 published by IUCN have invaded China. In line with this, among the 640 world endangered species listed in the International Convention on Endangered Wild Fauna and Flora, 156 are all in China. Therefore, it is urgent to maintain biodiversity and fully resist the invasion of alien species.