SELECTIVE CONSUMPTION OF DECOMPOSING WHEAT-STRAW BY EARTHWORMS

Three species of earthworm, Lumbricus terrestris L., Aporrectodea longa (Ude) and Allolobophora chlorotica (Savigny), were offered a choice of mixtures of soil and small wheat straw fragments which had been inoculated individually with six saprotrophic fungi. All earthworm species showed preferences between the six fungal species offered. Early straw decomposers, capable of utilizing water-soluble sugars and cellulose, were preferred in most cases to the lignin-decomposing fungi characteristic of the later stages of decomposition. The removal of fungal-inoculated straw pieces from the soil surface by L. terrestris followed the same pattern. The palatability of two wheat pathogens to L. terrestris was found to be similar to that of the preferred saprotroph. The implications of these findings for fungal abundance and dispersal in wheat fields are discussed.