Induced defences in the neotropical tree Bauhinia brevipes (Vog.) to herbivory: effects of damage-induced changes on leaf quality and insect attack

Abstract

Induced defences to herbivory are physical, nutritional, and allelochemical traits that change in plants following damage or stress, and that reduce the performance and/or preference of herbivores. The aim of this study was to verify the occurrence and effect of induced responses in Bauhinia brevipes (Vog.) (Leguminosae) which defend it against herbivores, through the manipulation of its leaves, and their effects on herbivore foraging behaviour. We selected 15 plants in the field, and three shoots per plant were subjected to one of three treatments: (1) damaged shoots (simulation of the main types of foliar herbivory and insect exclusion); (2) damaged control shoots (insect exclusion); and (3) control shoots (not manipulated). Water and nitrogen content, tannin concentration, levels of herbivory, and shoot growth rates were compared among treatments. Leaf quality varied among treatments. Damaged leaves showed higher tannin concentration, and lower water and nitrogen content compared to undamaged leaves. On the other hand, they experienced higher rates of herbivory than leaves on control shoots. Moreover, shoots that were experimentally induced showed a higher increase in final shoot length. These results suggest that simulated herbivory on B. brevipes reduced the nutritional quality of its leaves and increased the amount of secondary compounds, therefore altering insect herbivore attack and increasing shoot performance.