title: Effects of deltamethrin (pyrethroid insecticide) on growth, reproduction, embryonic development and sex differentiation in two strains of Daphnia magna (Crustacea, Cladocera).
abstract: Acute and different chronic ecotoxic effects of deltamethrin have been investigated on two strains (coming from two different laboratories) of Daphnia magna. The effective concentrations immobilizing 50% of daphnids (EC50s) after 24 h and 48 h were 9.40 and 0.32 μg L(-1), 8.86 and 0.63 μg L(-1) for first strain (strain 1) and second strain (strain 2), respectively. Thus, there was an increase of deltamethrin ecotoxicity with time of exposure as confirmed by chronic studies. After 21 days of exposure to deltamethrin, daphnids have showed significant effects on survival at deltamethrin concentrations of 0.16 μg L(-1) and 0.31 μg L(-1) for strains 1 and 2, respectively. Eleven other endpoints were examined: body length, population growth rate and various reproductive parameters (days to first brood, number of broods, number of cumulative molts and number of neonates), embryotoxicity and appearance of males. IC10 values related to the number of juveniles per live adult were 11 and 46 ng L(-1) for strains 1 and 2, respectively. Furthermore, an increase in embryo deformities was observed at the highest concentrations tested for both strains. Following deltamethrin exposure, undeveloped second antennae, curved or unextended shell spines, and curved post abdomen spines were observed in live neonates. The production of male juveniles was only registered with strain 1 at 0.16 μg L(-1). Results suggest that deltamethrin could act as an endocrine disruptor in D. magna as it interferes with sex determination and development abnormality but there is a difference in sensitivity between the two tested strains.
authors: Laboratoire de Bio-surveillance de l'Environnement, Unité d'Hydrobiologie littorale et limnique, Université de Carthage, Faculté des Sciences de Bizerte, 7021 Zarzouna, Bizerte, Tunisie.
authors: H
authors: H
authors: Toumi
authors: M
authors: M
authors: Boumaiza
authors: M
authors: M
authors: Millet
authors: C M
authors: CM
authors: Radetski
authors: V
authors: V
authors: Felten
authors: C
authors: C
authors: Fouque
authors: J F
authors: JF
authors: Férard
mesh_terms: D000818:Animals; D049628:Body Size / Q000187:drug effects; D003621:Daphnia / Q000187:drug effects* / Q000254:growth & development*; D047108:Embryonic Development / Q000187:drug effects*; D005260:Female; D020128:Inhibitory Concentration 50; D007306:Insecticides / Q000633:toxicity*; D008297:Male; D009570:Nitriles / Q000633:toxicity*; D011722:Pyrethrins / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects; D012733:Sex Differentiation / Q000187:drug effects*; D012744:Sex Ratio; D013045:Species Specificity; D016019:Survival Analysis; D013997:Time Factors
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin