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Sounds (all files are in mp3 format)
Imported Fireants |
Since their accidental introduction to the United States via Mobile bay in 1918, imported fire ants (Solenopsis spp.) have spread throughout the southeastern United States becoming a major agricultural and urban pest costing Americans an estimated six billion dollars annually. To compound this problem further, there are no natural predators of the Imported Fire Ant (IFA) present in the United States, resulting in population densities up to five times those in the ant's homeland of South America. To date, control methods (both traditional and non-traditional pesticides) have been seemingly ineffective in decreasing IFA populations. |
New methods of reducing IFA populations are currently under investigation. A key area of interest is fire ant communication. Any manipulation of their communication could be valuable in making current pesticides more effective or possibly as a sole means of IFA control in itself. It is known that ant communication is multimodal by nature, but in the past, chemical communications (pheromones) have been the main area of focus of IFA communication research. With ever increasing IFA populations, researchers are challenged to seek new avenues of control such as manipulating acoustic communications.
From past research (namely vibration-based studies) it has been observed that IFA communicate by and respond to acoustical waves as part of multi-modal communication. It is still uncertain, however, on whether they respond to air-borne acoustical waves along with already proven behavioral responses to substrate transmitted acoustical waves.
Currently, the group is leading a study measuring wingbeat frequencies of fire ant alates (winged reproductives) in tethered flight. A 16-microphone circular array has been designed in order to measure the acoustic profiles of alate wingbeat frequencies in real time with regard to amplitude and directionality. The microphone array is implemented along with a high-speed digital video camera, using frame rates of 10,000 frames per second. This combined technology and subsequent information will allow NCPA researchers to develop an accurate computer model of IFA alates in nuptial flight.
Graduate biology student, Esther Mwangi, has been working on her ongoing thesis research project that involves studying the behavioral responses of black imported fire ants (Solenopsis richteri Forel) to substrate vibration and the subsequent effect on attack rate efficiency of the biocontrol agent, the decapitating phorid fly (Pseudacteon curvatus Borgmeier). The phorid fly, also native to South America, is an imported species-specific biocontrol agent that appears to keep IFA populations under control in their native land. The decapitating flies are currently being reared and introduced into the wild on an experimental basis by several USDA-ARS units. Ultimately, the objective of the study is to determine if substrate vibrations within fire ants colonies have an impact on the parasitizing behavior and success of the decapitating fly (Pseudacteon Curvatus). First, the individual tethered ants were tested to determine the frequencies and the acceleration magnitudes to which they responded. Second, small colonies were tested (using frequencies close to those in part 1) in arenas to assess how non-tethered ants responded to substrate vibrations as a group. Finally, colonies being subjected to predation by the phorid flies were tested to determine if substrate vibration (and subsequent increased physical activity of the ants) resulted in increased attack rates and successful predation by the flies.
Future directions of the group are aimed at recording and analyzing natural, dynamic alate flight as well as studying IFA stridulation behavior. Stridulation is the sound-generating action of fire ants in which they rub the washboard-like gaster against a scraper on the rim of the postpetiole in a flagging motion as a believed means of communication. NCPA researchers also intend to design a fire ant tub similar to the phorid fly attack arena with a built-in array of sensors in the base to independently excite substrate vibrations at various locations in order to observe subsequent fire ant behavior.
Research Collaborators
Douglas A. Streett, PhD, Research Leader, USDA-ARS, Biological Control of Pests Research Unit, Stoneville, MS and Biological Control Mass Rearing and Research Unit, Mississippi State, MS
Anthony Pranschke, Biological Technician, USDA-ARS, Biological Control of Pests Research Unit, Stoneville, MS
Larry Thead, PhD, Research Entomologist, USDA-ARS, Biological Control Mass Rearing and Research Unit, Mississippi State, MS
Evita Gourley, Biological Technician, USDA-ARS, Biological Control Mass Rearing and Research Unit, Mississippi State, MS
Paul K. Lago, PhD, Professor of Biology, University of Mississippi Richard Buchholz, PhD, Assistant Professor of Biology, University of Mississippi.
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