Field efficacy against the grape root borer Vitacea polistiformis (Lepidoptera: Sesiidae) and persistence of Heterorhabditis zealandica and H. bacteriophora (Nematoda: Heterorhabditidae) in vineyards

Field efficacy and persistence of Heterorhabditis zealandica strain X1 and Heterorhabditis bacteriophora strain GPS11 applied at different times for the control of the grape root borer, Vitacea polistiformis were evaluated from 2001 to 2003 in two vineyards in Ohio and one in Georgia and from 2005 to 2007 in two vineyards in Ohio. Pheromone trapping and pupal case surveys were used to confirm the presence of borers in the vineyards. Nematode applications were targeted at the larval stages of the grape root borer. Percent control based on the number of emerging adults in Ohio ranged from 55% to 92% and in Georgia from 55% to 78%. Overall no significant differences were found in the numbers or timings of nematode application indicating effective control of all GRB instars and a broad window of opportunity for the application of nematodes. The ability of H. zealandica to persist in the soil profile for a period of 1 year was minimal in Ohio and none in Georgia. In contrast, H. bacteriophora persistence in Ohio was positive for all treatments up to 1 year post-treatment and in one case up to 21 months post-treatment. These studies demonstrate the potential of H. bacteriophora strain GPS11 for long-term conservation approach in vineyards for the management of the grape root borer.