Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/1/2008
Publication Date: 6/1/2008
Citation: Mankin, R.W., Mizrach, A., Hetzroni, A., Levsky, S., Nakache, Y., Soroker, V. 2008. Temporal and spectral features of sounds of wood-boring beetle larvae: identifiable patterns of activity enable improved discrimination from background noise. Florida Entomologist. 91:241-248. Interpretive Summary: Scientists at the Center for Medical, Agricultural, and Veterinary Entomology and at research institutions in Israel collected and analyzed sounds produced by the red palm weevil, and two other species of wood boring insects to develop new methods for detecting hidden infestations of pests in economically important trees. It was found that analysis of the patterns of moving and chewing can help distinguish insect sounds from background more reliably than previously used analyses that relied primarily on the comparisons of frequencies alone.
Technical Abstract: Rhynchophorus weevil larvae produce economically important damage to ornamental and date palm crops that could be mitigated significantly by early detection and treatment. Acoustic technology has potential to enable early detection, but often it is difficult to distinguish insect sounds from background noise that contains energy at the resonant frequencies of stiff, fibrous structures in trees and other plants. Tests were conducted with currently available acoustic instrumentation and software to assess the capability of these methods to discriminate weevil, Cerambycid, and Buprestid larval sounds from background noise in woody structures. An approach to the discrimination problem is to monitor the temporal patterns of the 3-10-ms sound impulses produced by locomotory and feeding activities. Playback and computer analyses of larval sounds revealed trains of impulses separated by intervals of less than 500 ms that listeners often considered to be potential insect sounds. Further analyses identified a subgroup of trains, denoted as bursts, containing > 6 and < 200 impulses, which occurred frequently when larvae were present but only rarely when larvae were absent. The incorporation of bursts into the analysis process significantly improved the capability to distinguish sounds produced by beetle larvae from background noise when these insects were hidden in stiff, fibrous structures, and likely will be of assistance also in other applications where consistent activity patterns of hidden pests can be identified.