Common ringtail possums (Pseudocheirus peregrinus) tolerate high concentrations of unsubstituted B-ring flavanones in their diet

Plant secondary metabolites (PSMs) can influence the consumption of particular plants by herbivores. Unsubstituted B-ring flavanones (UBFs), which are compounds found in the leaves of Eucalyptus species from the Eucalyptus subgenus (common name monocalypt), deter feeding by common brushtail possums (Trichosurus vulpecula) when added to artificial diets at concentrations that reflect those found naturally in foliage. We hypothesised that common ringtail possums (Pseudocheirus peregrinus) would tolerate higher UBF concentrations, because, unlike brushtail possums, they regularly eat monocalypt foliage. This proved to be the case; ringtail possums were not deterred by two different UBFs, pinocembrin and flavanone, at concentrations up to 4.7% dry matter, which is substantially higher than the concentrations that deter brushtail possums. These results extend and refine our understanding of how variation in tolerance or susceptibility to eucalypt PSMs affects the diets of sympatric marsupial folivores, potentially reducing competition for food.