Non-Asian ash species are much more susceptible to EAB than their native congeners in China
There was a highly significant effect of ash species on EAB infestation level based on multinomial logistic regression analysis of historical and field survey data (MLR: df =12,χ 2=69.55, P <0.0001). North American and European ash species, including velvet, green, white and European ash, had significantly higher levels of EAB infestation in comparison with native ash species across China (ANOVA: df =7,182,F =10.63, P <0.0001) (Fig. 1). In comparison to heavy infestations on non-Asian ash species in China, EAB caused minimal damage to the three native ash species commonly used as hosts, namelyF. mandshurica , F. chinensis chinensis Roxb. and F. chinensis rhynchophylla (Hance) A.E.Murray (Fig. 1). In addition, the other six native ash species, including F. angustifolia syriaca(Boiss.) Yalt., F. baroniana Diels, F. bungeana A.DC.,F. griffithii C.B.Clarke, F. hubeiensis S.Z.Qu, C.B.Shang & P.L.Su and F. platypoda Oliv., have never been found to be attacked by EAB. There were highly significant differences in the EAB infestation indices among the nine (four exotic and five native) species of ash planted in the Oleaceae Common Garden (EAB infestation index:df =7,101, F =15.55, P <0.0001; Canopy index: df =7,101, F =11.59, P <0.0001; Bark split: df =7,101, F =8.92, P <0.0001; with one-way ANOVA analysis); all exotic ash had much higher levels of EAB infestation than native Asian ash (Table 2). In the Oleaceae Common Garden, North American and European ash trees were heavily damaged, while native Asian ash species were only lightly or never infested.