Bureau of Methods Development &
Biological Control

Bureau Chief: Dr. Trevor Smith,
Trevor.Smith@freshfromflorida.com

Assistant Bureau Chief: Abbie Jo Fox, Abbie.Fox@freshfromflorida.com

Project Staff
Amy Bass
Denise Matchett
Bobbie Jo Davis
Lee Edge

In August 2001, mass rearing of the phorid fly, Pseudacteon tricuspis, began for release as a biological control agent for the Imported Fire Ant, Solenopsis invicta, in cooperation with USDA-ARS and APHIS as well as personnel from several agencies and southern states. In the first fiscal year, about 450,000 phorids were produced from 6 specialized attack boxes, used mostly to increase production and improve rearing techniques. It is hoped to build the colony to 16 attack boxes as flies, ants and personnel permit.

The USDA-Aphis Gulfport Laboratory coordinates the field releases with various Federal and state agencies. In the spring of 2002, over 18,000 phorids were released in Alabama, Louisiana, North Carolina and Oklahoma. Over 44,000 were released in the fall of 2002 in over 9 states and Puerto Rico. It is anticipated that 60,000 will be shipped in the upcoming release season. The goal is for this fly to become established throughout the southeastern United States within 3-5 years.

Pseudacteon curvatus, a second species, was added to the fire ant control program in December 2002. As other species are cleared by the USDA-ARS for field release they will be added. These additional species attack different size workers at various times of day. It is hoped that a complex of natural enemies will control the Imported Fire Ant in the infested areas, as in South America, to reduce the use of pesticides and to allow native ant species to reestablish themselves.

Phorid rearing is an extremely labor intensive process, especially since the adult phorid only lives a couple of days. Because of the short life cycle of the fly, large numbers of ants and phorids are needed to maintain the colony. To start the rearing process, Imported Fire Ants and brood are collected from various field sites. When they are brought back to the facility, they are separated from the soil by flooding with water. The ants and brood float to the top, are collected from the buckets, and then are sized to accommodate the various species of phorids.

Each of these is weighed and the ants and brood are placed in covered holding cups for 30 minutes. This allows the ants to form a bond with the brood. Each cup is emptied into a tray, 14 of which are placed into each attack box.

For each tray in the attack box, there are two cups suspended from strings attached to a 10-minute timer, operating in seesaw fashion. One cup is raised while the other is lowered. As the ants are introduced, they begin to move the brood to the lowered cup. After 10 minutes the other cup is lowered. This causes the ants to trail, which signals the phorids to attack. The phorids parasitize the ants by injecting an egg into the thorax. Each group of ants is exposed for 48 hours with a nocturnal cycle when the lights are off and the cups are stationary. At this time, the ants rest under the lowered cup and the flies rest in various parts of the attack box.