Phorid Flies Help Researchers Tame Fire Ants

An ongoing war has been waged between Texas red imported fire ants and researchers for years. The newest weapon of choice: parasitic flies.

The Texas Cooperative Extension for Dallas County recently released another round of phorid flies to help control fire ant colonies in nearby Denton County and provide vital information for researchers.

According to a recent press release by AgNews, thousands of the Pseudacteon tricuspis species of flies were released during a two-week time window during mid to late October near the vicinity of Ray Roberts Lake, located 45 miles northwest of Dallas.

The flies, one of several imported species from South America, are being released by researchers and Extension to evaluate ways of controlling ant populations biologically. The two main species used in the releases are Pseudacteon tricuspis and Pseudacteon curvatus.

The flies are parasites only on the red imported fire ant. The adult female fly will lay an egg into the body of an imported fire ant worker. The hatched maggot develops in the ant's body for about ten days when the ant dies as the larva moves into the ants head. The maggot then eats the contents of the head and enters the pupa stage. In the pupa stage, the ant's head falls from the rest of the body, which is caused by the fly's enzymes dissolving the ant's connective tissue. Three weeks later, the adult fly emerges from the head, ready to attack again.

Extension entomologist Bart Drees said the flies' main impact is to disrupt the ant colony's day-to-day activities, such as foraging for food and mound building. Once the flies attack, the remaining worker ants will seek shelter and do not attempt to forage for food. This disrupts the provisioning of the nest with food and with protection of the colony and territory. Native ant species can then take advantage of the red imported fire ant's distraction and reclaim lost territory.

The releases are part of a larger, ongoing project between the US Department of Agriculture (http://www.ars.usda.gov/saa/cmave/ifahi), Texas Cooperative Extension and University of Texas in Austin (http://uts.cc.utexas.edu/~gilbert/research/fireants/fireant.html), that started in the late 1990s. TCE started making the releases in 2001 with the USDA's Agricultural Research Service (ARS) and Animal and Plant Health Inspection Service (APHIS) making the flies available to the entities for research purposes.

The research has grown from its beginnings in Travis and Burleson counties to several counties in Texas, including locations in Walker, Polk, Bexar, Colorado, Waller, Brazos and Orange counties. Additional release sites are being conducted throughout the southeast to further study the flies' effectiveness in controlling the ants.

The results collected will help researchers develop a develop sustainable biological control of ant populations in all areas, including wetlands, to provide suppression of imported fire ant colonies in the southeastern United States. See http://fireant.tamu.edu for more information on managing the red imported fire ant.