Directional change in tunneling of subterranean termites (Isoptera: Rhinotermitidae) in response to decayed wood attractants.
Wood discs decayed with brown rot fungi and polymer discs impregnated with acetone extract of decayed wood were embedded in sand of a two-dimensional foraging arena to evaluate their attractant potential in directing termite tunnels toward them. Termites were released near one arena corner and were guided to follow the physical guideline of the arena edges. In the absence of the attractants, termites generally formed a relatively linear tunnel along the edges. When decayed wood discs or treated polymer discs were placed in wet sand near one side of the arena, termite tunnels departed from the arena edges and were oriented toward them. The attraction distance ranged from 12 to 18 cm. The attractant properties were most likely water soluble and permeated through wet sand to cause termites to change their orientation. The results demonstrated that when such attractants are placed near a bait station in the field, they may be used to direct termite foraging toward the station.
Termite Attractant from Fungus-Infected Wood
Field observations suggested that subterranean termites might follow a concentration gradient of attractive material to find decaying wood. Laboratory cultures of the brown rot fungus, Lenzites trabea Pers. ex. Fr., on pine blocks formed a material attractive to the eastern subterranean termites, Reticulitermes flavipes (Kol.) and R. virginicus Banks, and a Costa Rican termite, Nasutitermes columbicus (Holmgren). Such a potent termite attractant may be useful in termite surveys and control.
Super-resolution of overlapped waves in time and frequency domain in a directional borehole radar measurement
The Multiple Signal Classification (MUSIC) algorithm is modified in order to resolve multiple waves and to estimate reflection points in 3-D space. This algorithm is suitable for directional borehole radar with a circular dipole array antenna. Making use of the spatial frequency difference of acquired array signals, the signals are decorrelated, and the 3-D MUSIC algorithm is applied. The time domain signals of the singlehole array-type borehole radar are used in order to form a measurement vector in the MUSIC algorithm. A computer simulation confirms that the proposed algorithm may estimate the directions of arrival (DOA) for three signals. Applying the proposed algorithm to field experiment data successfully estimates the DOA of a reflected wave from a fracture in rock.