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United States Department of Agriculture

Agricultural Research Service

Title: Establishment and Dispersal of the Fire Ant Decapitating Fly Pseudacteon Tricuspis in North Florida

Authors
item Porter, Sanford
item Nogueira DE Sa, Luiz - "COSTA LIMA" BRAZIL
item Morrison, Lloyd

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2003
Publication Date: January 6, 2004
Citation: Porter, S.D., Nogueira de Sa, L.A., Morrison, L.W. 2004. Establishment and dispersal of the fire ant decapitating fly Pseudacteon tricuspis in North Florida. Biological Control. v. 29. p. 179-188.

Interpretive Summary: Fire ants are a major medical, agricultural, and environmental pest. Biological control offers the only hope for long term area wide control. USDA-ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL released the decapitating fly Pseudacteon tricuspis at eight sites in North Florida between the summer of 1997 and the fall of 1999 as a self-sustaining biocontrol agent of the red imported fire ant, Solenopsis invicta. These flies were imported into the U.S. with the aid of EMBRAPA scientists in Jaguariuna, Brazil. Overwintering populations of flies were successfully established at 6 of 8 release sites. Over several years, fly populations at these sites increased to levels as high or higher than those normally seen in their South American homeland. By the fall of 1999, flies had expanded out 1-4 miles from five release sites and occupied about 50 square miles. By the fall of 2000 the five release sites had fused into one large area about 40 miles in diameter. The flies had expanded out another 10-18 miles and occupied about 1,200 square miles. By the fall of 2001 the flies had expanded out another 6-19 miles and occupied approximately 3,100 square miles. Based on these rates of dispersal and an establishment rate of 66%, we estimate that a state the size of Florida would require 5-10 releases spaced over a 3-year period to cover the state in 5-7 years. These results are very encouraging because they show we have established a very vigorous population of decapitating flies and because large areas can be covered by relatively few releases.

Technical Abstract: The decapitating fly Pseudacteon tricuspis Borgmeier was released at eight sites in North Florida between the summer of 1997 and the fall of 1999 as a self-sustaining biocontrol agent of the red imported fire ant, Solenopsis invicta. Several releases used parasitized fire ant workers while most involved adult flies released over disturbed ant mounds. Establishment and ddispersal of fly populations were monitored by disturbing about 10 fire an mounds at each site and then inspecting them closely for hovering flies over a period of about 30 min. Overwintering populations of flies were successfully established at 6 of 8 release sites. Over several years, fly populations at these sites increased to levels as high or higher than those normally seen in their South American homeland. By the fall of 1999, flies had expanded out 1-6 km from five release sites and occupied about 125 km2. By the fall of 2000 the five initial release sites plus one new site had fused into one large area about 70 km in diameter. The flies had expanded out another 16-29 km and occupied about 3,300 km2. By the fall of 2001 the flies had expanded out another 10-30 km and occupied approximately 8,100 km2 . Based on these rates of dispersal and an establishment rate of 66%, we estimate that a state the size of Florida would require 5-10 releases spaced over a 3-year period to cover the state in 5-7 years.

Last Modified: 10/25/2014
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