Morpho-physiological characterization of grapevine attacked by ground-pearl

Abstract

The ground pearl Eurhizoccoccus brasiliensis (Hemiptera: Margarodidae), is an important pest of Brazilian viticulture, related to symptoms of decline and death of plants. Despite this evidence, there is no technical information on insect-plant interactions and how the symptoms are established. Therefore, this study aimed to expose the physiological mechanisms related to the symptoms of the ground pearl attack. Seedlings of ‘Cabernet Sauvignon’ and adult plants of a commercial vineyard of ‘Isabel’, were evaluated in vegetative development of commercial area, nutrition and metabolism of leaves by the contrast of healthy and infested plants by the insect. In attacked plants it was possible to verify a significant reduction of vegetative growth. However, foliar symptoms were not expressed in two years old seedlings. In adult plants attacked, leaves, tissues of branches, roots and fruits were evaluated. The largest effects were observed in necrotic leaves, which showed a reduction of potassium (-26%), boron (-21%), total chlorophyll (-43%) and photosynthetic rate (-45%), in comparison to healthy plants. However, these same necrotic leaves showed a significant accumulation of starch (+316%). Therefore, these results suggest that ground pearl promotes the symptoms on the vine in a systemic way by blocking the transport of assimilates from leaves to other plant tissues.