Title: Imported Fire Ant (Hymenoptera: Formicidae)Bioturbation and Its Influences on Soils and Turfgrass in a Sod Production Agroecosystem Authors
Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 2007
Publication Date: January 18, 2008
Citation: Defauw, S.L., Vogt, J.T., Boykin, D.L. Imported Fire Ant (Hymenoptera: Formicidae)Bioturbation and Its Influences on Soils and Turfgrass in a Sod Production Agroecosystem. Journal of Entomological Science. 43(1): 121-127. 2008. Interpretive Summary: Imported fire ants disrupt soil quality as well as turfgrass nutrient assessments in sod production environments. Nutrient enrichments and losses were studied for both ant-affected as well as undisturbed soils and turfgrass from a commercial turf farm. Mound soils exhibited increased carbon, nitrogen, organic matter, zinc levels and soil alkalinity when compared with undisturbed soils. Turfgrass harvested from ant mounds had much higher concentrations of nitrogen, phosphorus, calcium, copper, iron, sulfur, and sodium compared to undisturbed turf. These studies will help improve remote sensing detection tools used in surveying imported fire ant infestations in “high value” turfgrass settings.
Technical Abstract: Mound-building imported fire ants (IFA) actively modify the biogeochemical and physical properties of soil. Soil alterations result from worker ants’ nest construction and foraging activities as well as colony-wide food sharing and metabolic functions. Bioturbators, especially invasive soil-inhabiting pests, impact management-oriented soil-quality as well as crop nutrient assessment efforts at the field and landscape scales. However, IFA influence on nutrient levels in surrounding vegetation is poorly understood. Nutrient enrichments and depletions were simultaneously documented for both ant-affected as well as undisturbed soils and warm-season turfgrass (Cynodon dactylon x transvaalensis, Tiffway 419 cultivar) in a sod production agroecosystem. Collection of soils and turfgrass was timed to coincide with peak IFA biomass. Total C, total N, C/N ratios, organic matter (OM), and Zn2+ concentrations as well as pH of mound soils were significantly higher than control soils. Turfgrass harvested from ant mound perimeters exhibited elevated N, P, Ca2+, S, Cu2+, Fe2+, and Na+ concentrations. The complexity of biogeochemical interactions within ant nests was most likely further enhanced by plant uptake and excretion in the rhizosphere coupled with continuous soil mixing by colony workers. In addition, chemical contributions from other organisms co-existing in the mound environment and mineral soil abiotic factors may vary substantially from one season to the next, triggering colony relocation as well as influencing colony fitness through time. Therefore, further study of IFA nest soil ecosystem dynamics across seasons is warranted.