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Grapevine leafroll disease (GLD) is caused by a complex of vector-borne virus species in the family Closteroviridae. GLD is present in all grape-growing regions of the world, primarily affecting wine grape varieties. The disease has emerged in the last two decades as one of the major factors affecting grape fruit quality, leading to research efforts aimed at reducing its economic impact. Most research has focused on the pathogens themselves, such as improved detection protocols, with limited work directed toward disease ecology and the development of management practices. Here we discuss the ecology and management of GLD, focusing primarily on Grapevine leafroll-associated virus 3, the most important virus species within the complex. We contextualize research done on this system within an ecological framework that forms the backbone of the discussion regarding current and potential GLD management strategies. To reach this goal, we introduce various aspects of GLD biology and ecology, followed by disease management case studies from four different countries and continents (South Africa, New Zealand, California-USA, and France). We review ongoing regional efforts that serve as models for improved strategies to control this economically important and worldwide disease, highlighting scientific gaps that must be filled for the development of knowledge-based sustainable GLD management practices.

Ant species like Pheidole megacephala (F.), Solenopsis invicta (Buren), and the Argentine ant, Linepithema humile (Mayr), have repeatedly been reported to be strongly associated with honeydew-producing arthropods like aphids, scale insects, and mealybugs, effectively protecting them from biological control agents like parasitoids. Here we report the results of a successful trial using pheromone dispensers to suppress Argentine ant activity over large sections in a commercial vineyard over a period of two months and preventing ant access into and foraging within the vine canopy. We found Argentine ant activity to be significantly reduced in pheromone-treated plots for the duration of the trial period compared with control plots. Our results showed a significant reduction in the numbers of Argentine ant workers recruited to randomly placed food resources within treated plots compared with untreated plots. Furthermore, spatial distribution of Argentine ants alongside transects in untreated plots remained relatively continuous, while increasing sharply beyond the borders of treated plots. Lastly, we measured the body fat content of workers and found a significant reduction in fat among workers from treated plots compared with untreated plots, suggesting an adverse effects on nest fitness. Additionally, we provide an initial assessment of the feasibility of the presented approach. Our results showed that it is possible to control Argentine ant, preventing them access to and foraging within the vine canopy, thereby reducing Argentine ants' access to honeydew. [ABSTRACT FROM AUTHOR]

BACKGROUND Invasive ants, such as the Argentine ant, have often been reported to facilitate honeydew-producing hemipteran pests such as mealybugs, which can be vectors of plant pathogens. Synthetic pheromones may offer a target-specific method to control such ants and consequently lower the abundance of honeydew-producing pests. Here we report the results of a trial to suppress Argentine ants in grapevines using ant pheromone dispensers. RESULTS Compared with untreated controls, we observed a significant drop in Argentine ant activity on the ground, irrespective of whether pheromone dispensers were placed at ground level, within the canopy or in both locations. Ant counts in the canopy confirmed that Argentine ant abundance was reduced under the influence of the pheromone dispenser placed at ground level compared with untreated controls. However, placing dispensers only in the canopy did not reduce the numbers of ants within the canopy compared with untreated controls. CONCLUSION Our results showed that pheromone dispensers can significantly reduce Argentine ant foraging in grapevines if they are positioned appropriately. This technique could potentially reduce the abundance of associated mealybugs and potentially attendant virus vectoring areawide. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND The identification of new attractants can present opportunities for developing mass trapping, but standard screening methods are needed to expedite this. We have developed a simple approach based on quantifying trap interference in 4 × 4 trap arrays with different spacings. We discuss results from sex pheromones in Lepidoptera (light brown apple moth, Epiphyas postvittana), Diptera (apple leaf curling midge, Dasineura mali) and Homoptera (citrophilous mealybug, Pseudococcus calceolariae), compared with a kairomone for New Zealand flower thrips ( Thrips obscuratus). RESULTS The ratio of catch in corner traps to catch in centre traps was 25:1 at 750 D. mali traps ha−1, and was still ∼5:1 at 16 traps ha−1, suggesting trap interference even at such low trap densities. Trap competition for sex pheromone lures at close spacing (<5 m) was evident in 16-trap arrays of P. calceolariae, but less so for E. postvittana. No trap competition was observed at 4 m spacings with the kairomone for T. obscuratus. CONCLUSIONS The ratio of catch in traps in the corner and centre of a 16-trap array at different spacings offers a rapid preliminary assessment method for determining the potential for mass trapping. Additional knowledge of vital rates and dispersal is needed for predicting population suppression. Our approach should have value in mass trapping development. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]