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ABUNDANCE OF INVASIVE ASIAN JUMPING WORMS ACROSS FOUR
WISCONSIN HABITATS
Rylan Benson, Sarah McPherson, Annie Uhing, Natalie Wilson
Abstract
Like all species of earthworms,Asian jumping worms are not native to Wisconsin habitats.
Jumping worms possess the ability to consume leaf litter and other organic materials more aggressively
than other worm species,making their negative impact on the environment far greater. This study
examined the abundance of Asian jumping worms throughout four Wisconsin habitats including prairie,
deciduous forest, coniferous forest,and oak savanna ecosystems within the UW-Madison Arboretum. We
hypothesized that the deciduous forest would contain the highest abundance of jumping worms due to
higher levels of organic matter. In order to test this hypothesis, we collected and speciated worms from
eight random plots within each habitat. Our data did not support this theory since the deciduous forest did
not contain significantly more Asian jumping worms than any other habitat; no relationship exists
between the amount of organic matter present and the abundance of jumping worms. However,our results
do suggest that Asian jumpings worms persist throughout multiple Wisconsin habitats, which gives us
reason to believe that they possess the ability to invade a variety of ecosystems.
Introduction
The last Ice Age approximately 11,000 years ago completely extirpated native earthworms from
Wisconsin. Since this event, introductions of over twenty European species of earthworms (Lumbricidae)
occurred in Wisconsin including that of the red wiggler (Eisenia Foetida),redworm (Lumbricus rubellus),
common nightcrawler (Lumbricus terrestris),and pink nose (Aporrectodea) (Deatsman 2012).
Earthworms frequently spread to new areas through common human activities such as harvesting, fishing
and community mulch piles (Tennesen 2009).
Given that early North American habitats developed without worms, their presence has the
potential to negatively alter a habitat in significant ways. Earthworms mix soil layers together, and

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consume leaf litter and other organic materials, which act as rooting mediums for potential growth
(Tennesen 2009). By removing leaf litter, earthworms also disturb and expose the soil, which may lead to
increased water runoff, compaction, soil erosion, infiltration of invasive species and a decrease in native
biodiversity (Deatsman 2012).
In comparison to European species, Asian jumping worms (Amynthas agrestis) have a greater
impact on various ecosystems because their consumption of organic matter is more aggressive, causing
soil to become granular and dry (Williams and Klug 2015). The unique life cycle of jumping worms
exacerbates their negative impact because they reproduce asexually and hatch before European species.
As a result, jumping worms have the ability to multiply quickly without interspecies competition, leading
to high levels of infestation. While adult worms cannot survive harsh Wisconsin winters, jumping worms
bury their cocoons deep under the soil and can go undetected until the growing season (Williams and
Klug 2015). The Department of NaturalResources (DNR) verified the presence of jumping worms in
five Wisconsin counties as well as in the University of Wisconsin-Madison Arboretum (Williams and
Klug 2015, UW-Madison Arboretum 2014) (See Figure 1). Due to these adverse effects,it is important to
continue to document the spread of Asian jumping worms throughout the state.
This study seeks to identify which habitats are at greater risk for experiencing negative ecological
effects as a result of Asian jumping worms in order to better focus conservation efforts. We examined the
abundances of all worm species in four key Wisconsin habitats: deciduous forest,coniferous forest,
prairie and oak savanna. We predict that the deciduous forest will contain the greatest amount of
available organic matter for Asian jumping worms to consume. Therefore,the presence of jumping
worms (Amynthas agrestis)is greatest in the deciduous forest habitats as opposed to oak savannas,
tallgrass prairies or coniferous forests.
Methods
We sampled for Asian jumping worms, red wigglers, red worms, common nightcrawlers and pink
nose worms from four areas within the University of Wisconsin-Madison Arboretum. We first collected
data from Curtis Prairie, a restored, tallgrass prairie that mainly consists of native species such as Big

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Bluestem and Indian Grasses (UW-Madison Arboretum 2015). Next, we sampled from Wingra Woods, a
deciduous forest; this forest is a remnant area made to resemble the northern Wisconsin forest and
contains sugar maple, basswood, beech and hemlock trees (UW-Madison Arboretum 2015). The third
area sampled, Aldo Leopold Memorial Forest, is a coniferous forest habitat dominated mainly by white
and red pines (UW-Madison Arboretum 2015). Lastly, we collected data from the Wingra Oak Savanna,
which is a remnant area and characterized by frequent fires and scattered trees (UW-Madison Arboretum
2015).
In all four habitats, we selected eight sites at random, recorded their GPS coordinates, and created
square-foot plots by clearing debris, such as fallen leaves and twigs, to expose the soil. We prepared a
solution consisting of one-third a cup of mustard powder mixed in a gallon of water to pour on each plot;
this solution irritates the skin of worms, causing them to rise to the surface of the soil. For each plot, we
evenly poured half of the mustard solution and waited for it to fully absorb. If a plot did not absorb the
mixture well, we poured smaller portions of the solution at a time. The pouring process took
approximately three to four minutes per plot. For an additional five minutes after the absorption of the
last pouring, we collected worms in plastic bags as they emerged from the soil. When determining
sampling duration, we took into account factors such as precipitation and temperature,which can alter the
worm’s rate of emergence from the soil. We used the Great Lakes Worm Watch Dichotomous Key to
speciate each worm (Great Lakes Worm Watch 2011). If unable to speciate or catch a worm, we labeled it
as “unknown”. In addition, data collected from each habitat site included percent canopy cover, organic
matter ground cover, and tree cover. After we recorded all of our data, we returned the worms to an
undisturbed area and re-covered the exposed soil with organic leaf litter.
In order to analyze our data, we utilized an ANOVA test to determine whether there is a
significant difference between the average number of Asian jumping worms per plot in each ecosystem.
Next, we used four separate independent t-tests to determine if a significant difference exists between the
number of jumping worms and the number of all other species of worms combined in each habitat. Lastly,

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two linear regression models were used to compare percent organic matter and percent canopy cover to
the abundance of Asian jumping worms.
Results
Results from the ANOVA analysis conclude that a significant difference exists between the mean
number of Asian jumping worms found per plot in each habitat (p=0.002751). Figure 2 illustrates that the
oak savanna contains a significantly greater average number of jumping worms than the prairie and
deciduous forest (p<0.01). There is not a significant difference between any of the other habitats.
Next, independent t-tests were utilized to examine the correlation between the abundance of
Asian jumping worms and all other species of worms. We found a statistically significant difference
between the number of Asian jumping worms and number of all other species of worms combined in each
habitat (pCP=0.000191, pDF=0.0095145, pCF =0.001538, pOS=0.00752). This data is illustrated in Figure 3,
which indicates a negative correlation between the presence of jumping worms and the abundance of
other worm species.
The first linear regression showed no correlation between percent organic ground cover and
abundance of Asian jumping worms(R=0.06892)(See Figure 4). The second linear regression similarly
calculated no relationship between percent canopy cover and the total number of Asian jumping worms
(R=0.01643)(See Figure 5).
Discussion
We hypothesized that the abundance of Asian jumping worms (Amynthas agrestis) is greatest in
the deciduous forest habitats because it has the greatest availability of organic matter for the worms to
consume. Our results do not support this hypothesis. The deciduous forest did not contain a significantly
greater quantity of Asian jumping worms than any other habitat; no correlation exists between the percent
organic ground cover and the abundance of worms or between percent canopy cover and the abundance of
Asian jumping worms.
Potential sources of error in this experiment result from the following limitations imposed by the
research design. The greatest limitation in this study arises from the lack of certainty during speciation. It

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is difficult to classify worms based solely on their physical attributes without DNA samples. An example
of this includes differences in appearance between juvenile and adult jumping worms. Mature Asian
jumping worms have a developed white clitellum, while juveniles do not. During collection we identified
juvenile worms with a slight white pigmentation where a clitellum would develop as Asian jumping
worms.
Another limitation in the study design is that data was only collected in one region of each of the
four habitat types in the arboretum. The regions sampled only serve as models and may not represent all
ecosystems of these types in Wisconsin. In addition, all of these habitats are remnants or restored. For
example, Curtis prairie is a restored prairie and perhaps does not represent a true prairie habitat with
minimal disturbances.
Weather also may have altered the results of our study. Not all data was collected on the same
day or under the same weather conditions; differences in precipitation and temperature cause worms to
move to the surface at varying rates which could affect the number of worms collected.
Variation in these results may also be explained by the ambiguity in measuring the percent
ground coverage of organic matter and percent canopy cover. All plots within the habitats appeared to
contain consistent amounts of both canopy cover and organic matter ground cover. However, since we
measured both of these variables by sight, we do not have definitive values.
Our results suggest that multiple types of habitats are at risk of invasion by Asian jumping
worms. These worms are non-native to Wisconsin but were found to inhabit seventy-five percent of the
areas sampled. This suggests that Asian jumping worms have a large potential to spread and thrive in a
variety of ecosystems,including those not studied. Since the oak savanna had significantly more jumping
worms than the deciduous forest and prairie, we believe that it may be more at risk for experiencing
negative effects associated with Asian jumping worms.
Not only are Asian jumping worms fast invaders, they can negatively impact the diversity of
habitats. In each habitat where we found jumping worms a negative correlation exists between jumping
worms and other worm species. A likely mechanism to explain this trend may involve the competitive

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exclusion principle put forth by Georgii Gause; this principle states that two species that compete for the
same resource cannot coexist (Ricklefs 2014). It is likely that jumping worms outcompete other species
because they are aggressive consumers. This makes coexistence unfavorable and could help explain why
we did not find high levels of both Asian jumping worms and other worm species in the same area.
Future studies should address the limitations in our study and examine other factors that may
affect the presence of jumping worms. We determined that there is not a correlation between presence of
jumping worms and organic matter. However,it is necessary to determine why certain habitats have a
greater presence of jumping worms in order to focus conservation efforts. Factors to consider studying
include soil composition, available nutrients, and the presence of other plant and animal species. In
addition, other studies should determine if our results are generalizable by conducting similar studies in
the same habitat types throughout Wisconsin. If other studies demonstrate the same results, this would
create greater confidence in our data. Other studies should also expand on ours to include a greater variety
of Wisconsin habitat types, such as marshes and farmland. Lastly, future studies should determine the best
method for managing the spread of Asian jumping worms. Conservation efforts are especially important
to consider because of the damage that Asian jumping worms can have on ecosystems. Asian jumping
worms have already spread throughout five Wisconsin counties and it is imperative to minimize their
distribution throughout the state and potentially the country.

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References
Deatsman,R. 2012. Little Worms, Big Consequences. http://dnr.wi.gov/wnrmag/2012/12/worms.htm.
Accessed November 13, 2015.
Great Lakes Worm Watch. 2011. Key To Exotic Earthworm Species Common in the Great Lakes Region.
http://www.nrri.umn.edu/worms/downloads/identification/dichotomous_key.pdf. Accessed
December 8, 2015
Tennesen, M. 2009. Invasive Earthworms Denude Forests in U.S Great Lakes Region.
http://www.scientificamerican.com/article/invasive-earthworms-denude-forests/?page=1.
Accessed November 13, 2015.
Ricklefs, R. and R. Relyea. 2014. Pages 372-373. Ecology The Economy of Nature.W.H. Freeman and
Company, New York, NY.
University of Wisconsin-Madison Arboretum. 2014. Invasive 'Jumping Worm' Found at Arboretum.
https://arboretum.wisc.edu/news/arboretum-news/jumping-worm-release/. Accessed November
13, 2015.
University of Wisconsin-Madison Arboretum. 2015. Remnants and Restorations.
https://arboretum.wisc.edu/explore/remnants/. Accessed December 8,2015.
Williams, B. and Klug, C. 2015. Jumping Worms. http://dnr.wi.gov/wnrmag/2015/06/worms.htm.
Accessed November 13, 2015.

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Figures
Figure 1. Map of the distribution of Asian Jumping worms throughout five counties in Wisconsin.

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Figure 2. Oak savanna contains a significantly greater average number of jumping worms than the prairie
and deciduous forest (p<0.01). There is not a significant difference between any of the other habitats.
Figure 3. Abundance of Asian jumping worms compared to abundance of other worm species in each
habitat type shows a statistically significant difference.

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Figure 4. A linear regression comparing percent organic cover and total number of Asian jumping worms
shows no significant correlation (R2
=0.00475, R=0.06892).
Figure 5. A linear regression comparing percent canopy cover and the total number of Asian jumping
worms shows no statistical correlation (R2
=0.00027, R=0.01643).

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