Ant Diversity in an Area of the Amazon Forest in Acre, Brazil

Knowledge on the diversity of ants is important for understanding ecological relations in the ecosystems, especially in the Amazon, where very little is known about these insects. The purpose of this work was to survey the ant fauna in an area of the Amazon forest in the State of Acre, Brazil. Sampling was conducted in the Western Amazon in areas of: primary forest (Forest); secondary forest of approximately 16 years of age ("Capoeira"); 16-year old secondary forest, experimentally cut, burned and cleaned (Regeneration) and a farm area ("Matriz"); they all constituted a mosaic at the margin of a reservation area. Two hundred and forty pitfall samples per each of the above areas were taken from June 2001 through January 2005, both in the dry and wet seasons, totaling 2,400 samples. The collected ants were identified to species level. A total of 106,018 individuals belonging to the subfamilies Myrmicinae (49.64%), Formicinae (14.49%), Ponerinae (13.04%), Dolichoderinae (6.88%), Ecitoninae (5.43%), Ectatomminae (4.71%), Pseudomyrmecinae (4.71%) and Cerapachyinae (1.09%) were collected. They represented 276 species in 57 genera. The species richness was: in Forest, 267; in "Capoeira," 123; in Regeneration, 164 and in "Matriz," 172. The Shannon-Weaver (H') index for the Forest (4.29) suggests that it has higher diversity than "Capoeira" (3.61), Regeneration (3.47) and "Matriz" (3.06). This is the first report of a survey of the ant fauna of the Acre State, Brazil. It demonstrates the great biodiversity of the region and suggests that further studies could add to these results.