“Collective response of leaf-cutting ants to the effects of wind on foraging activity”

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Andrea Marina Alma, Alejandro G. Farji-Brener, and Luciana Elizalde

Social organisms such as ants can collectively mitigate the adverse effects of the environment

Wind affects not only foraging of leaf-cutting ants, but also their division of labor

Foraging activity of the leaf-cutting ant Acromyrmex lobicornis in Patagonia.
(Credit: Alejandro G. Farji-Brener)

In regions characterized by strong and constant wind, leaf-cutting ants take more time to bring resources back to the nest. Wind negatively affects ant movement, decreasing their speed and blowing ants off foraging trails. Recently, it has been found that in leaf-cutting ants the total force of adhesion increases with body size due to an increase in pad efficiency. In light of this, Andrea Marina Alma and colleagues tested whether the leaf-cutting ant Acromyrmex lobicornis reduces the problems imposed by Patagonia’s strong winds by increasing the number of workers that are better able to deal with this environmental factor (i.e., larger ants). To study this, the researchers worked with different colonies located in Patagonia, Argentina, and measured the length of both outbound and inbound laden ants, as well as the effect of experimental wind (generated by computer coolers in the field) on larger and smaller ants. They find that wind delays smaller ants more than larger ones and that in windy conditions, colonies increase the number of larger ants, which are better able to deal with wind. Very small ants were almost absent in windy conditions, and very large ants were only present in windy conditions. By assigning larger ants to forage in windy conditions, colonies reduce the negative effect of wind in their foraging by 32%. These results illustrate how environmental factors can affect division of labor and how social organisms can collectively mitigate the negative effect of environmental factors, highlighting one of the most important advantages of group living. Read the Article