Effects of invasive jumping worms ( Amynthas spp.) on microhabitat and trophic interactions of native herpetofauna

Invasive species can affect native communities through multiple mechanisms, including habitat modification and trophic interactions. In North America, invasive jumping worms ( Amynthas spp . ) may alter microhabitats used by native herpetofauna or serve as a novel prey resource for herpetofauna predators. We investigated effects of recently introduced Amynthas and previously established Lumbricus spp. earthworms 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 southern Wisconsin, USA. In mesocosms, Amynthas and Lumbricus reduced leaf litter biomass but did not have strong effects on soil conditions (pH, moisture, and temperature) or survival of American toad metamorphs ( Anaxyrus americanus ). In laboratory trials, American toads preyed on Amynthas but were less successful at capturing Amynthas than Lumbricus or crickets ( Acheta domesticus ). Attack success differences were likely due to unique defensive behaviors of Amynthas . Amynthas spent less time moving than Lumbricus , which was a behavior associated with delayed prey detection times by toads. In our diet surveys, we found novel evidence of Amynthas consumption by common garter snakes ( Thamnophis sirtalis ). We did not find Amynthas in stomach contents of American toads or red-bellied snakes ( Storeria occipitomaculata ), though additional surveys would help 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.