Perception of carbon dioxide and other ?air-condition? parameters in the leaf cutting antAtta cephalotes

Social insects often build subterranean nests to protect themselves and their brood from predators and environmental influences. These nests can reach remarkable sizes, covering an area of up to 40 m and reaching 6 m below the surface [1]. The fungus gardening leaf cutting ants (genus Atta) have special demands for their nests, including stable microclimatic conditions required by the fungus. The climatic parameters, such as humidity, temperature, and the concentration of CO2 , have direct impact on the development of the brood and on the fitness of the whole colony [2]. The ants appear to be able to regulate these conditions by constructing and, when needed, altering ventilation channels, which are an important part of the nest [3]. Various types of sensilla, often hairshaped sensory organs with up to 30 receptor neurons densely cover the antennae and perceive chemical and mechanical stimuli. In A. cephalotes there are about 1400 sensilla on each antenna, and thus an enormous number of sensory cells relay the information to the brain [4]. In addition to pheromones, food odors, and mechanical stimuli, changes in environmental parameters are detected by antennal sensilla.