Here I thought I was doing a good thing, getting involved in vermiculture, recycling my organic wastes, keeping plastics out of landfill...BUT, and here's the rub, my red wigglers may be an INVASIVE SPECIES! The word at the Farmers' Martket is that earthworms along with all other topsoil were scraped off the face of North America clear on down to the southern states at the last great ice age AND that since they only travel very short distances, they were missing from the species list when the first European settlers came to Canada. Consequently, or so my informant claims, all current species in Canada are European invaders!!! Including my little Eisenia feotida - maybe. The impact of these surface, manure worms could be potentially damaging to our northern forests which depend on at least three deep layers of old leaves to help keep the moisture in the soil. Having not had the opportunity to adapt to the worms, the trees could be in peril. So - I must pursue these alarming possibilities...
http://www.wormdigest.org/content/view/200/2/ - yes Eisenia feotida IS an invader, along with 17 other species, only two are actually native to Ontario. Introduced through commercial cultivation, E. feotida is now found in the wild and was brought in by European settlers a century or two ago. Localized for the most part around human settlements.
http://www.wormdigest.org/content/view/129/2/ E. feotida are indigenous to Australia
http://www.wormdigest.org/content/view/398/2/ A history of the great worm invasions: "The invasion in the investigated aspen forest by mineral soil dwelling earthworm species presumably is slow due to the climatic restrictions on growth, reproduction and activity of these species. However, this study indicates that earthworm invasions can have dramatic impacts on vegetation, soil microarthropods, microorganisms and soil chemistry"
What about worms in compost piles?
http://www.dnr.state.mn.us/invasives/terrestrialanimals/earthworms/index.html Lists damage done to forested areas by invasive worm species in Minnesota - "If you are concerned about spreading non-native worms with your compost, you can kill worms and their eggs by freezing the compost for at least 1 week."
http://www.nrri.umn.edu/worms/ Minnesota Worm Watch site
http://www.naturewatch.ca/english/wormwatch/ Canadian Worm Watch