ARS | Publication request: HOST SPECIFICITY OF THE MICROSPORIDIAN PATHOGEN VAIRIMORPHA INVICTAE AT FIVE FIELD SITES WITH INFECTED SOLENOPSIS INVICTA FIRE ANT COLONIES IN NORTHERN ARGENTINA

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 5, 2007
Publication Date: September 1, 2007
Citation: Porter, S.D., Valles, S.M., Davis, T.S., Briano, J.A., Calcaterra, L.A., Oi, D.H., Jenkins, R.A. 2007. Host specificity of the microsporidian pathogen vairimorpha invictae at five field sites with infected solenopsis invicta fire ant colonies in northern argentina. Florida Entomologist. 90(3):447-452.

Interpretive Summary: The microsporidian pathogen Vairimorpha invictae is being evaluated for release in the United States as a potential self-sustaining biological control agent for imported fire ants. USDA-ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL and the South American Biological Control Laboratory in Buenos Aires, Argentina examined the host range of this pathogen at five sites in northern Argentina where fire ant colonies had high levels of infection (28-83%). They were assisted by scientists from Clemson University at three sites near Corrientes, where 509 non-fire ants from 61 collections, 12 genera, and 19 species were collected and tested using a PCR-based screening procedure. None of these ants in other genera were infected with V. invictae. At two sites near San Javier in Santa Fe Province, 350 km to the south, another 438 non-fire ants from 44 baits, 4 genera, and 4 species were collected and tested, again with no infections. At the Corrientes sites, 235 non-ant arthropods from 10 orders, 43 families, and more than 80 species were collected and tested. None were infected with V. invictae. The results of this study indicate that, in its native South American range, V. invictae is specific to fire ants. This result is important because it provides evidence that release of this pathogen in the United States as a fire ant biocontrol agent will not be a threat to native ants or native insects.

Technical Abstract: The microsporidian pathogen Vairimorpha invictae is being evaluated for release in the United States as a potential classical or self-sustaining biological control agent for imported fire ants. We examined the host range of this pathogen at five sites in northern Argentina where Solenopsis invicta fire ant colonies had high levels of infection (28-83%). At three sites near the city of Corrientes, we examined 509 non-Solenopsis ants from 61 collections, 12 genera, and 19 species using a polymerase chain reaction-based screening procedure, but none were infected with V. invictae. At two sites near San Javier in Santa Fe Province, 350 km to the south, we screened another 438 non-Solenopsis ants from 44 baits, 4 genera, and 4 species, again with no infections. At the Corrientes sites, we also examined 235 non-ant arthropods from 10 orders, 43 families, and more than 80 species. None were infected with V. invictae. The results of this study indicate that, in its native South American range, V. invictae is specific to Solenopsis fire ants.