The effects of light on foliar chemistry, growth and susceptibility of seedlings of a canopy tree to an attine ant.

Abstract

Seedlings of Inga oerstediana Benth. (Mimosaceae) growing in three different light environments (the understory, tree-fall gaps and full sun) were tested for differences in chemistry (nutrients and tannins), wound-induced increases in tannins, growth, and susceptibility to leaf-cutter ants, Atta cephalotes (L.) (Formicidae: Attini). I hypothesized that seedlings of I. oerstediana would contain higher concentrations of tannins when growing in high light conditions and, therefore, would be less susceptible to leaf-cutter ants.Foliar concentrations of condensed tannins were much higher in plants growing in full sun compared to those growing in the understory. The concentrations of condensed tannins did not increase following damage. Despite higher concentrations of condensed tannins in sun foliage, leaf-cutter ants found these leaves more acceptable. The preference for sun leaves was consistent with higher concentrations of foliar nutrients. I suggest that the magnitude of the increase in condensed tannins was not great enough to override the benefits of increased concentrations of foliar nutrients. Finally, based on these results and those of others, I suggest that foraging by leaf-cutter ants may be an important factor determining patterns of succession in early successional habitats.