First of all, alien invasive species can easily lead to the accelerated extinction of local species. Take the well-known Chinese alligator eel as an example. Because it is very fierce and feeds on meat, there are basically no other fish where it can live. If this continues, it will directly destroy the local ecological balance and accelerate species extinction. The same is true of the notorious street sweeper, because it likes to eat garbage and eggs of other fish, so it has a great impact on the environment.
Secondly, alien invasive species will pose a threat to human health. For example, the common red imported fire ants in southern cities are acidic. Once exposed to humans, it will cause skin allergies, blisters, redness, pain, and even some people will die of shock because of exposure to acidic substances in the body of red imported fire ants. This creature appears in cities and rural areas, which not only affects the environment, but also threatens human health. It is an extremely dangerous alien invasive species.
Finally, alien invasive species will lead to reduced grain production. For example, Solidago canadensis has a fast propagation speed and can adapt to various environments. Only one plant can produce tens of thousands of plants, and can absorb nutrients and water in the land, so that the original plants and crops can not survive normally, thus reducing grain production and bringing certain economic losses to the people. Every year, the customs will detect many alien invasive species, which is also very important. We shouldn't take things too simple.