Damage caused by Tetranychus urticae Koch (Tetranychidae) in grapevine leaves Vitis vinifera (Vitaceae)

Grapevines (Vitis vinifera) require care from budding to harvest and are susceptible to both biotic and abiotic factors, such as infestations by insects, mites, fungi, and pathogenic viruses. This study aimed to evaluate the changes in i) the concentration of chlorophyll a (Chl a), b (Chl b), and total chlorophyll (Chl t), ii) plasma membrane integrity, and iii) stomatal density caused by Tetranychus urticae in different initial population densities maintained on Chardonnay grapevine leaves. The experiment was conducted with four treatments: control (0 mites/leaf), T<sub>25</sub> (25 mites/leaf), T<sub>50</sub> (50 mites/leaf), and T<sub>100</sub> (100 mites/leaf), over eight days. Statistical analysis of the data indicated that the mite density on the leaves did not significantly influence stomatal density or the average levels of Chl a and Chl t. No difference was observed in the number of stomata between treatments. However, a significant difference was observed in the average amount of Chl b at T<sub>25</sub>, and a continued increase in leaf perforations was noted as a function of mite density. The results suggest that, although the infestation did not alter all the assessed parameters, the presence of T. urticae impacts Chl b and leaf integrity, thereby affecting the health and productivity of the vine. These findings underscore the importance of monitoring and managing mite populations in vineyards to minimize damage.