Asian Crazy Worm | Amynthas agrestis

California Pest Rating for
Asian Crazy Worm | Amynthas agrestis Goto & Hatai, 1899
Pest Rating: A

 


PEST RATING PROFILE
Initiating Event:

On May 3, 2017, Nick Condos (Director, CDFA) requested information on Amynthas agrestis in California.  Therefore, the status and risk of this pest to California’s agricultural and natural environments are herein assessed and a rating is proposed.   

History & Status:

BackgroundAmynthas agrestis, commonly known as Asian crazy worm, snake worm or Alabama jumper, is an invasive earthworm that is native to East Asia.  These earthworms are extremely active, aggressive, and have voracious appetites.  True to their name, they jump (known to jump off the ground or out of a bait can) and thrash immediately when handled behaving more like a threatened snake than a worm, sometimes even breaking and shedding their tail when caught (Williams, 2014).  Asian crazy worms are considered aggressive as they out-compete common European earthworms (Tiddens, 2015).  These worms are up to 8 inches in length and are characteristically marked by a light (milky white to gray) band (clitellum) around a dark body.  They breed en masse and constantly produce cocoons at the soil surface (Barncard, 2014; Williams, 2014; Tennesen, 2009). Hatchlings have been observed after air temperatures reached above 10°C and die when air temperatures reach below 5°C. Adults develop in about 60 days (or in lab studies, 77-93 days at 1000°C growing degree days accumulated from time of hatching).  They can reproduce without mating or asexually (parthenogenetic). Cocoons can survive at soil temperatures below -20°C (Görres et al., 2016).    Taxonomically, Amynthas agrestis are annelid ringed or segmented worms in the family Megascolecidae, and subclass Oligochaeta of the phylum Annelida.

Amynthas agrestis has not been reported in California and is not regulated by the State’s Fish and Game Code or the California Code of Regulations.  Bait regulations (section 4) would allow A. agrestis as bait: “Legally acquired and possessed invertebrates…may be used for bait”. Subsections a-f of section 4 provide exceptions to this, none of which apply to A. agrestis (Personal communications: Martha Volkoff, Environmental Program Manager, Invasive Species Program, California Department of Fish and Wildlife).

Hosts:  Amynthas agrestis has been found in deciduous and mixed deciduous-coniferous forests, hardwood forests, compost, mulched beds, ornamental beds amended with municipal leaf litter waste, plant containers and gardens (Görres, 2014).

Damage Potential: Unlike other earthworms that are considered friends of the ecosystem due to their ability to loosen and aerate soil, crazy worms pose a significant threat to forest health (Barncard, 2014). They are destructive and cause severe damage to hardwood forests, especially those consisting of maple, basswood, red oak, poplar or birch species which rely on thick layers of leaf litter that serve as rooting medium.  Crazy worms are voracious feeders and can devour such a thick organic mat so to deplete it completely in 2-5 years (Tennesen, 2009).  Consequently, these earthworms disrupt the natural decomposition of leaf litter on forest floors turning the soil into grainy, dry worm castings that cannot support understory forest plants and alter forest soils from a fungal to a bacterial-dominated system which speeds up the conversion of leaf debris to mineral compounds thereby robbing plants of organic nutrients.  Also, by clearing the forest floors of understory plants and leaf debris, the worms encourage erosion and provide more accessible avenues for infection by other invasive species of organisms.  Some northern hardwood forests that once had a lush understory are reported to now have only a single species of native herb and virtually no tree seedling.   They can also cause harm to ornamental plantings and turf.  Demise of lawns due to abundant castings of this earthworm have been reported in Connecticut.  Once established in environment, crazy worms are impossible to eradicate.  Crazy worms have been found in abundance in nursery field and container stock, as well as in mulch and compost that may then be transported to residential and commercial gardens and parks thereby threatening production and resulting in significant losses in horticultural crop production (Görres, 2014; Tennesen, 2009).

Spread:  On their own, Amynthas agrestis can only move 5-10 meters in a year.  Possible means of spread to non-infested sites are therefore, passive and through crazy worm-contaminated soil and leaf debris adhering to off-road vehicles, municipal leaf litter waste, bait used by anglers, logging equipment, nursery field and container stock, compost, and mulch (Görres, 2014; Tennesen, 2009).

Worldwide Distribution: Asian crazy worms were originally found in Japan and the Korean peninsula and are believed to have been introduced to the USA through landscape plants imported from those native Asian regions (Barncard, 2014).  They have been in the US, particularly the southeastern states, for many years and have also been reported from Wisconsin, Illinois, Vermont, and other northeastern states (Loria, 2014; Tiddens, 2015; Görres. 2014; Görres et al., 2016).

A different species, Amynthas gracilis, also called the Asian crazy worm and apparently very similar to A. agrestis, was reported in 2016 from Oregon – including within Josephine County which borders California.  Some articles have reported the worm in Oregon as A. agrestis, but the lead agency in Oregon for this pest, Oregon Department of Agriculture, has record only of A. gracilis in the state and not of A. agrestis (Personal communications: Martha Volkoff, Environmental Program Manager, Invasive Species Program, California Department of Fish and Wildlife).

Official Control:  Wisconsin Natural Resources Law Rule NR 40 lists Asian crazy worms, Amynthas agrestis, as a prohibited species (Görres, 2014).

California Distribution:   Asian crazy worm, Amynthas agrestis, has not been reported from California.

California Interceptions: None reported.

The risk Amynthas agrestis would pose to California is evaluated below.

Consequences of Introduction:   

1) Climate/Host Interaction: It is likely that Asian crazy worm, Amynthas agrestis, will be able to establish a widespread distribution through California’s forest habitat and ornamental production sites particularly in residential and commercial environments.

Evaluate if the pest would have suitable hosts and climate to establish in California.

Score: 3

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.

– Medium (2) may be able to establish in a larger but limited part of California.

High (3) likely to establish a widespread distribution in California.

2) Known Pest Host Range: Asian crazy worms are not parasites of living plants. However, the worms have been found in deciduous and mixed deciduous-coniferous forests, hardwood forests, compost, mulch, ornamental beds amended with municipal leaf litter waste, nursery field and container stock, and horticultural gardens.  Because of its association with a large range of living plants and non-living plant growth-influencing media, the “host range” category is evaluated as high.

Evaluate the host range of the pest.

Score: 3

– Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

High (3) has a wide host range.

3) Pest Dispersal Potential: Amynthas agrestis reproduce very quickly.  On their own, they can only move 5-10 meters in a year.  Possible means of spread to non-infested sites are therefore, passive and through contaminated soil and leaf debris adhering to off-road vehicles, municipal leaf litter waste, bait used by anglers, logging equipment, nursery field and container stock, compost, and mulch.

Evaluate the natural and artificial dispersal potential of the pest.

Score: 3

– Low (1) does not have high reproductive or dispersal potential.

– Medium (2) has either high reproductive or dispersal potential.

High (3) has both high reproduction and dispersal potential.

4) Economic Impact: Asian crazy worms pose a serious threat primarily to California’s forests.  However, they may also be detrimental to commercial ornamental nurseries due to the presence of the pest in field and containerized plants that may be distributed to residential and commercial gardens and parks.  In addition, contaminated mulches and compost used in private and commercial sites may result in economic losses of ornamental crop production.  Asian crazy worms can deplete thick layers of leaf litter that serve as rooting media thereby, disrupting the natural decomposition of leaf litter on forest floors and turning the soil into grainy, dry worm castings that cannot support understory forest plants. They can alter forest soils from a fungal to a bacterial-dominated system which speeds up the conversion of leaf debris to mineral compounds thereby robbing plants of organic nutrients.  Similar affects may occur in residential and commercial plant production sites. Once crazy worms are established, they are impossible to eradicate.

Evaluate the economic impact of the pest to California using the criteria below.

Economic Impact: A, B, C, D

A. The pest could lower crop yield.

B. The pest could lower crop value (includes increasing crop production costs).

C. The pest could trigger the loss of markets (includes quarantines).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

G. The organism can interfere with the delivery or supply of water for agricultural uses.

Economic Impact Score: 3

– Low (1) causes 0 or 1 of these impacts.

– Medium (2) causes 2 of these impacts.

High (3) causes 3 or more of these impacts.

5) Environmental Impact: The destruction of forest habitats could have significant environmental impact by lowering biodiversity, threatening natural communities and endangered/threatened species.  Moreover, the pests may significantly impact ornamental plantings in home/urban gardens.

Evaluate the environmental impact of the pest on California using the criteria below.

Environmental Impact: A, B, C, E

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B. The pest could directly affect threatened or endangered species.

C. The pest could impact threatened or endangered species by disrupting critical habitats.

D. The pest could trigger additional official or private treatment programs.

E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Environmental Impact Score: 3

– Low (1) causes none of the above to occur.

– Medium (2) causes one of the above to occur.

High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Amynthas agrestis:

Add up the total score and include it here. (Score)

-Low = 5-8 points

-Medium = 9-12 points

High = 13-15 points

Total points obtained on evaluation of consequences of introduction of Amynthas agrestis to California = (15).

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

(Score: 0)

Not established (0) Pest never detected in California, or known only from incursions.

-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (Score:15)

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 15

Uncertainty: 

Asian crazy worm, Amynthas agrestis, has not been reported from California.  The definitive presence of this pest in California is currently not known.  Future in-state detections/reports may result in an alteration of the currently proposed rating for A. agrestis.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Asian crazy worm, Amynthas agrestis is A.

References:

Barnard, C.  2014.  Hungry, invasive ‘crazy worm’ makes first appearance in Wisconsin.  University of Wisconsin-Madison.  News.  http://news.wisc.edu/hungry-invasive-crazy-worm-makes-first-appearance-in-wisconsin/

Görres, J.  2014.  Invasive earthworms in the Northeastern USA and the Horticulture Industry.  http://www.uvm.edu/~entlab/Greenhouse%20IPM/Workshops/2014/InvasiveEarthworms.pdf

Görres, J. H., K. Bellitȕrk, and R. D. S. Melnichuk.  2016.  Temperature and moisture variables affecting the earthworms of genus Amynthas Kinberg, 1867 (Oligachaeta: Megascolecidae) in a hardwood forest in the Champlain Valley, Vermont, USA.

Loria, K.  2014.  These ‘crazy worms’ are poised to wreak havoc on the Midwest.  Business Insider, Science, July 16, 2014. http://www.businessinsider.com/crazy-worms-have-invaded-wisconsin-2014-7

Ridden, T.  2015.  Pest Alert: Amynthas agrestis (crazy worm or jumping worm).  My Chicago Botanic Garden, September 11, 2015. http://my.chicagobotanic.org/horticulture/crazy-worm-or-jumping-worm/

Tennesen, M.  2009.  Invasive earthworms denude forests in U. S. Great Lakes Region.  Scientific American, March 1, 2009.  https://www.scientificamerican.com/article/invasive-earthworms-denude-forests/#

Williams, B.  2014.  Crazy worms fact sheet Amynthas agrestis.  Wisconsin DNR Forest Health.  http://host.madison.com/crazy-worms-fact-sheet/pdf_abb51687-cf96-5e27-9f48-956a6ed25884.html

Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health@cdfa.ca.gov


Comment Period: CLOSED

May 17, 2017 – July 1, 2017


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Consequences of Introduction:  1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

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Pest Rating: A


Posted by ls