There are currently no effective methods to eradicate established earthworm populations without unacceptable non-target effects. Thus the main technique for managing invasions is prevention of introductions, via various pathways (Cameron et al., 2007; Keller et al., 2007).
Preventative measures: One of the major pathways for earthworm introductions is believed to from release by anglers discarding unwanted live bait. Keller et al. (2007) suggest two alternatives to reduce the likelihood of further establishments while preserving the economically important live trade of earthworms. These are: 1) Replace the species currently sold with earthworm species that are unlikely to establish populations, e.g. Eudrilus eugeniae which has an extremely low invasion risk in the U.S. Midwest, and 2) Strengthen efforts to educate anglers to dispose of live earthworms responsibly, i.e. in the trash where landfill conditions are likely to kill them (Keller et al., 2007) or to prohibit the abandonment of live bait (Cameron et al., 2007).
Similarly, transport of cocoons and earthworms via vehicular transport is a major pathway for introduction to new locations. Thus construction of fewer roads, restricting the amount of traffic on roads or reclaiming roads where possible would minimize spread of earthworms (Cameron & Bayne, 2009).
Management and regulatory strategies should also take into account the fact that some earthworm species, such as Lumbricus rubellus have larger impacts than others. This species is less widely distributed than other exotic species. Thus preventing its introduction to new areas is important, even if those areas are already infested with other species (Hale et al., 2006). Similarly, some forests will be more susceptible to invasion than others. Litter calcium content is likely to be an important predictor of litter decomposition rates by exotic earthworms (Holdsworth, 2008).
Callaham et al. (2006) suggest various policy measures that could be adapted to prevent the spread of exotic earthworms. The authors suggest restrictions on transportation of soils from infested areas to non-infested areas, unless a special permit certifying that the material is free from earthworm propagules has been granted. Formalized earthworm introduction decision making tools are also recommended as an alternative to the ad hoc decisions made by regulating agencies at present. This decision-making process allows for the quarantine of materials containing propagules of earthworms that have not been identified or widely introduced previously. These quarantines would provide time to determine the ecological risk posed by the introduction of a given earthworm species into particular systems. Suggested types of information needed to determine ecological risk include mode of reproduction, number of embryos per cocoon, ecological “strategy”, and temperature, pH and moisture requirements (Callaham et al., 2006).
Cultural measures: Successful establishment of earthworm populations is influenced by management of the site. For example, synergistic effects of the invasive weed buckthorn and exotic earthworms could be minimized by early control measures to limit the weed (Heneghan et al, 2006).
Chemical control: Where non-native earthworms are not well established or are found in discrete populations, the use of chemical treatments to eradicate undesirable worms may be successful. Chemical control have been used in the management of golf courses. While these treatments are highly effective, the non-target effects of chemicals should be examined before large-scale utilization (Callaham et al., 2006).
Location Specific Management Information
2. Cameron, Erin K. & Erin M. Bayne, 2009. Road age and its importance in earthworm invasion of northern boreal forests. Journal of Applied Ecology Volume 46, Issue 1, pages 28–36, February 2009
3. Cameron, Erin K.; Bayne, Erin M.; Clapperton, M. Jill, 2007. Human-facilitated invasion of exotic earthworms into northern boreal forests. Ecoscience. 14(4). 2007. 482-490.
4. Hendrix F. Paul (Ed). 2006. Biological invasions belowground earthworms as invasive species. SpringerLink Dordrecht, Netherlands: Springer.
5. Hendrix, F. Paul & Patrick J. Bohlen, 2002. Exotic Earthworm Invasions in North America: Ecological and Policy Implications. BioScience September 2002 : Vol. 52, Issue 9, pg(s) 801-809
6. Keller, Reuben P.; Cox, Annie N.; Van Loon, Christine; Lodge, David M.; Herborg, Leif-Matthias; Rothlisberger, John, 2007. From bait shops to the forest floor: Earthworm use and disposal by anglers. American Midland Naturalist. 158(2). OCT 2007. 321-328.
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