What are the biological invasions?

First of all, alien species include:

Invasive microorganisms: mainly refer to pathogenic microorganisms that do harm to crops, trees and economic fish and shrimp, excluding human and livestock 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 the production of agriculture, forestry, animal husbandry and fishery.

Blattella germanica

Blattella germanica is native to Germany, so it is called Blattella germanica. Due to international trade, it was imported into China in the process of commodity circulation and transportation. Because its posture is very similar to that of Periplaneta americana, its individual size is one quarter of that of Periplaneta americana, and it belongs to a species of cockroach. The reproductive speed of Blattella Blattella is thousands of times faster than that of ordinary cockroaches. After about half a month, its young eggs can grow into adults, and the population number is several times or even thousands of times more than that of ordinary cockroaches. The living habits of Blattella are similar to those of common 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, which is harmful to people's life and health.

Blattella germanica is the smallest indoor cockroach, with a body length of less than 15mm. 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's egg sheath is dragged at the end of the female insect until the nymph is hatched. Nymphs therefore spread everywhere with the mother.

The nymph becomes an adult after molting for 5-7 times, and the nymph period is 3-56 days.

Blattella germanica has officially settled in China on a large scale for nearly twenty years, and it has spread from a few big cities to almost small and medium-sized cities and even small market towns and rural areas. According to the relevant 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 become extremely resistant, and most pesticides are ineffective. Because of the existence of Blattella germanica and its difficulty in control, cockroaches have replaced mice as the first of the four pests!

Blattella germanica

With the increasingly frequent and close economic and cultural exchanges between countries and regions, and 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 of countries around the world and the global ecological security.

The rampant reproduction of water hyacinths (commonly known as "water hyacinths" in China), known as "purple demons", is a typical example of alien species invasion. In 1884, Eichhornia crassipes, which originated from Venezuela in South America, was sent to the 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. Little did they know that Eichhornia crassipes, which has strong reproductive ability, has since become the number one harmful plant in various countries. In Africa, Eichhornia crassipes is all over the Nile; In Thailand, Eichhornia crassipes is covered with Chao Phraya River; In the southern part of the United States, the inland river along the Gulf of Mexico is also blocked by dense layers of Eichhornia crassipes, which not only leads to the impassability of ships, but also leads to the extinction of fish and shrimp, and the river stinks; Dianchi Lake in Yunnan, China, was once accused by experts of suffering from "ecological cancer" because of the crazy spread of water hyacinth.

in addition, kudzu vine was introduced to the United States, which not only has strong growth ability, but also can improve the soil environment. After the United States was introduced from Japan again in 193, many destroyed agricultural land and sand slopes became fertile land with abundant vegetation, which was praised as "the doctor of the earth". In the mid-195s, there were nearly 1, kudzu vines in the United States. However, Kudzu is "wildfire never quite consumes them, they are tall once more in the spring wind" like a beast. In just 2 years, he went from "the doctor of the earth" to the "green monster" wanted in the United States, and the Alabama government declared kudzu vine 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, Eupatorium adenophorum, Spartina, Bursaphelenchus xylophilus, Solidago canadensis, Crayfish and Hyphantria cunea which invaded China. 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 economic losses caused by the invasion of alien species to the world exceed 4 billion US dollars every year.