Host range of emerald ash borer, Agrilus planipennis Fairmaire, its damage and the countermeasures

The host range of emerald ash borer (EAB), Agrilus planipennis Fairmaire, a destructive wood borer, is limited to ash trees of the genus Fraxinus in the family Oleaceae. EAB attacked ash species in the Section Fraxinus and Section Meliodes of Subgen. Fraxinus, such as F. americana, F. pennsylvanica var. subintegerrima, F. velutina, F. nigra, and F. mandshurica. Contrary to reports in the early literature, EAB was rarely found infesting native species F. chinensis Roxb. and F. rhynchophylla Hance. EAB was also found attacking different ash species of Section Meliodes, such as two species native to North America, F. pennsylvanica and F. velutina, more heavily than those of Section Fraxinus, such as the native species F. mandshurica. Native ash trees of China may be more resistant to indigenous pests such as EAB due to the evolution of natural defenses over long time. It is likely that the severity of this pest in some regions of China resulted from the high susceptibility of introduced ash tree species from North America to EAB. EAB has been reported in Tianjin city, Heilongjiang, Jilin, Liaoning, Hebei, Shandong, Sichuan and Taiwan provinces, and Xinjiang, Inner Mongolia autonomous regions in China. Ash trees are distributed in every province and autonomous region in China with the exception of Qinghai and Hainan provinces and Tibet autonomous region. The north and northwest of China where North American ash species have been widely introduced, and the northeast of China where F. mandshurica has been planted recently are places of the potential outbreaks of this pest. EAB has been listed as a quarantine forest pest in some provinces of China, so the strict quarantine will be the first step to stop its diffusion. The outbreaks of EAB occurred on introduced North American ash trees showed that the evaluation of adaptability of these ash species in China needed further work, and the native ash species should be paid more attention in the environmental management. In the management of EAB, the mixed plantation, advanced cultivating measures, cleaning out damage trees and appropriate chemical control techniques are recommended to adopt.