Author
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Morrison, Lloyd |
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Submitted to: Ecology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/5/2002 Publication Date: N/A Citation: N/A Interpretive Summary: The red imported fire ant, Solenopsis invicta, is a serious invasive pest in the southeastern U.S. Numerous studies have documented that S. invicta reaches high densities in its introduced range, often decreasing the diversity and abundance of native ants and other arthropods. One of the most in-depth studies of the initial effects of the S. invicta invasion was sconducted in central Texas in 1987. A scientist working at the University of Texas and now with the USDA-ARS, Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, FL, sampled the same community by the same methodology in 1999, to compare the short- and long- term impacts of the invasion. Although the abundance and diversity of native ants and other arthropods greatly declined immediately after the invasion, they had returned to near pre-invasion levels after 12 years, even though S. invicta was still the most abundant ant species. These results reveal the resiliency of some native arthropod communities, and suggest that if populations of exotic ant species can be controlled, native arthropod communities may naturally return to diversities resembling pre-invasion levels. Technical Abstract: Invasive ant species represent a serious threat to the integrity of many ecological communities. Numerous studies have documented that the invasion of an aggressive exotic ant has resulted in decreases in abundance and species richness of both native ants and other arthropods. One of the most in-depth and well-known studies of this type documented a severe impact of the imported fire ant, Solenopsis invicta, on the native ant and arthropod fauna of a biological field reserve in central Texas during the initial invasion in the late 1980's. I sampled the community again in 1999, 12 years later, utilizing the same methodology, to compare the short- and long- term impacts of this invasion. Pitfall traps and baits were used to obtain quantitative measures of the ant and arthropod community, and hand collecting was additionally employed to determine the overall ant species composition. Although the abundance and species richness of native ants and several other arthropod groups decreased precipitously immediately after the S. invicta invasion, all measures of native ant and arthropod species diversity had returned to pre-invasion levels after 12 years. Solenopsis invicta was still the most abundant ant species, but not nearly as abundant as it was during the initial phase of the invasion. The results of this study indicate that the impact of such invasive ants may be greatest during and shortly after the initial phase of the invasion. Possible reasons for the return of the community toward the pre-invasion equilibrium include adaptation of competing native species, a diminishment of food resources of the invader, and the acquisition of natural enemies. |
