Secondary chemicals protect mould from fungivory

Abstract

The vast repertoire of toxic fungal secondary metabolites has long been assumed to have an evolved protective role against fungivory. It still remains elusive, however, whether fungi contain these compounds as an anti-predator adaptation. We demonstrate that loss of secondary metabolites in the soil mould Aspergillus nidulans causes, under the attack of the fungivorous springtail Folsomia candida, a disadvantage to the fungus. Springtails exhibited a distinct preference for feeding on a mutant deleted for LaeA, a global regulator of Aspergillus secondary metabolites. Consumption of the mutant yielded a reproductive advantage to the arthropod but detrimental effects on fungal biomass compared with a wild-type fungus capable of producing the entire arsenal of secondary metabolites. Our results demonstrate that fungal secondary metabolites shape food choice behaviour, can affect population dynamics of fungivores, and suggest that fungivores may provide a selective force favouring secondary metabolites synthesis in fungi.

Figure 1

Egg-laying activity and survival of F. candida on WT and ΔlaeA A. nidulans. The curves illustrate springtail survival. Bars indicate mean number of eggs per F. candida individual (+s.e.).

Figure 2

Effect of fungivory on changes in biomass of WT and ΔlaeA A. nidulans. Data were obtained by subtracting the weight of single undisturbed control colonies from randomly assigned single colonies treated with springtails (see §2).