Trissolcus japonicus, an important egg parasitoid of Halyomorpha halys in Asia, was first detected in the USA in 2014. To evaluate the effect of habitat and the seasonality of T. japonicus detections in the USA, yellow sticky traps were placed in the canopy of Ailanthus altissima growing at the edge of isolated patches of trees, windbreaks, and woodlots in northern Virginia in 2018 and 2019. In both years, captures occurred from May to September, and peaked in July and August. While T. japonicus was detected in all habitats, there was not a consistent effect of habitat type on capture frequency. To evaluate tree species effects on T. japonicus captures, in 2017 and 2018, yellow sticky traps deployed in the canopy of A. altissima bordering apple orchards were paired with a nearby trap in one of several wild tree species along a common woods edge. In 2019, these traps were deployed in A. altissima, black walnut, and black locust growing in the same windbreaks. No consistent association between captures of T. japonicus or native parasitoids of H. halys and the tree species sampled was observed among years. Results are discussed in relation to the ecology and sampling optimization of T. japonicus.

The emerald ash borer (EAB), Agrilus planipennis Fairmaire, is the most destructive invasive pest on ash (Fraxinus spp.) in the United States. We determined whether ash trees injected with emamectin benzoate (EB) could protect untreated neighboring ash trees. We also determined whether the selective treatment of ash trees with EB injections had adverse effects on the establishment of introduced larval parasitoids Tetrastichus planipennis Yang and Spathius galinae Belokobylskij & Strazenac. In experiment one, trees were treated with EB and then retreated 3 years later. Five years post initial treatment, we found that 90% of treated ash trees retained healthy crowns, significantly higher than those of untreated control ash trees (16%). For experiment two, trees only received one treatment of EB and after 2 years 100% of treated ash trees retained healthy crowns, significantly higher than those of untreated ash trees (50%). In both experiments, we found that distance from the central EB-treated tree was not a significant predictor for tree health or presence of EAB exit holes. Although distance from the EB-treated trees appeared to have a significant positive relationship with woodpecker feeding signs on neighboring trees, such relationships did not result in significant differences in the proportion of neighboring ash trees retaining healthy crowns between EB treatment and control plots. The introduced EAB parasitoids appeared to have established equally well between treatment and control plots. Findings are discussed in the context of integration of EB trunk injection with biological control for protection of North American ash against EAB.

Spathius galinae Belokobylskij (Hymenoptera: Braconidae) se encuentra entre varios parasitoides introducidos como agentes de biocontrol clásico para el control del barrenador esmeralda del fresno invasivo, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), en los EE. UU. Sin embargo, el establecimiento exitoso de este parasitoide y su eficacia para suprimir el barrenador esmeralda del fresno varían entre los sitios y regiones de liberación. Nuestra hipótesis es que los microhábitats del bosque y los estadios de vida de hibernación del parasitoide afectan la sobrevivencia, el desarrollo y la fenología de emergencia de los adultos en la primavera. Para probar esto, colocamos troncos que contenían 3 estadios larvales diferentes de S. galinae (larva de estadio temprano, larva de estadio tardío y capullo) en frascos ventilados en dos sitios de microhábitat distintos, un bosque urbano y un bosque natural maduro. Estos se desplegaron a fines del otoño del 2020 y permanecieron en el campo durante el invierno. Se registró la aparición de parasitoides adultos desde la primavera hasta el verano del 2021. Los parasitoides en el sitio urbano más cálido emergieron más rápidamente, emergiendo 12 días antes que los parasitoides en el sitio de bosque maduro más frío. Ninguno de los S. galinae se desplegó como larvas de estadio temprano en diapausa en sitios urbanos o forestales. En ambos hábitats, entre el 27,1 y el 32,1% de las larvas de estadio tardío entraron en diapausa. A lo largo de los estadios larvales de hibernación, la media del tiempo de emergencia de S. galinae fue de aproximadamente 24 días en el microhábitat urbano, significativamente más corto que el (36 días) observado en el microhábitat de bosque maduro. Nuestros hallazgos sugieren que los factores ambientales afectan profundamente la fenología de S. galinae y, en consecuencia, el control biológico del barrenador esmeralda del fresno.