Surface Damaged by Xylotrechus arvicola Larvae on Vitis vinifera: Relationship With Resistance and Breaking Times

Background and Aims: The main wine-producing areas of the Iberian Peninsula are affected by Xylotrechus arvicola, an insect pest species which causes structural and biomechanical damage in vineyards (Vitis vinifera) due to the ingestion of vascular tissues.

Methods and Results: To evaluate the mechanical properties of wood affected by X. arvicola larvae, we performed compressive and flexural tests. Damaged trunk wood samples presented a larger damaged section (DS) than that in branch wood samples. The compressive strength × DS interaction yielded significant differences, which suggest a stronger relationship between DS and loss of resistance in branches. Both loading (Time 1) and breakage (Time 2) times decreased as DS increased for branch wood samples (fresh and dry); however, significant differences were observed in Time 2, suggesting that, in branches, DS causes greater fragility. Maximum bending moment was higher in undamaged branch wood samples than that in damaged ones (dry or fresh); this demonstrates that undamaged wood fibers are less resistant than those attacked by X. arvicola larvae.

Conclusions: The grape weight and/or the vibration applied by harvesting machines in affected wood branches can produce production losses and cause serious economic losses to the wineries or owners of the affected vineyards and, therefore, could be recommended to remove annually the affected parts to avoid the accumulation of dead wood due to the ingestion of its vascular tissues at the first insects attacks.