Abstract: Invasive earthworms are key drivers of biodiversity loss. Asian pheretimoid earthworms of the genera Amynthas and Metaphire (aka “jumping worms”) have invaded forests and manicured landscapes throughout the United States and portions of southern Ontario. Their presence is correlated with horticultural products such as mulch, compost, and potting soil, primarily in urban settings. However, little is known about their population dynamics and habitat preferences over time and space. Therefore, we replicated a jumping worm survey conducted in 2017 in Madison, WI (our urban study area), and added rural sites in Dane County, WI to compare and examine spatio-temporal trends. Here, we investigated: 1) how the presence of jumping worms changed over five years across urban landcover types, 2) how the abundance of jumping worms changed over five years across urban landcover types, and 3) whether jumping worms are found in similar land cover types in rural environments. We engaged citizen scientists to sample jumping worms at randomly selected sites of several landcover types, including: forests (urban n=16, rural n=10), grasslands (urban n=20, rural n=9), open space (urban n=14, rural n=8), and paired residential gardens (urban n=36, rural n=12) and adjacent lawns (urban n=36, rural n=12) in Madison, WI and bordering rural sites in Dane County, WI. Additionally, in the rural areas, we surveyed paired agricultural (n=8) and forest edges (n=8) and municipal yard waste drop-off sites (n=6).
Overall, in the urban survey, 145 jumping worms were collected in 2022 vs 247 in 2017, a reduction of 41%. Jumping worms in forests and residential gardens decreased by 82% and 42%, respectively, but increased in residential lawns by 50%. Jumping worms were found in two additional forests, one less open space, and six additional residential lawns compared to 2017. Overall, there was no change in the number of residential gardens with jumping worms. Worms were not found in grasslands at either survey year. Jumping worms were collected at two rural forests, one unpaired residential garden and lawn site respectively, and three municipal yard waste sites. Our study highlights that jumping worms in urban Madison, WI have shown moderate spread over five years, despite significant reduction in abundance. Low jumping worm presence in rural landcovers could reflect a newer invasion emanating from the urban area, but additional monitoring is needed to confirm this phenomenon.
