Influence of Soil Temperature and Moisture on the Cocoon Production and Hatching of the Exotic Earthworm Pontoscolex corethrurus

Laboratory experiments with split—plot block design were conducted to examine the effects of soil temperature and moisture on cocoon production and hatching of the exotic earthworm Pontoscolex corethrurus under controlled conditions. Results showed that consecutive cocoon production and hatching took place at all three soil temperatures and at the two higher soil moisture conditions, used in this experiment. Cultivation time, soil moisture and temperature had significant effects on cocoon production and hatching of P. corethrurus. Earthworms suffered a diapause or even died when reared in soil with 20% moisture content. The greatest cocoon production and hatching rate were observed at 35% soil moisture content. When soil moisture was preferable (e.g. 35%), cocoon production was greater at higher temperatures than at lower temperatures. Hatching rate increased with soil temperature if the soil moisture content was preferable; however it was restrained if the temperature was too high or too low. The greatest hatching rate only occurred at a combination of 25°C soil temperature and 35% soil moisture content. The results also showed that soil moisture was the primary factor limiting the reproduction of P. corethrurus, the effects of soil temperature on earthworm reproduction was influenced by soil moisture.