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.