What bup? Identifying which Agrilus sp. is responsible for hybrid hazelnut damage in the eastern US

Hybrid hazelnuts [Corylus avellana x C. americana or C. cornuta] are a burgeoning
industry for the upper midwestern United States. Recently, wood-boring beetles in the Agrilus
genus (Coleoptera: Buprestidae) have been noted by growers as potential pests of the plants in
the region, especially during times of drought. Our goals were to identify what Agrilus sp. (or
spp.) was observed in a hybrid hazelnut planting in southeastern Minnesota, determine what
levels of damage the insects were causing to the plants, and evaluate whether Agrilus
preferentially colonized stems with pre-existing conditions such as fungal infection.
Morphological and molecular identification of the adult and larval buprestids found in the hybrid
hazel plants revealed that Agrilus pseudocoryli Fisher was the only buprestid species present.
Sixteen percent of the hybrid hazel plants exhibited 25-100% branch dieback from A.
pseudocoryli. Plants that showed signs of being infected with eastern filbert blight were found to
have higher damage ratings than those without. Initial findings suggest that A. pseudocoryli has
a potential to impact hazelnut yield. However, because Agrilus spp. are often secondary pests
of already stressed trees, more research is needed to elucidate interactions between pests,
hosts, and environmental conditions.