Ecologia de interações entre Inga sessilis (Vell.) Mart. (Fabaceae, Mimosoideae), formigas e herbívoros associados : padrões espaço-temporais da defesa anti-herbivoria

Abstract

The interspecific interactions s increased the ecosystems complexity and diversity.. However, environmental impacts can affect the arthropods population dynamics and the relationships they establish with the plants, generating these last differences in their symmetry. The present study analyzed the spatiotemporal patterns of ecological interactions established among a population of Inga sessilis (Fabaceae, Mimosoideae), their herbivores insect and mutualist ants in a of mesophytic forest fragment in City of Morrinhos, in Southeast of Goiás State, Brazil. Field samplings were made at the edge (anthropic region) and the interior (preserved) of vegetation from December 2014 up to February 2016. We hypothesize that in the interior, better preserved, the ants would be more effective in herbivory avoidance, which in turn would lower leaf asymmetry. We sampled 45 individuals of I. sessilis (Fabaceae). The herbivorous insects and visiting ant species were quantified and the role of ants on inhibition of herbivory was tested. The herbivores damage the floating asymmetry and the presence of secondary defense compounds were compared between edge and interior plants. Moreover, it was analyzed the importance of secondary metabolites on herbivory avoidance. Four species of ants were more abundant in the studied system (Camponotus lespesii, Crematogaster limata, Ectatomma tuberculatum e Wasmannia auropunctata). The proportion of leaf consumed by herbivores were similar among plants with and without ants. Furthermore, there was difference in measurements between the left and right sides of the leaves, indicating the presence of directional asymmetry in plants located within the vegetation. Finally, the secondary compounds were more important to defense against herbivory than defense provide by ants. The studied area probably suffers by intense fragmentation and edge effects. Such effects can considerably reduce the populations of herbivorous insects, weakening the mutualism between plants and ants.