Functional relationships between Collembola and plant pathogenic fungi of agricultural soils

The interactions between the collembolan Mesaphorura krausbaueri and four s oilborne plant pathogenic fungi all living in the same layer of agricultura l soil were studied under laboratory conditions. Mycelia of Gaeumannomyces graminis var. tritici, Fusarium culmorum and Rhizoctonia cerealis were pala table to Collembola and were a food source adequate for reproduction. Hypha e of Bipolaris sorokiniana were toxic and repellent for M. krausbaueri, but its conidia were eaten and proved to be a sufficient diet for reproduction . The four fungi fed had a different impact on the life processes of M. kra usbaueri. Depending on the species of fungus, the animals produced signific antly different numbers of eggs and had different life spans. In particular , animals fed with G. graminis var. tritici showed early maturation, early burst in egg production, early loss of fertility and early death. The diffe rent nutritional values of the four fungi pathogen for cereals might have a different influence on the life strategy of Collembola in the field. Thus, since these fungi usually coexist in agricultural soils, though in differe nt percentages, this influence might also affect the capacity of different fungi to attack the plant and thus modulate the appearance of disease.