Trophic interactions of soil fungi and Collembola

Results of our studies on interactions between different species of soil fungi and collembola in vitro, and in planta are summarised. The feeding preference of collembolan Protaphorura armata, Mesaphorura krausbaueri, Onychiurus tuberculatus, and Folsomia candida were investigated in Petri dishes, each containing contemporaneously Fusarium culmorum (Fc), Gaeumannomyces graminis var. tritici (Ggt), Bipolaris sorokiniana (Bs) and Rhizotonia cerealis (Rc) colonies. In some experiments Bs was replaced by Trichoderma harzianum (Th). All springtails grazed preferably on the mycelium of Fc, but Ggt and Rc hyphae were also consumed. Bs mycelium had repellent and/or lethal effect on animals, Th mycelium was repellent, whereas conidia of both fungi were palatable. A diet based on Fc, Ggt, and Rc mycelium or Bs conidia showed different impact on the life processes of M. krausbaueri. The fate of conidia during gut passage was also considered. The majority of Th conidia were not damaged during transit through the gut, and thus they were viable and formed colonies. On the contrary, transit through gut damaged the conidia of Fc. In planta studies have shown that P. armata significantly controlled disease caused by Fc or Ggt on wheat seedlings. The compatibility between Th and springtails in presence of Ggt was also investigated in in planta assays. It has been observed that when Th propagules coated wheat seeds, springtails showed biocontrol effect against Ggt disease. On the contrary, when Th inoculum was mixed with the substrate of plant growth, the animals were not able to control disease severity. In all experiments the biomass of wheat plants was not reduced by springtails.