Effective section on grapevine plants (Vitis vinifera L.) attacked by Xylotrechus arvicola Olivier (Coleoptera: Cerambycidae) grubs: Influence and effects on its resistance

<i>Xylotrechus arvicola</i> Olivier 1795 (Coleoptera: Cerambycidae) is an insect pest that affects <i>Vitis vinifera</i> L. 1753 (Vitales: Vitaceae) plants in the main wine-producing regions of Spain. <i>X. arvicola</i> larvae bore into grapevine wood, causing both direct damage (ingestion of vascular tissues) and indirect damages (introduction of wood fungi) to the plant. The aim of research was to evaluate the effective section of wood damaged by larvae and assess its resistance capacity through compression tests and loading and breaking times. Compressive tests (on trunks) and flexural tests (on branches) were performed to evaluate the effective section. Trunk samples exhibited a higher effective section than branches samples, with effective section percentages ranging from 91.49 % to 93.53 % in trunks and decreasing from 84.91 % to 86.95 % in branches. Both loading times (Time 1) and breakage times (Time 2) increased with the effective section of the wood, although these times were lower in damaged wood samples of both trunks and branches. Additionally, significant differences were observed in the interactions between loading time x effective section and breakage time x effective section in dry trunks. This indicates a stronger relationship between the effective section and increased resistance in trunks. The results suggest that, in 'Tempranillo' variety, branches with a lower effective section are more prone to breakage when affected by <i>X. arvicola</i> larvae, whereas trunks, with a greater effective section, maintain better stability. This research should be continued with the evaluation of other vine varieties and different years of <i>X. arvicola</i> attacks, as the current findings are based on a single variety ('Tempranillo') over a period of ten years.