Suitability of blue ash (Fraxinus quadrangulata) and green ash (F. pennsylvanica) to emerald ash borer (Agrilus planipennis) and the larval parasitoid Tetrastichus planipennisi

Green ash trees (Fraxinus pennsylvanica) are among the most susceptible Fraxinus spp. to emerald ash borer (Agrilus planipennis) in North America. In comparison, blue ash (F. quadrangulata) appears to be the least susceptible and may actually be able to survive EAB attack. I infested blue and green ash trees with EAB and an introduced parasitoid, Tetrastichus planipennisi when majority of EAB larvae were 3^rd instar or larger. EAB eggs used to infest the trees were 86.7% viable. Overall, 52.5% of viable larvae in green ash survived to the end of the first summer. Additionally, EAB larvae in green ash were able to develop to 3^rd instar or larger, while preliminary data showed blue ash EAB larvae were smaller at the beginning of September 2013. Tetrastichus planipennisi successfully parasitized EAB larvae on 36% of infested green ash trees.  This rate of attack may have been low because average bark thickness, 3.08 mm was close to the maximum thickness that this parasitoid can penetrate with its ovipositor. Although only 11.2% of the larvae were parasitized, parasitism rates on individual trees reached as high as 66.7%.