The role of substrate preparation in the symbiosis between the leaf-cutting ant Acromyrmex octospinosus (Reich) and its food fungus


Department of Applied Zoology, University College of North Wales, Bangor, Gwynedd LL57 2UW.


Abstract. 1. In laboratory nests the ants thoroughly licked leaf fragments by a rasping action of their glossa before inoculating the food fungus. The extent of this licking varied with the substrate and was influenced by the thickness of surface leaf waxes and by the chemical attractiveness of the substrate.

2. Microscopy and wettability studies showed that licking removes the wax layer present on leaves. It also removes or inhibits micro-organisms present.

3. Chemically de-waxed and decontaminated leaves and ant-licked leaves proved the best substrates for artificially culturing the ant fungus.

4. The process of substrate preparation circumvents some of the normal defence mechanisms of green plants against fungal attack. The ant fungus thus utilizes nutritionally richer resources of green leaves normally available only to specialized parasitic fungi, rather than the nutritionally inferior shed leaves normally available to saprophytic fungi.