Spatiotemporal insights into Halyomorpha halys and its egg parasitoid, Trissolcus japonicus: Are parasitoid captures correlated with those of its host?

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is a significant, invasive agricultural and nuisance pest from Asia, for which biological control may offer important and sustainable contributions to its management. Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), the predominant egg parasitoid of H. halys in Asia, has been proposed as a classical biocontrol agent against this pest in the USA and other countries where H. halys has established. Since 2015, adventive populations of T. japonicus have been detected annually in Frederick County, VA. Monitoring of these adventive populations has identified two peaks of seasonal abundance, although spatial and temporal relationships between the abundance of T. japonicus and H. halys have not been investigated. To examine these relationships, T. japonicus and H. halys were sampled for two consecutive seasons in Frederick County, VA. Concurrent monitoring of H. halys and T. japonicus was conducted at 10 and 20 sites in 2020 and 2021, respectively, using one yellow sticky card deployed in the mid-canopy of a mature, female tree of heaven and one ground-deployed sticky trap baited with the H. halys aggregation pheromone per site. Captures of both species were recorded weekly between May and August each year. In 2020, there were significant positive correlations between captures of T. japonicus and 2^nd instar H. halys nymphs, and between captures of T. japonicus and total H. halys captures. Data from 2021will provide additional insights into the spatiotemporal dynamics between T. japonicus and H. halys.