title: Behavioral and sex ratio modification of Japanese medaka (Oryzias latipes) in response to environmentally relevant mixtures of three pesticides.
abstract: We exposed Japanese medaka (Oryzias latipes) to environmentally relevant concentrations of azinphos-methyl, chlorothalonil, endosulfan, and mixtures of all three to determine if combinations of these pesticides result in additive, less-than-additive, or more-than-additive effects. Medaka were exposed from fertilization until 7 days posthatching, and end points included survival, time to hatch, size at 7 days posthatching, activity level (as measured by distance swam) and foraging ability at 3 weeks posthatching, and adult size, liver size, and sex ratio at 5 months posthatching. Although exposure to individual pesticides or pesticide mixtures did not affect survival, hatching time, or foraging ability, fry exposed to azinphos-methyl were significantly smaller at 1 week of age, and those exposed to chlorothalonil and a combination of the chemicals showed reduced activity. Adult sex ratios were biased toward females in all groups exposed to pesticides, with those exposed to azinphos-methyl, chlorothalonil, and the pesticide mixture departing significantly from an even sex ratio. There was no evidence of additive or synergistic effects of pesticide mixtures.
authors.affiliation: Department of Biology, University of Prince Edward Island, Charlottetown, PEI, Canada C1A 4P3. kteather@upei.ca
authors.forename: Kevin
authors.initials: K
authors.lastname: Teather
authors.forename: Carrie
authors.initials: C
authors.lastname: Jardine
authors.forename: Karen
authors.initials: K
authors.lastname: Gormley
mesh_terms: D000818:Animals; D001387:Azinphosmethyl / Q000633:toxicity*; D049628:Body Size; D004347:Drug Interactions; D004726:Endosulfan / Q000633:toxicity*; D005247:Feeding Behavior; D005260:Female; D005659:Fungicides, Industrial / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D007814:Larva / Q000254:growth & development; D008297:Male; D009570:Nitriles / Q000633:toxicity*; D009990:Oryzias / Q000502:physiology*; D012744:Sex Ratio; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D005659:Fungicides, Industrial; D007306:Insecticides; D009570:Nitriles; D014874:Water Pollutants, Chemical; D001387:Azinphosmethyl; C005806:tetrachloroisophthalonitrile; D004726:Endosulfan