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United States Department of Agriculture

Agricultural Research Service

Title: Post-Release Host-Specificity Testing of Pseudacteon Tricuspis, a Phorid Parasitoid of Solenopsis Invicta Fire Ants.

Authors
item Morrison, Lloyd
item Porter, Sanford

Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 11, 2004
Publication Date: May 1, 2006
Citation: Morrison, L.W., Porter, S.D. 2006. Post-release host-specificity testing of Pseudacteon tricuspis, a phorid parasitoid of Solenopsis invicta fire ants. Biocontrol. 51: 195-205.

Interpretive Summary: Imported fire ants are serious pests in the southern U.S. The release of natural enemies such as parasitoid Pseudacteon species (Diptera: Phoridae) may reduce the abundance of these pests. Inherent in any biological control program, however, is the risk of nontarget effects. Scientists working at the USDA-ARS, Center for Medical, Agricultural, and Veterinary Entomology, in Gainesville, FL, studied released populations of P. tricuspis Borgmeier, a parasitoid phorid fly, that has been introduced to the United States from South America as a potential biocontrol agent of the red imported fire ant, Solenopsis invicta Buren. We monitored disturbed mounds of S. invicta and a closely related species, S. geminata (F.), during the expansion of P. tricuspis across north Florida and after populations had been established for about 3 years. We also tested host acceptance in established populations of P. tricuspis by offering trays containing S. invicta, S. geminata, and 14 additional ant species representing 12 different non-Solenopsis genera. Although P. tricuspis was commonly observed to hover over and attempt to oviposit on S. invicta, we never observed any parasitization attempts on any other ant species. As predicted by laboratory tests, released populations of P. tricuspis appear to be highly host specific and pose no obvious threat to nontarget species.

Technical Abstract: Inherent in any biological control program is the risk of nontarget effects. Pseudacteon tricuspis Borgmeier, a parasitoid phorid fly, has been introduced to the United States from South America as a potential biocontrol agent of the red imported fire ant, Solenopsis invicta Buren. We conducted tests of host specificity on released populations of P. tricuspis, which are attracted to alarm pheromones released by their hosts during events such as mound disturbances and interspecific interactions. We monitored disturbed mounds of S. invicta and its close congener, S. geminata (F.), during the expansion of P. tricuspis by offering trays containing S. invicta, S. geminata, and 14 additional ant species representing 12 different non-Solenopsis genera. Although P. tricuspis was commonly observed any parasitization attempts on any other ant species. As predicted by laboratory test, released populations of P. tricuspis across north Florida and after populations had been established for ~3 years. We also tested host accceptance in established populations of P. tricuspis by offering trays containing S. invicta, S. geminata, and 14 additional ant species representing 12 different non-Solenopsis genera. Althouhg P. tricuspis was commonly observed to hover over and attempt to oviposit on S. invicta, we never observed any parasitizationn attempts on any other ant species. As predicted by laboratory tests, released populations of P. tricuspis appear to be highly host specific and pose no obvious threat to nontarget species.

Last Modified: 10/24/2014
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