Anthropogenic transport mechanisms of invasive European earthworms: a review

Abstract

Invasive earthworms create widespread ecological changes after they are introduced. Non-native earthworms are transported mainly through anthropogenically-mediated activities, including fishing, agriculture, horticulture, and development. Here, we review the ways in which non-native earthworms are transported to new environments. Our conceptual framework involves invasion filters (human activities filter and climate & edaphic filter) that constrain which non-native earthworm species are transported within specific contexts. Differences in earthworms’ ecological behaviors, life cycle, and physiological tolerance of environmental conditions influence which species are transported and which regions can successfully be invaded. Within the human activities filter, we utilize the six invasion pathways that follow a continuum of human intention as laid out by Hulme et al. (J Appl Ecol 45(2):403–414, 2008). Five of these pathways are associated with human activity. Of these, the release, escape, and contaminant pathways are associated with commodities, and the stowaway plus corridor pathways with transportation infrastructure. Major human activities that transport invasive earthworms include the discarding of fishing bait, agriculture, composting and horticulture, and development (e.g., the construction of roads, trails, houses, or campgrounds), but the magnitudes that specific activities transport earthworms are vastly understudied. We conclude that more research needs to be conducted to understand the methods that transport non-native earthworms in order to slow their spread.