Available online at www.sciencedirect.com SCIENCE DIRECT* @ Agriculture Ecosystems & Envwonment Agriculture, Ecosystems and Environment 97 (2003) 107-115 www.elsevier.com/locate/agee Litter-twig dwelling ant species richness and predation potential within a forest fragment and neighboring coffee plantations of contrasting habitat quality in Mexico Inge Armbrecht arbv*, Ivette perfecto a Departamento de Biologia, Universidad del Valle,Apartado Ae'reo 25360, Cali, Colombia School of Natural Resources and Environment, University of Michigan, Dana Building, 430 East University, Ann Arbor, MI 48109-1115, USA Received 12 December 2001 ; received in revised form 11 February 2003; accepted 11 February 2003 Abstract To assess the influenceof distance from forest and coffee habitat quality on the speciesrichness of leaf litter- and twig-nesting ants, two hundred 1 m2 plots were established as follows: a forest fragment, an organic traditional polyculture coffee plantation, a shaded monoculture coffee plantation (four distances from the forest in both coffee plantations) and a dirt road. Litter ant nests, foraging ants, predation on Ceratitis capitata (Diptera: Tephritidae) and habitat variables were examined on each plot. A dramatic reduction of twig-nesting ants in the shaded coffee monoculture was found as the distance from the forest fragment increased. In contrast, twig-nesting ant species richness increased with the distance from the forest in the traditional coffee polyculture. Cluster analysis confirmed the strong influence of habitat quality on nesting ants. Canopy cover was the most important habitat variable causing differences in ant species richness between the two coffee systems. Ant predation on C. capitata pupae was prominent in all habitats studied. nig-nesting ants that showed potential to control the coffee berry borer (Hypothenemus hampei) were recorded in both the forest and traditional polyculture coffee farm. This study suggests that the quality of coffee habitat is important for the conservation of native population such as twig- and litter-nesting ants living in forest fragments. O 2003 Elsevier Science B.V. All rights reserved. Keywords: Agricultural matrix; Ant biodiversity; Coffee plantation; Forest fragment; Litter-twig-nesting ants; Mexico 1. Introduction icals (Matson et al., 1997). Coffee growing is one of the most illustrative systems showing how the in- The intensification and industrialization of agricul- tensification of agriculture negatively affects biodiver- ture has led to extensive low-diversity monocultures sity (Perfecto et al., 1997; Moguel and Toledo, 1999; that depend on high inputs of water and agrochem- Vandermeer and Perfecto, 2000). Coffee is tradition- ally grown under a canopy of shade trees, resembling a tropical forest. However, this shaded system is be- * Corresponding author. Tel.: +57-2-339-32-4311-734-936-1522; fax: +57-2-339-24-4011-734-764-1433, ing transformed into coffee farms that have little or no E-mai1,addresses: iarmbrec@umich.edu, shade and require high agrochemical inputs (Perfecto inge@mafalda.univalle.edu.co (I. Armbrecht). et al., 1996). 0167-88091031$ - see front matter 0 2003 Elsevier Science B.V. All rights reserved. doi: 10.1016lS0167-8809(03)00128-2