Examples of biological invaders

Eight invasive plants, such as water hyacinth, Alternanthera philoxeroides, Spartina alterniflora and Mikania micrantha, have brought serious harm to agriculture and forestry, while 14 species are the most harmful pests, including Hyphantria cunea, Bursaphelenchus xylophilus and potato beetle. The 16 harmful alien species announced by the State Environmental Protection Administration are Eupatorium adenophorum, Mikania micrantha, Alternanthera philoxeroides, ragweed, poisonous wheat, Spartina alterniflora, Eupatorium odoratum, Bichhornia crassipes, false sorghum, sugarcane moth, slash pine mealybug, bark beetle, American white moth, African snail, pomacea canaliculata, etc. In 1884, Eichhornia crassipes, which originated in Venezuela, 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. However, 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, has also been accused by experts of suffering from "ecological cancer" because of the crazy spread of water hyacinth. In addition, there are "rabbit disaster" in Australia, "poisonous algae" in the Mediterranean, "zebra mussel" in the Great Lakes of the United States, "frog sound" in Hawaii and "Eupatorium adenophorum", "Spartina", "pine wood nematode" and "Solidago canadensis" that 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. According to the report of China Broadcasting Network, Fujian Province, which is located in the frontier of biological invasion, has stopped the spread of alien harmful species with effective scientific research results in recent years and achieved certain results.

Bactrocera dorsalis is a worldwide fruit killer, which seriously harms more than 25 kinds of fruit trees and vegetables, and the country loses tens of billions of yuan every year. Through research, experts in Fujian province found a biological method to deal with Bactrocera dorsalis. The staff first captured the male Bactrocera dorsalis and irradiated them with a certain amount of cobalt 6 rays, making them lose their fertility. Then, the staff will release these flies back to nature. In this way, after mating, females and males will not have children.

Alternanthera philoxeroides, which originated in Brazil, spread all over ridges, rivers and vegetable fields, competing with crops for water and fertilizer, becoming a malignant weed. Fujian Academy of Agricultural Sciences has effectively curbed the ecological damage caused by this harmful grass by using lotus grass which specializes in Alternanthera philoxeroides.

in order to avoid the flooding of water hyacinth, Fujian agricultural scientists and technicians have found a way to kill water hyacinth by spraying mixed herbicides through research. A new method developed by Fujian Academy of Agricultural Sciences is expected to make water hyacinth a water purifier for rivers.

Spartina is known as the "beach killer" because of its crazy growth and occupation of the beach, resulting in the loss of growth and breeding places for a large number of organisms such as fish, shellfish and algae. In eastern Fujian alone, the direct economic loss caused by fishing is more than 464 million yuan every year. The reporter learned that Fujian Agriculture and Forestry University, Academy of Agricultural Sciences and other units have also found ways to deal with the growth of Spartina, which can make Spartina rot in the beach and turn into the sea.