INFLUÊNCIA DE GRADIENTES AMBIENTAIS E FORMIGAS MUTUALISTAS NA ARQUITETURA E HERBIVORIA DE INGA LAURINA (Fabaceae)

Abstract

The interactions between ants and plants are based on the exchange of favors. Plants offer a sugared solution in the form of extrafloral nectaries (EFNs) and ants act as plant guards by warding off herbivores. These mutualistic interactions are influenced by physical conditions such temperature, humidity and luminosity, and can also be under the effect of the environment. In this study we investigated how different sites (edge and interior of a fragment) and the presence of ants influence the architecture (growth and the number of leaves), the number of EFNs and leaf herbivory in Inga laurina (Sw.) Willd. (Fabaceae: Mimosoidae). The plants (n = 88) were planted along 200 meters within an urban forest fragment; the plants were also assigned to two groups, one with and one without ants. Ants were excluded with the aid of a resin which was applied to the plant foot. The fieldwork was carried from December 2019 to May 2020. Data of temperature, humidity and luminosity made it possible to clearly distinguish between edges (high temperature and luminosity, low humidity) and the interior of the fragment. Plant height was affected by both ants and site; plants without ants were taller in one edge. The number of leaves neither was influenced by ants nor sites. The number of EFNs was higher in plants without ants in the interior of the fragment. Ants had conditional effects on leaf herbivory, because in one edge plants with ants had low levels of leaf damage in comparison to plants without ants; however, in other edge the results were the opposite an in the interior no difference was found between plant groups. We conclude that the development of I. laurina is not sensitive to environmental gradients, because its architecture was weakly influenced by sites. Furthermore, despite being myrmecophilous, I. laurina benefited from ant presence in only a limited site within the fragment, and evidence of how ant-plant interactions can be conditional.