Effect of Two Agroecological Management Strategies on Ant (Hymenoptera: Formicidae) Diversity on Coffee Plantations in Southwestern Colombia

Abstract

Simplification of agroecosystems because of industrialization of agriculture may cause the loss of associated animal biodiversity of both vertebrates and invertebrates. To measure how the agricultural intensification on coffee plantations affects ant biodiversity, we intensively sampled ants in Caldono (Cauca, Colombia). We surveyed 15 sites classified into three management types: sun coffee plantations, shaded coffee plantations, and forest patches. Fifteen 50-m linear transects, each one consisting of 5 pitfall traps and 5 tuna baits, were set at each sampling location between December of 2009 and February of 2010. We collected 18,186 ants that represent 82 ant species, 34 genera, and 9 subfamilies of Formicidae (Hymenoptera: Formicidae). The management intensification index showed an increasing intensification gradient along the 15 sampling locations from forest patches to shaded coffee to sun coffee plantations. Shaded coffee plantations harbored the highest number of species (60), followed by forest (56) and sun coffee (33). Ant species composition and plant structure on shaded coffee plantations resembled the forest patches more than the sun coffee plantations. Forest and shaded coffee plantations had a more equitable distribution of ant species, whereas in sun coffee plantations, Linepithema neotropicum (Emery) and Ectatomma ruidum (Roger) typically outnumbered all other ant species. Evidence from functional groups indicated that specific habitat and feeding requirements exist among the species that are found together. Our results confirmed that intensification of agriculture negatively affects ant diversity, despite the fact that farms were located in a heterogeneous landscape, suggesting that agroecological management is a strong determinant in the conservation of wild fauna.