Ecological consequences of arthropod grazing on VA mycorrhizal fungi

Abstract

SynopsisSoil Collembola may be partially responsible for observed reductions in effectiveness of vesicular-arbuscular mycorrhizal (VAM) associations in the field, compared with sterile soil experiments. Feeding damage to hyphae in soil is envisaged as a mechanism by which translocation of phosphorous from beyond root depletion zones to the plants is reduced. Previous work has demonstrated such effects in pots and in a cultivated field plot, and direct observation of feeding has been made. This paper briefly reviews this evidence and presents an experiment in which insecticide reduced the density of Collembola in a seminatural grassland soil, and increased phosphorus inflow into roots of Holcus lanatus. In addition, survey data are reported which show that hyphal grazing is ecologically feasible, as Collembola and infected roots are spatially associated with one another in the soil profile. It is suggested that hyphal grazing by these arthropods has important consequences for VAM function in natural vegetation systems.