Moisture preferences, growth and reproduction of the African nightcrawler, Eudrilus eugeniae (Oligochaeta)

Abstract

As part of a comprehensive study of the biology of the economically important earthworm species Eudrilus eugeniae, the water relations of this species were studied. Moisture preferences were studied with the aid of cylindrical moisture towers filled with cattle manure. The cattle manure was dried, ground to a particle size of 500> <1000 (im and moistened. A moisture gradient was allowed to develop in the towers, the worms were added and the towers kept in an environmental control chamber at a temperature of 25°C and a relative humidity of 80%. The moisture preferences of both juvenile and adult worms were studied. The clitellate worms showed a wider preference range than the juveniles and the preference range of the juveniles coincided with the moisture levels at which cocoons were deposited. The highest frequency of occurrence for clitellate worms was between moisture levels of 80 and 82%. For cocoon deposition the highest frequency was at moisture levels between 79 and 80,5% and most juvenile worms showed a preference for a moisture range between 77,5 and 79%. The cocoons produced were incubated and the number of hatchlings per cocoon noted. The biggest number of offspring per cocoon hatched from cocoons originating from the moisture range of 79 to 80,5% coinciding with the highest frequency of cocoon deposition. From the results it appears that this earthworm species could be utilized in organic waste material with a relatively high moisture content.