Morphological and chemical analysis of Hylotrupes bajulus (old house borer) larvae-damaged wood and its FTIR characterization

In this study, the biodegradation of wood and chemical changes caused by the Hylotrupes bajulus beetle were revealed for the first time using FTIR spectroscopy. In the study, Scots pine (Pinus sylvestris), fir (Abies nordmanniana), and spruce (Picea orientalis) wood species were exposed to damage by H. bajulus larvae for four months. Morphological measurements and chemical analysis were carried out for the fine powdery dust (FPD) and frass (FR) produced by H. bajulus and compared to control samples. In addition, the FPD and FR of the larvae were examined by FTIR analysis and changes in the wood structure were determined. According to the morphological measurement data obtained from the study, the dimensions of the larval FR were 1 × 0.55 mm screened at 20-mesh, and 0.37 × 0.24 mm at 60-mesh. Holocellulose analysis showed that less holocellulose was detected in the FR and FPD than in the control wood. In the sugar analysis performed via HPLC, the glucose, xylose, galactose, mannose, and arabinose components decreased compared to the control wood, whereas the content of acid-insoluble lignin increased. The FTIR spectra of the wood species (especially in Scots pine) showed that the carbohydrate band intensity at 1735, 1370, 1321, and 897 cm⁻¹ decreased and the carbohydrate bands at 1735, 1321, 1369, and 897 cm⁻¹ were nearly absent in the FPD and FR after H. bajulus larva degradation. However, absorption band intensity at 1508, 1458, 1268, and 1031 cm⁻¹ related to the lignin bands increased significantly. According to these results, H. bajulus larvae degraded cellulose and hemicellulose from the wood components, but they did not degrade lignin.