Title page for ETD etd-0710102-225727

Type of Document Dissertation
Author Colby, Deanna M.
URN etd-0710102-225727
Title Effects of Fire Frequency and the Red Imported Fire Ant on Native Insects in a Louisiana Longleaf Pine Savanna
Degree Doctor of Philosophy (Ph.D.)
Department Entomology
Advisory Committee
Advisor Name Title
Dorothy Prowell Committee Chair
C. Carlton Committee Member
Linda M. Hooper-Bui Committee Member
William J. Platt Committee Member
Earl H Weidner Dean's Representative
  • restoration
  • solenopsis invicta
  • conservation
  • pinus palustris
  • biodiversity
Date of Defense 2002-07-05
Availability unrestricted
Ants and ground beetles were collected in pitfall traps from a longleaf pine savanna in the early stages of restoration. Insect abundance and species richness were compared among four treatment combinations of two fire frequencies and presence and absence of an exotic ant, Solenopsis invicta, the red imported fire ant. AmdroŽ was used to suppress S. invicta. Fire treatments consisted of a single fire in a two year period or two fires in a two year period, one applied each year. Fires were applied late in the growing season both years.

Ten of the 28 ground beetle species collected were single individuals. Samples were not large enough analyze statistically. Burning a fire-maintained habitat does not typically alter ground beetle populations, but there were not enough data to validate this claim.

Twenty-six species of ants were collected from pitfall traps. Six species were exotic. Exotics comprised 23% of the species richness and 98% of the individuals collected. Solenopsis invicta far exceeded other species' abundances and accounted for 95% of total ants collected. Excluding S. invicta, natives and exotics were relatively equal in abundance. Regression analyses of species ranks and abundances were not different among treatments. Species composition among treatments was more similar following treatment applications.

After many years of fire suppression, many ant species increased in abundance following the first applied fire. However, the second applied fire did not elicit the same magnitude of response. Soil moisture, soil temperature, and leaf litter dry weights were not correlated with ant abundance. Because there were no differences in native abundance among treatments, it was concluded that AmdroŽ was not necessary to maintain a balance between S. invicta and native ants. A single applied fire without AmdroŽ produced the same results with respect to S. invicta and native ant abundance as two fires with AmdroŽ. The greatest number of exotic ants were collected from treatments with two fires and no AmdroŽ, suggesting more frequent fires increase exotic ant abundance. Data suggest that native ants are able to coexist with S. invicta and other exotics even when vastly outnumbered by them.

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