Assemblages of litter ants as bioindicators of the conservation of Atlantic Forest remnants in the extreme South of Bahia State

Abstract

In the extreme south of Bahia State, the Atlantic rainforest has been strongly affected by anthropogenic actions for a long time. Ants are seen as good biological indicators because of their abundance and sensitivity to changes of environmental conditions, thus allowing the evaluation of environmental impacts. The purpose of this study was to evaluate the environmental quality in four Atlantic Forest remnants through the study of Formicidae assemblages. Four reserves sampled during the experiment were: the school of agriculture EMARC (CEPLAC) in Teixeira de Freitas; Vista Alegre Farm in Alcobaça; FIBRASA Farm in Itamarajú; and Riacho das Pedras Farm in Prado. In each area, 50 units of one square meter of litter were sampled at intervals of 50m and 100m of the border using “Winkler” traps. The most frequent ants in EMARC reserve were: Wasmannia auropunctata (60%) and Solenopsis sp.1 (58%); in FIBRASA farm: W. auropunctata (64%) and Solenopsis sp.1 (46%); in Riacho das Pedras farm: Pyramica eggersi (80%) and Solenopsis sp.1 (64%); in Vista Alegre farm: Pheidole sp.1 (34%), Hypoponera sp.8 (32%) and Pyramica denticulata (24%). The highest value of diversity index (Shannon-Weaver) was observed in FIBRASA farm (3.41), followed by Riacho das Pedras farm (3.31), Vista Alegre farm (3.00), and EMARC reserve (2.33). The largest number of species was observed in FIBRASA and in Riacho das Pedras farms (55 species), followed by Vista Alegre (33) and EMARC (22). The area with the highest estimated diversity is the FIBRASA farm, while the reserve of EMARC had the lowest estimate. There were correlations between the level of human impact, the species found and generic richness, as well as with other ecological variables. All the studied areas had a high occurrence of species typical of degraded lands, showing that urgent conservation measures are needed to the increasingly more rare remnants of forest in the extreme South Bahia State.