Spiders, Sowbugs, and Earthworms as Invaders and their Impact
South University, DoctorSpider LLC, and Adjunct Clemson University, Columbia, South Carolina, USA
Correspondence: rwolff@southuniversity.edu
Spiders (Order Araneae) are generally not considered important as invasives, but recent range expansions of the Brown Widow Spider and Hobo spider are of concern due to their reported toxic bites. An exotic tarantula and a brown spider (Loxoceles) have both become established in the U.S. among many other species that are of less concern. Sowbugs (woodlice, Order Isopoda) have not raised alarms, but are actually of concern due to their impact on the organic layers of the soil. Most of the species in the U.S. are exotics, and they have come to dominate the soil fauna in most locations. Exactly what their ecological impact is on the plant and animal communities is unknown, they do speed the breakdown of the detritus. Exotic earthworms (Class Oligochaeta) on the other hand cause tremendous ecological damage to soils and their communities. They are similar in that they now dominate most soil communities and are also found in very high populations. They have even changed soil structure so drastically that the soil belongs to a different order following invasion, and have led to localized extinctions of plant species. Their ecological impact affects all plant and animal species, including increasing wildlife species that feed on earthworms. Support in part comes from the National Park Service R5240050019 [CESU-CU COSW].
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