Earthworms as invasive species

Last updated August 24, 2023

Earthworms are invasive species throughout the world. Of a total of about 6,000 species of earthworm, about 120 species are widely distributed around the globe. These are the peregrine or cosmopolitan earthworms.^[1]^[2] Some of these are invasive species in many regions.

Australia

Australia has 650 known species of native earthworm that survive in both rich and in nutrient-poor conditions where they may be sensitive to changes in the environment. The total native species numbers are predicted to exceed 1,000.^[3]

Introduced species are commonly found in agricultural environments along with persistent natives. 66 exotic species are known by 1999, most of which have been introduced accidentally.^[3]

North America

Approximately 182 earthworm taxa in twelve families are reported from the United States and Canada, of which sixty (about 33%) are introduced.^[4] Only two genera of lumbricid earthworms are indigenous to North America while introduced genera have spread to areas without any native species, especially in the north where forest ecosystems rely on a large amount of undecayed leaf matter. When worms decompose that leaf layer, the ecology may shift making the habitat unsurvivable for certain species of trees, ferns and herbs. Larger earthworms such as the nightcrawler Lumbricus terrestris and L. rubellus and the Alabama (technically Asian) jumper, Amynthas agrestis , can be eaten by adult salamanders, which is beneficial for their populations, but they are too large for juvenile salamanders to consume, which leads to a net loss in salamander population.^[5]

Currently there is no economically feasible method for controlling invasive earthworms in forests.^[6] Earthworms normally spread slowly, but can be quickly introduced by human activities such as construction earthmoving, plantings, and the release of worms used as fishing bait.

United Kingdom

For the 69-70 known species,^[7] a recent threat to earthworm populations in the UK is the New Zealand flatworm (Arthurdendyus triangulatus), which feeds upon earthworms but has no local natural predator itself. Sightings of the New Zealand flatworm have been mainly localised, but it has spread extensively since its introduction in 1960 through contaminated soil and plant pots. Any sightings of the flatworm should be reported to the Scottish Crop Research Institute, which is monitoring its spread.

East Asia

In Taiwan, Pontoscolex corethrurus is known invasive with evidence of it displacing native worms. Eudrilus eugeniae has potential to do the same.^[8] For vermicompost, the native or naturalized Perionyx excavatus is recommended.^[9]

Control

At this point there is no known way to remove the earthworms from the soil, so proposals have focused on ways to slow their spread.^[10] One simple measure is to reduce the number of worms released during fishing practices. The Minnesota Department of Natural Resources, in cooperation with local groups, has launched a public education campaign using posters in bait shops and other outreach efforts.^[11]

The movement of dirt from one location to the other could also be regulated so that dirt from areas where earthworms are common is not moved into forests without the invasive species.^[12]^[11] To prevent the spread of invasive earthworms, it is recommended that people should only purchase compost or mulch that has been heated to appropriate temperatures and duration following protocols that reduce pathogens and kill the earthworm cocoons, or eggs.^[13]

In areas that have already been colonized, the number of worms can be reduced by removal of introduced shrubs such as common buckthorn ( Rhamnus cathartica ) and honeysuckle (e.g., Lonicera × bella), which produce leaf litter favored by worms.^[14] This may help mitigate negative impacts on the ecosystem.

Mustard pours can be used to survey for invasive worms at a site. A mustard pour can be created by mixing a gallon of water with one third cup of ground yellow mustard seed. Pouring the solution slowly over the soil will drive worms to the soil's surface without harming the plants.^[15] People with invasive worms on their property are advised not to move plants or soil from their property.

Related Research Articles

<i>Lumbricus terrestris</i> Species of annelid worm

Lumbricus terrestris is a large, reddish worm species thought to be native to Western Europe, now widely distributed around the world. In some areas where it is an introduced species, some people consider it to be a significant pest for out-competing native worms.

<span class="mw-page-title-main">Lumbricidae</span> Family of annelid worms

The Lumbricidae are a family of earthworms. About 33 lumbricid species have become naturalized around the world, but the bulk of the species are in the Holarctic region: from Canada and the United States and throughout Eurasia to Japan. An enigmatic species in Tasmania is Eophila eti. Currently, 670 valid species and subspecies in about 42 genera are recognized. This family includes the majority of earthworm species well known to Europeans.

Megascolecidae is a taxonomic family of earthworms native to Madagascar, Australia, New Zealand, Southeast Asia, and North America. All species of the Megascolecidae belong to the Clitellata class. The Megascolecidae comprise a large family of earthworms and they can grow up to 2 meters in length. The intercontinental distribution of Megascolecidae species favours the continental drift theory.

The New Zealand flatworm is a large land flatworm native to New Zealand. It can vary from 5 mm in length when hatched to approximately 17 centimetres (6.7 in) in mature adults.

Geoplanidae is a family of flatworms known commonly as land planarians or land flatworms.

<span class="mw-page-title-main">Earthworm</span> Terrestrial invertebrate, order Opisthopora

An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class Oligochaeta. In classical systems, they were in the order of Opisthopora since the male pores opened posterior to the female pores, although the internal male segments are anterior to the female. Theoretical cladistic studies have placed them in the suborder Lumbricina of the order Haplotaxida, but this may change. Other slang names for earthworms include "dew-worm", "rainworm", "nightcrawler", and "angleworm". Larger terrestrial earthworms are also called megadriles as opposed to the microdriles in the semiaquatic families Tubificidae, Lumbricidae and Enchytraeidae. The megadriles are characterized by a distinct clitellum and a vascular system with true capillaries.

Bipalium is a genus of large predatory land planarians. They are often loosely called "hammerhead worms" or "broadhead planarians" because of the distinctive shape of their head region. Land planarians are unique in that they possess a "creeping sole", a highly ciliated region on the ventral epidermis that helps them to creep over the substrate. Native to Asia, several species are invasive to the United States, Canada, and Europe. Some studies have begun the investigation of the evolutionary ecology of these invasive planarians.

<span class="mw-page-title-main">Invasive earthworms of North America</span>

Invasive species of earthworms from the suborder Lumbricina have been expanding their range in North America. Their introduction can have marked effects on the nutrient cycles in temperate forests. These earthworms increase the cycling and leaching of nutrients by breaking up decaying organic matter and spreading it into the soil. Since plants native to these northern forests are evolutionarily adapted to the presence of thick layers of decaying organic matter, the introduction of worms can lead to loss of biodiversity as young plants face less nutrient-rich conditions. Some species of trees and other plants may be incapable of surviving such changes in available nutrients. This change in the plant diversity in turn affects other organisms and often leads to increased invasions of other exotic species as well as overall forest decline. They do not require a mate to reproduce, allowing them to spread faster.

Amynthas is a genus of earthworms in the family Megascolecidae. They are known as jumping worms, snake worms, or crazy worms because of their erratic thrashing behaviour when disturbed. The genus is native to East Asia, but they are invasive in many areas of the United States. They are a matter of concern in many states, as they disrupt the native forest ecology by affecting soil structure and chemistry.

Dendrodrilus rubidus is a species of earthworm in the family Lumbricidae. It is native to Europe, and it is a widespread introduced species, occurring on every continent except Antarctica, as well as many islands. It is often invasive. It is sometimes used as fishing bait, and is marketed under many nonspecific names, including red wiggler, jumping red wiggler, red trout worm, jumbo red worm, and pink worm. Other common names include bank worm, tree worm, and gilt tail.

Samuel James is an American scientist, a researcher specializing in evolutionary biology, focusing on earthworm taxonomy. James, with fellow researchers, has discovered numerous species of annelids, including Diplocardia californiana, Diplocardia woodi, Diplocardia montana, and a new species related to the Giant Palouse earthworm.

Obama nungara is a species of land planarian in the family Geoplanidae. It is native to South America, but has been introduced in Europe.

Octochaetus multiporus, commonly known as the New Zealand earthworm, is a megascolecid worm endemic to New Zealand. It is mainly found in the south of Manawatu but may also be found along the east coast of the South Island. A bioluminescent worm, Octochaetus multiporus secretes a luminescent fluid from its mouth when disturbed or punctured.

Moniligastridae is a family of earthworms native to South and Eastern Asia, containing around 200 species and five genera.

Amynthas mekongianus, the Mekong worm or Mekong giant earthworm, previously known as Megascolex mekongianus, is a species of earthworm in the family Megascolecidae. It is native to the vicinity of the River Mekong in southeastern Asia and may have more than 500 segments and grow to a length of 2.9 m (10 ft).

Megascolecidae earthworm Amynthas japonicus was a Japanese native probably collected from Nagasaki in the 1820s. It was one of three native earthworms featured in Dr P.F.B. von Siebold’s extensive collection and recorded as one of Japan’s earliest pheretimoid species. It is now deemed extinct given that a 2018 Nagasaki expedition and earlier 1930s reports failed to locate it. It is featured on The Recently Extinct Plants and Animals Database.

Amynthas agrestis, the Asian jumping worm, is a species of worm in the family Megascolecidae. It has a smooth, glossy, grey or brown body with a milky-white clitellum, and can range from 1.5 to 8 in in length. Amynthas agrestis is native to Japan and the Korean Peninsula, and was introduced to North America due to increased human activity during the 19th century; it is considered to be an invasive species in the United States. Worms within the genus Amynthas reproduce and develop quicker than their European counterparts.

Amynthas tokioensis, the Asian jumping worm, is a species of earthworm in the family Megascolecidae. It is native to Japan and the Korean Peninsula. It is an invasive species in North America.

Octolasion lacteum is a species of earthworm of the genus Octolasion. In New Zealand it has been found in West Coast soils and in Canterbury. They are found in mostly moist areas deep under the soil as they feed in the nutrients within the soil. Unlike other worm species, these are known to survive in acidic soil as well as soil that is not as organic compared to other places. They provide some important roles in the ecosystem as well as threats to other species as well. After a drought, they help the soil get more organic by adding more carbon dioxide in the soil and the waste from the O. lacteum also provides nutrients for the soil. In another case, they can also be invasive in a way that they suck up carbon in the soil which means plants have less causing a disruption to the food web. Lastly, they reproduce by cross parthogenic reproduction.

Pontoscolex corethrurus is an earthworm in the genus Pontoscolex. It has a circumtropical distribution, although it originates in the Neotropics, probably in the Guiana Plateau.

References

↑ Cosmopolitan Earthworms
↑ Plisko, J.D. 2010. Megadrile earthworm taxa introduced to South African soils (Oligochaeta: Acanthodrilidae, Eudrilidae, Glossoscolecidae, Lumbricidae, Megascolecidae, Ocnerodrilidae). African Invertebrates 51 (2): 289-312. Africaninvertebrates.org.za Archived 2012-03-12 at the Wayback Machine
1 2 Blakemore, Rob, Diversity of exotic earthworms in Australia - a status report. Transactions of the Royal Zoological Society of New South Wales, 1999 "Approximately 350 native species in about 30 genera are currently described for Australia, but an estimate of total number is about three times as large (Blakemore 1997a)."
↑ Blakemore, R. 2006 American earthworms (Oligochaeta) from north of the Rio Grande.
↑ Crawling to Oblivion, Scientific American, 300, 3 (March 2009), p. 22
↑ "Great Lakes Worm Watch - What can I do?". University of Minnesota. 2011. Retrieved 31 January 2019.
↑ Blakemore, R.J. 2008 http://www.annelida.net/earthworm/Britain%20&%20Ireland.pdf
↑ "並非蚯蚓就是好外來蚯蚓大量混養引發生態衝擊" [Earthworms aren't all good; Exotic earthworms are mix-kept en masse, causing ecological shock]. 上下游News&Market (in Chinese (Taiwan)). 22 November 2016. Retrieved 22 May 2022.
↑ "印度藍蚯蚓：你不知道養殖上有多好用的本土種——太平二號與牠們的產地（三）". PanSci 泛科學 (in Chinese (Taiwan)).
↑ Lee E. Frelich, Cindy M. Hale, Stefan Scheu, Andrew R. Holdsworth, Liam Heneghan, Patrick J. Bohlen and Peter B. Reich. 2006. Earthworm invasion into previously earthworm-free temperate and boreal forests. Biological Invasions 8: 1235–245. doi : 10.1007/s10530-006-9019-3
1 2 Callaham, Mac A. Jr.; González, Grizelle; Hale, Cynthia M.; Heneghan, Liam; Lachnicht, Sharon L.; Zou, Xiaoming (1 September 2006). "Policy and management responses to earthworm invasions in North America". Biological Invasions Belowground: Earthworms as Invasive Species (PDF). pp. 1317–1329. doi:10.1007/978-1-4020-5429-7_11. ISBN 978-1-4020-5428-0.{{cite book}}: |journal= ignored (help)
↑ Nico Eisenhauer, Stephan Partsch, Dennis Parkinson and Stefan Scheu. 2007. Invasion of a deciduous forest by earthworms: changes in soil chemistry, microflora, microarthropds, and vegetation. Soil Biology and Biochemistry 39: 1099-110. doi : 10.1016/j.soilbio.2006.12.019
↑ F., Hendrix, Paul; J., Bohlen, Patrick (2002-09-01). "Exotic Earthworm Invasions in North America: Ecological and Policy ImplicationsExpanding global commerce may be increasing the likelihood of exotic earthworm invasions, which could have negative implications for soil processes, other animal and plant species, and importation of certain pathogens". BioScience. 52 (9): 801. doi: 10.1641/0006-3568(2002)052[0801:EEIINA]2.0.CO;2 . ISSN 0006-3568.{{cite journal}}: CS1 maint: multiple names: authors list (link)
↑ Madritch, Michael D.; Lindroth, Richard L. (13 May 2008). "Removal of invasive shrubs reduces exotic earthworm populations". Biol. Invasions. 11 (3): 663–671. doi:10.1007/s10530-008-9281-7. S2CID 26504134.
↑ "Earthworm Sampling Methods". Great Lakes Worm Watch. University of Minnesota Duluth. Retrieved January 30, 2020.