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National Institute of Biology Ljubljana, Slovenia (Part. No. 3) Dr. Andrej Čokl

Q-DETECT 7th Consortium Meeting 18/02/2013 EPPO/Q-DETECT Workshop for Phytosanitary Inspectors Ljubljana 19-21/02/2013 Work package 6 - Acoustics. Developing Quarantine Pest detection Methods for Use by National Plant Protection Organizations (NPPO) and Inspection Services

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National Institute of Biology Ljubljana, Slovenia (Part. No. 3) Dr. Andrej Čokl

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  1. Q-DETECT 7th Consortium Meeting 18/02/2013 EPPO/Q-DETECT Workshop for Phytosanitary Inspectors Ljubljana 19-21/02/2013Work package 6 - Acoustics Developing Quarantine Pest detection Methods for Use by National Plant Protection Organizations (NPPO) and Inspection Services Grant Agreement No.: 245047 Theme KBBE-2008-1-4-01 Call: FP7-KBBE-2009-3 National Institute of Biology Ljubljana, Slovenia (Part. No. 3) Dr. Andrej Čokl Federal Forest Research Centre, Vienna, Austria (Part. No. 8) Ing. Martin Brandstetter

  2. Why vibrations? VIBRATIONS ARE ALL AROUND US Thousands of years before human, predators and parasitoids began eavesdropping on communication as well as feeding and movement sounds and vibrations to find a mate, prey and hosts. After one of the first articles on acoustic detection of insects (Main 1909) the number of articles dealing with this topics significantly increased in the last 20 years due to rapid development of sensitive recording technology. An excellent overview on acoustic detection of insects is given in the article: RW Mankin, Hagstrum DW, Smith MT, Roda AL and Kairo MTK (2011). Prespective and Promise: a Century of Insect Acoustic Detection and Monitoring. American Entomologist 57(1):30-44.

  3. WHAT DID WE WANT TO DO? The Q-DETECT consortium responses to the real need for rapid, simple and robust detection methods that can be deployed by national plant protection organizations in the field with inspection services to enable early detection of quarantine pests. The aim of the WP 6 (Acoustics) joined groups from Vienna and Ljubljana was to develop and upgrade detection methods based on registration of vibratory signals emitted by everyday activity of wood boring insects. Cooperation of two partners was nnecessary because of their specific know-how , technology and experience on acoustics in two different media- air and/or solids.

  4. ADVANTAGES AND DISADVANTAGES OF SOUND AND VIBRATIONS The main driver for development of acoustic insect detection methods is their potential for automatic, real-time, non-destructive and remote monitoring and detection of hidden infestations. One disadvantage is the inactivity of the insect hidden in some substrate due tospecies specific seasonal or day/night rhythms, low temperature, outside disturbance etc. Basic knowledge on the target species biology is thus necessary before any routine use of acoustics in the field. The second problem is the choice of the relevant recording technique. To avoid wrong decision one needs some basic knowledge on sound and vibration in different media and an insight into development of new technologies.

  5. COCTAIL-PARTY PROBLEM WITH THE NOISE Signal-to-noise ratio is the common and major problem in detection of low magnitude insect wood-borne vibrations. The main sources of noise are electronics and environment. Background electronic noise is nowadays a minor problem due to highly advanced electronic technology. Nevertheless care has to be taken to avoid electronic “broom” by false by connectingand shielding of different apparatus. Background environmental noise in the laboratory can be minimizedby experiments conducted in sound insulated rooms. Box-within-a-box construction with sound absorbing material decreases efficiently the background airborne noise and heavy plates on rubber gum supports decrease the environmental substrate-borne noise. We can not avoid background noise in the field. Knowing basic frequency and time characteristics of the target species wood-induced vibrations enables software low-pass, high-pass and band-pass filtering which increases amplitude signal-to-noise ratio.

  6. WHO ARE YOU, WHAT DO YOU DO, WHERE ARE YOU? Identification of the target species at the basis of fixed spectral properties needs a critical approach. Different wood fiber mechanical (resonance) properties depending on their length, diameter and stiffness of the trunk shift the peak of the background noise which consequently shifts the overall spectra profiles of recording signals. Still in 99% the RPWhas been successfully detected in the field at the basis of the spectral features in the field. Temporal patterns like signal repetition rate and duration are more stable and help a lot when combined with less stable frequency characteristics. The signal properties depend also on insect size and stage. Adult Tribolium castanea produces about 80 times more sounds than larvae. The rates of insect sounds from a piece of wood is highly correlated with the number of insects present. Sound production increases with increasing ambient temperature. Disturbance of insects by activities may decrease, silence or increase their activities to produce signals. The right timing of listening to the hidden insects significantly influences on the detection success. Shorter sampling periods of sound recording have to be accompanied by the use of more sensors.

  7. SOUND AND/OR VIBRATION? The basic choice between detecting the airborne or substrate-borne component of sounds produced by wood-boring insects depends in principle on sound magnitude at the source and properties of the transmission medium. The latter depends on the target species size, stage and general biology on one side and on the physical properties of their environment. Low magnitude signals usually demand recording of the substrate-borne component. Substrate (structure, plant, wood)-borne vibrations can be detected by contact and/or non-contact recording techniques. Each of them has advantages and disadvantages but basically the choice of the relevant technique depends on the target species, its environment and the question we to which we look for the answer.

  8. CONTACT METHODS TO RECORD SUBSTRATE-BORNE VIBRATIONS 1/ Electronic stethoscopes work well when their base can be placed flush with the substrate surface or when signals cover narrow frequency range. 2/ Magnetic cartridges (piezo-electric crystal of quartz, stimulated by a stylus made of saphire or diamond) have been often used but are nowadays replaced by more sensitive devices. 3/ Geophones detect low-amplitude and low-frequency (0-400 Hz) signals which is mainly outside the main emitted energy spectral range of wood-boring insects. 4/ Accelerometersare more expensive but better calibrated and more rugged than contact microphones. Their response range is flat in modern ones between 0-13 kHz. 5/ Piezoelectric sensors have greater sensitivity but narrower frequency range of response. Ultrasonic sensors are useful to detect broad-band signals emitted by termites for example. Because piezoelectric transducers detect vibrations in a narrow spectral range their choice depends on the spectral properties of signals of the target species

  9. Advantages and disadvantages of contact recording techniques The vibratory contact recording techniques are generally less expensive and are enough sensitive in many situations. Their weak point for field use is in many cases proper sensor-substrate interface which is time consuming and demands adaptations of the natural substrate surface. Calibration of many contact vibration sensors is not precise enough. Contact methods may change the mechanical properties of the investigated substrate.

  10. NON-CONTACT METHODS TO RECORD SUBSTRATE-BORNE VIBRATIONS 1/ Vibrations of the substrate may be registered by an electromagnet which is positioned 1-3 mm from the investigated surface on which a small magnet is glued. Vibrations of the substrate change the distance between both magnets and thus change the electromagnetic field; the voltage output is the measure of substrate vibrations. The method is technically to complicated for the practical everyday use. 2/ Nowadays laser vibrometers represent the best choice detect and measure substrate vibrations without any contactin it. We represent the widely used Polytec PDV 100 laser vibrometer which is designed for field work.

  11. PDV-100 Polytec laser vibrometer The Portable Digital Vibrometer Type 100 (Polytec, Waldbronn, Germany) is designed for field work in the temperature range from +5 to +400C and humidity up 80% (not condensing). It measures vibrations in the frequency range from 0 to 20 kHz and dynamic range >90 dB at the working distance fom 0.1 to ca. 30 m. Its weight is 2.6 kg and calibration accuracy of the analog output +/- 1% (+/- 0.2% for the digital output). Powered by DC 11-14.5 V, 2 rechargeable Li-ion battteries for normal 5 hours work, power AC/DC adapter 100-240 V, 50-60 Hz. Velocity resolution 0.05 μm/s, maximum acceleration at the most sensitive recording level is 2.7 m/s2, .

  12. Recording and storing vibrational signals Airborne and substrate-borne sound signals recorded by different methods are nowadays almost exclusively digitized and stored in computersby different software. In the case of the present vibratory signal investigation we routinely digitize laser vibrometer recorded signals via a Sound Blaster Audigy 4 sound card (Creative Labs. Inc., Singapore) and store them in a computer by the aid of the Cool Edit Pro 2 (Synthrilium Software, Phoenix, Arizona) software.

  13. Software for vibratory signal analyses Several different computer programs are available for the analses of vibratory signals. In our case we use the Sound Forge 4.5 (Sonic Foundry Inc., Madison, Wisconsin) or Raven Pro 1.4 (Cornell Lab of Ornitology, New York) software.

  14. frequency (Hz) frequency (Hz) frequency (Hz) 2 s 2 s 2 s frequency (Hz) Vibrational signals of Nezara viridula FEMALE CALLING SONG (FCS) MALE CALLING SONG (MCS) 400 400 frequency (Hz) 100 100 MALE COURTSHIP SONG (MCrS) FEMALE COURTSHIP SONG (FCrS) 400 400 100 100 MALE RIVAL SONG (MR) DUETTING 400 100

  15. ARE YOU IN?

  16. 3 cm 4 cm 30 cm 46 cm 70 cm 2 ms Asian longhorn beetle Anoplophoraglabripennis(Coleoptera: Cerambycidae)

  17. Spondylis buprestoides (Cerambycidae) “BURST”

  18. Q-DETECT 7th Consortium Meeting 18/02/2013 EPPO/Q-DETECT Workshop for Phytosanitary Inspectors Ljubljana 19-21/02/2013Work package 6 - Acoustics

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