Changes in Leaf Quality Following Clipping and Regrowth of Urtica dioica, and Consequences for a Specialist Insect Herbivore, Aglais urticae

Publisher Website
Google Scholar
Abstract
The hypothesis that interruption of normal plant phenology may provide opportunities for insect herbivores to escape the nutritional constraints imposed by their food-plant is tested using Urtica dioica and its specialist herbivore Aglais urticae. The changes in water content, total organic nitrogen, soluble protein nitrogen, insoluble organic nitrogen and fibre were measured in U. dioica leaves at one site for two years both before and after summer cutting. Leaf water content and nitrogen levels were high during the spring followed by a decline during flowering. Subsequent increases were noted in plants regrowing after being cut. Mature uncut plants did not show increases in water and total organic nitrogen. Growth rates of larvae feeding on regrowth plants were higher than those on mature plants and pupal weights were greater. Higher efficiencies of conversion of ingested and digested food appear to be the major contributors to this. The consequence of interrupted plant phenology for the life cycles of insects are discussed.