Effect of Solenopsis invicta presence on species diversity of ground-dwelling arthropods at Brackenridge Field Laboratory

Abstract

The invasive ant species Solenopsis invicta, more commonly known as the Fire Ant, made its first appearance in the Southern United States in the 1930’s. These ants adapted quickly to the landscape of Southern states and grew rapidly in population size. Soon, S. invicta’s widespread and invasive presence was reflected in vertebrate and invertebrate populations alike, a trend which encouraged studies over the environmental impact of the ant. While earlier studies in areas with S. invicta concluded that the species diversity of ground-dwelling arthropod populations was significantly less, later studies in those same areas concluded that the species diversity of ground-dwelling arthropods had returned to preinvasion levels. As a response to these former experiments, I conducted an experiment at Brackenridge Field Laboratory in Austin, Texas, which replicated previous testing methods for arthropod diversity. This experiment was conducted using several plots in which bait traps were first deployed to test for the presence of S. invicta in the plot. Once S. invicta presence was determined in a plot, pitfall traps were purposefully set in marked plots both with and without S. invicta in order to test for arthropod species richness. After counting and identifying the collected arthropods, one-tailed and two-tailed t-tests were run to determine the significance of the difference between the species richness of arthropod populations in plots with S. invicta presence and arthropod species richness in plots lacking S. invicta. I concluded that there was no significant difference in species diversity of arthropod populations between plots containing S. invicta and plots lacking S. invicta. Despite some external variables such as inconsistencies of weather and sampling procedures, the resulting conclusions corresponded with my null hypothesis and expectations from preliminary research on the subject.