Litter-twig dwelling ant species richness and predation potential within a forest fragment and neighboring coffee plantations of contrasting habitat quality in Mexico

To assess the influence of distance from forest and coffee habitat quality on the species richness of leaf litter- and twig-nesting ants, two hundred I m 2 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. Twig-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. (C) 2003 Elsevier Science B.V. All rights reserved.