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Comparative studies were performed to evaluate composting potential, biomass growth and biology of a non-native (Eisenia fetida) and an endemic (Lampito mauritii) species of earthworm in the semiarid environment of Jodhpur district of Rajasthan in India. Earthworms were reared in a mixed bedding material comprised of biogas slurry, cowdung, wheat straw, leaflitter, sawdust and kitchen waste. The percentage of organic carbon of the culture bedding material declined upto 105 days with E. fetida and 120 with L. mauritii. The percentage of nitrogen, phosphorous and potassium increased as a function of the vermicomposting period. In contrast, C/N and C/P ratios decreased day by day. Both species were effective for decomposition and mineralization of mixed bedding in the semiarid environment. A comparative assessment of biomass growth of E. fetida and L. mauritii was done under controlled laboratory conditions. The optimum temperature, moisture content and pH for E fetida were 25 degreesC, 70% and 6.5, respectively. However, the optimum temperature, moisture content and pH for growth and development of L. mauritii were 30 degreesC, 60% and 7.5, respectively. The biology and reproductive rates of both species were also studied in the laboratory using mixed bedding. Cocoon production was higher for E fetida than L. mauritii. The net reproductive rate was 9 per month in the case of E. fetida and 1 per month for L. mauritii. Fertilized eggs of E. fetida and L. mauritii developed into adults within 4 and 5(1)/(4) months, respectively. These observations indicate E. fetida may be a more efficient breeder than L. mauritii in the desert region of Rajasthan. (C) 2003 Elsevier Ltd. All rights reserved.