Effect of plant extracts on the production of Daphnia pulex (Cladocera : Daphnidae) under laboratory conditions

We tested the enriching effect of radish leaf (Raphanus sativus) and spinac h leaf (Spinacea oleracea) extracts when added separately to the fermented wheat bran (Triticum aestivum) for producing Daphnia pulex. The experiments were conducted in 20 l glass bottles containing 14 1 of dechorinated tap w ater. The initial inoculation density was 200 organisms/bottle. The culture s were allowed to grow for 21 days; during this time the controls received only the fermented wheat bran (Triticum aestivum), while the test container s received either extract of radish leaf (Raphanus sativus) or that of spin ach leaf (Spinacea oleracea), in addition to ferment wheat bran (Triticum a estivum). We also measured some physico-chemical variables of the medium du ring the experimental period. These are: water temperature, dissolved oxyge n, pH, conductivity, alkalinity and total hardness. These variables remaine d more or less the same in all test bottles reflecting non-significant vari ations. After the test period, the net production of D. pulex in terms of n umbers was: 1 722 organisms/bottle in the controls while that receiving rad ish leaf (Raphanus sativus) extract with 7 997 organisms/bottle and that wi th spinach leaf (Spinacea oleracea) extract with 8 921 organisms/bottle. Te st of analysis of variance showed significant differences among the culture s (Fisher p< 0.005). This study showed that the enrichment of fermented whe at bran (Triticum aestivum) with spinach (Spinacea oleracea) extract was a better nourishing source of food for culturing Daphnia pulex under laborato ry conditions.