Invasive species

Definition

A non-native organism introduced by human activity that establishes self-sustaining populations and causes measurable ecological, economic, or environmental harm in its new range. The term implies both successful establishment beyond initial introduction points and demonstrable negative impact on native biodiversity, ecosystem function, agriculture, or human health; not all introduced species qualify as invasive.

Etymology

From Latin invadere (to enter, attack) + species (kind, appearance)

Example

The red imported fire ant (Solenopsis invicta), native to South America, is an invasive species in the southern United States and Australia, where it displaces native ants, damages crops, and inflicts painful stings on humans and livestock.

Synonyms

• alien invasive
• pest species
• ecological invader

Related Terms

• introduced species
• native species
• range expansion
• Biological control
• propagule pressure
• invasion biology

Usage Notes

Distinguished from 'introduced species' or 'non-native species' by the requirement of demonstrated harm; some specialists reserve 'invasive' for species spreading rapidly across landscapes, using 'established non-native' for localized introductions. In entomology, many high-profile invasives are insects (e.g., emerald ash borer, spotted lanternfly, Asian tiger mosquito). The term is relative to defined spatial and temporal scales—a species invasive in one region may be native or even declining elsewhere. 'Invasive' is sometimes used informally as a synonym for 'non-native,' but this usage is discouraged in technical writing.