Facultative mushroom feeding by common woodland ants (Formicidae, Aphaenogaster spp.)

Despite the remarkable diversity of food resources exploited by ants, fungi are rarely known to be part of their diet. The notable exception is the fungal-feeding specialists in the tribe Attini, which cultivate fungi inside their nests in what is one of the earliest forms of agriculture. Previous accounts of fungivory in ants outside these fungal-feeding specialists have been questioned due to whether or not ants consume fungal tissue or prey on mycophagous insect larvae present in or on mushrooms. Here we show that ants in the widespread genus Aphaenogaster recruit to mushroom baits in the field regardless of whether or not mushrooms contained insects upon which ants might prey. When dye-stained mushrooms were provided to colonies in the lab, ants fed on mushroom tissue and dye was visible throughout their digestive tract. Evidence of mushroom feeding in Aphaenogaster suggests that facultative fungal feeding is more common in ants than previously reported, including within the myrmecine clade that contains the attines. Previous accounts of fungivory in ants have been limited to fungal-feeding specialists, but mushroom feeding by Aphaenogaster shows that fungi can also be part of a generalist ant diet. By feeding on mushrooms and transporting mushroom tissues back to the nest, Aphaenogaster workers may also serve as dispersers of fungal spores.