Spatio‐temporal population sampling of a fire ant parasitoid

The spatial and temporal population structure of Pseudacteon tricuspis Borgmeier (Diptera: Phoridae), an introduced parasitoid of the invasive red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), was investigated at three locations in Louisiana, USA, during the fall of 2005. Georeferenced disturbed fire ant mounds that attracted adult P. tricuspis were analyzed using Spatial Analysis by Distance IndicEs to model the population structure of this parasitoid on a local spatial scale, and relate spatial abundance to host colony social form and infection with the fire ant pathogen, Thelohania solenopsae Knell, Allen and Hazard (Microsporidia: Thelohaniidae). Spatial associations between P. tricuspis counts and host S. invicta colonies infected with T. solenopsae were not detected. Overall, spatio‐temporal count patterns of P. tricuspis were largely random. However, high P. tricuspis counts were significantly associated with areas of polygyne host colonies. Occasional aggregations of P. tricuspis populations into discrete spatial patches and gaps were also found. The implications of this study are that population surveys of P. tricuspis should be conducted in several areas at a location to account for local patchiness in fly populations and/or varying densities and social form of host ant colonies.