Comparison of AE-apparatus for detection of activity of Old house borer larvae, including reality check

As part of the German funded project 'InsectDetect' comparative measurements were done with three different Acoustic-Emission-(AE)-apparatus on 14 pine beams in order to assess presence of active attack by the Old house borer (Hylotrupes bajulus (L.)). In all beams active attack was measured, though in varying intensity. This was corroborated by completely dissecting 10 of the beams. All three AE-systems proved suitable to find active attack, although their results in terms of numbers of events are different even when used in the same situation. Therefore, it is important that the operator is familiar with the technical functioning of the system that is used in order to be able to interpret the results reliably. The dissection of the beams showed that there is also an element of chance in these measurements regarding proximity of sensors to gnawing larvae and temporal larval inactivity. Still, such measurements with these apparatuses can give an answer to the question whether active attack of wood-boring insects is present.