Many animals, plants, and microorganisms have been spread outside their native range by human activities, and become established in parts of the world where they do not naturally occur. Some of these species have adapted so well to their new environments that they have become very abundant. These invasive alien species can have huge impacts on biodiversity, agriculture, health, and economics.
For example, the Asian long-horned beetle, which has recently become established in the USA and Canada, could cause billions of dollars worth of damage to shade trees in cities as well as in native forests. The brown tree snake, which arrived in the Pacific island of Guam during the Second World War, has driven 9 native bird species to extinction.
In Alberta, introduced plant species, such as oxeye daisy and tall buttercup, are spreading in pasture and rangeland, reducing their productivity, while crops are threatened by introduced insects such as the orange wheat blossom midge and the cabbage seed pod weevil.
One of the reasons that invasive species can become so abundant is that they have escaped from the natural enemies, such as parasites, predators, and diseases, that limited their populations in their native range. Thus, one of the important tools in the effort to manage invasive species is biological control.
Links to more Information on invasive species: