Tools for monitoring and study of peregrine pheretimoid earthworms (Megascolecidae)

Abstract

Peregrine pheretimoid earthworms, commonly known as jumping worms, are members of the family Megascolecidae that have become widely established outside of their native ranges. In many parts of the world this represents a second wave of earthworm invasions, following the introduction of peregrine European earthworms in the family Lumbricidae during the colonial era. Forest ecologists, turf managers, gardeners, and other land managers are concerned about the observed or presumed negative effects of jumping worms on invaded habitats. Although research on jumping worms has accelerated in recent decades, our understanding of their ecology remains limited. We compiled techniques useful to researchers working to fill voids in our understanding. Similar past efforts have focused on tools used to study common European species. Differences in life cycle, behavior, morphology, and physiology make it difficult to transfer experiences with European earthworms to pheretimoids. For example, the loss of reproductive features in many pheretimoid populations poses a challenge for identification, and techniques for individually tagging lumbricid earthworms have been less successful for megascolecids. The active and ongoing expansion of pheretimoid populations in many areas requires increased attention on distributed methods, such as citizen-science protocols, for detecting and tracking their expansion. Finally, the desire to limit populations of pheretimoids, including those invading gardens and other environments that might be successfully restored, has exposed the lack of options for targeted, effective control of unwanted earthworms. We identify opportunities to address these voids in our methodological tool kit and encourage the adaptation of techniques previously used in the study and management of other invasive animals.