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Title	Effects of mound building and selective seed predation by the red imported fire ant (Solenopsis invicta Buren) in an old field plant assemblage
Author	Seaman, Renee Elizabeth
Date	1999
Affiliation/College	College of Graduate Studies
Department	Environmental Studies
Extent	iv, 29 leaves : illustrations; 29 cm
Source	W 4A S4 1999
Subject.MeSH	Academic Dissertations Academic Dissertations--South Carolina Ants Ambrosia Seeds
Keywords	Fire Ants, Ragweed
Collection	MUSC Theses and Dissertations
Contributing Institution	Waring Historical Library (MUSC)
Rights	Copyright is held by the author.
Language	English
Type	Text
Format	application/pdf
Media Type	Manuscripts
Resource Identifier	mtd1999_seaman_re
Abstract	The red imported fire ant (Solenopsis invicta Buren) is an introduced species that is rapidly invading the southeastern United States. I examined how selective seed predation by the red imported fire ant influenced an old field plant assemblage by observing the ants' effects on ragweed (Ambrosia artemisiif olia) distribution and growth. Ragweed had significantly higher coverage on ant mounds, and plants growing on the mounds had a significantly higher aboveground biomass than plants growing one meter from mounds. Nitrate was significantly higher on ant mound soil, while organic matter, phosphorus, magnesium, copper, and zinc were significantly higher off ant mounds. Higher nitrate levels on ant mounds may contribute to the greater above ground plant biomass and perhaps increa-sed dominance within the assemblage. In seed predation experiments, ragweed seeds were selected significantly less often than those of five other early successional species: pigweed (Amaranthus retroflexus), bluegrass (Poa annua), common lamb's quarters (Chenopodium album), and goldenrod (Solidago altissima). Of seeds similar in size to ragweed (radish variety whitetipped sparkler [Raphanus species], cabbage variety wakefield jersey [Brassica species], thistle [Carduus species] and white millet [Pennisetum species]), thistle and white millet were selected significantly more often than ragweed in a second experiment, indicating that selection was not affected by seed size. In a final experiment to determine if distance from ant mounds affected seed selection or predation rates, pigweed seeds (a highly preferred species) were placed 1, 2, 3 and 4 meters from each mound. Nearly all seeds were consumed. These results suggest that the distance of seeds from the mound does not affect predation by the red imported fire ant. Both fire ants and ragweed are early successional species that rapidly invade disturbed areas created by humans and natural disasters. Fire ants significantly contributed to the success of ragweed plants growing in an old field community. Not only do fire ants swarm and sting with potent venom; they increase the biomass of a weedy species that is a common source of human allergies (ragweed). Increased reproductive success and abundance of ragweed in old field communities may increase the amount of pollen in the air during allergy seasons.

Effects of mound building and selective seed predation by the red imported fire ant (Solenopsis invicta Buren) in an old field plant assemblage

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