USDA, Southern States to Release Fly Against Fire Ants

By Jan Suszkiw
November 15, 2000

CORAL GABLES, Fla., Nov. 15--Phorid flies, parasites that decapitate imported fire ants, will be mass-reared beginning this spring for release in fire-ant-infested southern states in a new biological control initiative.

The campaign pitting fly against fire ant is part of a five-year program involving the U.S. Department of Agriculture’s chief scientific research agency, the Agricultural Research Service (ARS); USDA’s Animal and Plant Health Inspection Service (APHIS); and the Florida Department of Agriculture and Consumer Services (FDACS).

Fire ant stings
raise painful
pustules.

 

Phorid fly (upper
left) selects
a victim.

“Through this initiative, we’ll pool resources, scientific expertise, facilities and personnel to mass-rear phorid flies on a scale not possible before,” said Richard J. Brenner, research leader of ARS’ Imported Fire Ant and Household Insects Unit in Gainesville, Fla.

Starting in spring 2001, the FDACS Division of Plant Industry (DPI) will begin mass- rearing Pseudacteon tricuspis, the top candidate of nearly 20 phorid fly species known to parasitize fire ants. The flies then will be shipped to field sites for release in southern states including Florida, Georgia, North Carolina, South Carolina, Louisiana, Mississippi, Texas, Alabama, Arkansas, Oklahoma and Tennessee. Scientists from APHIS’ Gulfport, Miss., facilities will oversee the releases and assist the states in monitoring field sites.

ARS’ Gainesville laboratory has been rearing about 1,500 flies per day, a number sufficient only for two or three release sites per month. Under the initiative, DPI’s larger rearing facilities will double this production in 2001, with additional increases planned in subsequent years. APHIS methods development personnel in Gainesville also will work with DPI to improve the fly rearing technology.

“Increasing production will be critical to establishing phorid flies as self-sustaining biological control agents of imported fire ants,” Brenner said. He also noted that this initiative will greatly expand existing fly release programs established under the National Fire Ant Strategy, created in 1998 by ARS and the Council of State Governments' Southern Legislative Conference (SLC). Details of the initiative will be discussed today at the SLC’s fall meeting at the Hyatt Regency Hotel in Coral Gables.

Fire ants originally arrived in the United States from South America sometime in the 1930s, escaping their natural enemies in the process. Now established on 310 million acres in the South, the pest causes billions of dollars in agricultural losses, ecological damage and chemical control costs. A burning sting and aggressive nature make the pest dangerous to humans, livestock, pets and wildlife.

Phorid flies are fierce enemies of fire ants. First, a female fly injects an egg into the fire ant’s body. The larva that hatches burrows into the ant’s head, where it grows and eventually releases enzymes that cause the ant head to fall off. Inside the decapitated head, the larva pupates and emerges as a mature fly. Phorid flies attack only fire ants, and aren’t dangerous to other ant species or mammals.

APHIS, which manages programs to use biological control for invasive species, approached ARS earlier this year about increasing phorid fly production to facilitate reuniting these two insect adversaries.

“APHIS conducted a survey of all 50 states and asked state agricultural representatives which insects and weed pests might be biologically controlled. Seven southern states came back with imported fire ant ranked as top pest priority,” said Richard L. Dunkle, deputy administrator of APHIS’ Plant Protection and Quarantine Program. “It’s a really nice fit,” Dunkle said of APHIS’ partnering with ARS and DPI to rear the fly.

Over the next few years, state cooperators will closely monitor the phorid fly’s adaptability to release site conditions, spread to new areas and impact on fire ant populations.

Another objective is to establish other biocontrols that will complement the flies, including a smaller, cooler-climate phorid fly species, a parasitic ant and Thelohania solenopsae, a fire ant pathogen that causes disease in U.S. populations of the pest.

Scientific contact: Richard J. Brenner, Imported Fire Ant and Household Insects Unit, ARS Center for Medical, Agricultural, & Veterinary Entomology, Gainesville, Fla., phone (352) 374-5903, fax (352) 374-5818, rbrenner@gainesville.usda.ufl.edu.

APHIS contact: Hallie Pickhardt, APHIS Legislative and Public Affairs, Riverdale, Md., phone (301) 734-5175, fax (301) 734-5221, hallie.pickhardt@usda.gov.