A multi-university study involving researchers from The Ohio State University, the University of Alberta and Simon Fraser University has revealed how the non-native earthworms are invading Canadian forests and have said that with the current rate of spread, by 2056, earthworms will expand their territory from 3 per cent of the Alberta boreal forest to a whopping 39 per cent.

By using a technique called approximate Bayesian computation in a new way, the team was able to estimate population spread and new introductions simultaneously, and then use them to get an overall 50-year worm forecast for northern Alberta.

The increase in territory of earthworms is a problem according to researchers as they burrow beneath the surface where they mix different layers of soil and change the soil pH. Ultimately, these changes alter how organic and inorganic matter decomposes and result in fewer small invertebrates in the soil.

In an effort to track and possibly curtail their territory expansion, study co-author Erin Cameron and colleagues at the University of Alberta have developed a “citizen science program” and mobile app dubbed ‘Worm Tracker’, which will be released later this spring.

“The website for our program has sampling instructions and curricular materials for teachers, and participants can also view maps of their data and all other data that is collected,” said Cameron.

Though the app is geared toward students in Alberta, Cameron said that the information gathered through the app as well as the rest of the study, will be useful to researchers elsewhere.

“We’re looking for participants and data from across the province, so anyone in Alberta who wants to survey in their garden, fields, forest, or any other habitat can help out by downloading the app and following the steps to sample worms.”

Alberta Worm Invasion Project

Researchers have laid out some pointers if you wish to help out in the project.

Don’t dump
Don’t dump your earthworm bait on land or in water (earthworms can survive in water for days). Instead, save it for your next trip or throw it in the garbage. Because the larger endogeic and anecic species tend to have more severe impacts than the epigeic species that live in the leaf litter, disposing of bait properly can make a big difference in reducing the impacts of earthworms on our forests!

Clean tires
Cleaning the tire treads on your vehicle or ATV when moving to a new location in order to remove earthworms and cocoons (likely from the litter-dwelling epigeic species) is important because the changes epigeic species cause to soil structure are believed to make it easier for larger earthworms to establish and reproduce.

Avoid transporting
Avoid moving leaves, mulch, or soil between sites unless you are sure they do not contain earthworms or cocoons.

Freeze vermicompost before spreading it
If you use earthworms for composting and live in a remote area, freeze the compost for 1 week to a month before using it outside. This should kill the earthworms and their cocoons. The main earthworm species (Eisenia fetida) that is commercially sold for composting cannot survive in cold climates, but other species that can survive are sometimes mixed in.

Tell others
Tell others about earthworm invasions and how they can help reduce earthworm spread.