Nest Architecture Development of Grass-Cutting Ants

Atta bisphaerica are group of grass cutting ants that normally found at the Cerrado biome particularly in Brazilian savanna. It is an ancient biome comprising thousands species of plants, animals and fungi. Atta bisphaerica nest are visible externally with mound of loose soil showing a large number of holes inside. In which tunnels are made up in various diameter and shapes to interconnect the chambers allowing traffics among the ants. The tunnels exit through landfill where the ants transport soil from excavations and cut leaves towards opening of nest holes. However, very little is known about Atta bisphaerica architecture development. Thus, this research investigates the nest of Atta bisphaerica from Sao Paulo Brazil.

 

Internal architecture of  Atta bisphaerica

The depth and dimension of chambers were measured after digging using molds of cement to see the actual internal structures. The length, width and height of the chambers and tunnels were also calculated. Wherein lateral development of the nests increased over time but the depth shows no changes. At 14 months  the depth ranges from 1.2m-2.0m and at 18 months it ranges from 1.3m-2.9m. On the other hand Atta bisphaerica chambers that have fungus garden incorporated with plants are found at the soil surface. Signifying the adaptations of the species to withstand in varied soil environment. Since nest are usually found at an open space with the presence of direct sunlight.

 

Moreover,  Atta bisphaerica choose the best location in terms of temperature and humidity. With regards to the internal tunnels there were increased in width over time. As well as, the dimensions of chambers augmented because of colony growth and the flow of workers inside the nest. In addition, the narrow tunnel serves as the communication between larger tunnels. There is also circular and elliptical tunnel that has been observed.

 

The architectural nest of Atta bisphaerica differ at ages probably because of temperature and humidity of the soil. And the increased numbers of chambers over time is due to an increased in population sized inside the colony. Also the width of the tunnel enlarged because of the higher flow of workers. Indeed, this research contributes to the nest architectural development of grass-cutting ants Atta bisphaerica.

 

Source: Prepared by Joan Tura from Revista Brasileira de Entomologia

Volume 62, Issue 1, January–March 2018, Pages 46-50