Cocoon production, morphology, hatching pattern and fecundity in seven tropical earthworm species - a...

Data on the reproductive biology of seven Indian species of earthworms, viz. Perionyx excavatus Perrier, Lampito mauritii Kinberg, Polypheretima elongata (Perrier), Pontoscolex corethrurus (Muller), Eutyphoeus gammiei (Beddard), Dichogaster modiglianii (Rosa) and Drawida nepalensis Michaelsen are presented. The peregrine earthworms such as Perionyx excavatus, Pontoscolex corethrurus, Dichogaster modiglianii, and Polypheretima elongata are considered to be continuous breeders with high fecundity. Native Lampito mauritii and Drawida nepalensis are semi-continuous and Eutyphoeus gammiei discrete breeders. There is a dramatic increase in cocoon production by most earthworm species of Tripura in the summer and monsoon with a corresponding peak during April and July. Cocoon production decreased or ceased during winter. Temperature affected the incubation period of cocoons. With increase in temperature, incubation period increased in the endogeic worms, Pontoscolex corethrurus, Polypheretima elongata and Drawida nepalensis and decreased in the epigeic worms, Perionyx excavatus and Dichogaster modiglianii, within a temperature range between 28-32 degrees C under laboratory conditions. There was a significant (P < 0.05) positive correlation between number of hatchlings per cocoon and incubation period in Lampito mauritii. High rate of cocoon production, short development time with high hatching success, as well as continuous breeding strategies in the epigeic species Perionyx excavatus and Dichogaster modiglianii and the top soil endogeic species, Pontoscolex corethrurus, Drawida nepalensis and Lampito mauritii, indicate their possible usefulness in vermiculture. The giant anecic worm, Eutyphoeus gammiei, which has a very long cocoon development time, discrete breeding strategy and very low rate of cocoon production, is not a suitable species for vermiculture.