ROOT-FEEDING GRAPE PHYLLOXERA: APPROACHES FOR IMPROVED DETECTION AND REDUCED QUARANTINE RISK

Abstract

Unlike many other insect pests, radicole (root-feeding) grape phylloxera is relatively difficult to detect in the vineyard due to a combination of its subterranean habitat, small size, unpredictable spatial distribution and delayed expression of symptoms in the host plant foliage. In the last decade a range of 'novel' approaches have been tested to improve the efficacy of early detection for grape phylloxera. Approaches have included 'primary' detection, which focus on the insect or its DNA, and 'secondary' detection, which focuses on either the host plant or the soil environment. Primary detection can be done using either simple insect trapping techniques or a phylloxera-specific molecular probe for soil samples. Secondary detection can be achieved through the use of remote sensing techniques and plant metabolomics. However, the efficacy of each detection approach is dependent on biotic, abiotic and edaphic factors which influence spatiotemporal distribution of phylloxera. The risks of phylloxera dispersal from an infested site can be minimized by the use of scientifically validated pre- and post-harvest quarantine protocols and selection of the most appropriate rootstocks. An integrated approach to detection and quarantine is described which would improve the efficacy of detection and reduce the risks of human-assisted dispersal to a minimum.