INFLUENCE OF AZTECA-ALFARI ANTS ON THE EXPLOITATION OF CECROPIA TREESBY A LEAF-CUTTING ANT

The foraging activity of the leaf-cutting ant Ana laevigata in an earl y successional area near Manaus, Brazil, was monitored over a period o f 18 mo. Four Cecropia species were growing in that area and all were associated with the ant Azteca alfari. Unoccupied trees (those in whic h there was no ant response to mechanical disturbance of the stem) wer e attacked by leaf-cutting ants more often than were trees occupied by A. alfari colonies. Cecropia ulei was the most frequently attacked sp ecies. However, leaves of C. ulei were the least preferred ones during assays in which detached leaves of the four Cecropia species were pla ced alongside the foraging trails of leafcutting ant colonies. C. ulei had the largest number of unoccupied trees compared to the other spec ies. In addition, A. alfari colonies associated with C. ulei were smal ler than chose associated with C. distachya. These data suggest that A . alfari was influencing the selection of Cecropia species by A. laevi gata, which harvested more from species that were less defended by the ants (with a higher proportion of unoccupied trees or trees hosting s maller ant colonies), although these were less preferred.