EFFECT OF Planococcus ficus (SIGNORET) ON THE GROWTH OF THREE WINE GRAPE CULTIVARS

Damage caused by herbivores reduces plant survival and growth through its effects on mechanisms involved in tolerance to herbivory. Infestation by sap-sucking insects negatively affects the expression of metabolites related to photosynthesis and growth traits, which in an agricultural context can be useful for designing pest management and crop breeding programs. The effect of infestation by the vine mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) on chlorophyll content and plant growth in three varieties of Vitis vinifera L. (Garnacha, Tempranillo and Nebbiolo) was evaluated. A common garden experiment was conducted with 60 plants of each variety and two P. ficus infestation treatments (infested and non-infested). Plant height, number of leaves, leaf area and chlorophyll content index were measured before and after P. ficus infestation for each plant and, additionally, the relative change rate (RCR) for each trait was estimated. The infestation reduced the RCR of the number of leaves (22.57 %) and leaf area (41.65 %). The effect of infestation on plant growth changed between varieties. Nebbiolo plants with infestation showed a reduction of RCR in plant height compared to non infested plants (57.32 %), while Garnacha and Tempranillo varieties showed similar values in both treatments. A negative effect of P. ficus infestation on plant height, number of leaves and leaf area was found. Results suggest that the Nebbiolo variety is less tolerant to P. ficus attack. Farmers should adopt more rigorous monitoring and control measures when growing this variety.