This article was written by Jordan Thompson, a graduate student in the Department of Entomology working with Drs. Tom Kuhar and Alejandro Del Pozo. Jordan is a graduate student at Virginia Tech studying the Asian jumping worm in Virginia and hoping to find possible control methods. Jordant95@vt.edu

Earthworms might not be the first thing that comes to mind when thinking about invasive species. In fact, you might be familiar with all the benefits of earthworms, such as how they recycle nutrients by breaking down organic matter, making them more available to plants, or how they tunnel through the soil, aerating it, which in turn makes room for delicate plant roots to spread. You may have even purchased a bag of worm castings to spread in your garden, or perhaps you compost with red wigglers. Whatever your association with earthworms, the thought of eradicating them probably didn’t immediately come to mind.

Unfortunately, we now have a worm in the United States that is detrimental to our delicate soil ecosystems. Known as the Asian jumping worm (Amynthas spp.), this invasive earthworm is named for its signature jumping move, a form of predator evasion. They are characterized by their smooth iridescent skin, and their pale clitellum (band). The Asian jumping worm is able to quickly reshape invaded soil ecosystems, resulting in soil that offers minimal benefits to plants and other terrestrial organisms. Where there was once a rich organic matter layer, is now a dusty and lifeless earth, incapable of supporting certain plant life, thereby permanently altering the landscape and inviting other invasive species to move in and thrive. It is evident that these worms are far from being the allies we seek in maintaining a healthy ecosystem.

But how did they get here? Why does it do so well in so many diverse soils? What are the long-term effects of this species? Let’s break it down.

The Asian Jumping Worm: An Uninvited Guest

The Asian jumping worm originally hails from East Asia and is believed to have been introduced to other regions through various pathways, including horticultural trade, transportation of plants, and contaminated soil or plant material. One key factor contributing to the Asian jumping worm’s rapid spread is its ability to reproduce via parthenogenesis, meaning it can reproduce without a mate. Each worm produces tiny cocoons at around 60 days of age, and each cocoon will hold between 2 and 20 worms – which will again start producing more cocoons in about 60 days. This allows for about 2 generations per year. Often in a soil rich in organic matter, it is not unusual to find hundreds of worms living within an area of a few square feet. The juveniles are almost microscopic, resembling tiny white threads. The cocoons are the size of a mustard seed, and could easily be picked up by animals and humans walking through worm infested soil.

Additionally, the Asian jumping worm’s adaptability to different soil types is another reason for its success as an invasive species. Although it seems to prefer organic matter rich soils, it can thrive in a wide range of soil conditions, even in sandy or clayey soils. Moreover, unlike other earthworms which tend to stay within certain soil layers, Asian jumping worms are more surface-dwelling, making them highly mobile and able to colonize new areas rapidly.

Their ability to survive in colder climates also contributes to their successful spread. Adults will die with the first frost, but leave behind specialized cocoons that protect their eggs and developing juveniles during winter months. This enables them to establish populations in regions that experience cold winters.

In 2022, Asian jumping worms had been confirmed in a handful of counties in Virginia, but a bit of citizen science with the help of Facebook confirms their presence is being severely under-reported or simply, they’ve been surviving unnoticed, and have likely spread well beyond the original counties.

Disturbing the Ground: Impacts on Soil Ecosystems

Asian jumping worms have a voracious appetite for organic matter. They consume leaf litter, mulch, and other organic debris at an accelerated rate, rapidly depleting the available organic material in the soil. This feeding behavior disrupts the soil structure and leaves soil vulnerable to runoff, in addition to reducing the plant life capable of growing there. This specifically affects forest understories, where small trees and shrubs are essential in providing groundcover, soil stability, and forage for wildlife. When Asian jumping worms invade, it can alter the understory therefore altering the native habitat and displacing wildlife and native plant communities.

In residential areas, avid backyard vegetable growers might notice their gardens becoming less prolific. Their plants might begin to struggle and eventually they may see bare spots where once there were lush gardens. Compost piles can become breeding grounds as banana peels and grass clippings become fuel for more generations of jumping worms. In large turf areas such as golf courses, where worm castings already present an issue with aesthetics and maintenance, worms that altogether destroy the soil could spell disaster for ranges trying to maintain quality greens.

There is some understanding of how these worms alter soil chemistry, C/N (carbon to nitrogen) ratios, and soil electrical conductivity, but more research is needed to better understand the severity of these alterations and their long term effects. What we do know is that while soil development takes thousands of years, the Asian jumping worm can significantly alter soil composition in a matter of months. This poses a grave concern and demands our immediate attention.

Current Research and Areas of Study

Researchers from Virginia Tech’s Department of Entomology are actively studying the impacts of the Asian jumping worm in Virginia and exploring potential control methods. Through field observations and laboratory experiments, they are investigating the effects of Asian jumping worms on other soil arthropods, soil nutrient availability, soil electrical conductivity, and more. By understanding the mechanisms through which these worms degrade the soil, researchers aim to develop targeted management strategies. These may include exploring biological control agents, evaluating cultural practices, and assessing the efficacy of chemical interventions.

Current Research and Areas of Study

Researchers from Virginia Tech’s Department of Entomology are actively studying the impacts of the Asian jumping worm in Virginia and exploring potential control methods. Through field observations and laboratory experiments, they are investigating the effects of Asian jumping worms on other soil arthropods, soil nutrient availability, soil electrical conductivity, and more. By understanding the mechanisms through which these worms degrade the soil, researchers aim to develop targeted management strategies. These may include exploring biological control agents, evaluating cultural practices, and assessing the efficacy of chemical interventions.