title: Effects of dietary exposure to the pyrethroid pesticide esfenvalerate on medaka (Oryzias latipes).
abstract: The pyrethroid insecticide esfenvalerate is widely used on orchard crops throughout California. In the aquatic environment, this compound is likely to accumulate in sediments, food particles and benthic organisms due to its lipophilicity and environmental persistence. This pilot project tested the hypothesis that esfenvalerate is toxic to medaka (Oryzias latipes) when taken up with the diet. For 7 days fish were fed diets, which contained esfenvalerate in three different concentrations (4, 21, 148 mg/kg, measured). Endpoints measured were mortality, fecundity, fertilization and hatching success of embryos, viability of larvae and cellular stress protein (hsp60, hsp70, hsp90) levels. The toxicity of aqueous exposure of medaka to esfenvalerate was also determined. Whereas the 96-h LC50 in the aqueous exposure was <9.4 microg/l, the dietary exposure did not cause mortality. Possible effects of dietary esfenvalerate were seen on fertilization and hatching success and the number of non-viable larvae. Expression of hsp60 and hsp90 showed a dose-dependent response pattern.
authors.affiliation: Sehool of Veterinary Medicine, Department of Anatomy, Physiology and Cell Biology, University of California, Davis 95616, USA. iwerner@ucdavis.edu
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Werner
authors.forename: Juergen
authors.initials: J
authors.lastname: Geist
authors.forename: Mark
authors.initials: M
authors.lastname: Okihiro
authors.forename: Philipp
authors.initials: P
authors.lastname: Rosenkranz
authors.forename: David E
authors.initials: DE
authors.lastname: Hinton
mesh_terms: D000821:Animal Feed; D000818:Animals; D004032:Diet; D005260:Female; D005298:Fertility / Q000187:drug effects*; D005306:Fertilization / Q000187:drug effects; D007306:Insecticides / Q000008:administration & dosage / Q000009:adverse effects*; D007928:Lethal Dose 50; D008297:Male; D009570:Nitriles; D009990:Oryzias / Q000502:physiology*; D011722:Pyrethrins / Q000008:administration & dosage / Q000009:adverse effects*; D014874:Water Pollutants, Chemical / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D014874:Water Pollutants, Chemical; C017690:fenvalerate