Colonization of nonmycorrhizal plants by mycorrhizal neighbours as influenced by the collembolan, Folsomia candida

Soil microarthropods have been shown to stimulate or be detrimental to arbuscular mycorrhizal function by their grazing actions, but their role as dispersal agents has not been assessed. The ability of three species of arbuscular mycorrhizal (AM) fungi (Glomus etunicatum, Acaulespora denticulata, Scutellospora calospora) infecting Plantago lanceolata roots to further colonize neighbouring plants was measured in response to the distance between root systems and the presence of the collembolan, Folsomia candida. In the absence of collembola, all three fungal species infected neighbouring plants in two weeks or less (at short distances), but were not successful when neighbouring plants were placed 45 cm away or further. Colonization by G. etunicatum was the quickest at short distances, but S. calospora showed greatest ability to colonize at increasing distance,whereas A. denticulata was intermediate. In the presence of the collembolan, G. etunicatum took longer to colonize neighbouring plants, but was able to infect at least 30 cm further, illustrating the arthropod's ability to disperse the AM inoculum. A. denticulata increased its range by 10 cm in the presence of F. candida, but unlike C. etunicatum, there was no delay in the colonization. In contrast, colonization of neighbouring plants by S. calospora was negatively affected both in terms of overall distance and time. These data support the hypothesis that soil arthropods can act as dispersal agents for AM inoculum, but the extent of this is fungal species-specific.