Figure 1.

Distribution map and present root herbivore abundance of different T. officinale populations across central Europe. (a) Map of identified natural T. officinale populations evolving under high (local herbivory) or low (‘local control’ and ‘regional control’) M. melolontha infestation levels over the last 20 years. Circles inside insets denote individual T. officinale populations. CH, Switzerland. (b) Mean number of root herbivore larvae per T. officinale plant found during a field survey in 2013. M. mel, M. melolontha. p-values of Kruskal–Wallis rank sum tests are shown. Error bars correspond to standard errors (+s.e.). n.s., not significant (p > 0.10).