UV-induced anthocyanin in the host plant Sedum lanceolatum has little effect on feeding by larval Parnassius smintheus

Climate change has resulted in shorter periods of snow cover in alpine meadows, increasing the duration of UV exposure. We established the relationship between increased exposure to UV light and anthocyanin pigment levels in host plant Sedum lanceolatum and tested whether increased exposure changed the feeding behavior of its herbivore Parnassius smintheus. Anthocyanin concentrations were significantly greater in plants exposed to UV. Under field conditions, we found a preference of P. smintheus caterpillars for plants with slightly above average levels of anthocyanin; however, no-choice feeding experiments in which larvae ranging from 1 to 3 days old were placed on UV-rich and UV-low plants showed no difference in feeding. These results indicate that the reduction of snow cover in alpine meadows will change the pigment profile of plants, but these changes may have little effect on herbivory.