Forager size of the leaf-cutting ant Atta sexdens (Hymenoptera: Formicidae) in a mature eucalyptus forest in Brazil

• Published in: Revista de biología tropical Vol. 48; no. 4; pp. 983 - 988
• Main Authors: Tonhasca, Jr, A, Bragança, M A
• Format: Journal Article
• Language: English
• Published: Costa Rica Universidad de Costa Rica 01-12-2000
• Subjects: Animals; Ants - physiology; Atta cephalotes; Atta sexdens; Biodiversity Conservation; Biology; Body Constitution; Brazil; ecology; Eucalyptus; foraging; leaf-cutting ants; Physical Exertion; Plant Leaves; Plants, Medicinal; Weight-Bearing; Brazil; Atta cephalotes; foraging; ecology; Atta sexdens; leaf-cutting ants
• ISSN: 0034-7744; 2215-2075

We determined the size characteristics of foragers of the leaf-cutting ant Atta sexdens in a mature eucalyptus forest in Campos dos Goytacazes, Rio de Janeiro State, Brazil, at daytime (7:30 to 10:00 hr) and nighttime (19:00 to 23:00 hr). There were no significant differences between daytime and nighttime ant mass (Ma), but leaf fragment mass (Ml) and burden (B = [Ma + Ml]/Ma), which indicates relative load capacity, were significantly greater at daytime. There was a positive linear relationship between Ma and Ml for the combined daytime and nighttime data, and increases in Ma resulted in lower B. We compared A. sexdens characteristics with published results for Atta cephalotes, a closely related species. A. sexdens is larger and therefore able to carry heavier loads, but its burden is about 72% of the average value for A. cephalotes. We suggest that the lower load capacity of A. sexdens in comparison to A. cephalotes is related to its relatively larger size.