Effect of coffee residues on growth and reproduction of Hyperiodrilus africanus (Oligochaeta, Eudrilidae) in Ivory Coast

Hyperiodrilus africanus (Beddard) is a 12-cm to 16-cm-long earthworm, which is widely distributed in West and Central Africa. It lives in the upper 10-20 cm of the soil, and feeds on a mixture of soil and above-ground litter. Cocoons obtained in the laboratory hatched on average 17 days after deposition and produced two juveniles on average. Paired individuals fed soil amended with 2% coffee residues grew significantly (P<0.05) faster than those in the control soil. Daily individual weight increments were respectively 6.1 mg worm(-1) day(-1) and 1.0 mg worm(-1) day(-1) in supplemented and control soil. The generation time was short, and cocoon production reached 9.6 month(-1) (i.e. 115 cocoons adult(-1) year(-1)). When H. africanus collected from the field were raised in the laboratory, they grew slowly, laid fewer cocoons and mortality was high. Demographic parameters indicated an improvement when H. africanus were raised in batches rather than individually. Mating enhanced cocoon production although parthenogenesis was possible.