MOISTURE REQUIREMENTS IN THE LIFE-CYCLE OF PERIONYX-EXCAVATUS (OLIGOCHAETA)

The moisture content of the substrate is generally considered to be the major abiotic factor that influences the growth and reproduction of earthworms. The moisture requirements of P. excavatus were studied in cattle manure (particle size 500-1000 mum) at 25-degrees-C by exposing the worms to different, but constant moisture levels. The results showed that the worms grew and reproduced best between moisture levels of 75.2 and 83.2%. The moisture preferences of both juvenile and clitellate specimens were determined at 25-degrees-C in undivided moisture towers filled with a cattle manure medium in which a moisture gradient had developed. It was clear from the results that juvenile and clitellate worms preferred a moisture content of ca 81%, although cocoon deposition by clitellate worms was highest at a somewhat lower moisture level of 78.5%. It can be concluded that moisture influences the growth and reproducton of P. excavatus and that the most favourable moisture content for both is ca 80%.