earthworms 

"becomes a pest in the new location, threatening the local biodiversity."

I work on earthworms.  There are large stretches of the world where introduced species (in the temperate zone mostly Lumbricidae) are eliminating the local species.  One of the notable native earthworms of Oregon (Driloleirus macelfreshi) is probably extinct due to competition.  Lumbricids have fundamentally changed the soil characteristics in areas they invade.  If this does not fit the definition of "invasive", then perhaps we are speaking different languages.   03:36, 16 Feb 2004 (UTC)