Assessing Dispenser-Based Control on Mealybug (Hemiptera: Pseudococcidae) and Ant (Hymenoptera: Formicidae) Populations in Virginia Vineyards

Mealybugs (Hemiptera: Pseudococcidae) are one of the prevalent pests infesting wine grapes in the eastern United States. Their close association with ants (Hymenoptera: Formicidae) provides them with protection against natural enemies. Although sugar-based dispensers have been proposed as a strategy to disrupt this trophobiotic interaction, their field performance and indirect effects on mealybug infestation remain poorly understood. This study addresses this gap by identifying mealybug species present in Virginia vineyards, characterizing dominant ant genera associated with mealybugs, and evaluating the impact of sugar dispensers (with and without insecticide) on ant activity, mealybug density, and fruit cluster infestation. Field trials were conducted in two commercial vineyards in Virginia, USA, both with a history of mealybug infestations. Sampling plots with or without sugar dispensers were compared to assess differences in mealybug and ant population densities and fruit cluster infestation levels. Two mealybug species, Pseudococcus maritimus (Ehrhorn) and Ferrisia gilli Gullan, were detected at both sites. Some dominant ant genera, including Tetramorium Mayr, Lasius Fabricius, Solenopsis molesta (Say), Crematogaster Lund, and Pheidole Westwood, were found in close association with mealybugs. Ant activity remained low in untreated plots, whereas insecticide-treated dispensers initially attracted high ant numbers, which declined over time. Fruit cluster infestation was highest in plots lacking dispensers, indicating that dispenser deployment reduced mealybug impact. These findings demonstrate that sugar dispensers, particularly those containing insecticide, can suppress ant activity and reduce mealybug-related fruit damage, offering a practical non-disruptive tool for integrated pest management in small- and medium-sized vineyards.