Oviposition by the Cinnabar Moth, Tyria Jacobaeae, in Relation to Nitrogen, Sugars and Alkaloids of Ragwort, Senecio Jacobaea

Recent studies have demonstrated that relationships between nitrogen levels and oviposition, food selection, larval survival and/or damage to host plants are not simple. We studied the effect of different levels of nitrogen on oviposition in the cinnabar moth in relation to the concentrations of alkaloids, that are positively correlated with nitrogen, and of soluble carbohydrates that are negatively correlated with nitrogen. We could not demonstrate that total alkaloid concentration was important as a proximate factor in the selection of food plants. Cinnabar moth selected plants with a high concentration of organic nitrogen and sugars. Plants poor in both, as well as plants rich in only one of these substances received fewer egg batches.