S. invicta workers when compared to results observed with the native fire ants. These

results indicate that the Formosa biotype displays a high degree of specificity towards red

imported fire ants when compared to native fire ants.

 The Formosa biotype of P. curvatus was released after host-specifieity tests

demonstrated that this biotype was specific to imported fire ants. Field releases were

conducted at 3 sites in Florida in the spring and summer of 2003 and monthly monitoring

followed. Field releases were successful in that field reared flies were collected and

identified within 5 weeks at the first site and then monthly thereafter. As of May 2004,

field populations ofP. curvatus dispersed one mile North and South from the first release

site. Flies from the summer releases were found in April 2004. This was the first

successful establishment of P. curvatus on red imported fire ants in the United States.

 Post-release monitoring confirmed that the Formosa biotype ofP. curvatus was

not attracted to non-Solenopsis ants. Flies were attracted to the native fire ant, S.

geminata, at very low rates (<5% of that with S. invicta) but virtually no oviposition

attempts were observed. Overall results were consistent with laboratory predictions

except attraction rates to nontarget fire ants in the field were much lower than in the small

laboratory test chambers.