Exotic and Invasive Species: An Economic Perspective

Executive Order 13112 (Order), signed in 1999, defines an invasive species as alien to an ecosystem and potentially harmful to economic activity, the environment or human health if introduced (National Invasive Species Council, 2006). (We use alien, non-native, exotic, non-indigenous and foreign as synonyms.) A species native to one area can be alien and invasive to other areasof the USA. Exotic species under human control and domestication are not invasive, but the same species uncontrolled can be invasive. Invasive species include exotic pests and foreign animal diseases that harm agriculture and the environment, such as insects, nematodes, weeds and pathogens; zoonotic pathogens that can be transmitted between humans and animals; and seeds, eggs, spores and other biological material capable of propagating pests and diseases. The Order contains an economic definition of invasive species, comparing a species’ benefits to its harm or costs. So, exotic species that provide net benefits, such as some crops, ornamentals, livestock, biological control agents or fish and game species, are not invasive.