Ant–fungus mutualism en.wikipedia.org
Secondary symbiotic relationships
There are additional symbiotic relationships that affect fungal agriculture. The fungus Escovopsis is a parasite in ant colonies, and the bacterium Pseudonocardia has a mutualistic relationship with ants. Pseudonocardia resides on the ants' integuments and assists in defending the ants from Escovopsis through the production of secondary metabolites.[13] In fact, some species of ants have evolved exocrine glands that apparently nourish the antibiotic-producing bacteria inside them.[14] A black yeast interferes with this mutualism. The yeast has a negative effect on the bacteria that normally produce antibiotics to kill the parasitic fungus and so may affect the ants' health by allowing the parasite to spread.[15]
skookin wrote
"A further specialization occurred from the opportunity that this coevolution offered. Up until this point the ant host had been feeding their cultivars primarily with detritus and fecal matter [26]. The shift towards herbivory consisted of certain groups of attine ants (the ancestors of Atta and Acromyrmex) shifting towards fresh plant matter as a substrate for growing their gardens [27] [28]. This shift provided the opportunity for the development of industrial-scale agriculture that we now see in the Atta and Acromyrmex genera."