The change in the structure of hydrogen bonds in elm wood due to damage by European elm bark beetle <i>Scolytus multistriatus </i>(Marsham) (Coleoptera: Curculionidae, Scolytinae)
Hydrogen bond (H-bond) provides the necessary flexibility and stability of biological systems, including wood. It is possible to use Infrared spectroscopy to study the energy and concentration of H-bonds in wood. In this case, it is possible to assess the nature of the hydroxyl groups based on the lengths and energies of H-bonds, known for hydrogen bonds in cellulose, lignin and other wood components, which had been studied earlier [Ivanov-Omskiy et al., 2017; Ivanova et al., 2016]. Of special interest is the solution of the problem of changing the strength and other properties of wood when the tree dies in case of damage by biological agents. In this paper, the task was to study the effect of damage by bark beetles on the structure of hydrogen bonds of wood. The object of research was elm Ulmus glabra Huds infested by the European elm bark beetle Scolytus multistriatus. This bark beetle is the vector of Dutch elm disease in St. Petersburg. Sections for spectral analysis are taken from the surface of the elm sapwood inhabited by bark beetle. The obtained results showed that on the sites damaged by the sapwood, the strongest intermolecular bond (which binds the cellulose molecules together and ensures the strength of the trunk) breaks down. The concentration of intramolecular bonds also increases. This means a fundamental change in the water metabolism of wood cells, associated with the destruction of aquaporins. This phenomenon may be related to the response of the elm to the violation of the movement of solutions through vessels during mechanical destruction of wood during the feeding of bark beetles and/or the ingestion of enzymes from their salivary glands, amylase or other carbohydrases. It is also possible that other enzymes (such as those produced by the beetles’ symbionts) come into contact with wood.