Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/27/2004
Publication Date: 10/26/2004
Citation: Vazquez, R.J., Porter, S.D., Briano, J.A. 2004. Host Specificity of a Biotype of the Fire Ant Decapitating Fly Pseudacteon curvatus (Diptera: Phoridae) From Northern Argentina. Environmental Entomology. 33(5):1436-1441. Interpretive Summary: Colonies of red imported fire ants in the U.S. cause a wide variety of problems including economic losses in agricultural crops, nuance to livestock, medical concerns to people with allergic reactions due to stings, and damage to electrical equipment such as air conditioners and power transformers. Scientists from the USDA-ARS laboratory in Gainesville, Florida and from a USDA-ARS South American biological control laboratory in Buenos Aires, Argentina studied the host specificity of a new biotype of the decapitating phorid fly Pseudacteon curvatus. The purpose of the specificity tests was to determine if this decapitating phorid fly collected from Formosa, Argentina would pose a risk to native fire ants. Results from the specificity tests demonstrated that this Formosa species is very specific to red imported fire ants. Production levels of offspring from these flies were minimal to nonexistent in the native fire ants Solenopsis xyloni and Solenopsis geminata. The results of this study demonstrated that this fly could be released from our quarantine facility under permission of a previous permit and that field releases of this fly to control populations of red imported fire ants would pose a negligible threat to colonies of native fire ants in the U.S. Release of this new fly will be a benefit to people throughout the southeastern U.S. by providing them with another means to control populations of red imported fire ants without the use of chemical baits.
Technical Abstract: We tested the host specificity of Pseudacteon curvatus Borgmeier from Formosa, Argentina on North American colonies of the red imported fire ant, Solenopsis invicta Buren, and the native fire ants, Solenopsis geminata (Fabricius) and Solenopsis xyloni McCook. No-choice tests showed that P. curvatus hovered over and attacked all three species of fire ants. The mean number of pupae successfully completing development to adult flies in the trials was 5.03 ± 1.55 (mean ± SE) per female fly in S. invicta, 0.66 ± 0.24 per female fly in S. xyloni, and 0 per female fly in S. geminata. Paired preference tests showed that P. curvatus preferred to hover over S. invicta instead of S. xyloni 77 ± 3% (mean ± SE) of the time and preferred S. invicta over S. geminata 87 ± 4% of the time. The oviposition attempts of active female P. curvatus were 2.8 times higher on S. invicta than on S. xyloni and 16 times higher on S. invicta than on S. geminata. These results demonstrate that this new biotype of P. curvatus is more host specific to North American red imported fire ants than a previous biotype collected from black fire ants.