Breakdown of mineral grains by earthworms and beetle larvae

Feeding experiments were conducted quantitatively to examine the breakdown of mineral grains by earthworm, Eisenia feida, and larva of beetle, Protaetia lugubris insperata. Crushed and sieved test minerals of K-feldspar and/or quartz were mixed with artificial humus that contained no mineral grains. The mixture was fed to the soil animals in the plastic containers. After 1-, 4- and 7-day experimental durations, the ingested mineral grains were collected from the casts excreted by the soil animals in each container. Even 1 day after feeding of mineral grains, the casts of soil animals contained finer, rounded mineral grains that were not included in the initial prepared mineral samples.