Influence of regulated temperature on growth and reproduction of the epigeic earthworm, Perionyx excavatus.

Abstract

To determine the influence of temperature on growth and reproduction, one week old juveniles of Perionyx excavatus were cultured in cattle manure for 16 weeks at controlled 25 degrees C, 30 degrees C, 35 degrees C, 37.5 degrees C, 40 degrees C (with prevailing corresponding per cent relative humidity (%RH) of 88.9, 78.2, 76.3, 73.2, 64.6) and natural environmental conditions (22.7-27.3 degrees C and 48.0-77.6% RH). Worms did not survive at 40 degrees C. Weight of the worms in controlled and uncontrolled temperatures increased gradually upto the end of 16th week without significant variations: However, growth tate was significantly (P < 0.01) affected by temperature. Enhanced growth, biomass and reproduction were observed :at 30 degrees C followed by natural environmental conditions and at 25 degrees C. At 35 degrees C, there were enhanced growth and biomass, but reproduction was retarded. All life processes of the worm were retarded at 37.5 degrees C. The close; resemblance of growth and reproduction between 30 degrees C and natural environmental conditions may be attributed to exposure Of worms to the range of temperature near thermal optima of 27.3 degrees C.