Surface properties of the mushroom Strobilurus ohshimae result in food differentiation by collembolan species

The basidiomycete Strobilurus ohshimae has fruiting bodies covered with prominently projecting hair-like cells called cystidia; it is not consumed by the collembolan Ceratophysella denisana but is consumed by Mitchellania pilosa. To explain this difference, we examined the effects of S. ohshimae cystidia on collembolan survival. In the field, several collembolan species, including C. denisana, were found dead on S. ohshimae, whereas no dead M. pilosa were found on the fungus. Survival of M. pilosa on S. ohshimae was 100%. In the laboratory, cystidium destruction experiments showed that the cystidia of S. ohshimae were capable of killing C. denisana on contact. A cystidium contact time experiment revealed that the cystidia were also capable of killing M. pilosa, although M. pilosa could survive when the contact time was short. In the field, M. pilosa frequently fed on the interior of S. ohshimae. Interior feeding may enable M. pilosa to feed on S. ohshimae by reducing contact time with the cystidia. The deadly surface of S. ohshimae deters the surface feeder C. denisana but not the interior feeder M. pilosa, resulting in food differentiation of these collembolans.