Effect of juvenoid hormone methyl farnesoate on the sex ratio of daphnia magna after a short time (4 days)‎ of exposure

الملخص EN

The water flea Daphnia magna is a prototypical organism for ecotoxicological studies.

D.

magna reproduces primarily by cyclic parthenogenesis and the population consists mostly of females.

However, various stimuli and changes in environmental conditions induce the switch into the sexual reproduction and, under these situations, daphnids produce more males.

One of the chemicals known to modulate sex ratio in D.

magna is methyl farnesoate (model crustacean juvenoid hormone) that has been shown to affect sex ratio in chronic (21 days) as well as short term (6-10 days) assays.

In the present study, it was demonstrated that sex ratio of neonate Daphnia can be modulated even after short exposure to methyl farnesoate.

Using a specific experimental design by exposure of eggs and embryos during the whole 4 days development cycle in maternal daphnids 0.1 mg / L of methyl farnesoate, a significant increase in the sex ratio of newborn daphnids was observed.

It has been proposed that the bioassay based on determination of sex ratio with D.

magna can successfully be used as a rapid tool for studies of endocrine disruptive compounds mimicking (or antagonizing) effects of juvenile hormones.