Reducing geographic spread of invasive earthworms

Background/Question/Methods

European species of earthworms, including Lumbricus rubellus and L. terrestris have caused substantial adverse changes to northern hardwoods forests by consuming leaf litter thereby altering plant germination and establishment.  On their own in these forests, earthworms expand their distribution about 10 m yr^-1.  Humans account for the vast majority of longer distance dispersal, and agriculture, agricultural machinery, gardening, fishing, hiking, and all-terrain vehicles (ATVs) have been implicated as key earthworm movement vectors.  Anglers are likely the most important vector into northern hardwoods forests.  We investigated how signage at boat ramps and labels on earthworm bait containers affected actual and reported behavior of anglers for disposal of leftover earthworms.  Using a replicated Latin square crossover design (4 replicated squares with 4 replications in each square), we measured disposal of bait containers. 

Results/Conclusions

About 44% of all of the bait containers were disposed near the lake entrance ramp.  Labeled bait was 1.8 times more likely to be disposed than unlabeled bait.  Signage had no effect on bait disposal.  These results suggest that environmental labels can affect consumer behavior and that labeling of live bait containers can reduce the spread of invasive earthworms into critical habitats.