Study On Acoustic Detection Technology For Monitoring Of Tree Trunk Borers

Tree trunk borers live covertly and harm seriously, so it is very difficult to monitor of them accurately when the hosts victim early. Acoustic detection technology is a newly-developing method with the advantages of convenience and efficiency. It is harmless to the trees and woods, so it is suitable for the early monitoring. The study planned to build a set of new acoustic detection system, selected several species of borers which are widespread, harmful and representative, explored the best condition of acoustic detection, and identified acoustic behavior of borers and acoustic characteristic of sound signal initially. The study has reached the following conclusions:1. The self-establishment acoustic detection system has acquisition system and analysis system. This system not only can identify borers quickly, but also can analyze the acoustic characteristics of sound signal. Against with the interference to weak acoustic signal of borers, the system tries to reduce noise by decreasing interfusion of noise and removing the existing of noise.2. This study compares the different results of AED-2010L under the influence of various factors. Number, position, temperature, time, month, and host have effects on the results of the test borers. Selecting the appropriate conditions of acoustic detection will improve the efficiency and accuracy of the monitoring. The study explores the way to improve the efficiency of acoustic detection. When the values are not obvious, knocking the hosts is helpful and simple. The study also detects Salix babylonica L., Melia azedarach L. and Casuarina equisetifolia L. in the field. The results substantially match the occurrence of borers in the hosts.3. Acoustic behaviors of Anoplophora glabripennis (Motschulsky) and A. chinensis (Forster) larvae are mainly classified into four types:feeding, moving, cleaning and self-protection for first time, feeding sound has the greatest proportion, the value reaches 34%. Acoustic behaviors have differences in time-domain graphs and spectrograms. Single sound pulse duration and dominant frequency of acoustic behaviors reflect major differences. The pulse duration of feeding sound is short, the values are 25.96 ms and 24.28 ms. The dominant frequency of feeding sound is highest, the value exceed 7.00 KHz among them. This study also finds that feeding sound can be easily identifiable in practical applications. Feeding sound has short pulse duration, large amplitude and high frequency.4. This study analyzes and compares 7 species of tree trunk borers, Monochamus urussovi Fisher, S. bifasciatus Motschulsky, P. aubei Perris, Arhopalus rusticus L., A. glabripennis Motschulsky, A. chinensis Forster, A. nobilis Ganglbauer on acoustic characteristics of their feeding sound. The results show that the sound is consist of discontinuous single pulse, the waveform graphs of time domain all have a maximum amplitude at the front, and then gradually converge at the back with irregular changing. The waveform graphs of frequency domain all have a main peak and present serrate. The sound pulse duration is all shorter than 50.00 ms and the dominant frequency is below 8.00 KHz, there is no significant law between in different species. After compared by cluster analysis, the borers belong to the same genera exhibit a very high degree of similarity, that have same host also show some correlation in the respect of acoustic characteristics.