Termite Head-Banging: Sounding the Alarm
Tom Fink – email@example.com
Lichuan Gui, Yong Wang, Zhonghua Cao, Adarsh Jaiswal, Orwa Tahaineh, Vijay Ramalingam, Roger Hasse, *Alan Lax, John Seiner
National Center for Physical Acoustics
1 Coliseum Drive
University of Mississippi
University, MS 38677
*USDA ARS, SRRC
1100 Robert E Lee Blvd.
New Orleans, LA 70124
Popular version of poster paper 5aAB7 presented at the 152nd ASA Meeting in Honolulu, Hawaii.
Figure 1. Formosan Subterranean termites: Soldiers have the dark amber colored heads and dark pointy mandibles. The rest of the termites seen here are workers.
Video 1: Click above to see video of FST head-banging and tremulation in a Camphor tree.
Sound Clip 1: play to hear termite head-banging from a River Birch tree.
Sound Clip 2: play to hear termite chewing from the same River Birch tree.
In the second video below (Video 2) you will see a view inside an FST infested Black Willow tree. The central channel is the drill hole that allowed entry of the borescope video camera, while to the sides is the carton nest. A soldier can be seen vigorously head-banging for 2.5 minutes. Near the end of the clip another soldier joins, even more vigorously. Notice also that most of the soldiers are NOT head-banging. Perhaps some soldiers are more inclined to head-banging than others.
Video 2 (without sound): Click the picture above to see video of FST head-banging in a Black Willow tree.
Video 3: Click the picture above to see video of FST workers head-banging in a Slash Pine tree.
Video 4 (without sound): Click the picture above to see video of two RF soldiers head-banging.
Video 5: Click the picture above to see video of the waveform of one RF soldier head-banging.
Video 6: Click the picture above to see video of the waveform of one FST soldier head-banging.
Further Details of Head-Banging As Observed with High-Speed Video
Because FST and RF head-bang so fast the details can not be seen with the eye. Using high-speed video we can see the details as shown in this video of RF shown in slow motion (Video 7, original video taken at 10,000 frames per second, and shown here at 30 frames per second). In both species, RF and FST, the head is raised up by moving the prothorax up at its articulation with the mesothorax (the head is attached anteriorly to the prothorax, which possesses the first pair of legs, the mesothorax contains the second pair of legs and is attached to the prothorax by a movable junction). The legs are not used to raise the head. The head is then rapidly moved down like a battering ram and the head hits flat on the substrate. What can only be seen in slowed down views of high-speed video is that the head often rebounds, or bounces up after the initial impact and then hits the substrate again in about 4 milliseconds. This can be seen on head-bangs 1 and 3 in video 5. This rebound substrate hit produces an additional substrate vibration.
Video 7: Click the picture above to see video of one RF soldier head-banging.
Practical Use of Head-Banging by Humans
Because termite head-banging results in the loudest and most diagnostic sound that termites make, it can be utilized for termite detection. The most difficult part of termite control is termite detection due to their subterranean and hidden tunneling habits. A useful sensor for termite vibration (due to head-banging and chewing) is a 1000 mv/g accelerometer (Figure 2). Termite vibrations are transmitted to the accelerometer sensor by a waveguide (bolt, screw, metal rod, etc.) which causes the piezoelectric material of the accelerometer to produce an electrical signal in proportion to the amplitude of the vibration. These electrical signals are then amplified by a signal conditioner and transduced into sound that can be heard through headphones or recorded.
Figure 2: Accelerometer, waveguide, signal conditioner and headphones used to detect head-banging of FST infesting the floor below the linoleum tiles.
Figure 3: Two heavily FST infested Aristocratic Pear trees (tree 86 is distal to 85 alongside the bench) in Jackson Square Park in New Orleans, November 2003. Both of these trees appeared not to be infested by visual methods but loud head-banging was detected acoustically.
Selected Representative Literature
- Connetable, S., A. Robert, F. Bouffault and C. Bordereau. 1999. Vibratory alarm signals in two sympatric higher termite species: Pseudacanthotermes spiniger and P. Militaris (Termitidae, Macrotermitinae). Journal of Insect Behavior 12: 329-342.
- Kirchner, W.H., I. Broecker and J. Tautz. 1994. Vibrational alarm communication in the Damp-wood termite Zootermopsis nevadensis. Physiological Entomology 19: 187-190.
- Mankin, R.W., W.L. Osbrink, F.M. Oi and J.B. Anderson. Acoustic detection of termite infestations in urban trees. Journal of Economic Entomology 95: 981-988.