Abstract of Thesis Presented to the Graduate School
 of the University of Florida in Partial Fulfillment of the
 Requirements for the Degree of Master of Science

 HOST-SPECIFICITY TESTS, FIELD RELEASES, AND ESTABLISHMENT OF THE
 SMALL DECAPITATING FLY, Pseudacteon curvatus BORGMEIER (DIPTERA:
 PHORIDAE), IN FLORIDA

 By

 Ricardo Jose Vazquez

 August 2004

Chair: Sanford D. Porter
Major Department: Entomology and Nematology

 In recent years, decapitating flies in the genus Pseudacteon Coquillett have been

studied extensively as potential biological control agents because many are common

parasitoids of red imported fire ants, Solenopsis invicta Buren. The purpose of this study

was to evaluate host-specificity of a biotype ofPseudacteon curvatus Borgmeier

collected from red fire ants in Formosa, Argentina, and determine if it is sufficiently host

specific to be released in the field. I also established three field populations and

monitored post-release nontarget effects of P. curvatus.

 I tested the host specificity of Pseudacteon curvatus Borgmeier from Formosa,

Argentina, on North American colonies of the red imported fire ant, Solenopsis invicta,

and the native fire ants, Solenopsis geminate (Fabricius) and Solenopsis xyloni McCook.

In no-choice tests, rates of pupal production were 87% lower in S. xyloni compared to S.

invicta and zero in S. geminate. In choice tests, the Formosa biotype preferred to hover

77-87% of the time, attack at a ratio of 10 to 1, and produce higher numbers of pupae on