Pupal exuviae sampling versus pheromone trapping to assess grape root borer infestations in Virginia vineyards

Grape root borer, Vitacea polistiformis (Harris) (Lepidoptera: Sesiidae) is an endemic, oligophagous and indirect pest of grapevines in the eastern United States. Larvae feed on the roots of wild and commercially important Vitis species and rootstocks. At least three sampling methods (pupal exuviae collections, sex pheromone traps, vine removal) have been employed to monitor and/or assess grape root borer populations in vineyards, although destructively sampling vine roots is not a reasonable option for growers. In this study, the number of pupal exuviae collected from the around the base of a grid of sample vines in commercial vineyards in northern Virginia was compared with the number of male moths captured in pheromone traps. The results showed that there was not a significant correlation between these two variables and that captures of males in traps were not a useful indicator of the infestation status of individual vineyard blocks. In a related study, annual variations in the number of grape root borer pupal exuviae collected from the same sample vines were assessed in several northern Virginia vineyards over three consecutive years.

Key words: Vitacea polistiformis; pupal exuviae; pheromone trapping; sampling; grape