History of Jumping Worms | IPM and Pollinator Conservation

Jumping Worm History

According to Bennett et al. 2024 (see paper below), Earthworms can act as ecosystem engineers by altering soil structure, which impacts other organisms and ecosystem functioning. Jumping worms (family Megascolecidae) originating in Asia have been spreading in North America, extending their northern range limits to Ontario, Canada in the last decade and to New Brunswick in 2021. At the northern limits of their current range, little research has been done to examine the effects of jumping worms in these new habitats since their recent establishment. Further research is needed in managed landscapes, urban areas, and forests to determine the ecosystem impacts and invasion dynamics of jumping worms in Canada as this invasion progresses.

Native earthworms were almost entirely removed from soils in the northern United States and Canada during the last glaciation (i.e., the Wisconsin glaciation), nearly 12,000 years ago. Therefore, most contemporary soils in this region developed in the absence of earthworms. However, the arrival of European settlers to North America, approximately 400 years ago, introduced non-native earthworms. Since their introduction, European earthworms have spread across the continent, with their range expansion being facilitated by recreational and industrial human activities (e.g., fishing, vehicles, agriculture). These non-native earthworms have caused substantial impacts on forest ecosystems in North America, including shifts in soil chemical properties and changes in plant and animal communities.

Recently, a “second wave” of earthworm invasions has begun in North America. This is due to the spread of pheretimoid or “jumping worms’’ which are a group of earthworms within the family Megascolecidae originating from eastern and southeastern Asia (i.e., Japan, Korea, and China). Their common name “jumping worms” originates from the thrashing behavior that they make. These species are believed to have been introduced to the United States through horticultural practices that involve the transport of soils and now appear to be concentrated around human establishments, with most reported sightings from urban parks, residential yards, greenhouses, and compost piles. A total of sixteen species have now been identified in North America, of which Amynthas agrestis (Goto and Hatai, 1899), Amynthas tokioensis (Beddard, 1892), and Metaphire hilgendorfi (Michaelsen 1892) appear to be the most invasive in forested ecosystems.

In the United States, jumping worms have successfully established in 38 states ranging from the Northeast to Midwest. In Canada, jumping worms were first found in 2014 near Windsor, Ontario, and five species have now been recorded across Ontario, Nova Scotia, and New Brunswick, although there has been little investigation of distributions thus far in Canada. The effects of jumping worms at their current northern limit in Canada have not yet been examined, but research in the United States indicates jumping worms can have substantial impacts when they invade. In general, their larger body sizes, faster reproduction, and wider dietary flexibility as compared to some European earthworm species can result in a competitive advantage over these lumbricids and in larger impacts on ecosystems. Indeed, in Tennessee, USA, the presence of the European earthworm Lumbricus rubellus had no impact on jumping worms, but the presence of jumping worms negatively affected the ability of L. rubellus to consume leaf litter and soil microbes. Jumping worm invasions in North American forest stands have been associated with decreased litter depth, increased soil pH, and changes in carbon (C) and nitrogen (N) availability. Alterations to soil C depend on forest soil type and earthworm density. In sugar maple forests, soil C availability increased with earthworm density, whereas in oak forests, soil C availability decreased with increasing earthworm density. Jumping worms have also been associated with increases in concentrations of both NH4 + and NO3 − and may have greater impacts on soil nitrogen concentrations than lumbricids. Soil N is a key limiting factor for plant growth in many ecosystems such as temperate forests.

Vera Krischik, Garima Gupta, Simran Rana, Julie Semrow, and Sophia Stone.