An investigation into the growth and reproduction of the earthworm Lumbricus terrestris L. under controlled environmental conditions

Butt, Kevin Richard (1990). An investigation into the growth and reproduction of the earthworm Lumbricus terrestris L. under controlled environmental conditions. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000dfcf

Abstract

Earthworm inoculation for soil amelioration has been shown to be valuable in a range of experiments. At present, inoculation on a large scale is limited by the supply of larger deep-burrowing species of earthworm. This work aimed to assess the feasibility of intensively producing deep-burrowing earthworms for soil amelioration projects. Lumbricus terrestris, whose behaviour is well documented, was chosen.

The scientific literature was used to identify points within the life cycle of this earthworm where manipulation of conditions might lead to increased rates of production. Feed quality, environmental temperature, time of year, population density and age of breeding stock were all recognised as important variables. Experiments were performed to identify the optimal conditions for L.terrestris reproduction, cocoon development and growth.

Results suggested that reproduction would occur throughout the year and mean annual figures of 37 cocoons per worm were recorded from intensively produced earthworms. Recently matured worms showed greatest levels of cocoon production. As previously reported seasonal variation in reproduction was found even at constant temperature. Cocoon development was most rapid at a temperature of 20°C, taking 70 days, with a cocoon viability of 83%. Growth from a mean hatchling weight of 53mg to sexual maturity at 5g, took twelve weeks. Growth at constant temperatures of 15 and 20°C was not significantly different.

A synthetic feed, with a carbon to nitrogen ratio of 40:1, created from paper waste and yeast extract, led to greatest recorded figures for both growth and cocoon production.

The results suggest that an intensive production system is technically feasible, and the economic viability needs to be tested.

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