Video (all files are in .mpg format)
Subterranian Termites |
A visit to the United States Department of Agriculture's Southern Regional Research Center in New Orleans, Louisiana, in October 2002, demonstrated first-hand to members of the Insect Acoustics group the devastating impact the Formosan termite species Coptotermes formosanus Shiraki is having on the historic city of New Orleans. The intense winds of Hurricane Lili resulted in the collapse of 43 trees in City Park and surrounding residential areas, and the trees that collapsed were severely damaged due to Formosan termite infestations. In order to address the issue of structural damage caused by this urban pest, technical personnel at the National Center for Physical Acoustics (NCPA) have been working with research entomologists at the USDA-ARS over the past 1½ years to field test and implement highly sensitive commercial transducers used for the distinct purpose of detecting and monitoring hidden Formosan and Reticulitermes spp. termite colonies. |
In response to the urgent need for an acoustic detection system capable of locating termites in trees and telephone poles in a noninvasive manner, Research and Development Engineer Roger Hasse and the USDA-ARS research collaborators referenced below have co-developed a field-portable probe used to sensitively measure the seismic vibrations produced by termites during normal behavioral activities. A field-portable single-channel anti-aliasing filter was designed and constructed for use in conjunction with the acoustic probe, with signal output compatibility for headphone monitoring or signal analysis DAQ hardware. A custom LabVIEW
a program has been developed for the purpose of monitoring and recording termite acoustic emissions in WAV format, or calculating averaged power spectra in ASCII format, using a laptop computer.
Motivated by past studies of termite infestations in City Park (see literature below), a research effort has been under way for the past several years focused on the inspection and monitoring of the more than 2000 trees located within the confines of the park, using visual inspections, monitoring traps, and acoustic detection technologies. Representative species of trees found in City Park include the Bald cypress, Southern live oak, and Loblolly pine. To date, 253 of the 608 trees examined are infested with both the Formosan and Reticulitermes spp. Termite, for a total of 42 %. Acoustic detection was the only means of successful detection for 78 % of the trees examined (traditional methods such as visual inspections and monitoring traps failed to reveal the presence of hidden termite colonies).
Once the entire tree population has been inspected (to be completed in summer 2004), a pilot study will be initiated to treat the trees in designated sections of the park using bait traps and/or chemical foams. Periodic inspections using acoustic detection technology will provide essential feedback on the efficacy of these treatments, based on the measured power spectra of the acoustic signals.
The recent additions of Senior Research Scientist Dr. Carrick Talmadge and Associate Research and Development Biologist Charlie Dawson to the NCPA Acoustics Group will provide additional technical expertise (e.g. advanced signal processing, data acquisition, and GPS capabilities) to help in this research effort. Plans are under way to utilize a commercially available acoustic detection system to determine whether termite acoustic emissions are concentrated in the ultrasonic or seismic bandwidths, in side-by-side comparisons with the aforementioned acoustic probe detection system.
In addition to the above efforts, Dr. John Seiner, Associate Director of the NCPA, is working on the development of a mulit-point Laser Doppler Vibrometer (LDV) system, with the eventual goal of rapidly detecting termite-induced damage in natural and man-made structures (e.g. an interior wall in a home) by using acoustical excitation and laser-based measurement techniques to study the modal responses of the object under investigation. A parallel goal of the research is to develop finite-element models of any given structure and then simulate its degradation due to the destructive presence of termites. Preliminary Laser Doppler Vibrometer (LDV) measurements have been performed on a mock room at the NCPA which clearly detected artifical damage to a 2-by-4 vertical stud located behind the drywall surface. The measurements were performed with good resolution in less than 5 minutes duration using a coarse scanning grid.
Research Collaborators
Dr. Alan R. Lax, Formosan Subterranean Termite Research Leader, USDA-ARS-SRRC, New Orleans, Louisiana
Dr. Weste L.A. Osbrink, Research Entomologist, USDA-ARS-SRRC, New Orleans, Louisiana
Dr. Tom J. Fink, Research Biologist, USDA-ARS-SRRC, New Orleans, Louisiana
Mr. Akshay Singh, Doctoral Candidate, Mechanical Engineering, Louisiana State University, on-site at the USDA-ARS-SRRC.
Carly Bulliard, Biological Science Technician, USDA-ARS-SRRC, New Orleans, Louisiana
Adrian Mejia, Biological Aide, USDA-ARS-SRRC, New Orleans, Louisiana
Pertinent Literature
Osbrink, W.L.A. and Lax, A.R. 2002. Termite Gallery Characterization in Living Trees using Digital Resistograph Technology. In: Jones, Zhai, and Robinson, eds. Proceedings of the 4th International Conference on Urban Pests, pp. 251-257.
Mankin, R.W., Osbrink, W.L., Oi, F.M., and Anderson, J.B. 2002. Acoustic Detection of Termite Infestations in Urban Trees. J. Econ. Entomol. 95 (5): 981-988.
Osbrink, W.L.A.,Woodson, W.D., and Lax, A.R. 1999. Populations of Formosan subterranean termite, Coptotermes formosanus (Isoptera: Rhinotermitidae), established in living urban trees in New Orleans, Louisiana, U.S.A. In: Robinson, W.H., Rettich, F., and Rambo, G.W., eds. Proceedings of the 3rd International Conference on Urban Pests, Czech Republic: Graficke zavody Hronov, pp. 341-345.
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