Use of Vertebrate Tissue by the Leaf-Cutting Ant Atta texana (Hymenoptera: Formicidae: Attini)

Abstract

Leaf-cutting species of the tribe Attini are primarily neotropical ants, known for their cultivation of fungus gardens. The fungus is cultivated on carefully prepared surfaces of leaves, insect feces, bits of wood, or insect carcasses which are found while foraging (Weber, 1972). Attine ants derive sustenance from the juices of cut leaves (Quinlan and Cherrett, 1979) and from fungus and are considered generalist herbivores (Wheeler, 1910; Weber, 1972; Howard, 1988) or quasiherbivores (Bowers and Porter, 1981). There appear to be no reports of an attine ant collecting vertebrate tissue; this note describes such behavior in Atta texana, a common leaf-cutting ant in southern and eastern Texas (Moody and Francke, 1982). The incident occurred during a field project examining the effects of the red imported fire ant (Solenopsis invicta Buren) on small mammal community diversity and habitat utilization. The study site was located in a mixed bunchgrass community on the Rob and Bessie Welder Wildlife Refuge, 12 km northeast of Sinton, Texas (San Patricio Co.). Granular 5% diazinon was placed underneath each Sherman live trap to reduce bait predation by ants (Chabreck et al., 1986) and to reduce S. invicta predation on small mammals in traps (Masser and Grant, 1986; Flickinger, 1989). This technique successfully excluded S. invicta from traps but not A. texana. Leaf-cutting ants were noticed in only a few traps the first morning but were present in 52% of 216 traps by the fourth morning. On 29 September 1989, I discovered a dead northern pygmy mouse (Baiomys taylori) in a trap. About 40 A. texana were in the trap, and about 20 were on the carcass. Tissue had been