Lions, and Tigers, and Jumping Worms, Oh My!
Big and small farms, nurseries, and backyard gardens are continuously threatened by various invasive species. Perhaps none strikes fear in our hearts more than the invasive Asian jumping earthworm (Amynthas spp.). Over the last several decades, species such as Amynthas agrestis, Amynthas tokioensis, and Amynthas hilgendorfi have been running rough shod across the United States, causing significant disruption to local ecosystems. Backyard gardens are especially vulnerable to their adverse affects. With that said, there are things gardeners can do to safeguard their soil and protect their crops. So, in today’s post, let’s explore the dangers posed by the invasive Asian jumping earthworms, and chat about how our farm mitigates these risks through sustainable and self-contained farming practices.
What Are Invasive Asian Jumping Earthworms?
Invasive Asian jumping earthworms, (sometimes called crazy worms or snake worms) belong to the genus Amynthas. The most infamous are these three species: Amynthas agrestis, Amynthas tokioensis, and Amynthas hilgendorfi. They’re native to East Asia, including regions of Japan and Korea and have been “introduced” to North America through various pathways. (More on that in a minute).
Asian jumping earthworms are distinct from what we call “crawlers” in several ways. The name “jumping earthworms” describes their vigorous, snake-like thrashing when disturbed. This trait can help them escape predators because they become surprised at the spastic movement. These earthworms have a smooth, glossy body and can grow up to 8 inches long! Their color varies from a light gray to brown, and they have a prominent, pale-colored band called the clitellum near their head.
These earthworms reproduce rapidly and establish large populations very quickly which is one of their worst traits. Unlike our night crawlers, they don’t require mating to reproduce; instead, they can grow new worms simply from the body fragments. YIKES! This is called parthenogenetic reproduction and it contributes to their invasiveness.
How Did Asian Jumping Earthworms Get here?
Global trade has significantly contributed to the spread of invasive species, including Asian jumping earthworms. Asian jumping earthworms first appeared in the United States in the early 20th century, but the significance of spread is a bit more recent. The primary “pathway” has been through the importation of plants from other countries.
Global trade has significantly contributed to the spread of invasive species, including Asian jumping earthworms.
When plants are shipped internationally, they’re accompanied by soil or compost that contains these earthworms. Once these plants are distributed and sold across the United States, the worms escape into local eco-systems.
Another pathway for the introduction of these earthworms is through the use of compost and soil amendments from farms already plagued by these critters. If compost is not adequately processed or sterilized it runs the risk of containing the invasive earthworm “cocoons”. So when compost is bought from farms with invasive jumping worms, they’re then introduced to new areas.
Believe it or not, recreational activities like fishing, camping, and hiking can also spread jumping worms. Fishermen, for example, might unknowingly use these worms as bait and, as a result, accidentally release them into the wild. Hikers and campers might transport soil and cocoons on their gear and footwear, leading to the establishment of these earthworms in new states.
Farm machinery and tools that have been used in infested areas can carry earthworm cocoons or adult worms in soil residues. This can lead to the spread of these invasive species within a farm or from one farm to another. Small farms with limited resources for decontamination and sanitation of equipment are at a heightened risk.
Gardeners who rely on external sources for their seedlings and plants are particularly vulnerable. One of the primary risk factors for the introduction of invasive earthworms is through nursery plants in the United States. These earthworms (or their cocoons) can be inadvertently transported in the soil of potted plants, garden supplies, and other nursery products from big nurseries who order their plants from other nurseries (a common practice).
Gardeners that rely on external sources for their seedlings and plants are particularly vulnerable.
Once introduced, these earthworms can quickly establish themselves and spread, leading to widespread soil degradation.
Ecological and Agricultural Impact of Invasive Asian Jumping Earthworms
Soil Structure and Health
Native earthworms are indispensable as they provide a wide-range of benefits including increased soil health and plant growth. They aerate the soil, decompose organic matter, recycle nutrients, improve soil structure, enhance microbial activity, help to balance the soil pH, and aid in pest control! Whoa, so many benefits! This makes them a must-have ingredient for sustainable and productive gardening.
Invasive Asian jumping earthworms, however, are not helpful AT ALL. They have voracious appetites and, as we stated earlier, reproduce rapidly. Unlike native worms, these species eat organic matter at a much faster rate. Say goodbye to beneficial leaf litter and organic topsoil. Their accelerated rate of consumption also disrupts the natural decomposition process. This means a loss of important nutrients and the destabilization of the soil structure itself. The soil will become granular and loose (imagine your soil looking a bit like coffee grounds). This affects water retention and increases soil erosion. For gardens, this essentially means decreased soil fertility, reduced yields, and increased susceptibility to drought, which are all problematic due to an already changing climate.
Nutrient Cycling and Plant Growth
Invasive jumping worms negatively impact nutrient cycling. In a nutshell, they cause a rapid breakdown of organic matter leading to a surge in nutrient availability, particularly that of nitrogen and phosphorus. This surge is then followed by a rapid decline in both of those nutrients. So, in effect, you might see plants experience a growth spurt but then become stunted. This equates to lower yields and even more unproductive gardens over time.
Biodiversity and Ecosystem Disruption
One of the most alarming aspects of these these invasive worms is that they outcompete native earthworm species and other beneficial organisms which eventually leads to a decline in the overall biodiversity of the local ecosystem. This affects all of the local microbial communities including the other plants and animals that depend on a good soil balance for survival. This is sort of a cascading effect that leads to less resilience…to pests, diseases, and environmental changes.
Mitigation Strategies
Organic Closed System Farming
As part of our certification process we have to prioritize biosecurity and sustainable farming practices and have a written system plan that is reviewed, inspected and updated yearly. This safeguards us against invasive species like these worms.
For example, as part of our composting procedures, we work to maintain “optimal composting conditions”. This basically involves recording temperatures, ensuring appropriate moisture levels, and regular aeration (pile turning with our tractor) to facilitate the breakdown of organic matter. Our composting process is designed to reach high enough temperatures (141 degrees for over a week) that eliminate potential pathogens and invasive species. We produce all compost on-site and meticulously document our turning and temperature checks for MOFGA review. Because we produce our own compost, we have zero risk of introducing these worms. And, they’re also never introduced where our compost is use. To learn more about composting methods, please click here.
Seed Starting and Plant Management
By starting all plants from seeds, Rime Nor Reason Farm maintains complete control over the growth process. This practice eliminates the need for big nursery plants, which as we stated earlier are a common vector for invasive species like these dreaded jumping worms. The farm’s seed starting protocol includes selecting high-quality seeds, using new, sterile growing mediums, and implementing rigorous germination and transplanting processes to ensure healthy and robust plant growth.
Buying seedlings from small organic farms are a safer bet every time.
SHOP SMALL AND LOCAL
The invasive Asian jumping earthworms pose a significant threat to gardeners, with their potential to disrupt soil health, nutrient cycling, and biodiversity. However, shopping locally at small organic farms ensures that you are also adopting a closed system approach to farming. Small local farms can effectively mitigate invasive species risks. Small farms produce their own compost, they start plants from seeds, and implementing rigorous biosecurity measures that are constantly reviewed and tweaked. Small certified organic farms do work hard to protect themselves against invasive species ensuring long-term sustainability.
Resources to Learn More
Maine Public Article:
How to Identify them:
https://www.maine.gov/dacf/php/horticulture/jumpingworms.shtml#What
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