A study which was published in the open access journal PLOS ONE by the University of Wurzburg, Germany state that leaf-cutting ants know which plants are not suitable for the fungus gardens which is the source of their food before they leave the colony.

These leaf-cutting ants according to Phys, usually harvest the leaf fragments and carry them back to their nests. They use it to grown a symbiotic fungus which is considered as their primary source of food. If an individual plant in the garden is not suitable for growing fungus, the leaf-cutting ants will stop collecting them.

Leaf-cutting ants learned to avoid plants that are not appropriate for growing fungus even if it had not been directly exposed to plants or their effects on the fungus. The researchers revealed naïve leaf-cutting ants to waste from the fungus gardens that has fungicide treated privet leaves to know how the ants learn to identify unsuitable plants.

According to PLoS Journal, the leaf-cutting ants learn to establish two colonies of 1,000 workers ants in the lab. They fed the fungicide-treated privet leaves to one colony as well as the untreated leaves to the second.

Furthermore, the researchers discovered that waste from the fungicide-treated privet leaves made the leaf-cutting ants avoid the foraging on privets. It only proves that the cues which could be found in the colony's waste dump are enough for insects to learn how to identify which plants are not suited to their fungus gardens.

35 percent of the leaf-cutting ants that had foraged in the previous day have visited the waste dump which has big implications for their social learning. These life-cutter ants cut the various type of foliage into pieces and bring it to the colony where they grind up the plant. They inoculate the leaves with a fungus. The harvested fungus is used as the source of their food.