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Pseudacteon obtusus, Fire Ant Decapitating Fly
Dr. Robert Plowes - Brackenridge Field Laboratory, The University of Texas
Dr. Lawrence Gilbert, Brackenridge Field Laboratory, The University of Texas
Pseudacteon obtusus
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Image processing: Dr. Jessie Maisano
Publication Date: 29 Feb 2016


The following is an excerpt from an article entitled 'Introduction of the Fire Ant Decapitating Fly Pseudacteon obtusus in the United States: Factors Influencing Establishment in Texas' by R.M. Plowes, E.G. LeBrun and L.E. Gilbert (BioControl, 56, 295-304):

Parasitoid phorid flies in the genus Pseudacteon (Diptera: Phoridae) are among several prospective biocontrol candidates being evaluated or introduced for biocontrol of red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), in the United States. Fire ants are regarded as one of the more serious invasive ant species capable of causing major disruptions to biodiversity (Wojcik et al. 2001) and incurring high economic impacts (Pimentel et al. 2000). The introduction of Pseudacteon parasitoid flies from South America is part of a wide effort to establish self-sustaining biocontrol agents including parasitoids and pathogens against fire ants, and thereby dampen their impacts. There are several pathways by which phorid flies may impact fire ant populations including direct mortality of workers (typically less than 1% parasitism rates within colonies) (Morrison and Porter 2005), reduction of foraging efficiency of workers (Feener and Brown 1992), and as possible vectors of pathogens (Oi et al. 2009). The impact of phorid flies on the foraging efficiency of S. invicta is likely to be dependent on several factors such as the community of competing ants, resource availability and environmental conditions (Feener et al. 2008). However any additional stresses on fire ant colonies, even if transient or seasonal, may reduce the degree of competitive asymmetry in these ant communities.

About the Species

This specimen was lab-reared at Brackenridge Field Laboratory, The University of Texas at Austin. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Drs.Robert Plowes and Lawrence Gilbert of Brackenridge Field Laboratory, The University of Texas at Austin. Funding for scanning and image processing was provided by UTCT.

About this Specimen

The specimen was mounted to the tip of a toothpick with wax and scanned by Jessie Maisano on 29 May 2014 along the coronal axis for a total of 737 slices. Voxel size is 2.29 microns.

About the


Feener, D.H. Jr., and Brown, B.V. 1992. Reduced foraging of Solenopsis geminata (Hymenoptera: Formicidae) in the presence of parasitic Pseudacteon spp. (Diptera: Phoridae). Annals of the Entomological Society of America 85:80–84.

Feener, D.H., Orr, M.R., Wackford, K., Longo, J.M., Benson, W.W., and Gilbert, L.E. 2008. Geographic variation in resource dominance—discovery in Brazilian ant communities. Ecology 89:1824–1836.

Morrison, L.W., and Porter, S.D. 2005. Phenology and parasitism rates in introduced populations of Pseudacteon tricuspis, a parasitoid of Solenopsis invicta. BioControl 50:127–141.

Oi, D.H., Porter, S.D., Valles, S.M, Briano, J.A., and Calcaterra, L.A. 2009. Pseudacteon decapitating flies (Diptera: Phoridae): are they potential vectors of the fire ant pathogens Kneallhazia (=Thelohania) solenopsae (Microsporidia: Thelohaniidae) and Vairimorpha invictae (Microsporidia: Burenellidae)? Biological Control 48:310–315.

Pimentel, D., Lach, L., Zuniga, R., and Morrison, D. 2000. Environmental and economic costs of nonindigenous species in the United States. Bioscience 50:53–65.

Wojcik, D.P., Allen, C.R., Brennan, R.J., Forys, E.A., Jouvenaz, D.P., and Lutz, R.S. 2001. Red imported fire ants: impact on biodiversity. American Entomologist 47:24–50.

& Links

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To cite this page: Dr. Robert Plowes, Dr. Lawrence Gilbert, Brackenridge Field Laboratory, The University of Texas, 2016, "Pseudacteon obtusus" (On-line), Digital Morphology. Accessed July 12, 2024 at http://digimorph.org/specimens/Pseudacteon_obtusus/.

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