Potential of Infrared Thermography to Detect Insect Stages and Defects In
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JOURNAL FÜR KULTURPFLANZEN, 65 (9). S. 337–346, 2013, ISSN 1867-0911, DOI: 10.5073/JFK.2013.09.01 VERLAG EUGEN ULMER KG, STUTTGART Originalarbeit Nils Hoffmann1, Thomas Schröder1, Friedrich Schlüter2, Peter Meinlschmidt2 Potential of infrared thermography to detect insect stages and defects in young trees Potenzial von Infrarotthermographie zur Detektion von Insektenstadien und -schäden in Jungbäumen 337 Abstract Zusammenfassung Living stages of the quarantine pest Anoplophora chinen- In den vergangenen Jahren wurden in den EU-Mitglied- sis Forster, the so called Citrus Longhorned Beetle (CLB), staaten lebende Stadien des Citrusbockkäfers (CLB), have been detected repeatedly during import inspections Anoplophora chinensis, im Rahmen der Importkontrolle of young trees in several European Union member states. an Jungbäumen festgestellt. Die in dem Durchführungs- CLB infested plants show almost no external symptoms beschluss 2012/138/EG festgelegten Einfuhrvorschriften for identification by visual inspection. Therefore, accord- der Europäischen Union fordern derzeit eine zerstörende ing to the European Union plant health legislation (EU- Prüfung einer bestimmten Anzahl der Pflanzen. Hinter- Commission-Implementing Decision 2012/138/EG), de- grund ist, dass trotz Befall mit dem CLB äußerlich keine structive sampling of the plants at random is required. Symptome vorhanden sind, die bei einer reinen visuellen Infrared thermography has been assessed as alternative, Inspektion festgestellt werden können. Im Rahmen des non-destructive testing method. Due to the quarantine EUPHRESCO-Projektes ANOPLORISK wurde in der vor- status of CLB, the native goat moth, Cossus cossus L., was liegenden Untersuchung aus einer Reihe von zerstörungs- used as surrogate for the studies. Three types of ther- freien Prüfverfahren die Infrarotthermographie als zer- mography cameras have been tested using standardized störungsfreies Prüfverfahren angewandt. Aus Quarantä- wooden samples during two long-term measurements. negründen wurde mit heimischen Weidenbohrerlarven, Neither passive nor active thermographic methods were Cossus cossus L. (Modellorganismen), die den CLB-Lar- able to visualize enough differences in temperatures to ven in Größe und Fraßbild ähneln, gearbeitet. Mittels detect larvae, boreholes or boredust inside of wooden standardisierter Prüfkörper und präparierter Bohrlöcher samples. Therefore infrared thermography with its cur- wurden drei Thermographiekamera-Typen untersucht. rently available technology seems to be no appropriate Weder passive noch aktive Thermographieverfahren technique for detecting insect stages or defects in young konnten ausreichende Temperaturkontraste darstellen, trees. um Larven, Bohrlöcher oder Bohrspäne innerhalb des Holzes zu identifizieren. Infrarotthermographie scheint Key words: Infrared thermography, non-destructive kein geeignetes Verfahren zur Aufspürung von Insekten- testing, Anoplophora chinensis, wood boring insect stadien und -schäden in Jungbäumen zu sein. Institute Julius Kühn-Institut (JKI) – Federal Research Centre for Cultivated Plants, Institute for National and International Plant Health, Braunschweig, Germany1 Technology for Wood-based Materials, Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut, Braunschweig, Germany2 Correspondence Dr. Thomas Schröder, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for National and Interna- tional Plant Health, Messeweg 11–12, 38104 Braunschweig, Germany, E-Mail: thomas.schrö[email protected] Accepted 19 October 2012 NILS HOFFMANN, THOMAS SCHRÖDER et al., Potential of infrared thermography … Stichwörter: Infrarotthermographie, zerstörungsfreie tion of woody biomass, currently global research is con- Originalarbeit Prüfverfahren, Anoplophora chinensis, holzzerstörende ducted to verify capabilities of non-destructive testing Insekten technologies for assessment of wood and wood-based material (BRASHAW et al., 2009). The first and even today used non-destructive evalua- 1 Introduction and objectives tion method of wood is the visual inspection. Joining the development of scientific non-destructive testing in the As a result of globalization and international trade of early 20th century and the aim for assessment of wood plants for planting, tree destructive pests are arriving properties by theory of elasticity, a number of techno- European regions from countries around the world logies using mechanical behaviour and electromagnetic (RABITSCH, 2010). Since several years exotic wood-boring radiation established for characterization of wood have insects such as the Citrus Longhorned Beetle (CLB), Ano- been developed (BUCUR, 2003a; BUCUR, 2003b). plophora chinensis Forster form malasiaca (Coleoptera: For the current study the major limitation factor of Cerambycidae) have been detected repeatedly in Euro- non-destructive techniques is the material behaviour at pean Union (EU) member states at imported young trees the date of observation. The trees to be investigated are (COCQUEMPOT and LINDELÖW, 2010). living but in dormant stage, whereas objects described in CLB is a devastating organism on Citrus and ornamen- the mentioned test methods were either dried, larger or tal trees in its native range in Asia and is able to be spread standing with liquid transport processes. Furthermore 338 undetected within Bonsai and plants for planting. Host the defect can differ concerning size and distance to ob- plants cover a wide range of deciduous tree species jects surface and important physical characteristics. (SCHRÖDER and MASPERO, 2008). CLB is classified as quar- Given the stated factors above, no non-destructive antine pest in the EU. Infestations and outbreaks have been techniques described in the literature to identify insects detected in Italy (established (EPPO, 2006c)), France within young deciduous trees. Little evidence was given (eradicated (EPPO, 2006b)) and the Netherlands (eradi- for detecting insects respectively holes, cracks or knots cated (EPPO, 2006a)) as well as findings of single beetles inside of wooden material and standing trees. A few in different regions of Germany and in Switzerland methods deal with locating and tracing of high amount of (HÉRARD et al., 2006). insects and other pests and diseases (incl. fungal degra- According to the import prescriptions of the Commis- dation), inducing altering processes of wooden objects. sion Implementing Decision 2012/138/EG import inspec- No methods have been assessed on its applicability on tions have to include destructive sampling of a specified young wooden plants with stem diameters at the root amount of plants (EU, 2012). The background is that in- collar of less than five cm. However, with respect on festations with CLB almost show no external symptoms small-scaled and cut wooden materials and entomologi- for identification by visual inspection. Destructive sam- cal backgrounds, few non-destructive techniques have pling by hand using rose scissors is time consuming, risky been observed more or less successfully at least: Micro- for the inspector and destroys parts of the plant consign- computed tomography and wood wasp larvae (JENNINGS ment. Therefore efforts are underway for assessment and and AUSTIN, 2011) computed tomography and house borer development of new technologies for efficiently but non- larvae (KRAJEWSKI et al., 2005), ground penetrating radar destructive inspection of plants. and house borer larvae (SACHS et al., 2008) and noncon- In the current study infrared thermography was inves- tact ultrasound and cotton wood borer (FLEMING et al., tigated using wooden samples of three European tree 2005). species (Acer platanoides L., Acer pseudoplatanus L., Salix Infrared thermography (IR-thermography) was chosen alba L.) to capture thermal images of surrogate wood- for the current study with the aim to detect larval gal- boring larvae (Cossus cossus L.) and larval galleries, as leries and insect stages in young plants. The technique well as borings inside the cavities at long-term measure- was already used in the framework of decay detection on ments. Furthermore, the attempt was to visualize larval standing trees (CATENA, 2002; 2003; CATENA and CATENA, motions and activities based on differences in their tem- 2008) and successfully assessment of wood properties perature in comparison with ambient test objects. (moisture content, structure, density, etc.). It was also part of investigations for displaying internal heteroge- Non-destructive testing neities (defects, decay, delaminations, knots, etc.) in The method of non-destructive testing of material is a lumber and wood-based material (KLINE et al., 1992; steady educing process (BRASHAW et al., 2009), founded MURATA and SADOH, 1994; MASUDA and TAKAHASHI, 1998; by simple mechanical handlings (for example taping of QUIN et al., 1998; WYCKHUYSE and MALDAGUE, 2001; LUD- ceramic) in prehistoric times. However, the economic WIG et al., 2004; MEINLSCHMIDT, 2005; KANDEMIR-YUCEL et meaning by implementation of physical applications for al., 2007; VAN DYK and LEMASTER, 2010; ADERHOLD et al., material inspection is relative young and engendered by 2011). Active thermography was particularly applied for magnetic methods in 1868 (MÜLLER, 1975). detecting galleries of wood worms, Anobium punctatum In the background of worldwide ascending “emphasis to L. (Coleoptera: Ptinidae), in a dried lath at the Fraun- addressing forest and ecosystem health issues” (BRASHAW hofer Institute for Wood Research, Wilhelm-Klauditz-