Growth and cocoon production by the earthworm Metaphire houletti (Oligochaeta) in different food sources

 Quantitative observations on the biology of Metaphire houletti were made in cow and horse manure and oak litter in laboratory conditions over a period of 240 days. The study revealed that copulation is not a prerequisite for production of viable cocoons, indicating that M. houletti may be parthenogenetic. The mean growth rate was 2.86 mg worm^–1 day^–1 reaching sexual maturity at 45 days and producing 0.015 cocoons worm^–1 day^–1 (kept singly) and 2.82 mg worm^–1 day^–1, reaching sexual maturity at 45 days and producing 0.03 cocoons worm^–1 day^–1 (kept in batches) in cow manure; 4.08 mg worm^–1 day^–1, reaching sexual maturity at 46 days and producing 0.02 cocoons worm^–1 day^–1 (kept singly) and 2.97 mg worm^–1 day^–1, reaching sexual maturity at 45 days and producing 0.016 cocoons worm^–1 day^–1 (kept in batches) in horse manure; 3.73 mg worm^–1 day^–1 reaching sexual maturity at 45 day and producing 0.023 cocoons worm^–1 day^–1 (kept singly) and 2.73 mg worm^–1 day^–1, reaching sexual maturity at 47 days and producing 0.028 cocoons worm^–1 day^–1 (kept in batches) in oak litter. After an incubation period of 31.9±1.2 days 82% of the cocoons hatched with a mean of 1.12±0.06 hatchlings per cocoon. The earthworms reared in batches did not demonstrate any advantage over those reared singly in all substrates. Higher growth rates were observed in earthworms raised singly than those raised in batches in all substrates. Received: 30 April 1998