Effects of thiophanate-methyl and glyphosate on asexual and sexual reproduction in the rotifer Brachionus calyciflorus Pallas
Xi, Y.-L.; Feng, L.-K.
Bulletin of Environmental Contamination and Toxicology 73(4): 644-651
ISSN/ISBN: 0007-4861 PMID: 15389328 DOI: 10.1007/s00128-004-0475-0
An experiment was conducted to study the effects of different rates of thiophanate-methyl (0.05, 0.1, 0.2 and 0.4 mg/litre) and glyphosate (2.0, 4.0, 6.0 and 8.0 mg/litre) on the asexual and sexual reproduction of the freshwater rotifer B. calyciflorus. Based on the 24-h acute toxicology assays for thiophanate-methyl and glyphosate, the LC50 values of B. calyciflorus were 5.02 and 28.0 mg/litre, respectively. Compared to the control, 0.05, 0.1 and 0.2 mg thiophanate-methyl did not significantly influence the population growth rate, however, 0.4 mg thiophanate-methyl/litre significantly decreased the population growth rate. The population growth rates were significantly larger than the control when treated with 4.0, 6.0 and 8.0 mg glyphosate/litre. On the other hand, 2.0 mg glyphosate/litre did not significantly affect the population growth rate. Both the mictic rate and the resting egg production in the rotifer population were not significantly affected at 0.05 mg thiophanate-methyl/litre. When the toxicant concentration was higher than 0.05 mg/litre, no mictic females appeared, and no resting eggs were produced. Compared with thiophanate-methyl, 2.0-8.0 mg glyphosate/litre significantly increased the mictic rate and the resting egg production in the rotifer population.