Variações nas estratégias de defesa ao longo do desenvolvimento ontogenético foliar de Copaifera langsdorffii Desf. e Hymenaea stigonocarpa Mart. ex Hayne

Abstract

During ontogenetic development, plant leaves go through changes that affect the interactions with insect herbivores. The main leaf ontogenetic changes involve variations in tissue nutritional quality, variations in timing of leaf expanding/maturation, and indirect defenses. This study aimed to evaluate the effects of leaf ontogeny the anti herbivores defense strategy in Copaifera langsdorffii and Hymenaea stigonocarpa, testing two hypotheses: (i) leaves that present higher initial growth rates accumulate more tannins and (ii) ants that forage in NEFs of C. langsdorffii and H. stigonocarpa negatively affect the insect herbivores. Twenty-nine C. langsdorffii and Twenty-nine H. stigonocarpa individuals were selected and observed during seven consecutive weeks from November to December 2010. To measure leaf growth the leaf expanding rate was calculated and tannin concentration was compared between both species. An ant exclusion experiment was realized where two branches of each plant were marked and monitored during leaf expansion. The results of this work revealed that leaves of H. stigonocarpa exhibit higher initial growing and higher tannins concentration than leaves of C. langsdorffii. The ants exerted an effective defense against herbivores insects only in C. langsdorffii – branches were ants were excluded exhibit more herbivores than branches where ants were allone. A reduction in ant abundance along the leaf development was observed as well. These results indicate that the direct defenses (temporal escape and tannin production) prevailed in Hymenaea stigonocarpa whereas the indirect defense was more effective in Copaifera langsdorffii