Author Institution: Department of Biology, State University of New York at Fredoni

Bimber, David L.

Mitchell, Robert A.

The Ohio Journal of Science

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50 ISADORE NEWMAN ET AL Vol. 78BRIEF NOTEEFFECTS OF DIQUAT ON AMPHIBIAN EMBRYO DEVELOPMENT1DAVID L. BIMBER and ROBERT A. MITCHELL, Department of Biology, State Universityof New York at Fredonia, Fredonia, NY 14063OHIO J. SCI. 78(1): 50, 1978Diqua t (1 :l'-ethylene-2:2'~dipyridy-lium dibromide) has been extensively ap-plied to aquatic communities with littleconsideration of its toxicity to the aquaticfauna (Bimber et al 1976; May et al 1973;Nicholson and Clerman 1974). In a pre-liminary series of experiments, we haveevaluated the possible influence of theherbicide on the development of the eggsof Rana pipiens. The initial concentra-tion of 100 ppm was chosen so that anyembryological pathology would be obvi-ous to the observer. Field applicationconcentrations of 1-5 ppm are normallyused during aquatic weed control efforts,but local concentrations may significantlyexceed the recommended dosages.Females of at least 74 mm body lengthand males of at least 70 mm body lengthwere used to insure that proper repro-ductive age criteria had been met. Ovu-lation was induced utilizing methods de-veloped by Wright and Flathers (1961).Approximately 1200 eggs were dividedinto the 4 groups indicated in table 1.Fertilization was performed as describedby Rugh (1962), except when 100 ppmDiquat was added to a portion of the'-Manuscript received February 9, 1977 and inrevised form as a note April 28, 1977 (#77-16).sperm suspensions. Static bioassays wereconducted at 18°C under subdued light-ing conditions in an environmental cham-ber. A ratio of 25 eggs/liter of test solu-tion was used during the incubationperiod and the incubation media werechanged daily. Tests were terminatedafter 21 days. During the experiments,dead specimens were removed and de-jellied (if necessary) in 5% chlorox priorto staging (Shumway 1940).All groups showed reduced viabilitywhich we attributed to inducing ovulationin January and February of the year(Wright 1945; Wright and Flathers 1961).Fertilization efficiency was somewhat re-duced when Diquat was added to thesperm suspensions but not to a statisti-cally significant level (table 1). Littledifference was observed in the survivor-ship of the test subjects and controlsprior to hatching (approx. 7 days). How-ever, none of the tadpoles subjected toDiquat, either during fertilization orlater development, survived beyond 14days after hatching. The frequency ofexogastrulation appeared to be elevatedin both groups incubated in Diquat dur-ing development. Our data indicate thatalthough the eggs of R. pipiens were rela-Ohio J. Sci.ControlsNF/DQ*DF/Norm**DF/DQtCANINESurvival of frogSampleSize18219681108DIROFILARIASIS IN OHIOTABLE 1embryos exposed to Diquat (100 ppm)% Survival to Each Developmental StageMorula54474144Gastrula Hatch29 930 833 323 614 DaysPost-hatch7000Exogastrula tion5115751*NF/DQ = Normal fertilization, Diquat present throughout development.**DF/Norm = Diquat present during fertilization only.fDF/DQ = Diquat present during fertilization and development.tively insensitive to the Diquat concen-tration (100 ppm) used in this study, in-creased rates of exogastrulation and mor-tality may occur. The mechanism ofthis toxicity/teratogenesis is currently un-known and should be the object of futureinvestigation.Acknowledgments. Partial support for thisproject was provided by the EnvironmentalResources Center, SUNY at Fredonia, Fre-donia, New York 14063.LITERATURE CITEDBimber, D. L., R. W. Boenig and M. L. Sharma1976 Respiratory stress in yellow perch in-duced by subtoxic concentrations of Diquat.Ohio J. Sci. 76: 87-90.May, B. E., R. S. Hestand and J. M. Van Dyke1973 Comparative effects of Diquat pluscopper sulfate on aquatic organisms. WeedSci. 21: 249-253.Nicholson, S. A. and R. J. Clerman 1974Toxicity of Diquat to the crustacean am-phipod Hyalella from Chautauqua Lake.Environ. Lett. 7: 215-227.Rugh, R. 1962 Experimental Embryology.Burgess Publishing Co., Minn. 500 p.Shumway, W. 1940 Stages in the normal de-velopment of Rana pipiens. Anat. Rec. 78:139-147.Wright, P. A. 1945 Factors affecting in vitroovulation in the frog. J. Exp. Zool. 100:565-75.and A. Flathers 1961 Facilitation ofpituitary-induced frog ovulation by pro-gesterone in early fall. Proc. Soc. Exp.Biol. Med. 1: 346-7.

Brief Note  Effects of Diquat on Amphibian Embryo Development

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Brief Note Effects of Diquat on Amphibian Embryo Development

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