Growth and reproduction of Perionyx excavatus (Perr.) (Megascolecidae) as factors in organic waste management

The life cycle of Perionyx excavatus has been studied and the potential of this epigeic earthworm species for breaking down and processing organic wastes is well known. Understanding of its optimal environmental requirements is required in order to optimize and accelerate the vermicomposting process. The rates of growth and reproduction of P. excavatus, on a variety of organic wastes, were evaluated in these experiments. The time of maturation and the rates of growth of this species, under various population density pressures and temperatures between 15 degrees C and 30 degrees C, were also assessed. Increasing temperatures up to 30 degrees C accelerated the growth of earthworms and lessened the time to sexual maturity. However, the highest rates of reproduction occurred at 25 degrees C both in cattle solids and sewage sludge. The mean time to egg hatching decreased and the degree of hatching success increased with increasing temperature. Earthworms grew at similar rates in cattle solids, pig solids and aerobically digested sewage sludge, but the earthworms did not grow well in horse solids and grew only poorly in turkey wastes. The maximum individual growth rates as a function of earthworm population and the maximum earthworm weights as a function of time with a constant food supply at four different temperatures were assessed.