Bioenergetics of the Southern Harvester Ant, Pogonomyrmex Badius

Abstract

The bioenergetics of the southern harvester ant were studied on the Savannah River Project, Aiken, South Carolina. Excavation of hills revealed that density of ants ranged from 4,000 to 6,000 per hill. Labeling ants with P32 indicated that only 10% of the ants in a colony were active above ground during any 2—week period (the limit of recognition of the label); thus, short—term marking recapture estimates based on above—ground individuals greatly underestimate the size of the colony. There were 27 hills per hectare on the study area. The consumption of oxygen of workers at various temperatures was determined in a simple respirometer, and the temperature at which the ants were living in the field was determined during a year's observation at mounds. The energy expense of heat production was calculated from the oxygen consumption and activity temperature records. Total energy flow (heat production plus tissue growth) was highest in summer and lowest in winter. The annual range was from 14 to 48 kgcal/m2/yr. Tissue growth was estimated to amount to only 0.09 kgcal/m2/yr. Energy flow in this species was higher than that of 2 vertebrate granivores studies in the same field, the old—field mouse and the savannah sparrow.