Effects of the sesquiterpene lactone,helenin, on feeding rates and survival of the tundra redback vole Clethrionomys rutilus

The sesquiterpene lactone, helenin, acts as a feeding deterrent to redback voles, Clethrionomys rutilus. When given a choice between normal and treated food, these animals avoided food containing at least 0.05% of helenin. However, when only offered food with various concentrations of helenin, feeding rate and consequently body weight of voles were sharply reduced when the helenin concentration was 1.5% or higher. Voles given food containing 3.0–7.0% of helenin died in 3–5 days. It is suggested that these effects of helenin are the result of its antifeedant property and subsequent starvation of animals as well as its interference with digestive processes. The data presented support the view that helenin and other sesquiterpene lactones may play an important role in the defence of plants against herbivorous mammalian predators.