Introductions of South American Phorids to Texas: Improving Methods of Release, Monitoring Outcomes and Assessing Impact of South American Phorids on Ant Community Interactions and Fire Ant Populations
Principal investigator:
Lawrence E. Gilbert
Section of Integrative Biology
University of Texas
Austin, TX 78712-1064
Email: lgilbert@mail.utexas.edu
Funding Amount/2 Years: $330,856
Relevance/Implication of Project:
Biological control of the imported fire ant
is the only hope for low cost and sustained suppression of this exotic species
below economically and ecologically damaging thresholds. Phorid flies have great
potential to be a major part of a biological solution to the fire ant problem.
Understanding how best to introduce a parasitoid, how to monitor success of its
establishment, and how to assess its biological control potential in the field
are fundamental elements of any biocontrol attempt.
Summary of Work to be Done:
This project continues and extends experimental introductions of
Pseudacteon tricuspis in Texas with baseline studies of ant communities
at release and control sites. The most significant impact of Pseudacteon
phorids on the imported fire ant is to shift the pest's competitive edge against
native ant species by altering imported fire ant workers' foraging and defensive
behaviors around food sources and nest sites. How such behavioral ecological
interactions are structuring ant communities prior to and during the expansion
of introduced phorid populations is an important key to interpreting the outcome
of release attempts. Subprojects organized under this umbrella project involve
laboratory and field experiments on how phorids influence S. invicta
behavioral ecology, population biology, and community ecology. All are
integrated with, and applied to, ongoing attempts to introduce phorids for
biological control (subproject A). In the laboratory, we will use experimental
imported fire ant colonies to measure the demographic consequences of phorid
suppression of food gathering in a competitive environment (subproject D). This
research will be the first to quantitatively connect foraging disruptions due to
phorids to the growth rates and caste structures of colonies and will aid in
developing predictive models of population level impacts in the field. Outdoors,
we will extend past studies of S. invicta x S. geminata competition
to include dominant natives such as Forelius (subproject
C). All proposed field experiments assessing phorid impacts on fire ant
native ant interactions will be conducted at selected release sites and thus
will simultaneously contribute to introducing fly populations at such
localities. Finally, in a greenhouse, we continue to explore for improved
methods for introducing phorids into ant populations in the field (Subproject
B). Such an integrated approach is motivated by a very limited supply of phorid
flies, of suitable sites for release, and of manpower.