Abstract
Invasive species can affect native communities through multiple mechanisms, including ecosystem engineering and trophic interactions. In North America, invasive jumping worms ( Amynthas spp.) may alter microhabitats used by native herpetofauna or serve as a novel food resource for herpetofauna predators. We investigated effects of Amynthas on leaf litter microhabitat and trophic interactions of native herpetofauna using an outdoor mesocosm experiment, laboratory feeding trials, and field surveys of predator stomach contents in Wisconsin, USA. In mesocosms, Amynthas reduced leaf litter biomass but did not have clear effects on soil conditions (pH, moisture, and temperature) or survival of American toad metamorphs ( Anaxyrus americanus ). In laboratory trials, American toads preyed on Amynthas, though toads were less successful at capturing Amynthas compared with alternative prey, namely European earthworms ( Lumbricus spp.) and crickets ( Acheta domesticus). The differences in prey attack success were likely due to unique defensive behaviors of Amynthas . Amynthas also spent less time moving than Lumbricus , which was associated with later prey detection times by toads. Based on diet surveys, Amynthas are consumed by common garter snakes ( Thamnophis sirtalis ) in southern Wisconsin. We did not find evidence of Amynthas consumption by American toads or red-bellied snakes ( Storeria occipitomaculata ), although additional surveys will be needed to definitively determine whether these taxa are consuming Amynthas . Our findings highlight the importance of studying multiple mechanisms by which invasive species affect native communities and suggest that unique anti-predator behaviors may influence how Amynthas are incorporated into food webs as a novel prey resource.
Leaf litter traits of invasive species slow down decomposition compared to Spanish natives: a broad phylogenetic comparison